CN1128550C - NTSC interference detectors using comb filters that suppress DTV pilot carrier to extract NTSC artifacts - Google Patents

NTSC interference detectors using comb filters that suppress DTV pilot carrier to extract NTSC artifacts Download PDF

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CN1128550C
CN1128550C CN98119617A CN98119617A CN1128550C CN 1128550 C CN1128550 C CN 1128550C CN 98119617 A CN98119617 A CN 98119617A CN 98119617 A CN98119617 A CN 98119617A CN 1128550 C CN1128550 C CN 1128550C
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signal
comb filter
digital television
ntsc
symbol
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CN1212581A (en
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艾伦·L·林伯格
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Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0064—Concatenated codes
    • H04L1/0065—Serial concatenated codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/015—High-definition television systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03114—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
    • H04L25/03133—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals with a non-recursive structure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/21—Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
    • H04N5/211—Ghost signal cancellation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03375—Passband transmission
    • H04L2025/03382—Single of vestigal sideband
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/41—Structure of client; Structure of client peripherals
    • H04N21/426—Internal components of the client ; Characteristics thereof

Abstract

A co-channel interference detector of digital TV receiver includes a 1st comb filler generated of the 1st filter in which the artifact signal is suppressed; a 2nd comb filler generated of the 2nd filter in which the artifact signal is intensified; the DC item of the 1st filter response is similar to the 2nd response; the 1st and the 2nd amplitude detector detect separately filter response, the amplitude comparator compare amplitude detecting response, and only when the amplitude detecting response difference exceed a regulated value, it is indicated that the co-channel interference intensity is too large to be used.

Description

Digital television signal receiver
Technical field
The present invention relates to digital television system, relate in particular to the cochannel interference search gear that is used for determining whether to exist the cochannel interference that in digital television receiver, adopts at the NTSC anolog TV signals.
The application is according to 35 U.S.C.111 (a), a complete application according to 35 U.S.C.119 (e) (1) submission, it has continued to use the Application No. of submitting on September 19th, 1998 is 08/933,394 the applying date, this application was converted into provisional application according to 35 U.S.C.111 (b) afterwards.
Background technology
The digital television standard of being published by advanced television system committee (ATSC) September 16 nineteen ninety-five has been stipulated residual sideband (VSB) signal of transmitting digital TV in the television channel of 6MHz bandwidth (DTV) signal.The DTV signal transmits with a certain very high frequency(VHF) transmission channel that adopts at present in the air broadcast of NTSC (NTSC) anolog TV signals.VSB DTV signal is designed to make its frequency spectrum just to disturb the frequency spectrum of NTSC anolog TV signals to interweave with a cochannel.The symbol frequency of this DTV signal is 3 times of NTSC colourity wavelet frequency, and 3.58Mhz wavelet frequency is 455/2 times of NTSC horizontal scanning line rate.The pilot frequency carrier wave of this DTV signal and homophony width of cloth residual sideband frequency localization are on the odd-multiple of 1/4th horizontal scanning line rates of NTSC anolog TV signals, this makes these DTV signal components drop between the even-multiple of 1/4th horizontal scanning line rates of NTSC anolog TV signals, and cochannel disturbs the brightness of NTSC anolog TV signals and most of energy of chromatic component to reduce on even-multiple.The video carrier of NTSC anolog TV signals is by the lower frequency limit of distance television channel skew 1.25MHz.The carrier wave of DTV signal is apart from the horizontal scanning line rate of the NTSC anolog TV signals of 59.75 times of this video carrier skews, and about 309 with the lower frequency limit of distance television channel, 877.6kHz is provided with the carrier wave of this DTV signal.Correspondingly, the carrier wave of this DTV signal is about 2,690 apart from the intermediate frequency of television channel, 122.4Hz.
In the digital television standard really and symbol (symbol) rate be 4.5MHz sound carrier of the video carrier skew (684/286) times in the NTSC anolog TV signals.The symbolic number of each the bar horizontal scanning line in the NTSC anolog TV signals is 684,286th, and the factor of the horizontal scanning line rate in the multiplication NTSC anolog TV signals is to obtain being offset the 4.5MHz sound carrier of the video carrier in the NTSC anolog TV signals.Symbol rate is per second 10.762238 million symbols, and this can obtain the VSB signal that is extended to 5.381119MHz from the DTV signal carrier.That is, the VSB signal can be limited in being extended to from the lower frequency limit of television channel the frequency band of 5.690997Mhz.
Can transmit any in high definition TV (HDTV) form of two kinds of 16: 9 formula ratios in the ATSC standard of U.S. DTV signal terrestrial broadcasting.A kind of HDTV display format adopts 1920 sampled points of every scan line, 2: 1 1080 the level of significance scan lines of every 30Hz frame down that interweave.Another kind of HDTV display format adopts the scan line of 1280 luma samples points of every scan line, 720 progression scannings of every 60Hz frame.The ATSC standard also provides the transmission of DTV display format rather than HDTV display format, such as the parallel transmission of comparing four kinds of TV signal with normal definition with the NTSC anolog TV signals.
In the terrestrial broadcasting of the U.S., the DTV that transmits by residual sideband (VSB) amplitude modulation (AF) comprises the data field that a sequence time is continuous, and each data field comprises 313 continuous data segments of time.Data field can be thought the mould 2 of serial number, and each is numbered the data field of odd number and the data field that is numbered even number of back is formed a Frame.Frame per second is 20.66 frame per seconds.Each data segment has the delay of 77.3 microseconds.So each data segment has 832 symbols when symbol rate is 10.76MHz.Each data segment with the having of 4 symbols+S ,-S ,-S and+data segment sync (DSS) code-group of S successive value begins.Value+S be in maximum positive according to the following one-level of skew, value-S is the one-level more than maximum negative data is offset.The primary data section of each data field comprises synchronous (DFS) code-group of the data field of a training to the process of inhibition of channel equalization and multipath (training) signal encoding.Training signal is the pseudo noise sequence (or " PN sequence ") of 511 sampled points, follows the PN sequence of 3 63 sampled points thereafter.The intermediate point of the PN sequence of 63 sampled points is conveyed into first row of each data field that is numbered odd number in the DFS code-group according to one first logic convention, be conveyed into first of each data field that is numbered even number according to one second logic convention and go, the first and second logic conventions are complementary to each other.
Data in the data line are to adopt the trellis coding of the 12 trellis sign indicating numbers that interweave, and each 2/3 rate trellis sign indicating number has a not bits of coded that is encoded in advance.The trellis sign indicating number that interweaves carries out error correction coding through Read-Solomon, and it provides the burst error that is produced by the noise source correction of (as near unscreened automotive ignition system).The Reed Solomon Coding result is used as airborne 8 grades (3 bit/symbol) one dimension constellation symbol coding transmission.The Reed Solomon Coding result is used as 16 grades of (4/symbol) one dimension constellation symbol coding transmission of wired broadcasting, and this symbol that is transmitted in produces the back without any precoding.The intrinsic carrier wave of VSB signal is suppressed, and the percentage of modulation is depended in the variation of its amplitude.
The be fixed pilot signal ripple of amplitude of intrinsic carrier wave replaces, and this amplitude is corresponding with the percent modulation of regulation.By introducing the pilot signal ripple that a DC component displacement (shift) produces this fixed amplitude to modulation voltage, this modulation voltage offers the balanced modulator that produces amplitude-modulation sideband, and this amplitude-modulation sideband is input to provides the filter of VSB signal to respond as it.If 8 grades of 4 bit signs coding have standardization (normalized) value-7 in carrier (boc) modulated signals ,-5 ,-3 ,-1 ,+1 ,+3 ,+5 and+7, then pilot signal has a standardized value 1.25.The standardized value of+S is+5, and the standardized value of-S is-5.
In the early stage research of DTV technology, imagination DTV speech amplifier should be required whether symbolization precoder in transmitter of decision.This symbol precoder should be followed after symbol produces circuit, and when being used in each DTV signal receiver with a comb filter, provides the symbol filtering of coupling.This comb filter is arranged in before the symbol decoder circuit data limiter of DTV signal receiver, as encoder behind the symbol.The interference that whether reckons with from cochannel NTSC broadcasting station is depended in this decision.The symbol precoding probably can not be used in the data segment that data segment sync code-group or data field synchrodata be transmitted therein.Cochannel disturbs in distance NTSC broadcasting station to be lowered and probably to satisfy under the condition of certain ionosphere at a distance and occurs, and the possibility that cochannel disturbs in the month in summer in strong year of solar activity is obviously big.If there is not cochannel NTSC broadcasting station certainly, this interference just can not occur.If in the possibility that the area that its broadcasting covers has NTSC to disturb, just suppose HDTV speech amplifier meeting symbolization precoder from NTSC disturbs so that the HDTV signal is easier to separate; And correspondingly, comb filter will be installed in the DTV signal receiver to carry out matched filtering as encoder behind the symbol.If do not have the possibility of NTSC interference or faint possibility is arranged, can infer and utilize the symbol precoder can make that DTV broadcasting is discontinuous.Correspondingly, encoder will not be activated behind the symbol in each DTV signal receiver, so that smooth pectrum noise can not cause the value of symbol in the trellis decoder to produce erroneous decision.
Authorize R.W.Citta and other people title on November 9th, 1993 and adopt back encoder comb filter selectively in for the U.S. Patent No. 5,260,793 of " encoder is selected circuit behind the receiver ".This filter suppresses to be accompanied by the artifactual epochs that the cochannel NTSC of the base band component (I channel) of the real part of composite output signal of the demodulator that uses in the DTV receiver or homophase disturbs.The existence of these artifactual epochs in the I channel component of demodulator response is detected with automatic generation control signal and makes comb filter can maybe can not be used to suppress cochannel NTSC interference.During each data field sync interval, the input signal of comb filtering type NTSC rejects trap and output signal all compare with a signal that is considered to take out in the memory set and from the HDTV signal receiver separately in the DTV signal receiver.If with input signal minimum result's relatively energy less than with the output signal minimum result relatively of NTSC rejects trap, this just shows that the main cause different with desirable reception is that random noise rather than cochannel NTSC disturb.So far related specific digital television receiver, not using precoding and back coding to receive in system will be better, and the supposition speech amplifier does not use precoding.If with input signal minimum result's relatively energy greater than with the output signal minimum result relatively of NTSC rejects trap, this just shows that the main cause different with desirable reception is that cochannel NTSC disturbs rather than random noise.So far related specific digital television receiver, using precoding and back coding to receive in system will be better, and the supposition speech amplifier uses precoding.
Authorize K.S.Kim and other people title U.S. Patent No. 5 for " NTSC interference search gear " on August 13rd, 1996,546,132 have described when extracting at NTSC when detecting the existing of this interference in the response of comb filter to the I channel, are used to suppress the use of the back encoder comb filtering that cochannel NTSC disturbs.U.S. Patent No. 5,546,132 the imaginary part or the quadrature base band component (Q channel) of the composite output signal that is provided by the demodulator in the DTV signal receiver is not provided particularly.One makes VSB AM signal and the synchronous demodulator of the common employing of DTV signal receiver of base band, this demodulator comprises an in-phase synchronization detector that the I channel signal that receives is provided for trellis decoding (if used precoding at the transmitter place, then after the coding of back).This demodulator also comprises a quadrature synchronization detector that is used to provide the Q channel signal that receives.Received Q channel signal is low pass filtering to produce the local oscillator that an automatic frequency and phase control (AFPC) signal are given provides sync carrier.In on December 26th, 1996 authorize C.B.Patel and A.L.R.Limberg, the title that transfers Samsung Co., Ltd is the U.S. Patent No. 5 of " be included in having in the HDTV receiver the logical position of the band digital VSB detector of tracker mutually ", 479,449 specification and accompanying drawing are listed in herein for your guidance.Reader's attentiveness is guided into U.S. Patent No. 5,479 especially, the parts 22-27 of the Fig. 1 in 449 accompanying drawings and its specification description of them.These parts are used to be used to carry out the compound demodulation of the last intermediate-freuqncy signal of VSB AM in the described DTV signal receiver.U.S. Patent No. 5,479,449 have described the compound demodulation that the last I-F signal of VSB AM carries out with digital form, but the compound demodulation of the last I-F signal of design VSB AM is carried out compound demodulation with analog form in another kind of digital television receiver.
In U.S. Patent No. 5,260, in 793 and 5,546,132, during disturbing, uses tangible cochannel NTSC the back coding, and whether other situation does not make the back coding, use the control signal of back coding to produce from the I channel signal that receives.Make cochannel disturb the complexity that becomes of determining of progression by the direct current biasing that is accompanied by cochannel NTSC interference (this direct current biasing is to survey from the in-phase synchronization of the pilot signal of VSB AM DTV signal to produce).This controls especially individual problem in the DTV signal receiver of strictly calibrating the amplitude of being surveyed the I channel signal that covers by in-phase synchronization that is received at automatic gain.
The video carrier of a NTSC signal is 1.25MHz apart from the edge of the broadcast channel of 6MHz bandwidth, yet is 310kHz to the DTV signal carrier of air broadcast apart from the edge of the broadcast channel of 6MHz bandwidth on ground.Cochannel NTSC signal does not demonstrate the amplitude-modulation sideband with respect to the carrier wave symmetry of the vestigial sideband amplitudemodulation that carries digital information (VSB AM).Correspondingly, the artifactual epochs of the artifactual epochs (artifacts) of the ntsc video carrier wave of the 940kHz that removes from the DTV signal carrier and its sideband is not eliminated quilt and the synchronous DTV signal of base band well.Certainly the artifactual epochs of NTSC sound carrier and sideband thereof are not eliminated well yet, and the NTSC sound carrier of 5.44MHz is removed from the DTV signal carrier.
The digital television standard ATSC that is published in September 16 nineteen ninety-five does not allow to use at DTV transmitter place the precoding of all data to disturb to suppress cochannel NTSC to compensate the back coding that uses comb filtering in the subsidiary follow-up DTV signal receiver.Replace, have only in the trellis coding initial symbol by precoding.Be unfavorable for adopting the DTV signal receiver of comb filter before the data limit process begins, to suppress cochannel NTSC interference by its this process of oneself carrying out.A DTV signal receiver that did not suppress the artifactual epochs of cochannel NTSC interference before the data limit process begins can not carry out good reception under the situation that strong co-channel disturbs.This situation be since this DTV signal receiver away from the DTV transmitter or a simulated television transmitter is nearby arranged.With the synchronous DTV signal of base band in, it is 59.75f that cochannel disturbs the artifactual epochs of the video carrier of NTSC colour TV signal H, f HIt is the horizontal frequency of that signal.The artifactual epochs of colour subcarrier is 287.25f H, the artifactual epochs of unmodulated NTSC sound carrier is 345.75f H
The inventor points out, the comb filtering process does not have people fully in addition to suppress the artifactual epochs of this frequency modulation NTSC sound carrier satisfactorily, under the big situation of particularly warbled therein carrier frequency shift.This is because the sampled point of FM carrier wave relevant (or inversely related) may be not good especially on some time points that separated by fixing basically arbitrarily delay.Quote the U.S. Patent number that is entitled as " the DTV receiver of band filter is to suppress the FM sound carrier of cochannel NTSC interference signal in the I-F circuit ", authorizes the inventor at this and be 5,748,226 patent document with for referencial use on May 5th, 1998.Be in 5,748,226 the United States Patent (USP) in the patent No., the inventor is proposed to be used in the filtering of setting up whole bandwidth that intermediate frequency amplifies can suppress the FM sound carrier that any cochannel disturbs the NTSC anolog TV signals.
The comb filtering process is separated the baseband DTV signal than other artifactual epochs of the cochannel NTSC signal that other people produces from video carrier, low video with near the carrier chrominance signal frequency of color carrier wave satisfactorily.This is because the inversely related of being correlated with and trending towards demonstrating between the sampled point of being separated by the delay interval of some other appointment that these artifactual epochs are trending towards demonstrating between the sampled point of being separated by the delay interval of some appointment.
Be in 5,748,226 the patent document at U.S. Patent number, the inventor advocate when disturb enough big so that to data when restriction causes adverse effect in the DTV signal receiver of a band comb filtering advance data restriction with inhibition cochannel NTSC interference.The inventor points out, is optionally carried out when comb filtering, how to compensate in the symbol decoding process this comb filtering to character-coded influence.That is, determine when that cochannel NTSC disturbs that it still be useful when being considered to accept the little designated value in ground greater than one, thereby make this decision can be used for controlling to suppress the selection use of the comb filter that cochannel NTSC disturbs.
As long as cochannel NTSC disturbs and to appear in the real part or homophase base band component (I channel) of composite output signal, cochannel NTSC disturbs in the imaginary part or quadrature base band component (Q channel) that just appears at a composite output signal that is used in a demodulator in the DTV signal receiver.Correspondingly,, a NTSC interference search gear make its NTSC extraction filter in response to the Q channel signal that is received thereby can being set, rather than the I channel signal that is received.If cochannel NTSC disturbs too many error in the trellis decoding cause the balanced I channel signal that is received by following the Read-Solomon decoder in the trellis decoder back to correct, then cochannel NTSC interference volume is an effective dose.By determining whether the effective dose that cochannel NTSC disturbs follows the Q channel signal that is received, can reasoning determine whether the effective dose that a cochannel NTSC disturbs follows the I channel signal that is received.Cochannel NTSC disturb progression accurately determine trend towards more simplifying because after synchronizing detection device and pilot signal reach frequency locking, there is not direct current biasing to result from the pilot signal and quadrature synchronization detection of VSB AM DTV signal basically.
Summary of the invention
An object of the present invention is to provide a kind of insensitive cochannel NTSC of direct current biasing interference search gear to the synchronizing detection that results from pilot signal.This cochannel NTSC interference search gear allows directly to determine whether effective dose that a cochannel disturbs is followed the I channel signal that is received and be need not to suppress to result from the equalization filter of direct current biasing of the synchronizing detection of pilot signal.A kind of equalization filter like this has the equalization filter of response more to be difficult to realize than one in zero frequency.And, there is not the equalization filter of response to control (AGC) and automatic frequency and the mutual interference mutually of phase control (AFPC) loop in zero frequency with the automatic gain in a certain DTV signal receiver.In DTV signal receiver in response to the Q channel signal that is received, whether effective in order to determine that cochannel NTSC disturbs, still use the insensitive cochannel NTSC of the direct current biasing interference search gear that the synchronizing detection from pilot frequency carrier wave is produced.
The invention provides a kind of Digital Television (DTV) signal receiver of digital television signal, this digital television signal is received as the vestigial sideband amplitudemodulation signal of a carrier wave, and this digital television signal is easy to be attended by the cochannel interference simulation TV signal of the intensity that does not meet the requirements often.According to digital television signal receiver of the present invention, comprise the cochannel interference search gear of the insensitive specific type of DC terms of the system function of a pair of its previous circuit.This digital television signal receiver comprises: amplifying circuit is used to provide the digital television signal of the vestigial sideband amplitudemodulation of amplification; Demodulator circuit, it responds the digital television signal of the vestigial sideband amplitudemodulation of described amplification, and so that at least one baseband signal to be provided, this baseband signal offers the cochannel interference search gear as its input signal.This at least one baseband signal comprises an I channel baseband signal, and to offer the symbol decoding device that comprises in the DTV signal receiver, this I channel baseband signal comprises the artifactual epochs of any cochannel interference simulation TV signal.This symbol decoding device comprises: the filter of a selectively actuatable, being used to suppress to be accompanied by will be by the artifactual epochs of any cochannel interference simulation TV signal of the I channel baseband signal of symbol decoding.And if only if, and the symbol decoding device receives a signal when (effective dose that this signal indication has cochannel NTSC to disturb exists), can operate this filter.Be included in the error correction circuit in the DTV signal receiver, connect this error correction circuit to be used for proofreading and correct the symbol decoding result's who provides from the symbol decoding device error.This cochannel interference search gear has following structure.One first comb filter, this base-band input signal that will offer the cochannel interference search gear as input signal with through this baseband signal difference ground combination of the delay of the first differential delay amount to produce the response of first comb filter.In the response of this first comb filter, the DC terms of the system features that produces from the synchronizing detection of carrier wave is suppressed, and also is suppressed from the artifactual epochs that the synchronizing detection of described cochannel interference simulation TV signal produces.One second comb filter will be as input signal this base-band input signal that offers the cochannel interference search gear and this baseband signal difference ground combination that postpones through the second differential delay amount to produce the response of second comb filter.In the response of this second comb filter, the DC terms of the system features that produces from the synchronizing detection of carrier wave is suppressed, and the artifactual epochs who produces from the synchronizing detection of cochannel interference simulation TV signal is reinforced.One first magnitude detector is used to survey the amplitude that described first comb filter responds, to produce the first amplitude probe response; With one second magnitude detector, be used to survey the amplitude of described second comb filter response, to produce the second amplitude probe response.Amplitude comparator is used for the more described first and second amplitude probe responses.When the difference of the described first and second amplitude probe responses that and if only if surpassed an ormal weight, this magnitude detector provided this signal that shows the described effective dose existence that cochannel NTSC interference is arranged.
Specifically, according to one aspect of the present invention, a kind of digital television signal receiver of digital television signal is provided, this digital television signal is received as the vestigial sideband amplitudemodulation signal of a carrier wave, and this digital television signal is easy to be attended by the cochannel interference simulation TV signal of the intensity that does not meet the requirements often, and described digital television signal receiver comprises:
Amplifying circuit is used to provide the digital television signal of the vestigial sideband amplitudemodulation of amplification;
Demodulator circuit, it responds the digital television signal of the vestigial sideband amplitudemodulation of described amplification, so that at least one baseband signal to be provided;
One I-channel baseband signal is carried out symbol decoding to produce symbol decoding result's symbol decoding device, connected described symbol decoding device, receive the I channel baseband signal as input signal from described demodulator circuit, described symbol decoding device comprises:
One can select the filter that moves, being used to suppress to be accompanied by will be by the artifactual epochs of any cochannel interference simulation TV signal of the I channel baseband signal of symbol decoding, during and if only if the symbol decoding device receives signal that effective dose that an indication has cochannel NTSC to disturb exists, described filter just moves;
Error correction circuit is used for proofreading and correct the error from the symbol decoding result of symbol decoding device;
A connected cochannel interference search gear, receive a further base-band input signal from described demodulator circuit, described cochannel interference search gear is a kind of detector of the insensitive type of DC terms of the system function to the baseband signal in the input signal that it received, and it comprises:
One first comb filter, the signal combination that described further base-band input signal and himself are postponed through the first differential delay amount to be to produce the response of first comb filter, and wherein the artifactual epochs who produces from the synchronizing detection of described cochannel interference simulation TV signal is suppressed;
One second comb filter, the signal combination that described further base-band input signal and himself are postponed through the second differential delay amount to be to produce the response of second comb filter, and wherein the artifactual epochs who produces from the synchronizing detection of described cochannel interference simulation TV signal is reinforced;
One first magnitude detector is used to survey the amplitude that described first comb filter responds, to produce the first amplitude probe response;
One second magnitude detector is used to survey the amplitude that described second comb filter responds, to produce the second amplitude probe response; And
Amplitude comparator is used for the more described first and second amplitude probe responses, and the difference of and if only if described first and second amplitude probe responses provides the described signal that has described cochannel to disturb effective dose to exist that shows when surpassing an ormal weight.
According to another aspect of the present invention, a kind of digital television signal receiver of digital television signal is provided, this digital television signal is received as the vestigial sideband amplitudemodulation signal of a carrier wave, and this digital television signal is easy to be attended by the cochannel interference simulation TV signal of the intensity that does not meet the requirements often, and said digital television signal receiver comprises:
Amplifying circuit is used to provide the digital television signal of the vestigial sideband amplitudemodulation of amplification;
Demodulator circuit, it responds the digital television signal of the vestigial sideband amplitudemodulation of described amplification, so that at least one baseband signal to be provided;
Connected symbol decoding device, it is from the I channel baseband signal of described demodulator circuit reception as an input signal, and this I channel baseband signal comprises the artifactual epochs of any cochannel interference simulation TV signal;
Be included in first data limiter in the described symbol decoding device, be used for described I channel baseband signal being carried out symbol decoding to produce the first symbol decoding result at least the first period;
Be included in first comb filter in the described symbol decoding device, the signal combination that is used for described I channel baseband signal and himself are postponed through the first differential delay amount to be to produce the response of first comb filter, and wherein the artifactual epochs who produces from the synchronizing detection of described cochannel interference simulation TV signal is suppressed;
Be included in second data limiter in the described symbol decoding device, be used for described first comb filter response being carried out symbol decoding to produce the second symbol decoding result in second period;
Be included in second comb filter in the described symbol decoding device, the signal combination that is used for selecteed symbol decoding result and itself are postponed through the second differential delay amount is to produce last symbol decoding result, correspondence is in the described first symbol decoding result in first period with in the described second symbol decoding result in second period as a result for described selecteed symbol decoding, and the described first differential delay amount has identical symbol time of occurrence with the second differential delay measurer;
Error correction circuit, be used for correcting the error of last symbol decoded result, as long as artifactual epochs's intensity in described I channel baseband signal of any cochannel interference simulation TV signal is weaker than the described intensity that does not meet the requirements, described error correction circuit can be corrected described selected as the error among described last symbol decoding result's the first symbol decoding result; And
The cochannel interference search gear, be used for receiving a further base-band input signal from described demodulator circuit, described cochannel interference search gear is a kind of detector of the insensitive type of DC terms of system function of the baseband signal to its input signal of conduct that it received, and comprising:
One the 3rd comb filter, the signal combination that described further base-band input signal and himself are postponed through the 3rd differential delay amount, to produce one the 3rd comb filter response, the artifactual epochs who wherein results from the synchronizing detection of described cochannel interference simulation TV signal is suppressed;
One the 4th comb filter, the signal combination that described further base-band input signal and himself are postponed through the 4th differential delay amount, to produce one the 4th comb filter response, the artifactual epochs who wherein results from the synchronizing detection of described cochannel interference simulation TV signal is reinforced;
First magnitude detector is used to survey described the 3rd comb filter response amplitude, to produce one first amplitude probe response;
Second magnitude detector is used to survey described the 4th comb filter response amplitude, to produce one second amplitude probe response; And
An amplitude comparator that is used for the more described first and second amplitude probe responses, and the difference of and if only if described first and second amplitude probe responses is when surpassing an ormal weight, the intensity that shows the cochannel interference simulation TV signal in described I channel baseband signal is enough strong, thereby make error correction circuit can not correct on request from the error among the first symbol decoding result of described first data limiter, this indication result as an order that offers described second comb filter to select result except the described first symbol decoding result as described last symbol decoding result.
Description of drawings
Fig. 1 is the block diagram of part of the digital television receiver of a symbol decoder that comprises a band cochannel NTSC codan, according to one aspect of the present invention, activates this cochannel NTSC codan selectively.This selection activation manipulation depends on the response of the cochannel NTSC interference search gear that comprises a comb filter, and this comb filter is extracted the DTV pilot frequency carrier wave that the NTSC artifactual epochs also suppresses to follow those artifactual epochs from the baseband I channel signal.
Whether Fig. 2 is the operational flowchart of the part of Fig. 1 digital television receiver, demonstrate according to adopting the balancing procedure of comb filtering inhibition cochannel NTSC interference how to be modified.
Fig. 3 is the block diagram of part of the digital television receiver of a symbol decoder that comprises a band cochannel NTSC codan, according to one aspect of the present invention, activates this cochannel NTSC codan selectively.This selection activation manipulation depends on the response of the cochannel NTSC interference search gear that comprises a comb filter, and this comb filter is extracted the DTV pilot frequency carrier wave that the NTSC artifactual epochs also suppresses to follow those artifactual epochs from base band Q channel signal.
Whether Fig. 4 is the operational flowchart of the part of Fig. 3 digital television receiver, demonstrate according to adopting the balancing procedure of comb filtering inhibition cochannel NTSC interference how to be modified.
Fig. 5 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 when NTSC band resistance comb filter has adopted the delay of 12 symbols the part details of DTV signal receiver.
Fig. 6 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 when NTSC band resistance comb filter has adopted the delay of 6 symbols the part details of DTV signal receiver.
Fig. 7 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 when NTSC band resistance comb filter has adopted the delay of 2 video lines (1368 symbols) the part details of DTV signal receiver.
Fig. 8 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 when NTSC band resistance comb filter has adopted the delay of 262 video lines (179,208 symbols) the part details of DTV signal receiver.
Fig. 9 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 when NTSC band resistance comb filter has adopted the delay of 2 frame of video (718,200 symbols) the part details of DTV signal receiver.
Figure 10 is a frame principle figure according to the general type of a cochannel NTSC interference search gear employing of the present invention's structure.Be used for extracting the comb filter that cochannel NTSC disturbs the artifactual epochs of (not being attended by the DTV pilot frequency carrier wave), the input signal of this detector carries out difference (differentially) and makes up through the delay time time delayed signal of (differential delay) of 6 symbol difference with it.
Figure 11 is the frame principle figure of the cochannel NTSC interference search gear among a kind of Figure 10, wherein, in the comb filter that is used for suppressing the artifactual epochs that cochannel NTSC disturbs, the input signal of cochannel NTSC interference search gear and this signal carry out difference through the signal of 12 symbol differential delay and make up.
Figure 12 is the frame principle figure of the cochannel NTSC interference search gear among a kind of Figure 10, wherein, in the comb filter that is used for suppressing the artifactual epochs that cochannel NTSC disturbs, the input signal of cochannel NTSC interference search gear and this signal carry out difference ground through the signal of the differential delay of 2 video lines or 1368 symbols and make up.
Figure 13 is the frame principle figure of the cochannel NTSC interference search gear among a kind of Figure 10, wherein, in the comb filter that is used for suppressing the artifactual epochs that cochannel NTSC disturbs, the input signal of cochannel NTSC interference search gear and this signal carry out the combination of difference ground through the signal of the differential delay of 262 video lines or 179,208 symbols.
Figure 14 is the frame principle figure of the cochannel NTSC interference search gear among a kind of Figure 10, wherein, in the comb filter that is used for suppressing the artifactual epochs that cochannel NTSC disturbs, the input signal of cochannel NTSC interference search gear and this signal carry out the combination of difference ground through the signal of the differential delay of 2 frame of video or 718,200 symbols.
Figure 15 is the frame principle figure of the cochannel NTSC interference search gear among a kind of Figure 10, the shared delay element of the NTSC of the even progression data limiter front of DTV signal receiver band resistance comb filter among this cochannel NTSC interference search gear and Fig. 1.
Figure 16 is the block diagram of another common form of taking according to the cochannel NTSC interference search gear of the present invention structure.Each totally makes up the detector input signal of difference time-delay a pair of comb filter in Figure 10 detector.
Figure 17 is the block diagram of Figure 16 cochannel NTSC interference search gear, in the comb filter that is used for suppressing the artifactual epochs that cochannel NTSC disturbs, the input signal of cochannel NTSC interference search gear totally makes up with time delayed signal through 6 symbol difference time-delays.
Figure 18 and Figure 19 are the frame principle figures of digital television receiver of the invention process, the cochannel NTSC interference search gear that has adopted a plurality of comb filter and be associated in this DTV signal receiver, being used for selectively, filtering cochannel NTSC disturbs the artifactual epochs.
Embodiment
The different point of circuit in the accompanying drawings is inserted into calking (shimming) to postpone, thereby guarantees that operating sequence is correct, as being well versed in the people understood of Electronic Design by those.Can not conclusively show again in this specification, postpone unless need exceed general relevant specific calking.
Figure 1 shows that a digital television signal receiver that is used to recover error correction data, these data are suitable for by digital video cassette recorder (DVCR) record or MPEG-2 decoding and are presented on the television set.Fig. 1 DTV signal receiver is shown as from reception antenna 8 received tv broadcast signals, but also can be from cable network received signal.Television broadcasting signal offers " front end " electronic installation 10 as input signal.Should generally include a radio frequency amplifier and first detector that is used for radio television signal is converted to medium-frequency TV signal by " front end " electronic installation 10, medium-frequency TV signal is provided to intermediate frequency (IF) amplifier chain 12 of residual sideband DTV signal as input signal.The DTV signal receiver is taked multiple transition form in IF amplifier chain 12, comprise that is used to amplify an IF amplifier that is converted to the DTV signal of shf band by first detector, the DTV conversion of signals that second detector is used for amplifying is a very high frequency band, also has an IF amplifier to be used to amplify the DTV signal that is converted into the VHF wave band.If with digital form base band has been carried out demodulation, then IF amplifier chain 12 will further comprise one the 3rd detector, and the DTV conversion of signals that is used for amplifying is the final mf band of more close base band.
In UHF wave band IF amplifier, preferably adopt a surface acoustic wave (SAW) filter, be used for the shaping channel and select response and suppress adjacent channel.This SAW filter blocks just the frequency signal that surpasses 5.38Mhz fast to remove from the suppressed carrier of VSB DTV signal and pilot signal, pilot signal is identical frequency and fixing amplitude.Therefore, this SAW filter suppresses the frequency-modulated sound carrier wave of a large amount of any cochannel interference simulation TV signal.Remove the frequency-modulated sound carrier wave of any cochannel interference simulation TV signal in the IF amplifier chain 12, when last I-F signal is detected with the recovery baseband signalling, stop the artifactual epochs's generation of this carrier wave and the data limit of those baseband signallings that this artifactual epochs of prevention disturbs during symbol decoding.Thisly be better than and realize by before data limit, relying on comb filtering, if the differentiated delay particularly in the comb filter is more than the situation of several epoch in the data limit that prevents those baseband signallings that this artifactual epochs disturbs during the symbol decoding.
Offer a compound demodulator 14 from the last IF signal of IF amplifier chain 12 output, it with the vestigial sideband amplitudemodulation DTV signal demodulation in the last mf band with the baseband signal of recovering a real part and the baseband signal of an imaginary part.Can carry out in a few megahertz scopes with digital form after the analog-to-digital conversion of a last mf band at for example U.S. Patent No. 5,479,449 described demodulating processes.Perhaps, demodulating process may carry out with analog form, in this case, will carry out analog-to-digital conversion so that further handle to the result usually.Compound demodulation is preferably carried out in the mode of homophase (I) synchronous demodulation and quadrature (Q) synchronous demodulation.The numeric results of aforementioned demodulating process has 8 or high accuracy more usually, describes the 2N level symbol to N bit data coding.Here, 2N is 8 in the aerial broadcast situation of Fig. 1 DTV signal receiver reception by antenna 12, and receiving in the cable TV broadcast situation at Fig. 1 DTV signal receiver is 16.What the present invention considered is the reception of tellurian aerial broadcast, and Fig. 1 does not show that the DTV signal receiver is for receiving symbol decoding and the error correction decoding that cable TV broadcast transmission provides.
Sign synchronization and equalizing circuit 16 receive the digitized real part sample of (I channel) baseband signal of homophase from compound demodulator 14; In Fig. 1 DTV signal receiver, also demonstrate the digitized imaginary part sample that receives quadrature (Q one channel) baseband signal.Circuit 16 comprises an adjustable digital filter that is used for compensating the ghost image (ghost) of received signal and swings the weight coefficient of (tilt).Sign synchronization and equalizing circuit 16 provide sign synchronization or " remove rotation " (de-rotation) and amplitude equalization and elimination ghost image.Sign synchronization in sign synchronization and the equalizing circuit 16 was finished before amplitude equalization, and this is from U.S. Patent No. 5,479, and 449 as can be known.In this design, demodulator 14 will provide and comprise that the demodulator with baseband signal over-sampling imaginary part real part responds to sign synchronization and equalizing circuit 16.After sign synchronization, the over-sampling data are extracted (decimated) to extract the baseband I channel signal with normal symbol rate, reduce sample rate by the digital filtering that is used for amplitude equalization and elimination ghost image.The amplitude equalization of sign synchronization and equalizing circuit is prior to sign synchronization, and " removing rotation " or " Phase Tracking " are also known for the people who is well versed in digital signal reception designing technique.
Each sample of circuit 16 output signals is broken down into 10 bits or multidigit more, is actually a number WD of an analog symbol of one of an expression progression (2N=8).Circuit 16 output signals are by one of known several method gain controlling carefully, so be known for the desirable step-length progression of symbol.A kind of gain control method tendency adopts this method to be because the response speed of this gain controlling is fast extraordinarily, adjusts the DC component that offers the real part baseband signal of one+1.25 othogonal stage from compound demodulator 14.This gain control method is in U.S. Patent No. 5,479, described at large in 449, and in the U.S. Patent No. 5 of the title that is published on June 3rd, 1997 for " being used to receive the automatic gain control of the radio receiver of digital hdtv signal ", 573, ad hoc describe by C.B.Patel and other people in 574, list in herein for your guidance.
The output signal of circuit 16 offers data sync detection circuit 18 as input signal, and this circuit is from equalization base band I channel signal restore data field sync information D FS and data segment sync information D SS.Perhaps, can obtain for the signal of data sync detection circuit 18 inputs prior to equilibrium before.
Balanced I channel signal sample signal from the proper symbol rate of circuit 16 output offers NTSC band resistance comb filter 20 as an input signal.This comb filter 20 comprises that first deferred mount 201 that produces the different delayed data streams of a pair of 2N level symbol is used for the different delayed symbol data flow of linear combination to produce first linear combiner 202 of comb filter 20 responses with one.As U.S. Patent No. 5,260,793 is described, and first deferred mount 201 can provide a delay that equals 12 2N level symbol periods, and first linear combiner 202 can be a subtracter.Each sample of comb filter 20 output signals is broken down into 10 bits or more, and it is actually a number WD of an analog symbol of one of an expression progression (4N-1=15).
Sign synchronization and equalizing circuit 16 are considered to be designed to suppress the direct current deviatoric component of its input signal (as the DC terms at the system function as shown in the numeral sample).Be used as each sample of circuit 16 output signals of comb filter 20 input signals, be actually a number WD of an analog symbol of one of following standardization progression of expression :-7 ,-5 ,-3 ,-1 ,+1 ,+3 ,+5 and+7.These symbol progression are named as " odd number " symbol level and are surveyed to produce corresponding interim symbol decoding result 000,001,010,011,100,101,110 and 111 by an odd level data limiter 22.
Each sample of comb filter 20 output signals is actually a number WD of representing an analog symbol of one of following standardization progression :-1 4 ,-12 ,-10 ,-8 ,-6 ,-4 ,-2,0, last 2 ,+4 ,+6 ,+8 ,+10 ,+12 and+14.The symbol decoding result 001,010,011,100,101 that these symbol progression are named as " even number " symbol level and are surveyed to produce corresponding comb filtering by an even level data limiter 24,110,111,000,001,010,011,100,101,110 and 111.
Supposing that this data limiter 22 and 24 can be so-called " hard decision " type, perhaps can be so-called " soft decision " type of carrying out a Viterbi (Viterbi) decoding scheme.Odd level data limiter 22 and even level data limiter 24 are possible by the layout that a single data limiter substitutes, adopt multiplexer to connect to make its in circuit position change and provide biasing to revise its limited field, the complexity of operation is not preferentially adopted but these are arranged.
In the description in front, sign synchronization and equalizing circuit 16 are considered to be designed to suppress the direct current deviatoric component of its input signal (as the DC terms at the system function as shown in the numeral sample), and this direct current deviatoric component has one+1.25 standardization level also owing to the detection of pilot frequency carrier wave occurs the real part baseband signal that provides from compound demodulator 14.In fact sign synchronization and equalizing circuit 16 are configured to the direct current deviatoric component of preserving its input signal, and this has simplified the equalization filter of circuit 16 a little at least.Correspondingly, the data limit progression of odd level data limiter 22 is biased to consider the DC data component of companion data step-length in its input signal.If first linear combiner 202 is subtracters, the DC terms no matter circuit 16 is designed to suppress or preserve the system function of its input signal considers what influence the data limit progression in even level data limiter 24 does not all have.Yet, if the selected linear combiner 202 of winning that makes of difference delay that is provided by first deferred mount 201 is adders, the data limit progression of even level data limiter 24 should be biased to consider the twice DC terms of companion data step-length in its input signal.
The comb filter 26 of the inhibition symbol internal interference (intersymbol-interferencesuppression) after data limiter 22 and 24 produces a filter response, and wherein the symbol internal interference of being introduced by comb filter 20 (ISI) is suppressed.This ISI-suppresses comb filter 26, comprising: three inputoutput multiplexers, 261, the second linear combiners 262 and second time-delay mechanism 263 that equates with the time-delay of first time-delay mechanism 201 in the comb filter 20.If first linear combiner 202 is subtracters, then second linear combiner 262 is mould 8 adders, if first linear combiner 202 is adders, then second linear combiner 262 is mould 8 subtracters.This first linear combiner 202 and second linear combiner 262 can each constitute with read-only memory (ROM), with abundant raising linear combination service speed, thus the sample rate that support is adopted.The output signal of multiplexer 261 forms the response that ISI-suppresses comb filter 26, and this output signal is by 263 time-delays of second time-delay mechanism.Second linear combiner 262 is with the output signal combination of the pre-coded symbols decoded result and second time-delay mechanism 263 of even level data limiter 24.
The output signal of this multiplexer 261, by first, second and third state selection of the multiplexer controling signal that comes self-controller 28 that is applied to multiplexer 261, reproduction is applied to one of three input signals of multiplexer 261.When the data field synchronizing information DFS of balanced baseband I channel and data segment sync information D SS by by the data sync testing circuit between 18 convalescences, the first input end of this multiplexer 261 receives the ideal symbol decoded result that controller 28 built-in storagies provide.This controller 28 during this period of time offers multiplexer 261 with first state of multiplexer controling signal, and the ideal symbol decoded result that multiplexer 261 is provided controller 28 built-in storagies forms the last coding result as its output signal.This odd level data limiter 22 is transported to middle (interim) symbol decoding result second input of multiplexer 261 as its output signal.Multiplexer 261 reproduces intermediate symbols decoded result in the last coding result that multiplexer 261 provides according to second state of multiplexer controling signal.The symbol decoding result that this second linear combiner 262 suppresses ISI-filtering is applied to the 3rd input of multiplexer 261 as its output signal.This multiplexer 261 suppresses the symbol decoding result (ISI-suppression-filtered symbol decoding results) of filtering according to the ISI-in the last coding result of third state reproduction multiplexer 261 outputs of multiplexer controling signal.During data sync testing circuit 18 restore data field sync information D FS or data segment sync information D SS, by the ideal symbol decoded result that feedback controller 28 built-in storagies provide, can reduce the kinematic error among the symbol decoding result that ISI-that ISI-suppresses comb filter 26 suppresses filtering.
The output signal of multiplexer 261 comprises the last symbol decoded result of 3 parallel bit hytes in the ISI-inhibition comb filter 26, and it is collected so that be applied on the trellis decoder circuit 32 by Data Assembler 30.This trellis decoder circuit 32 uses 12 trellis decoder usually.The trellis decoded result of this trellis decoder circuit 32 offers the data deinterleaver circuit 34 of the usefulness that deinterleaves.Byte syntactic analysis circuit 36 converts data deinterleaver 34 output signals to the byte of the data of using Read-Solomon (Reed-Solomon) error correction coding, to be applied on the Read-Solomon decoder circuit 38, this RS decoder circuit 38 is carried out the RS decode operation and is offered the error correction data flow that data are removed randomizer 40 with generation.These data go randomizer 40 data of reproducing to be offered the remaining part (not shown) of receiver.The remaining part of a complete DTV signal receiver comprises: a packet classifier, an audio decoder,, a MPEG-2 decoder etc.The remaining part that is inserted into this DTV signal receiver in the digital video cassette recorder will comprise the circuit of the form that data transaction is become to be used to write down.
The insensitive cochannel NTSC of direct current biasing component interference detector 44 to its input signal is used for detecting the intensity that input signal cochannel NTSC disturbs the artifactual epochs who produces.Baseband I channel signal in the DTV signal receiver that these detector 44 input signals are Fig. 1.Whether strong this cochannel NTSC interference detector 44 offer controller 28 expression cochannel NTSC and disturb the mistake that generation can not be corrected when causing data limiter 22 to carry out data limit.If detector 44 expression cochannel NTSC interference signals are not strong like this, then in most of times, controller 28 offers multiplexer 261 with second state of multiplexer controling signal.If not this situation then had only on the time period of data sync testing circuit 18 restore data field sync information D FS and data segment sync information D SS, controller 28 offers multiplexer 261 with first state of multiplexer controling signal.The intermediate symbols decoded result that second state of its multiplexer controling signal makes multiplexer 261 reproduce to be provided by odd level time restriction device 22 is as its output signal.
If detector 44 expression cochannel NTSC disturb the strong mistake that generation can not be corrected when causing data limiter 22 to carry out data limit, then in most of times, controller 28 offers multiplexer 261 with the third state of multiplexer controling signal.If not this situation then had only on the time period of data sync testing circuit 18 restore data field sync information D FS and data segment sync information D SS, controller 28 offers multiplexer 261 with first state of multiplexer controling signal.The ISI-that the third state of its multiplexer controling signal makes multiplexer 261 reproduce the second linear combination result as second linear combiner 262 to be provided suppresses the symbol decoding result of filtering as its output signal.
Fig. 2 represents how whether basis has adopted comb filtering to suppress the flow chart that cochannel NTSC disturbs the balancing procedure in the DTV signal receiver of revising Fig. 1.The present invention points out: the artifactual epochs's that the cochannel NTSC in the baseband signalling coding disturbs existence makes in the calculating of equalization filter core coefficient and has introduced error, unless adopt special measurement to make the artifactual epochs not exist in calculating.
At initial step S1, compound demodulator 14 in Fig. 1 DTV signal receiver is the compound demodulation of combine digital TV signal continuously, to isolate an I channel baseband signal that is received and a Q channel baseband signal that is orthogonal and concerns with I channel baseband signal that received that received.At determination step S2, this step is to be carried out continuously by the cochannel NTSC interference detector in Fig. 1 DTV signal receiver 44, determines in this step whether the effective dose (significant amount) that cochannel NTSC disturbs is accompanied by the I channel baseband signal that is received.
The effective dose that cochannel NTSC in the DTV signal receiver disturbs is under general noise condition of acceptance, makes that the number of the mistake of generation causes essence to surpass the error correcting capability of the decoded two-dimentional RS decoding of trellis during trellis is decoded.Under the reception condition that the standard background noise is arranged, the bit number mistake of essence in the end appears in the data recovered.The effective dose that cochannel NTSC disturbs in the DTV signal receiver of particular design can easily be determined by the test of its typical machine.
Be accompanied by the I channel baseband signal that is received if in determination step S2, be determined the effective dose that no cochannel NTSC disturbs, then carry out the step S3 of the core weight of adjusting digital equalization filter and step S3 equalization filter response results is carried out the subsequent step S4 of symbol decoding.Carrying out the step S3 that adjusts the core weight makes digital equalization filter that the match responding to the I channel baseband signal is provided.The step S4 that symbol decoding is carried out in equalization filter response produces symbol decoding result that the symbol decoding result is carried out using among the subsequent step S5 of trellis decoding so that mistake is wherein carried out error correction.Be to the wrong Read-Solomon decoding step S6 of error correction and the step S7 of distortion Read-Solomon decoded result of carrying out in the trellis decoded result after the trellis decoding step S5.
Be accompanied by the I channel baseband signal that is received if in determination step S2, define the effective dose of a cochannel NTSC interference, then utilize a suitable comb filter, carry out the I channel baseband signal that is received is carried out the step S8 of comb filtering to produce the I channel baseband signal of comb filtering.In step S9, the core weight of digital equalization filter is adjusted, so that the response of the digital equalization filter of cascade and comb filter meets the ideal response of this filter cascade.Execution is carried out the step S10 of symbol decoding to the response of this filter cascade, then carries out the step S11 to symbol decoding response carrying out back coding, with the symbol decoding result of the correction that obtains to be used for trellis decoding step S5.Be still the Read-Solomon decoding step S6 of error correction in the trellis decoded result and the step S7 of distortion Read-Solomon decoded result after the trellis decoding step S5.
The submethod that is used to adjust digital equalization filter core weight in the step S3 of balanced digital equalization filter response is similar to the adjustment that is used for digital equalization filter core weight of the prior art.Adjustment can by calculate the data field synchronizing code received or wherein the discrete fourier transform of specified portions (DFT) and with ideal data field sync code or wherein the DFT of specified portions go to cut apart it and carry out, with the DFT of definite DTV transmission channel.The DFT of DTV transmission channel with respect to maximal term by normalization so that this channel characteristicsization, and the core weight of selecting digital equalization filter is to supply the normalized DFT that characterizes this channel.The method of this adjustment is being described by C.B.Patel and other people in the U.S. Patent No. 5,331,416 of " the elimination ghost image method of operating that is used for television receiver or video tape recorder " more meticulously as the title that is published on July 19th, 1994.This method is more suitable for the initialization of the core weight of digital equalization filter is regulated, because initialization is regulated than more promptly finishing by employing adaptive equalization.After the initialization that adaptive equilibrium method preferably is suitable for the core weight of digital equalization filter is regulated.A kind of functional block LMS (lowest mean square) method of carrying out adaptive equalization is at the United States Patent (USP) N0.3 of the title that is published on July 15th, 1994 for " be used for digital wireless receiver, as the quick renewal adaptive channel equalizer filtering of HDTV receiver ", described by J.Yang and other people in 648,987.Carrying out adaptive further LMS method is No.08/832 at the application number that applies on April 4th, 1997, and 674 titles are described by A.L.R.Limberg in the United States Patent (USP) of " dynamic self-adapting equalizer system and method ".
Among the step S9, can utilize DFT to carry out submethod, by this submethod, the core weight of digital equalization filter is adjusted, so that the response of the digital equalization filter of cascade and comb filter meets the ideal response of this filter cascade.When based on use data field synchronously (DFS) code or its established part carry out the fast initialization equilibrium when being transformed into adaptive equalization as training signal, DFT is particularly useful.The DFS code that calculating is received or the discrete fourier transform (DFT) of its established part are as the comb filtering that is undertaken by the comb filter 20 that suppresses the NTSC man-made noise.This DFT is cut apart by desirable DFS code or its established part, thereby by comb filtering, to determine the DFT of expression DTV transmission channel characteristics.The DFT of DTV transmission channel with respect to maximal term by normalization so that this channel characteristicsization, and the core weight of digital equalization filter is selected to supply the normalized DFT that characterizes this channel.Adaptive equilibrium method is suitable for being used after the initialization of the core weight of digital equalization filter is regulated.This adaptive equalization method be different from those be used for when by adopt comb filter 20 suppress the NTSC artifactual epochs, be doubled in the quantity of possible useful signal situation subtract 1, method during the artifactual epochs of no effective cochannel NTSC interference.
Figure 3 shows that a DTV signal receiver that is different from Fig. 1 DTV signal receiver, wherein base band Q channel signal rather than baseband I channel signal are applied on the cochannel NTSC interference search gear 44 as its input signal.Cochannel NTSC interference search gear 44 is used to survey the artifactual epochs's who results from cochannel NTSC interference base band Q channel signal intensity.The probe response of cochannel NTSC interference search gear 44 all is insensitive to the phase-locked any direct current deviatoric component that still may come across base band Q channel signal during foundation at compound demodulator 14 synchroprobes.So in the weight factor of the equalization filtering of counting circuit 16, the not conversion between baseband signal and comb filtering baseband signal.May come across the base band Q channel signal after the DTV signal that the DTV signal receiver obtained any direct current deviatoric component (as when weak signal receives owing to bad phase-locked) can not influence the probe response of cochannel NTSC interference search gear 44 yet.In Fig. 3 DTV signal receiver, determine that whether effective dose that cochannel NTSC disturbs is accompanied by the I channel baseband signal that is received is from determining whether effective dose that cochannel NTSC disturbs is accompanied by the Q channel baseband signal that is received and infers out.
Whether Fig. 4 shows according to adopting comb filtering to suppress cochannel NTSC interference how to revise the balancing procedure of Fig. 3 DTV signal receiver.The difference of Fig. 2 flow chart of Fig. 4 flow chart of Fig. 3 DTV signal receiver and Fig. 1 DTV signal receiver is to determine that determination step S02 that whether effective dose that cochannel NTSC disturbs is accompanied by the Q channel baseband signal that is received has replaced the determination step S2 whether effective dose that definite cochannel NTSC disturbs is accompanied by the I channel baseband signal that is received.
Fig. 5 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 and to adopt a kind of numbering (species) to be 120 NTSC band resistance comb filter 20 and a kind ofly to be numbered the details of a part that 126 ISI-suppresses the DTV signal receiver of comb filter 26.A subtracter 1202 is made first linear combiner in NTSC band resistance comb filter 120, mould 8 adders 1262 suppress to do in the comb filter 126 second linear combiner at ISI-.NTSC band resistance comb filter 120 adopts one to demonstrate first deferred mount 1201 that 12 symbol time of occurrences postpone, and ISI-suppresses comb filter 126 and adopts also to demonstrate second deferred mount 1263 that 12 symbol time of occurrences postpone.The delay of 12 symbols that shown by each deferred mount 1201 and 1263 approaches the artifactual epochs's of simulated television video carrier the delay of one-period, and this simulated television carrier wave is simulated television horizontal frequency f H59.75 times.The delay of these 12 symbols approaches 5 cycle delays of the artifactual epochs of simulated television chrominance carrier, and this simulated television chrominance carrier is f H287.25 times.The delay of 12 symbols approaches 6 cycle delays of the artifactual epochs of simulated television sound carrier, and this simulated television sound carrier is f H345.75 times.The response that 1202 pairs of Here it is subtracters differently postpone sound carrier, video carrier by first deferred mount and approach the difference combination of chrominance subcarrier frequency trends towards reducing the reason that cochannel disturbs.Yet vision signal is passed the edge part of horizontal scanning line at it, and the simulated television vision signal is very low in the associated volume of the horizontal space direction of this distance.
A kind of multiplexer 261 of 1261 of being numbered is controlled by a multiplexer control signal, and this signal disturbs and is not enough to produce under the error condition that can not correct most time at its second state in the output signal of data limiter 22 being determined cochannel NTSC.This multiplexer control signal is disturbed and to be enough to produce under the error condition that can not correct most time in its third state in the output signal of data limiter 22 being determined cochannel NTSC.Multiplexer 1261 is present in the mould 8 summation results of the control signal restriction of the third state with feedback adder 1262 by it, gives adder 1262 by 12 symbol time of occurrences that deferred mount 1263 postpones as a summand.This is the process of a mould accumulation, and a single error is propagated (propagate) as a kinematic error therein, and error is reappeared in per 12 symbol time of occurrences.The ISI-that ISI-suppresses comb filter 126 suppress kinematic error among the symbol decoding result of filtering be placed in its each data segment begin to locate 4 symbol time of occurrences first state and comprise data field synchronously the multiplexer 1261 of the whole period of each data segment of (DFS) code subdue.When this control signal at its first state, the desirable symbol decoding results of its output signal for being provided by the memory in the controller 28 are provided for multiplexer 1261.The output signal of the ideal symbol decoded result being introduced multiplexer 1261 can stop any kinematic error.Because each data segment has the individual symbol of 4+69 (12), the ideal symbol decoded result the position of each data segment mutually on sliding (slip) return 4 symbol time of occurrences (epoch), so there is not kinematic error can continue to surpass 3 data segments.
Fig. 6 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 to adopt a kind ofly to be numbered 220 NTSC band resistance comb filter 20 and a kind ofly to be numbered the details of a part that 226 ISI-suppresses the DTV signal receiver of comb filter 26.NTSC band resistance comb filter 220 adopts one to demonstrate first deferred mount 2201 that 6 symbol time of occurrences postpone, and ISI-suppresses comb filter 226 and adopts also to demonstrate second deferred mount 2263 that 6 symbol time of occurrences postpone.The delay of 6 symbols that show by each deferred mount 2201 and 2263 near 59.75 times to simulated television horizontal frequency f H0.5 cycle delay of artifactual epochs of simulated television video carrier.These 6 symbol delays approach 287.25 times to f H2.5 cycles of artifactual epochs of simulated television chrominance carrier.And these 6 symbol delays approach 345.75 times to f H3 cycles of artifactual epochs of simulated television sound carrier.An adder 2202 is made first linear combiner in NTSC band resistance comb filter 220, mould 8 subtracters 2262 suppress to do in the comb filter 226 second linear combiner at ISI-.Be shorter than deferred mount 1201 and 1263 delays that show by deferred mount 2201 and 2263 delays that show.So more likely obtain than useful being correlated with in the signal that makes up by subtracter 1202 differences by the useful inversely related in the signal of adder 2202 accumulation combinations.By near the artifactual epochs of frequency inverted analog tv signal video carrier and the chrominance subcarrier by in 220 responses of NTSC band resistance comb filter than in 120 responses of NTSC band resistance comb filter on wideer rejection band notch filter.This NTSC sound carrier artifactual epochs is by NTSC band resistance comb filter 120 notch filters, but NTSC band resistance comb filter 220 is not to NTSC sound carrier artifactual epochs notch filter.Yet if the sound carrier of a cochannel interference simulation TV signal is suppressed by the sound trap in SAW filtering or the IF amplifier chain 12, it will not be problem that the bad sound of comb filter 220 suppresses.The response at the synchronous tip (tip) during the NTSC band resistance comb filter 120 of the NTSC band resistance comb filter 220 that adopts Fig. 6 rather than Fig. 5 reduces, so reduced the ability that overcomes error correction in fact in trellis decoding and Reed Solomon Coding.
A kind of multiplexer 261 of 2261 of being numbered is controlled by a multiplexer control signal, this signal disturbs and to be not enough to produce under the error condition that can not correct most time at its second state in the output signal of data limiter 22 being determined cochannel NTSC, disturbs and is enough to produce under the error condition that can not correct most time in its third state in the output signal of data limiter 22 being determined cochannel NTSC.Multiplexer 2261 is present in the mould 8 difference results of the control signal restriction of the third state with feedback subtracter 2262 by it, gives subtracter 2262 by 6 symbol time of occurrences that deferred mount 2263 postpones as a minuend.This is a process that mould subtracts each other, and a single error is propagated as a kinematic error therein, and per 6 the symbol time of occurrences of error reappear.The ISI-that ISI-suppresses comb filter 226 suppress kinematic error among the symbol decoding result of filtering be in each data segment begin to locate 4 symbol time of occurrences of first state and comprise data field synchronously the multiplexer 2261 of the whole period of each data segment of (DFS) stop.When the control signal of multiplexer 2261 at first state, multiplexer 2261 reproduces the desirable symbol decoding result that provided by the memory in the controller 28 as its output signal.The ideal symbol decoded result is introduced kinematic error of the feasible minimizing of output signal of multiplexer 2261.Because each data segment has the individual symbol of 4+138 (6), the ideal symbol decoded result back slide 4 symbol time of occurrences in the position of each data segment on mutually, so there is not kinematic error can continue above 2 data segments.ISI-suppresses kinematic error continues in the comb filter 226 time and in fact suppresses little in the comb filter 126 than ISI-, and more frequent and influence doubles 12 trellis codings that interweave although kinematic error reappears ground.
Fig. 7 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 to adopt a kind ofly to be numbered 320 NTSC band resistance comb filter 20 and a kind ofly to be numbered the details of a part that 326 ISI-suppresses the DTV signal receiver of comb filter 26.NTSC band resistance comb filter 320 adopts one first deferred mount 3201, it demonstrates 1368 symbol time of occurrences delays, this postpones the time of occurrence of two horizontal scanning lines of as many as anolog TV signals, and ISI-suppresses comb filter 326 and adopts also to demonstrate second deferred mount 3263 that 1368 symbol time of occurrences postpone.First linear combiner in the NTSC band resistance comb filter 320 is a subtracter 3202, and second linear combiner that ISI-suppresses in the comb filter 326 is mould 8 adders 3262.
A kind of multiplexer 261 of 3261 of being numbered is controlled by a multiplexer control signal, and this signal disturbs and is not enough to produce under the error condition that can not correct most time at its second state in the output signal of data limiter 22 being determined cochannel NTSC.This multiplexer control signal is controlled at and is determined cochannel NTSC and disturbs and to be enough to produce under the error condition that can not correct most time in its third state in the output signal of data limiter 22.The DTV signal receiver preferably includes and is used for surveying the circuit that mixed sweep line that cochannel NTSC disturbs changes, so that controller 28 can refuse to provide the third state of multiplexer 3261 control signals in this case.
Multiplexer 3261 is present in the mould 8 summation results of the control signal restriction of the third state with feedback adder 3262 by it, gives adder 3262 by 1368 symbol time of occurrences that deferred mount 3263 postpones as a summand.This is the process of a mould accumulation, and a single error is propagated as a kinematic error in this process, and per 1368 the symbol time of occurrences of error reappear.This symbolic coding interval is longer than the length of a single data block of Reed one Saloman coding, so a single error is easy to be repaired in the Read-Solomon decoding.Kinematic error among the symbol decoding result of the ISI-inhibition filtering of ISI-inhibition comb filter 326 is begun to locate 4 symbol time of occurrences in the whole period of each data segment that comprises field sync and at each data segment, places the multiplexer 3261 of its first state to stop.When this control signal at its first state, multiplexer 3261 reproduces the desirable symbol decoding result that provided by the memory in the controller 28 as its output signal.The output signal of the ideal symbol decoded result being introduced multiplexer 3261 reduces any kinematic error.16.67 milliseconds duration of a ntsc video field (field) demonstrates the phase slip (slippage) with respect to 24.19 milliseconds duration of DTV data field (field), so comprise the whole NTSC frame grating of the final scanning of the DTV data segment of field sync.Each bar of 525 lines comprises 684 symbol time of occurrences in the NTSC frame grating, always has 359,100 symbol time of occurrences.This is less than 432 times symbol time of occurrences of 832 symbol time of occurrences in a DTV data segment that comprises field sync a little.So the kinematic error that can have sufficient reason to infer to last longer than 432 data fields will be by multiplexer 3261 eliminations of reproducing the ideal symbol decoded result in during comprising the DTV data segment of field sync.Owing to can obtain the initial code group of ideal symbol decoded result, between data segment and the ntsc video scan line phase slip be arranged also.Can estimate that 359,100 symbol time of occurrences (4 symbol time of occurrences in a code initial set 89,775 times) can be scanned during 89,775 continuous data segments.Owing to 313 data segments are arranged in each DTV data field, the kinematic error that can have sufficient reason to think so to last longer than 287 data fields will be reproduced the ideal symbol decoded result during the coding initial set multiplexer 3261 stops.The inhibition source of two kinematic errors is reasonably independent each other, is very inequality so last longer than 200 kinematic error or same data field.And, if cochannel NTSC disturbs reduction at a time when kinematic error occurs, being used to reproduce the multiplexer 3261 of the response of data limiter 22 as its output signal in order to limit, error can be than the Zao correction of other situation.
Fig. 7 NTSC band resistance comb filter 320 can be suppressed at the artifactual epochs of the demodulation that produces in the response of simulated television horizontal synchronization pulse and the artifactual epochs of a lot of demodulation of producing well in the response of simulated television vertical sync pulse and equalizing pulse.This artifactual epochs is that high-octane cochannel disturbs.In the video content of the anolog TV signals during two scan lines, except changing part at scan line to scan line, NTSC band resistance comb filter 320 also provides the inhibition of the suitable video content of not considering its color.If it is not suppressed by the tracking rejects trap in sign synchronization and the equalizing circuit, the inhibition of the FM sound carrier of anolog TV signals suits.The artifactual epochs of most of simulated television color bursts also is suppressed in 320 responses of NTSC band resistance comb filter.And the filtering that is provided by NTSC band resistance comb filter 320 suppresses into " quadrature " with the NTSC interference in being based upon the trellis decode procedure.
Fig. 8 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 to adopt a kind ofly to be numbered 420 NTSC band resistance comb filter 20 and a kind ofly to be numbered the details of a part that 426 ISI-suppresses the DTV signal receiver of comb filter 26.NTSC band resistance comb filter 420 adopts one to demonstrate first deferred mount 4201 that 179,208 symbol time of occurrence postpones.This postpones the time of 262 horizontal scanning lines of as many as anolog TV signals, and ISI-suppresses second deferred mount 4261 that also demonstrates this delay of comb filter 426 employings.A subtracter 4202 is made first linear combiner in NTSC band resistance comb filter 420, mould 8 adders 4262 suppress to do in the comb filter 426 second linear combiner at ISI-.
A kind of multiplexer 261 of 4261 of being numbered is controlled by a multiplexer control signal, and this signal disturbs and is not enough to produce under the error condition that can not correct most time at its second state in the output signal of data limiter 22 being determined cochannel NTSC.This multiplexer control signal is controlled at and is determined cochannel NTSC and disturbs and to be enough to produce under the error condition that can not correct most time in its third state in the output signal of data limiter 22.The DTV signal receiver preferably includes and is used for surveying the circuit that CY to CY (field-field) that cochannel NTSC disturbs changes, so that controller 28 can suppress to provide the third state of multiplexer 4261 control signals in this case.
Multiplexer 4261 is present in the mould 8 summation results of the control signal restriction of the third state with feedback adder 4262 by it, gives adder 4262 by 179,208 symbol time of occurrences that deferred mount 4263 postpones as a summand.This is the process of a mould accumulation, and a single error spreads as a kinematic error therein, and per 179,208 the symbol time of occurrences of error reappear.This symbolic coding (span) at interval is longer than the length of a single data block of Reed one Saloman coding, so a single error is easy to be repaired in the Read-Solomon decoding.Kinematic error among the symbol decoding result of the ISI-inhibition filtering of ISI-inhibition comb filter 426 is begun to locate multiplexer 4261 minimizings that 4 symbol time of occurrences place its first state by whole period and each data segment at each data segment that comprises field sync.When this control signal at its first state, multiplexer 4261 reproduces this desirable symbol decoding result of being provided by the memory in the controller 28 as its output signal.The output signal of the ideal symbol decoded result being introduced multiplexer 4261 stops any kinematic error.The greatest measure of eliminating the required data field of kinematic error in multiplexer 4261 output signals with eliminate required more or less the same of kinematic error in multiplexer 3261 output signals.Yet the number of times that error is reappeared in that time is cut down with the factor 131.
Fig. 8 NTSC band resistance comb filter 420 is suppressed at the most demodulation artifactual epochs that produce in the response of simulated television vertical sync pulse and equalizing pulse, and is suppressed at the whole demodulation artifactual epochs that produce in the response of simulated television horizontal synchronization pulse.This artifactual epochs is that high-octane cochannel disturbs.And NTSC band resistance comb filter 420 suppresses to result from CY to CY or the line artifactual epochs to the video content of indeclinable anolog TV signals between line, eliminates static decorative pattern and does not consider their horizontal space frequency or color.The artifactual epochs of most of simulated television color bursts also is suppressed in 420 responses of NTSC band resistance comb filter.
Fig. 9 is a frame principle figure, demonstrates among Fig. 1 or Fig. 3 to adopt a kind ofly to be numbered 520 NTSC band resistance comb filter 20 and a kind ofly to be numbered the details of a part that 526 ISI-suppresses the DTV signal receiver of comb filter 26.NTSC band resistance comb filter 520 adopts one and demonstrates 718,200 symbol time of occurrences postpone, this postpones first deferred mount 5201 of 2 frame periods of as many as anolog TV signals, and ISI-suppresses comb filter 526 and adopts second deferred mount 5263 that also demonstrates this delay.A subtracter 5202 is made first linear combiner in NTSC band resistance comb filter 520, mould 8 adders 5262 suppress to do in the comb filter 526 second linear combiner at ISI-.
A kind of multiplexer 261 of 5261 of being numbered is controlled by a multiplexer control signal, and this signal disturbs the most time that is not enough to produce in the output signal of data limiter 22 under the error condition that can not correct at its second state being determined cochannel NTSC.This multiplexer control signal is controlled at and is determined cochannel NTSC and disturbs the most time be enough to produce in the output signal of data limiter 22 under the error condition that can not correct in its third state.The DTV signal receiver preferably includes and is used for surveying the circuit that alternately (alternate) interframe conversion that cochannel NTSC disturbs changes, so that controller 28 can suppress to provide the third state of multiplexer 5261 control signals in this case.
Multiplexer 5261 is present in the mould 8 summation results of the control signal restriction of the third state with feedback adder 5262 by it, gives adder 5262 by 718,200 symbol time of occurrences that deferred mount 5263 postpones as a summand.This is the process of a mould accumulation, and a single error is propagated as a kinematic error therein, and per 718,200 the symbol time of occurrences of error reappear.This symbolic coding interval is longer than the length of a single data block of Reed Solomon Coding, so a single error is easy to be repaired in the Read-Solomon decoding.Kinematic error among the symbol decoding result of the ISI-inhibition filtering of ISI-inhibition comb filter 526 is begun to locate multiplexer 5261 minimizings that 4 symbol time of occurrences place its first state by whole period and each data segment at each data segment that comprises field sync.When this control signal at its first state, multiplexer 5261 reproduces the desirable symbol decoding result that provided by the memory in the controller 28 as its output signal.The output signal that the ideal symbol decoded result is introduced multiplexer 5261 stops any kinematic error.The greatest measure of eliminating the required data field of kinematic error in multiplexer 5261 output signals with eliminate required more or less the same of kinematic error in multiplexer 3261 output signals.Yet the number of times that error is reappeared in that time is cut down with the factor 525.
Fig. 9 NTSC band resistance comb filter 520 is suppressed at all demodulation artifactual epochs that produce in the response of simulated television vertical sync pulse and equalizing pulse, and is suppressed at the whole demodulation artifactual epochs that produce in the response of simulated television horizontal synchronization pulse.This artifactual epochs is that high-octane cochannel disturbs.And NTSC band resistance comb filter 520 suppresses to result from the artifactual epochs at the video content of the indeclinable anolog TV signals of two interframe, eliminates static decorative pattern and does not consider their spatial frequency or color.The artifactual epochs of all simulated television color bursts also is suppressed in 520 responses of NTSC band resistance comb filter.
Figure 10 shows that the general type of the cochannel NTSC interference search gear 44 of the DTV television receiver that is included among Fig. 1 and Fig. 3.Node 440 receives the input signal of detector 44, and this input signal can be the I channel baseband signal or the balanced Q channel baseband signal of the equilibrium that provides respectively by Fig. 1 DTV signal receiver or by the Symbol Synchronization Circuit 16 of Fig. 3 DTV signal receiver.This input signal can be by Fig. 1 DTV signal receiver after improving or the balanced I channel baseband signal or the balanced Q channel baseband signal that are provided by the compound demodulator 14 of Fig. 3 DTV signal receiver after improving.In the detector 44 in a NTSC band resistance comb filter, the input signal that the 3rd deferred mount 441 will offer node 440 carries out the delay of difference to produce the subtrahend and the minuend input signal of digital subtractor 442, from the difference signal of subtracter 442 outputs are NTSC band resistance comb filter response R, and the artifactual epochs of the synchronizing detection that results from described cochannel interference simulation TV signal wherein is suppressed.In detector 44, a NTSC selects in the comb filter, the input signal that the 4th deferred mount 443 will offer node 440 carries out the delay of difference to produce the subtrahend and the minuend input signal of digital subtractor 442, from the difference signal of subtracter 444 outputs is that a NTSC selects comb filter response S, and the artifactual epochs of the synchronizing detection that results from described cochannel interference simulation TV signal wherein is reinforced.A DC terms of system performance that results from the synchronizing detection of pilot signal is selected all to be suppressed among the comb filter response S at NTSC band resistance comb filter response R and NTSC.
NTSC from subtracter 442 selects the amplitude of comb filter response R to be surveyed by magnitude detector 445, NTSC from subtracter 444 is with the amplitude of resistance comb filter response S to be surveyed by magnitude detector 446, the result that magnitude detector 445 and 446 amplitudes are surveyed is compared to export a carry-out bit by amplitude comparator 447, and in fact whether the response of expression magnitude detector 446 surpass the response of magnitude detector 445.This carry-out bit is used for selecting between second and the third state of multiplexer 261 operations.For example, can be controller 28 from this carry-out bit of amplitude comparator 447 suppresses to offer in the comb filter 26 in two control bits of multiplexer 261 one at the ISI-of Fig. 1 or Fig. 3, and another control bit represents whether the signal that controller 28 provides is reproduced in the response of multiplexer 261.
Mode by example, magnitude detector 445 and 446 can be to have envelope (envelope) detector that equals several data sampling interlude constants, thereby makes the difference in the data part of their input signals trend towards reaching the low value (supposing that these data components are random value) of balance.Amplitude difference in the random noise of the difference output signal of following subtracter 442 and 444 also trends towards the null value that reaches average.Correspondingly, when the amplitude probe response difference of amplitude comparator 447 expression magnitude detectors 445 and 446 during greater than the amount of a regulation, just show that in the baseband signal that offers node 440 artifactual epochs of any cochannel interference simulation TV signal is higher than a level of significance.This effective level is corresponding to the level of significance of the I channel baseband signal of the equilibrium that is applied to odd level data limiter 22.As long as the artifactual epochs of cochannel interference simulation TV signal is maintained under this level of significance, can be corrected by trellis and Read-Solomon error correction coding by the error in the symbol decoding that the I channel baseband signal is carried out simple data restriction gained.
The artifactual epochs that cochannel NTSC disturbs is suppressed in the comb filter response R from subtracter 442, and the artifactual epochs that cochannel NTSC disturbs is selected in the comb filter response S from subtracter 444.When the amplitude of comb filter response S during in fact greater than the amplitude of comb filter response R, this species diversity can be thought that artifactual epochs that the cochannel NTSC by node 440 places disturbs exists and cause.Therefore the carry-out bit that is provided by amplitude comparator 447 makes multiplexer 261 can not operate at its second state in this case, does not select the interim symbol decoding that produced by the odd level data limiter 22 last symbol decoded result as multiplexer 261.
When in fact the amplitude of comb filter response S is not more than the amplitude of comb filter response R, this artifactual epochs who does not have difference can be considered to show in the signal of node 440, not exist cochannel NTSC to disturb.The carry-out bit that is provided by amplitude comparator 447 makes multiplexer 261 can not operate in its third state in this case, does not therefore select to suppress the last symbol decoded result of the symbol decoding result of filtering as multiplexer 261 by the ISI-that second linear combiner 262 produces.
In the preferred embodiment of the cochannel NTSC of Figure 11 to Figure 14 interference search gear 44,6 symbol delay devices 1443 are used as the 4th time-delay mechanism 443.
Figure 11 shows that a kind of Figure 10 cochannel NTSC interference search gear 44 of 144 that is numbered, it is suitable for the symbol decoding device of Fig. 5 especially.The difference time-delay of 12 symbols is provided between the subtrahend of the subtracter 442 of the 3rd deferred mount 1441 in comb filter and minuend input signal, and this comb filter is used to suppress to be accompanied by the cochannel NTSC interference artifactual epochs of the baseband signal that offers node 440.These artifactual epochs result from the anolog TV signals component that frequency is bordering on video carrier, color subcarrier and sound carrier frequency.It is long slightly or be shorter than time of delay of NTSC horizontal scanning line slightly that the 3rd deferred mount 1441 in a certain preferential embodiment of the present invention is chosen as delay, to suppress to result from the artifactual epochs that cochannel NTSC that frequency is bordering on the anolog TV signals component of video carrier and color subcarrier disturbs.
Figure 12 shows that a kind of Figure 10 cochannel NTSC interference search gear 44 of 344 that is numbered, it is suitable for the symbol decoding device of Fig. 7 especially.In this cochannel NTSC interference search gear 344, the 3rd deferred mount 3441 of 1368 symbols of NTSC band resistance comb filter provides the differential delay of 2 video line time of delays to suppress the artifactual epochs that cochannel NTSC disturbs.
Figure 13 shows that a kind of Figure 10 cochannel NTSC interference search gear 44 of 444 that is numbered, it is suitable for the symbol decoding device of Fig. 8 especially.In this cochannel NTSC interference search gear 444, the 3rd deferred mount 4441 of 179,208 symbols of NTSC band resistance comb filter provides the differential delay of 262 video line time of delays to suppress the artifactual epochs that cochannel NTSC disturbs.
Figure 14 shows that a kind of Figure 10 cochannel NTSC interference search gear 44 of 544 that is numbered, it is suitable for the symbol decoding device of Fig. 9 especially.In this cochannel NTSC interference search gear 544, provide the deferred mount 5441 of 718,200 symbols of the differential delay of 2 video frame-delay times to select the 3rd deferred mount of comb filter as the NTSC that is used to suppress the artifactual epochs that cochannel NTSC disturbs.
Figure 15 shows that certain is numbered Figure 10 cochannel NTSC interference search gear 44 of 044 and how can shares to be numbered in 020 the NTSC band resistance comb filter 20 and postpone 4431 as the 4th of first decay part.First remaining part 0201 that postpones and the 4th decay part 4431 connect so that different delay input signals is offered node 440, thus the subtrahend and the minuend input signal of generation digital subtractor 0202.Subtracter 0202 is as first linear combiner of NTSC band resistance comb filter 020.The difference output signal of subtracter 0202 offers its NTSC band resistance comb filter response as the input signal of magnitude detector 445, in addition the response of NTSC band resistance comb filter is offered even level data limiter 24 as input signal.The 3rd postpones the 441 cascade elements 4431 and 0201 by first delay that NTSC band resistance comb filter 020 also is provided provides; Subtracter 442 is provided by the subtracter 0262 in the NTSC band resistance comb filter 020.Therefore, in Figure 15, element 441 and 442 is included in the NTSC band resistance comb filter 020, and is not to occur in the mode of separating.The symbol internal interference of being introduced by NTSC band resistance comb filter 020 is numbered as 026 ISI inhibition comb filter 26 inhibition, and this ISI suppresses comb filter 26 and uses mould 8 digital adders 0262 as second linear combiner.
Figure 16 shows that another general type of the cochannel NTSC interference search gear 46 of the DTV television receiver that is included among Fig. 1 and Fig. 3.Node 460 receives the input signal of cochannel interference search gear 44, and this input signal can be the I channel baseband signal or the Q channel baseband signal of the equilibrium that provides respectively by Fig. 1 DTV signal receiver or by the Symbol Synchronization Circuit 16 of Fig. 3 DTV signal receiver.This input signal also can be by Fig. 1 DTV signal receiver after improving or the balanced I channel baseband signal or the balanced Q channel baseband signal that are provided by the compound demodulator 14 of Fig. 3 DTV signal receiver after improving.In the detector 46 in a NTSC band resistance comb filter, the input signal that the 5th deferred mount 461 will offer node 440 carries out the delay of difference to produce the addend input signal of digital adder 462, from adder 462 output with signal be a NTSC band resistance comb filter response R, the artifactual epochs of the synchronizing detection that results from described cochannel interference simulation TV signal wherein is suppressed.In detector 46, a NTSC selects in the comb filter, the input signal that the 6th deferred mount 463 will offer node 460 carries out the delay of difference to produce the addend input signal of digital adder 464, from adder 464 output with signal be that a NTSC selects comb filter response S, the artifactual epochs of the synchronizing detection that results from described cochannel interference simulation TV signal wherein is reinforced.In cochannel interference search gear 46, the DC terms of system performance that results from the synchronizing detection of pilot signal is selected all to be reinforced among the comb filter response S at NTSC band resistance comb filter response R and NTSC, and all is suppressed not resembling in cochannel interference search gear 44.
NTSC from adder 462 selects the amplitude of comb filter response R to be surveyed by magnitude detector 465, NTSC from adder 464 is with the amplitude of resistance comb filter response S to be surveyed by magnitude detector 466, the result that magnitude detector 465 and 466 amplitudes are surveyed is compared to transmit a carry-out bit by amplitude comparator 467, and this carry-out bit represents in fact whether the response of magnitude detector 466 surpass the response of magnitude detector 465.This carry-out bit is used for selecting between second and the third state of multiplexer 261 operations.For example, can be controller 28 from this carry-out bit of amplitude comparator 467 suppresses to offer in the comb filter 26 in two control bits of multiplexer 261 one at the ISI-of Fig. 1 or Fig. 3.Another control bit represents whether the signal that controller 28 provides is reproduced in the response of multiplexer 261.
Mode by example, magnitude detector 465 and 466 can be to have envelope (envelope) detector that equals several data sampling interlude constants, thereby makes the difference in the data part of their input signals trend towards reaching the low value (supposing that these data components are random value) of balance.Amplitude difference in following adder 462 and 464 and random noise output signal and DC terms also trends towards the null value that reaches average.Correspondingly, when the amplitude probe response difference of amplitude comparator 467 expression magnitude detectors 465 and 466 during greater than the amount of a regulation, just show that in the baseband signal that offers node 460 artifactual epochs of any cochannel interference simulation TV signal is higher than a level of significance.This effective level is corresponding to the level of significance of the I channel baseband signal of the equilibrium that is applied to odd level data limiter 22.As long as the artifactual epochs of cochannel interference simulation TV signal is maintained under this level of significance, can be corrected by trellis and Read-Solomon error correction coding by the error in the symbol decoding that the I channel baseband signal is carried out simple data restriction gained.
The artifactual epochs that cochannel NTSC disturbs is suppressed in the comb filter response R from adder 462, and the artifactual epochs that cochannel NTSC disturbs is selected in the comb filter response S from adder 464.When the amplitude of comb filter response S during in fact greater than the amplitude of comb filter response R, this species diversity can be thought what the artifactual epochs's that the cochannel NTSC by node 460 places disturbs existence caused.Therefore the carry-out bit that is provided by amplitude comparator 467 makes multiplexer 261 can not operate at its second state in this case, does not select the interim symbol decoding that produced by the odd level data limiter 22 last symbol decoded result as multiplexer 261.
When in fact the amplitude of comb filter response S is not more than the amplitude of comb filter response R, this artifactual epochs who does not have difference can be considered to show in the signal of node 460, not exist cochannel NTSC to disturb.The carry-out bit that is provided by amplitude comparator 467 makes multiplexer 261 can not operate in its third state in this case, does not therefore select to suppress the last symbol decoded result of the symbol decoding result of filtering as multiplexer 261 by the ISI-that second linear combiner 262 produces.
Figure 17 shows that a kind of Figure 106 cochannel NTSC interference search gear 46 of 244 that is numbered, it is suitable for the symbol decoding device of Fig. 6 especially.The adder 462 of the 5th deferred mount 2461 in comb filter and input signal between provide the difference time-delay of 6 symbols, this comb filter to be used to suppress to be accompanied by the baseband signal that offers node 460 cochannel NTSC disturb the artifactual epochs.These artifactual epochs result from the anolog TV signals component that frequency is bordering on video carrier, color subcarrier.The adder 464 of the 6th deferred mount 2463 in comb filter and input signal between the cochannel NTSC that frequency is bordering on video carrier, color subcarrier that results from of the baseband signal that provides the difference time-delay of 12 symbols, this comb filter to be used to strengthen being accompanied by to offer node 460 disturb the artifactual epochs.
Figure 18 shows that Fig. 1 DTV signal receiver described so far according to the further improved structure of the present invention, thereby can utilize even level data limiter A24, B24 and the C24 of a plurality of concurrent workings, each even level data limiter front corresponding NTSC band resistance comb filter, back ISI-of corresponding connection suppresses comb filter.Even level data limiter A24 converts the response of the NTSC band stop filter A20 of the first kind to the first pre-coded symbols decoded result that the ISI-that is used for the first kind suppresses comb filter A26.Even level data limiter B24 converts the response of the NTSC band stop filter B20 of second type to the second pre-coded symbols decoded result that the ISI-that is used for second type suppresses comb filter B26.Even level data limiter C24 converts the response of the NTSC band stop filter C20 of the 3rd type to the 3rd pre-coded symbols decoded result that the ISI-that is used for the 3rd type suppresses comb filter C26.Odd level data limiter 22 provides interim symbol decoding result to suppress comb filter A26, B26 and C26 to ISI-.Prefix A in the reference numbers of Figure 18 part, B and C distinguish corresponding different integer at those integers 2,3,4 and 5 when adopting as Fig. 6,7,8 and 9 as shown in those when receiver section.
The cochannel interference search gear A44 of the first kind determines how reduce the cochannel interference effect in the anolog TV signals of NTSC band stop filter A20 from the I channel signal of current equilibrium of the first kind from the Q channel signal.The cochannel interference search gear B44 of second type determines how reduce the cochannel interference effect in the anolog TV signals of NTSC band stop filter B20 from the I channel signal of current equilibrium of second type from the Q channel signal.The cochannel interference search gear C44 of the 3rd type determines how reduce the cochannel interference effect in the anolog TV signals of NTSC band stop filter C20 from the I channel signal of current equilibrium of the 3rd type from the Q channel signal.The inhibition of the pilot signal in the Q channel signal is beneficial to cochannel interference search gear A44, B44 and C44 provides the NTSC band to hinder the demonstration of the relative efficiency of comb filter A20, B20 and C20.
Symbol decoding selects circuit 90 to produce a best-estimated that is applied to the correct symbol decoding of Data Assembler 30.This best-estimated is in the ideal symbol decoded result by slave controller 28, suppress comb filter A26, B26 and C26 from the interim symbol decoding result neutralization of odd level data limiter 22 from ISI-ISI-suppresses to select to produce the symbol decoding result of filtering.Symbol decoding is selected the efficient indication of circuit 90 responses from cochannel interference search gear A44, B44 and C44, to be formulated this best-estimated, unless controller 28 selects circuit 90 to provide further symbol to select information to symbol decoding.Select information by the further symbol that controller 28 provides, comprise that indication, which indication that when synchronous coding produces make according to coming the ideal symbol decoded result of self-controller 28 to make this best-estimated (estimate).This best-estimated of symbol decoding result is used for correcting the preferential embodiment coupling comb filter A26 of Figure 18 DTV signal receiver, the cumulative process among B26, the C26.
If cochannel interference search gear A44, B44 and C44 indicate except when synchronous code on the time period beyond when occurring, the artifactual epochs of the essence of disturbing from cochannel NTSC not, the then symbol decoding selects circuit 90 to select the best-estimated as correct symbol decoding result from the interim symbol decoding result of odd level physical constraints device 22.This makes Johnson (Johnson) noise reduce to minimum to the influence of symbol decoding.
If cochannel interference search gear A44, B44 and C44 have an indication at least except when synchronous code on the time period beyond when occurring, the artifactual epochs that the essence of disturbing from cochannel NTSC is arranged, the then symbol decoding selects circuit 90 to select to suppress comb filter A26 from ISI-, the ISI-of B26 and C26 suppresses the symbol decoding result of filtering, and ISI-suppresses comb filter and lays respectively at by cochannel interference search gear A44, B44 and C44 determine suppresses the artifactual epochs's that disturbs from cochannel NTSC NTSC band resistance comb filter A20 best, the back of B20 and C20.
The high-octane demodulation artifactual epochs who results from response simulation television synchronizing pulse, equalizing pulse and the color burst is suppressed when the NTSC band hinders the frame of video of comb filter A20 stack ground combined and alternatively.And the artifactual epochs who results from indeclinable anolog TV signals video content between two frames is suppressed, and eliminates static pattern and does not consider their spatial frequency and color.The cochannel interference search gear A44 of Figure 18 and the symbol decoding circuit of Fig. 9 together use.
All the other problems that suppress the artifactual epochs of demodulation mainly are to consider to suppress the artifactual epochs that those result from some pixel location frame and frame difference in the anolog TV signals grating.The artifactual epochs of these demodulation can be suppressed by filtering technique in the frame.Can be by being correlated with according to horizontal direction, select NTSC band resistance comb filter B20 and ISI-to suppress comb filter B26 circuit, suppress to remain the demodulation human error, and relevant by according to vertical direction selects NTSC band resistance comb filter C20 and ISI-to suppress comb filter C26 circuit to suppress residue demodulation human error.Consider how such design decision can be by further perfect.
The sound carrier of supposing a cochannel interference simulation TV signal is suppressed by the SAW filtering in the IF amplifier chain 12 or a sound trap.NTSC band resistance comb filter B20 and ISI-inhibition comb filter B26 circuit preferably select NTSC band resistance comb filter 220 and ISI-among similar Fig. 6 to suppress comb filter 226 circuit typess so.This is because the inversely related between the video part is separated by each other and is had only 6 symbol time of occurrences (be better than usually being associated between the video part be separated by each other 12 symbol time of occurrences).The cochannel interference search gear B44 of Figure 11 and Fig. 6 symbol decoding circuit together use.
The optimal selection that NTSC band resistance comb filter C20 and ISI-suppress comb filter C26 circuit is not too direct.It is that the field interweaves that cochannel disturbs the NTSC signal.Whether the nearer line in space in temporary transient nearer scan line or the previous field in current scan line and the same field among the NTSC band resistance comb filter C20 is made up so must make one's options.Select scan line interim nearer in same normally better to select, suppress because the suddenly switching between the field is unlikely destroyed NTSC by comb filter C20.Use this selection, NTSC band resistance comb filter 320 and ISI-that NTSC band resistance comb filter C20 and ISI-suppress among the similar Fig. 7 of comb filter C26 circuit suppress comb filter 326 circuit typess.The cochannel interference search gear C44 of Figure 12 and Fig. 7 symbol decoding circuit together use.
The another kind of selection is that NTSC band resistance comb filter 420 and ISI-that NTSC band resistance comb filter C20 and ISI-suppress among the similar Fig. 8 of comb filter C26 circuit suppress comb filter 426 circuit typess.The cochannel interference search gear C44 of Figure 13 and Fig. 8 symbol decoding circuit together use.
Figure 19 shows that the improvement of Figure 18 DTV signal receiver, cochannel interference search gear A44, B44 wherein and C44 survey the artifactual epochs's of the cochannel NTSC interference in the Q channel baseband DTV signal existence, rather than survey the artifactual epochs's of the cochannel NTSC interference in the I channel baseband DTV signal existence.Survey the artifactual epochs's of the cochannel NTSC interference in the I channel baseband DTV signal existence, as what done in Figure 18 DTV signal receiver, preferably make cochannel interference search gear A44, B44 and C44 and NTSC band resistance comb filter A20, B20 and C20 share decay part.
Technical staff in the DTV receiver design field can design other embodiment of the present invention according to above-mentioned disclosed content, but includes in the described scope of claims subsequently.For example, also use the ISI rejects trap of other form in embodiments of the present invention, the U.S. Patent number that is entitled as " can reduce the VSB HDTV transmission system that the NTSC cochannel disturbs " that the ISI rejects trap of other form is to authorize on February 11st, 1992 Citta and Sgrignoli is 5, open in 087,975 the invention.

Claims (28)

1. the digital television signal receiver of a digital television signal, this digital television signal is received as the vestigial sideband amplitudemodulation signal of a carrier wave, and this digital television signal is easy to be attended by the cochannel interference simulation TV signal of the intensity that does not meet the requirements often, and described digital television signal receiver comprises:
Amplifying circuit is used to provide the digital television signal of the vestigial sideband amplitudemodulation of amplification;
Demodulator circuit, it responds the digital television signal of the vestigial sideband amplitudemodulation of described amplification, so that at least one baseband signal to be provided;
One I-channel baseband signal is carried out symbol decoding to produce symbol decoding result's symbol decoding device, connected described symbol decoding device, receive the I channel baseband signal as input signal from described demodulator circuit, described symbol decoding device comprises:
One can select the filter that moves, being used to suppress to be accompanied by will be by the artifactual epochs of any cochannel interference simulation TV signal of the I channel baseband signal of symbol decoding, during and if only if the symbol decoding device receives signal that effective dose that an indication has cochannel NTSC to disturb exists, described filter just moves;
Error correction circuit is used for proofreading and correct the error from the symbol decoding result of symbol decoding device;
A connected cochannel interference search gear, receive a further base-band input signal from described demodulator circuit, described cochannel interference search gear is a kind of detector of the insensitive type of DC terms of the system function to the baseband signal in the input signal that it received, and it comprises:
One first comb filter, the signal combination that described further base-band input signal and himself are postponed through the first differential delay amount to be to produce the response of first comb filter, and wherein the artifactual epochs who produces from the synchronizing detection of described cochannel interference simulation TV signal is suppressed;
One second comb filter, the signal combination that described further base-band input signal and himself are postponed through the second differential delay amount to be to produce the response of second comb filter, and wherein the artifactual epochs who produces from the synchronizing detection of described cochannel interference simulation TV signal is reinforced;
One first magnitude detector is used to survey the amplitude that described first comb filter responds, to produce the first amplitude probe response;
One second magnitude detector is used to survey the amplitude that described second comb filter responds, to produce the second amplitude probe response; And
Amplitude comparator is used for the more described first and second amplitude probe responses, and the difference of and if only if described first and second amplitude probe responses provides the described signal that has described cochannel to disturb effective dose to exist that shows when surpassing an ormal weight.
2. the digital television signal receiver of claim 1, wherein said demodulator circuit comprises:
The compound demodulator of the vestigial sideband amplitudemodulation digital television signal of a described amplification of response, be used for providing being applied in the I channel baseband signal of described symbol decoding device, and be used to provide the artifactual epochs's who comprises further any cochannel interference simulation TV signal Q channel baseband signal as its input signal.
3. the digital television signal receiver of claim 2, wherein said Q channel baseband signal from compound demodulator is used to described further baseband signal is applied in the cochannel interference search gear as its input signal.
4. the digital television signal receiver of claim 2, wherein said I channel baseband signal from compound demodulator is used to described further baseband signal is applied in the cochannel interference search gear as its input signal.
5. the digital television signal receiver of claim 1, wherein said first comb filter is a kind of signal difference ground combination that described further base-band input signal and himself are postponed through the described first differential delay amount producing the comb filter of described first comb filter response, and wherein said second comb filter is a kind of will described further base-band input signal the combination to produce the comb filter that described second comb filter responds with himself signal difference ground through described second differential delay amount delay.
6. the digital television signal receiver of claim 5, the wherein said second differential delay amount is 6 symbol time of occurrences.
7. the digital television signal receiver of claim 6, the wherein said first differential delay amount is 12 symbol time of occurrences.
8. the digital television signal receiver of claim 6, the wherein said first differential delay amount is the duration of 1368 symbol time of occurrences or 2 ntsc video scan lines.
9. the digital television signal receiver of claim 6, the wherein said first differential delay amount is the duration of 179,208 symbol time of occurrences or 262 ntsc video scan lines.
10. the digital television signal receiver of claim 6, the wherein said first differential delay amount is the duration of 718,200 symbol time of occurrences or 2 ntsc video frames.
11. the digital television signal receiver of claim 1, wherein said first comb filter is a kind of signal accumulation ground combination that described further base-band input signal and himself are postponed through the described first differential delay amount producing the comb filter of described first comb filter response, and wherein said second comb filter is a kind of described further base-band input signal to be made up to produce the comb filter that described second comb filter responds through the signal accumulation ground that the described second differential delay amount postpones with himself.
12. the digital television signal receiver of claim 11, the wherein said first differential delay amount is 6 symbol time of occurrences.
13. the digital television signal receiver of claim 12, the wherein said second differential delay amount is 12 symbol time of occurrences.
14. the digital television signal receiver of a digital television signal, this digital television signal is received as the vestigial sideband amplitudemodulation signal of a carrier wave, and this digital television signal is easy to be attended by the cochannel interference simulation TV signal of the intensity that does not meet the requirements often, and said digital television signal receiver comprises:
Amplifying circuit is used to provide the digital television signal of the vestigial sideband amplitudemodulation of amplification;
Demodulator circuit, it responds the digital television signal of the vestigial sideband amplitudemodulation of described amplification, so that at least one baseband signal to be provided;
Connected symbol decoding device, it is from the I channel baseband signal of described demodulator circuit reception as an input signal, and this I channel baseband signal comprises the artifactual epochs of any cochannel interference simulation TV signal;
Be included in first data limiter in the described symbol decoding device, be used for described I channel baseband signal being carried out symbol decoding to produce the first symbol decoding result at least the first period;
Be included in first comb filter in the described symbol decoding device, the signal combination that is used for described I channel baseband signal and himself are postponed through the first differential delay amount to be to produce the response of first comb filter, and wherein the artifactual epochs who produces from the synchronizing detection of described cochannel interference simulation TV signal is suppressed;
Be included in second data limiter in the described symbol decoding device, be used for described first comb filter response being carried out symbol decoding to produce the second symbol decoding result in second period;
Be included in second comb filter in the described symbol decoding device, the signal combination that is used for selecteed symbol decoding result and itself are postponed through the second differential delay amount is to produce last symbol decoding result, correspondence is in the described first symbol decoding result in first period with in the described second symbol decoding result in second period as a result for described selecteed symbol decoding, and the described first differential delay amount has identical symbol time of occurrence with the second differential delay measurer;
Error correction circuit, be used for correcting the error of last symbol decoded result, as long as artifactual epochs's intensity in described I channel baseband signal of any cochannel interference simulation TV signal is weaker than the described intensity that does not meet the requirements, described error correction circuit can be corrected described selected as the error among described last symbol decoding result's the first symbol decoding result; And
The cochannel interference search gear, be used for receiving a further base-band input signal from described demodulator circuit, described cochannel interference search gear is a kind of detector of the insensitive type of DC terms of system function of the baseband signal to its input signal of conduct that it received, and comprising:
One the 3rd comb filter, the signal combination that described further base-band input signal and himself are postponed through the 3rd differential delay amount, to produce one the 3rd comb filter response, the artifactual epochs who wherein results from the synchronizing detection of described cochannel interference simulation TV signal is suppressed;
One the 4th comb filter, the signal combination that described further base-band input signal and himself are postponed through the 4th differential delay amount, to produce one the 4th comb filter response, the artifactual epochs who wherein results from the synchronizing detection of described cochannel interference simulation TV signal is reinforced;
First magnitude detector is used to survey described the 3rd comb filter response amplitude, to produce one first amplitude probe response;
Second magnitude detector is used to survey described the 4th comb filter response amplitude, to produce one second amplitude probe response; And
An amplitude comparator that is used for the more described first and second amplitude probe responses, and the difference of and if only if described first and second amplitude probe responses is when surpassing an ormal weight, the intensity that shows the cochannel interference simulation TV signal in described I channel baseband signal is enough strong, thereby make error correction circuit can not correct on request from the error among the first symbol decoding result of described first data limiter, this indication result as an order that offers described second comb filter to select result except the described first symbol decoding result as described last symbol decoding result.
15. the digital television signal receiver of claim 14, wherein said demodulator circuit comprises the compound demodulator of the vestigial sideband amplitudemodulation digital television signal of a described amplification of response, be used for providing and be applied in the I channel baseband signal of described symbol decoding device as its input signal, and being used to provide the Q channel baseband signal, this Q channel baseband signal comprises the further artifactual epochs of any cochannel interference simulation TV signal.
16. the digital television signal receiver of claim 15, wherein said Q channel baseband signal from compound demodulator is used to described further baseband signal is applied in the cochannel interference search gear as its input signal.
17. the digital television signal receiver of claim 15, wherein said I channel baseband signal from compound demodulator is used to described further baseband signal is applied in the cochannel interference search gear as its input signal.
18. the digital television signal receiver of claim 14, wherein said second comb filter is in the 3rd period of appointment, selected a preferred symbol decoding result as described last symbol decoding result, obtain wherein said second period is to give the described instruction of described second comb filter selecting result except the described first symbol decoding result as described last symbol decoded result when described amplitude comparator beyond described the 3rd period, and that obtain wherein said first period is the result who obtains except the described second and the 3rd period.
19. the digital television signal receiver of claim 14, wherein said the 3rd comb filter is a kind of signal difference ground combination that described further base-band input signal and himself are postponed through described the 3rd differential delay amount producing the comb filter of described the 3rd comb filter response, and wherein said the 4th comb filter is a kind of will described further base-band input signal the combination to produce the comb filter that described the 4th comb filter responds with himself signal difference ground through described the 4th differential delay amount delay.
20. the digital television signal receiver of claim 19, wherein said the 4th differential delay amount is 6 symbol time of occurrences.
21. the digital television signal receiver of claim 20, wherein said first, second and the 3rd differential delay amount all are 12 symbol time of occurrences.
22. the digital television signal receiver of claim 20, wherein said first, second and the 3rd differential delay amount all are the duration of 1368 symbol time of occurrences or 2 ntsc video scan lines.
23. the digital television signal receiver of claim 20, wherein said first, second and the 3rd differential delay amount all are the duration of 179,208 symbol time of occurrences or 262 ntsc video scan lines.
24. the digital television signal receiver of claim 20, wherein said first, second and the 3rd differential delay amount all are the duration of 718,200 symbol time of occurrences or 2 ntsc video frames.
25. the digital television signal receiver of claim 14, wherein said the 3rd comb filter is a kind of signal accumulation ground combination that described further base-band input signal and himself are postponed through described the 3rd differential delay amount producing the comb filter of described the 3rd comb filter response, and wherein said the 4th comb filter is a kind of described further base-band input signal to be made up to produce the comb filter that described the 4th comb filter responds through the signal accumulation ground that described the 4th differential delay amount postpones with himself.
26. the digital television signal receiver of claim 25, wherein said the 3rd differential delay amount is 6 symbol time of occurrences.
27. the digital television signal receiver of claim 26, wherein said the 4th differential delay amount is 12 symbol time of occurrences.
28. the digital television signal receiver of claim 25, wherein said first, second and the 3rd differential delay amount all are 6 symbol time of occurrences.
CN98119617A 1997-09-19 1998-09-18 NTSC interference detectors using comb filters that suppress DTV pilot carrier to extract NTSC artifacts Expired - Fee Related CN1128550C (en)

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