MXPA98007649A - Interference detectors of the committee of the national television system that uses wave filters suppress the digital television pilot carrier to remove the artifacts from the committee of the television system nacio - Google Patents

Abstract

The present invention relates to a first wave filter differentially combining a baseband signal of the Q or I channel supplied as a delivery signal to an interference detector of the shared NTSC channel for a DTV receiver with this signal being subjected to a first differential delay, to generate a first wave filter response in which artifacts that are generated from the synchronous detection of the shared channel that interferes with the analogue television signal are eliminated, but a direct term is reinforced attributable to the pilot carrier wave which is detected synchronously. The detector includes a second wave filter that differentially combines the input signal with this signal is subjected to a second amount of differential delay to generate a second response of the wave filter in which the artifacts of the shared channel are reinforced as well as the term direct attributable to the pilot carrier wave that is detected synchronously. The amplitudes of the first and second response of the wave filter are detected by the first and second amplitude detectors, respectively. A judgment comparator compares the first and second response of the amplitude detection and indicates, when and only when the first and second response of the amplitude detection differ more than a prescribed amount, that the interfering shared channel is of sufficient intensity to be reprobab

Description

INTERFERENCE DETECTORS OF THE COMMITTEE OF THE NATIONAL TELEVISION SYSTEM THAT USES WAVE FILTERS THAT REMOVE THE DIGITAL TELEVISION PILOT CARRIER TO REMOVE THE ARTIFACTS FROM THE COMMITTEE OF THE NATIONAL TELEVISION SYSTEM FIELD OF THE INVENTION The present invention relates to digital television systems, and more particularly, circuits used in digital television receivers (DTV) to determine whether or not there is interference of a shared channel or co-channel in the signals of Analog television of the National Television System Committee (NTSC).

BACKGROUND OF THE INVENTION A Digital Television Standard published on September 16, 1995 by the Advanced Television System Committee (ATSC) specifies the bandwidth signals resulting from residual modulation (VSB) for transmitting digital television signals ( DTV) in the television channels with a bandwidth of 6 MHz these are currently used in the live transmission of the National Television System Committee (NTSC) analog to television signals within the United States. The VSB DTV signal was designed in such a way that its spectrum is REF .: 28437 similar to the inter-stratification with the spectrum of a shared channel that interferes with an analog TV signal NTSC. This is done by placing the pilot carrier wave and the main frequencies of the band resulting from the amplitude modulation of the DTV signal in multiple pairs of the horizontal scanning line speed of a quarter of the NTSC TV analog signal. This causes these components of the DTV signal to fall between multiple odds of the horizontal scanning line speed of a quarter of the NTSC analog TV signal in which multiple pairs can fall on most of the power of the luminance and chrominance components of a co-channel that interferes with the analog NTSC TV signal. The video carrier wave of an analog NTSC TV signal shifts to 1.25 MHz from the lower frequency limit of the television channel. The carrier wave of the DTV signal is shifted from such a video carrier wave by 59.75 times the speed of the horizontal scanning line of the analog NTSC TV signal, to place the carrier wave of the DTV signal about 309.877.6 kHz. limit of the lower frequency of the television channel. Accordingly, the carrier wave of the DTV signal is about 2.690122.4 Hz of the average frequency of the television channel.

The exact symbol speed in the Digital Television Standard is (684/286) times the carrier wave of the 4.5 MHz sound shifted by the video carrier wave in the analog NTSC TV signal. The number of symbols per horizontal scan line in an analog NTSC TV signal is 684 and 286 is the factor by which the speed of the horizontal scan line in the analog NTSC TV signal is multiplied to obtain the sound carrier wave 4.5 MHz shifted from the video carrier wave to an analog NTSC TV signal. The speed of the symbol is 10.762238 million symbols per second, which can be obtained in a signal that extends 5.381119 MHz of the DTV carrier wave. That is, the VSB signal can be limited to a band that extends 5.690997 MHz from the lower limit of the frequency of the television channel. The ATSC standard for the terrestrial transmission of the digital DTV signal in the United States of America is capable of transmitting two formats of high definition television (HDTV) with a 16: 9 aspect ratio of the image. An HDTV image format uses 1920 samples per scan line and 1080 active horizontal scan lines per 30 MHz bit cycle with an interlaced 2: 1 scanning field. The other HDTV image format uses 12.80 luminance samples per scan line and 720 scan lines progressively scanned from the television image per 60 Hz bit cycle. The ATSC standard also adapts the transmission of DTV image formats instead of HDTV image formats, such that the parallel transmission of the television signals have a normal definition compared to an analog NTSC television signal. The DTV transmitted by a residual band resulting from the modulation (VSB) of amplitude modulation (AM) during ground transmission in the United States of America comprises a succession of consecutive data fields in time each containing 313 data segments consecutive in time. The data fields can be considered to be consecutively numbered module-2, with each odd numbered data field and the next even numbered data field forming a cycle of data bits. The bit rate is 20.66 bit cycles per second. Each data segment is 77.3 microseconds in duration. Each data segment starts with a group of inline synchronization characters of four symbols that have successive values of + S, -S, -S and + S. The value + S is one level above the digression of the maximum negative data, and the value -S is one level below the digression of the maximum negative data. The initial line of each data field includes a group of synchronization characters that encodes an orientation signal for channel-equalization procedures and multidirectional elimination. The orientation signal is a pseudoruide sequence with 511 samples (or "PN sequence") followed by three PN sequences with 63 samples. Half of the PN sequences with 63 samples in the field synchronization codes are transmitted according to a first logical convention in the first line of each data field numbered with pairs and according to a second logical convention in the first line of each field of numbered data with odd, the first and second logical conventions that are complementary respectively with the others (that is, of opposite polarity senses).

The data within the data segments are coded in trellis or trellis form, using twenty interlayered lattice codes, each of the lattice codes with 2/3 ratio with a decoded bit. Interlaced lattice codes are subject to Reed-Solomon progressive error correction coding, which is provided for the correction of synchronization bit errors that originate due to noise sources such as an ignition system of an overdraft near. The results of the Reed-Solomon coding are transmitted as coding of one-dimensional constellation symbols (3 bits / symbol) level 8 for live transmission, such transmissions are made without precoding of symbols away from the trellis coding procedure. The results of Reed-Solomon coding are transmitted as coding of one-dimensional constellation symbols (4-bit symbol) level 16 for cable projection, such transmissions are made without precoding. The VSB signals have their natural carrier wave, which varies in amplitude depending on the percentage of modulation, suppressed. The natural carrier wave is replaced by a fixed-amplitude pilot carrier wave, such amplitude corresponds to a prescribed percentage of modulation. This fixed amplitude pilot carrier wave is generated by introducing a direct component of change in the modulation voltage applied to the balanced modulator that generates the band resulting from the amplitude modulation that is supplied to the filter that supplies the VSB signal as its response. If the eight levels of 4-bit symbol coding have normalized values of -7, -5, -3, -1, +1, +3, +5 and +7 on the carrier wave that modulates the signal, the carrier wave pilot has a normalized value of 1.25. The normalized value of + S is +5, and the normalized value of -S is -5. In the previous development of the DTV technique it was contemplated that the DTV transmission may resort to deciding whether or not to use a symbol precoder in the transmitter, such a symbol precoder could follow the set of circuits for the generation of symbols and provide a balanced filtering of symbols, when used in conjunction with a wave filter in each DTV signal receiver used before the data transducer in the set of symbol decoding circuits as a decoder. This decision will depend on whether or not the interference of an NTSC transmission station of a shared channel is expected. The precoding has not been used for the synchronization of the data line of the character groups or during the data alignment in which the synchronization data of the data field is transmitted. The interference of a shared channel at greater distances from the NTSC transmission station (s) is more likely to occur when certain ionospheric conditions are obtained, the summer months during the years of high solar activity that are notorious by the probability of interference of additional or co-channel channels. This interference will not be obtained of course if there are no additional channels of NTSC transmission stations. If there is a probability of NTSC interference within the coverage area of the transmission, it is presumed that the HDTV transmission will be used by the symbol precoder to facilitate the HDTV signal to be more easily separated from the NTSC interference. Accordingly, a wave filter or periodic frequency transfer configuration has been used as a symbol postcoder in the DTV signal receiver to complete the balanced filtering or adjustment. It is assumed that the DTV transmission would discontinue the use of the symbol precoder and there would be possibilities of NTSC interference. According to this, the post-encoder of symbols in each DTV signal receiver would be disabled, so that the flat spectrum noise would have less chance of causing erroneous decisions regarding the values of the symbols in the treññis decoder. The North American Patent No. 5, 260,793 issued November 9, 1993 by R. W. Citta et al and entitled "RECEIVER POST CODER SELECTION CIRCUIT" selectively employs a wave post-encoder filter. The filter suppression artifacts of the co-channel NTSC interference that accompanies an in-phase or real baseband component (channel I) of the complex output signal of a demodulator used in a DTV signal receiver. The presence of interference from these artifacts in the channel I component of the demodulator response is detected to develop automatic control signals to make it possible or desirable to enable or disable the suppression of artifacts from the interference of the shared channel or co-channel NTSC through wave filtering. During each data field synchronization interval, the input signal and the output signal of a wave filter type elimination filter in the receiver of the DTV signal each are compared with a respective signal known as a first. and it is extracted from the memory inside the HDTV signal receiver. If the minimum comparison result with the input signal has less energy than the minimum comparison result with the output signal of the NTSC elimination filter, it is indicative that the main cause of variation of the expected reception is erratic noise instead interference of the NTSC shared channel. As regards the digital television receiver DTV, the reception must be better precoded and not using the post-coding in the system, and it is presumed that the transmission does not employ precoding. If the minimum result of the comparison with the input signal has higher power than the result of the comparison with the output signal of the NTSC elimination filter, it is indicative that the main cause of the variation of the expected reception is the interference of the NTSC shared channel instead of erratic noise. As far as the particular digital television signal receiver is concerned, reception should be better by being precoded and by using post-coding in the system, and it is presumed that the transmission employs precoding. U.S. Patent No. 5,546,132 published August 13, 1996 by KS Kim et al and entitled "NTSC INTERFERENCE DETECTOR" discloses the use of the postcoder filter with periodic transfer function to eliminate the interference of the shared channel NTSC when the presence of such interference is detected. in the response of the NTSC elimination wave filter by channel I. US Patent No. 5,546,132 does not specifically disclose a component of the band resulting from the phase quadrature (Q channel) of a complex output signal that is supplied by the demodulator used in a digital DTV signal receiver. A digital DTV signal receiver that synchronizes the VSB AM signals in the resulting band of the modulation commonly employs a demodulator that includes a synchronous in-phase detector to supply signals received from the channel by the lattice decoder (after decoding, if precoding is used in the transmitter). This demodulator also includes a phase quadrature synchronous detector to supply the received signal from the Q channel. The signal received from the Q channel is filtered by the low pass to generate an automatic frequency signal and control phase (AFPC) for the local oscillator that supplies a carrier wave to synchronize. The specifications and drawings of U.S. Patent No. 5,479,449 issued December 26, 1996 by CB Patel and ALR Limberg, entitled "" DIGITAL VSB DETECTOR ITH BANDPASS PHASE TRACKER, AS FOR INCLUSION IN AN HDTV RECEIVER ", and assigned to Samsung Electronics Co., Ltd., is incorporated herein by reference. The attention of the reader is directed specifically to elements 22-27 in Figure 1 of the drawing of US Pat. No. 5,479,449 and the description thereof in the accompanying specification. These elements are used in the receiver of the described HDTV signal to carry out the complex demodulation of the final intermediate frequency signal VSB AM. The North American Patent No. 5, 479,449 describes the complex demodulation of the final IF signal VSB AM that is carried out in the digital regime, but in alternative designs of digital TV receivers for the complex demodulation of the final IF signal VSB AM is performed instead in the analog regime. In both US Patents Nos. 5,260,793 and 5,546,132, post-coding is allowed during times of substantial interference of the shared channel NTSC and otherwise becomes incapacitated, with the control signal for such selective possibility that is developed by the signal received from channel I. determination of NTSC interference levels of the shared channel, are complicated by the direct polarization that accompany the NTSC interference of the shared channel, such direct polarization grows from the synchronous detection in phase of the pilot carrier wave of the signal VSB AM DTV. This is particularly a problem in DTV signal receivers in which the gain control of amplification does not regulate well the amplitude of the signal received from the I channel recovered by synchronous phase detection. The video carrier wave of an NTSC signal is 1.25 MHz from the 6 MHz width end of the transmission channel, while the carrier wave for a DTV signal for terrestrial live transmission is 310 kHz from the end of the transmission width. 6 MHz of the channel transmission. An NTSC signal from the shared channel does not exhibit the resulting bands of amplitude modulation symmetric with respect to the carrier wave of the amplitude modulation with band resulting from the modulation of the residual amplitude (VSB AM) that carries the digital information. Accordingly, the artifacts of the NTSC video carrier wave at 940 kHz are removed from the carrier wave of the DTV signal and the artifacts of these sidebands are not properly canceled in the DTV signal as they are synchrodyzed to the sideband. Of course not, the artifacts of the carrier wave of the NTSC audio and its lateral bands are removed from the carrier wave of the DTV signal, the carrier wave of the NTSC audio that is in 5.44 MHz. The Digital Television Standard published by the ATSC September 16, 1995 that does not allow the use of precoding of all data in the DTV transmitter to compensate for incidental post-coding the subsequent use of wave filtering in a DTV signal receiver to reject interference from the shared NTSC channel. Instead, only the initial symbol in the latched decoding is precoded. This procedure by itself does not provide a DTV signal receiver that uses wave filtering to reject interference from the shared NTSC channel before the data separation procedures are undertaken.

A DTV signal receiver that does not reject the interference artifacts of the NTSC shared channel before data separation procedures are undertaken will not have good reception under strong interference conditions of the shared NTSC channel as may be caused by the DTV setial receiver. It is far from the analog TV transmitter very close. In the DTV signal that is synchronized to the band resulting from the modulation of the artifacts of the video carrier wave of a shared channel that interferes with the color TV signal are at 59.75 fH, fH which are the horizontal scanning frequency of this signal. The artifacts of the color subcarrier wave are at 287.25 fH, and the artifact of the demodulated NTSC audio carrier wave is at 345.75 fH. Wave filtering methods are not entirely satisfactory for removing artifacts from the NTSC frequency carrier wave with frequency modulation, particularly under conditions of frequency modulation where the frequency deviation of the carrier wave is large, the inventor notes. This is due to the correlation and (or anti-correlation) of samples of the FM carrier wave sometimes separated by any fixed substantial delay can not be particularly good. U.S. Patent No. 5,748,226 entitled "DTV RECEIVER ITH FILTER IN 1-F CIRCUITRY TO SUPPRESS FM SOUND CARRIER OF CO-CHANNEL NTSC INTERFERING SIGNAL" issued to the inventor on May 5, 1998 is incorporated herein by reference. In U.S. Patent No. 5,748,226 the inventor recommends that the filtering used to establish the amplification of the intermediate frequency of the total bandwidth be such that the FM audio carrier wave of any shared channel that interferes with the analog signal is rejected. TV NTSC. The filtering procedures are more satisfactory for separating the DTV signal from the band resulting from the modulation of the NTSC video carrier wave artifacts, the lower video frequencies, and the frequencies of the chrominance signal being close to the carrier wave Color, This is because these artifacts tend to exhibit good correlation between the samples separated by certain specific delay intervals and by exhibiting good anti-correlation between samples separated by certain other specific delay intervals. In the North American patent series No. 5,748,226, the inventor advocates to separate the preceding data in the receiver of the DTV signal with a wave filtering to suppress the interference of the shared channel NTSC when this interference is large enough to affect the separation. of data adversely. The inventor shows how to compensate the symbol decoding process by the effects of such wave filtering on the symbol coding when it becomes selective.

This is also useful to be able to determine when the interference of the shared NTSC channel is larger than a given prescribed value that is acceptably small, so this determination can be used to control the selective use of wave filtering to suppress the interference of the shared channel NTSC. The interference of the shared channel NTSC will appear in the component of the band resulting from the modulation of the quadrature of the phase or imaginary (channel Q) of the complex output signal in a DTV signal receiver as long as the interference of the shared channel NTSC appears in the component of the band resulting from the real or phase modulation (channel I) of the complex output signal. Accordingly, an NTSC interference detector can be arranged so that its responses from the NTSC extraction filter respond to the signal received from the Q channel, instead of the signal received from the I channel. By determining whether or not a significant amount of interference of the shared channel NTSC accompanies the signal received from channel Q, it is deductively determined whether or not a significant amount of interference from the shared channel NTSC accompanies the received signal from channel I, such that it causes many errors in lattice or trellis decoding of the received signal from the equalized channel i to be corrected by the Reed Solomon decoder followed by the lattice decoder. The exact determination of the NTSC interference levels of the shared channel tends to be simple, because essentially it does not cause polarization increases of the synchronous detection of the phase quadrature of the pilot carrier wave of the signal VSB AM DTV after the detection apparatus Synchronous has performed the phase synchronization with the pilot carrier wave. An interference detector of the shared channel NTSC that is insensitive to causing increased polarization by synchronous detection of the pilot wave was an object of the invention disclosed in this specification. Such as an interference detector of the shared channel NTSC that accompanies the signal received from channel I allows the direct determination of whether or not a significant amount of interference of the shared channel NTSC accompanies the received signal of channel I without the need for an equalization filter. which eliminates the direct polarization increase from the synchronous detection of the pilot carrier wave. As an equalization filter, it is more difficult to implement than an equalization filter having a zero frequency response. In a DTV signal receiver where whether or not a significant amount of shared channel interference NTSC accompanies the signal received from the I channel is determined indirectly with an interference detector of an NTSC shared channel responsive to the signal received from the Q channel, using an NTSC shared channel interference detector that is insensitive to direct polarization gain from synchronous wave detection 'pilot carrier provided by continuity in the initial adjustment of the equalization of the receiver of the DTV signal.

BRIEF DESCRIPTION OF THE INVENTION The invention is encompassed in a signal receiver (DTV) of digital television for digital television signals that are received as amplitude modulation with residual sideband of a carrier wave and which are apt to be accompanied sometimes by shared channels that interfere with analog television signals of undesirable intensities, such a DTV signal receiver includes a particular type of shared channel interference detector that is insensitive to a direct term of the system function of the circuits preceding it. The receiver of the DTV signal includes amplifier circuits for supplying a digital television signal with amplitude modulation with residual amplified sideband and the demodulation circuits sensitive to the DTV signal with amplitude modulation with residual sideband to supply at least one signal of sideband, whose sideband signal is supplied to the interference detector of the shared channel as its input signal. At least one signal from the sideband includes a signal from the sideband of channel I that contains artifacts from any shared channel that interferes with the analog television signal, supplied to the symbol decoding apparatus included in the DTV signal receiver. The symbol decoding apparatus includes a first data disconnector for decoding the symbols of the baseband signal of the channel I during the first times to generate the first symbol decoding result. The error correction circuits included in the receiver of the DTV signal are connected to correct the errors in the first result of the decoding of symbols while the artifacts of any interference of the channel shared with the analogue television signal are of less intensity in the signal from the baseband of the channel that undesirable intensities'. The interference detector of the shared channel is of the following construction. A first wave filter aurally combines the only signal of the baseband supplied as an input signal to the interference detector of the shared channel, with this the unique signal of the baseband is subjected to a first amount of differential delay, to generate a first response of the wave filter. In this first response of the wave filter, any direct term of the characteristic system originated by the synchronous detection of the carrier wave seems to be reinforced, but the artifacts originated by the synchronous detection of the interference of the shared channel with the analogue television signal are eliminated. One second The wave filter differentially combines the single baseband signal supplied as an input signal to the shared channel or co-channel interference detector with that baseband signal that is subjected to a second amount of differential delay to generate a second response of the wave filter. In this second response of the wave filter the direct term of the system characteristic arising from the synchronous detection of the analog television signal is reinforced. A first amplitude detector detects the amplitude of the first response of the first wave filter to generate an amplitude detection response, and a second amplitude detector detects the amplitude of the second wave filter response to generate a second amplitude detection response. An amplitude comparator compares the first and second amplitude detection responses and indicates, when and only when the first and second amplitude detection responses differ by more than a prescribed amount, this interference of the shared channel in the analog television signal in the baseband signal it is sufficient that the error correction circuits can be unable to consistently correct errors in the first symbol decoding results.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a block diagram of a portion of a digital television receiver that includes a symbol decoder with shared channel interference elimination circuits NTSC which, in accordance with one aspect of the invention, is selectively activated depending on the response of an interference detector of the shared NTSC channel using a wave filter that eliminates the DTV pilot carrier wave to extract the 15 'NTSC artifacts, the detector responds to the signals of the baseband I channel. FIGURE 2 is a flow chart of the operation in a portion of FIGURE 1 of the digital television receiver showing how equalization procedures are modified depending on whether or not wave filtering is employed to eliminate NTSC interference from the shared channel FIGURE 3 is a block diagram of a portion of a digital television receiver that includes a symbol decoder with NTSC shared channel interference elimination circuits which, according to one aspect of the invention, is selectively activated depending on of the response of an interference detector of the shared channel NTSC using a wave filter that eliminates the DTV pilot carrier wave to extract the NTSC artifacts, the detector responds to the signals of the Q channel of the base band. FIGURE 4 is a flow chart of the operation in a portion of FIGURE 3 of the digital television receiver showing how equalization procedures are modified depending on whether or not wave filtering is employed to eliminate NTSC interference from the shared channel FIGURE 5 is a schematic block diagram showing the details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 when the wave filter rejects the NTSC using a delay of 12 symbols. FIGURE 6 is a schematic block diagram showing the details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 when the wave filter rejects the NTSC using a delay of 6 symbols. FIGURE 7 is a schematic block diagram showing the details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 when the wave filter rejects the NTSC using a delay of (1368 symbols) of 2 video lines FIGURE 8 is a schematic block diagram showing the details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 when the wave filter rejects the ÑTSC using a delay of (179,208 symbols) of 262 video lines . FIGURE 9 is a schematic block diagram showing the details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 when the wave filter rejects the NTSC using a delay of (718,200 symbols) of 2 bit cycle Of video. FIGURE 10 is a schematic block diagram of the general form for an interference detector of the shared NTSC channel constructed in accordance with the invention. The detector input signal differentially combines with itself as subject to 6-symbol differential delay in a wave filter used to extract co-channel or shared channel NTSC interference artifacts that are not accompanied by the DTV pilot carrier signal . FIGURE 11 is a schematic block diagram of a species of the co-channel NTSC interference detector, of FIGURE 10, the input signal of which differentially combines with itself as subject to a differential delay of 12 symbols in a wave filter used to suppress artifacts from co-channel NTSC interference. FIGURE 12 is a schematic block diagram of a species of the co-channel NTSC interference detector of FIGURE 10, the input signal of which differentially combines with itself as subject to a differential delay of 1368 symbols or video of 2 lines in a wave filter used to suppress artifacts from co-channel NTSC interference. FIGURE 13 is a schematic block diagram of a species of the co-channel NTSC interference detector of FIGURE 10, the input signal from which differentially combines with itself as subject to a differential delay of 179,208 symbols or video of 262 lines in a wave filter used to suppress artifacts from co-channel NTSC interference. FIGURE 14 is a schematic block diagram of a species of the co-channel NTSC interference detector of FIGURE 10, the input signal of which differentially combines with itself as subject to a differential delay of 718,200 symbols or video of 2 lines in a wave filter used to suppress artifacts from co-channel NTSC interference. FIGURE 15 is a schematic block diagram of a species of FIGURE 10 of the shared channel interference detector NTSC that shares delay elements with the wave filter that rejects the NTSC preceding the data transducer of the receiver level of the receiver. the DTV signal of FIGURE 1. Figure 16 is a block diagram of an alternative general form taken by a co-channel NTSC interference detector constructed in accordance with the invention. The pair of wave filters in the detector of Figure 10, each one additively combines the differentially delayed detector input signal. Figure 17 is a schematic block diagram of a species of the co-channel NTSC interference detector of Figure 16, the input signal of which is additively combined with itself as subject to a differential delay of 6 symbols in a Wave filter used to suppress artifacts from the NTSC interference of the co-channel or shared channel.

Each of FIGURES 18 and 19 is a schematic block diagram of a digital television receiver encompassing the invention, in which the digital television signal receiver, a plurality of wave filters and interference detectors of the NTSC are employed. of co-channel or associated shared channel for selective filtering against NTSC interference artifacts from the co-channel or shared channel.

DETAILED DESCRIPTION OF THE MODALITIES PREFERRED At various points in the circuits shown in the FIGURES of the drawings, oscillating delays have to be inserted so that the operation sequence is corrected, as can be understood by a person skilled in the art in electronic design. Unless there is something out of the ordinary about an oscillating delay requirement, it will not be explicitly referred to in the following specification. FIGURE 1 shows a receiver of the digital television signal used to recover the corrected data from the error, such data is suitable for recording by a digital video cassette recorder (DVDR) or for decoding MPEG-2 and projection on a television set . FIGURE 1 shows the DTV signal receiver as a receiver of television transmission signals from a receiving antenna 8, but can instead receive signals from a cable network. The television transmission signals are supplied as an input signal to the electronic "tuning section" parts 10. The electronic "tuning section" parts 10 generally include a radio frequency amplifier and the first detector for converting the television signals of radio frequency to intermediate frequency television signals, supplied as an input signal to the string 12 of intermediate frequency (IF) amplifiers for residual sideband DTV signals.The receiver of the DTV signal is preferably of a plural type of conversion with the chain 12 of IF amplifiers including an IF amplifier for amplifying the DTV signals that are converted to an ultra high frequency band by the first detector, a second detector for converting the amplified DTV signals to a very high frequency band, and a IF amplifier to amplify the DTV signals that are converted to the VHF band. demodulation of the baseband is developed in a digital regime, the chain of amplifiers IF 12 will also include a third detector to convert the amplified DTV signals to an intermediate frequency band closer to the baseband. Preferably, a surface acoustic wave (SAW) filter is used in the IF amplifier for the UHF band, to form the response of the channel selection and reject the adjacent channels. This SAW filter eliminates rapidly separating only beyond 5.38 MHz the frequency of the suppressed wave of the VSB DTV signal and the pilot carrier wave, which is of similar frequency and fixed amplitude. This SAW filter therefore rejects most of the frequency-modulated sound carrier wave from any shared channel that interferes with the analog TV signal. Eliminating the FM sound carrier wave from any shared channel that interferes with the analog TV signal in the IF 12 amplifier chain prevents artifacts from this carrier wave that are generated when the final IF signal is detected to retrieve the band symbols base and prevent such artifacts from interfering with the transduction of the data of these baseband symbols during decoding. The prevention of such artifacts that interfere with the data transduction of these baseband symbols during symbol decoding is better than when they are performed by transmission in wave filtering prior to data transduction, particularly if the differential delay in the wave filter is greater than a few symbols. The final IF output signals of the IF amplifier chain 12 are supplied to a complex demodulator 14., which demodulates the DTV signal of amplitude modulation with residual sideband in the final intermediate frequency band to recover a signal with real baseband and an imaginary baseband signal. The demodulation can be done in a digital regime after the analog-to-digital conversion of an intermediate frequency band in a range of a few megahertz as described in U.S. Patent No. 5,479,449, for example. Alternatively, the demodulation can be done in the analog or analog regime, in which case the results are usually subject to analog to digital conversion to facilitate further processing. The complex demodulation is preferably done by synchronous demodulation in phase (I) and synchronous demodulation of the quadrature phase (Q). The digital results of the conventional demodulation procedures are 8-bit or more accurate and describe 2N level symbols that encode N bits of the data. Currently, 2N is eight in the case where the DTV signal receiver of FIGURE 1 receives through live transmission by means of antenna 12 and is sixteen in the case where the DTV signal receiver of FIGURE 1 receives the projection by cable. The interest of the invention is with the reception of live transmissions through the surface, and FIGURE 1 does not show the portions of the DTV signal receiver that provides the decoding of symbols and the decoding of the error correction for the transmissions of the projection received by cable. The synchronization and symbol matching circuits 16 receive at least the digitized real samples of the baseband signal (channel I) of the complex demodulator 14.; in FIGURE 1 the receiver of the DTV 16 signal is also shown receiving the imaginary digitized samples of the baseband signal with quadrature of the phase (Q channel). The circuits 16 include a digital filter with adjustable weighting coefficients that compensate for the phantom image and the distortion in the received signal. Synchronization and symbol matching circuits 16 provide symbol synchronization or "de-rotation" as well as equalization of the amplitude and elimination of the phantom image. Synchronization and symbol equalization circuits in which symbol synchronization is performed before equalization of amplitude is known from U.S. Patent No. 5,479,449. In such designs the demodulator 14 will provide response from the oversampled demodulator containing real and imaginary baseband signals to the sync and symbol match circuits 16. After symbol synchronization, the oversampled data was decimated to extract the signal from channel I of the baseband at a normal symbol rate, to reduce the speed of samples through the digital filtering used for the elimination of the ghost image and the equalization of the amplitude. The synchronization and equalization circuits in which the equalization of the amplitude precedes the synchronization of symbols, the "desrotating" or "phase tracking" is also known to a person skilled in the art of designing digital signal receivers. . Each sample of the output signal of the circuits 16 is solved in ten or more bits and is, in effect, a digital description of an analog symbol that exhibits one of the levels 10 (2N = 8). The amplification of the output signal of the circuits 16 is carefully controlled by one of the different methods, so the ideal step levels for the symbols are known. A method of gain control or amplification is preferred because the response speed of such amplification control is exceptionally fast, regulating the direct component of the real baseband signal supplied by the complex demodulator 14 to a normalized level of + 1.25. This method of amplification control is generally described in US Pat. No. 5,579,449 and is more specifically described by C.B. Patel et al in the North American Patent No. 5,573,454 published June 3, 1997, entitled "AUTOMATIC GAIN CONTROL OF RADIO RECEIVER FOR RECEIVING DIGITAL HIGH-DEFINITION TELEVISION SIGNALS, and is incorporated herein by reference. it is supplied as an input signal to the data synchronization detection circuits 18, which retrieves the synchronization information from the data field S of the signal from the base I channel of the matched base.Alternatively, the input signal to the circuits The data synchronization detection means 18 can be obtained before the equalization The samples of the channel signal matched at a normal symbol rate supplied as output signal from the circuits 16 are applied as the input signals to a wave filter. NTSC rejection 20. The wave filter 20 includes a first delay apparatus 201 to generate a pair of currents delayed differentially from the symbols of the 2N level and a first linear combiner 202 to linearly combine the differentially delayed symbol currents to generate the response of the wave filter 20. As described in US Patent No. 5, 260, 793, the first delay apparatus 201 can provide a delay similar to the period of twenty symbols of level 2N, and the first linear combiner 202 may be a subtractive filter. Each sample of the output signal of the wave filter 20 is solved in ten or more bits and is, in effect, a digital description of an analog symbol that exhibits one of the levels (4N-1) = 15. Synchronization and symbol matching circuits 16 are presumed to be designed to eliminate the direct polarized component of its input signal (as expressed in the digital samples), such a direct polarized component has a normalized level of +1.25 and appears in the signal of the real baseband supplied by the complex demodulator 14 due to the detection of the pilot carrier wave. Accordingly, each sample of the output signal of the circuits 16 applied as an input signal of the wave filter 20 in, in effect, a digital description of an analog symbol exhibiting one of the normalized levels: -7, -5, -3, -1, +1, +3, +5, +7. These symbol levels are referred to as "odd" symbol levels and are detected by an odd-level data transducer 22 to generate intermediate symbols that decode results of 000, 001, 010, 011, 100, 101, 110, respectively. sample of the output signal of the wave filter 20 is, in effect, a digital description of an analog symbol that exhibits one of the following normalized levels: -14, 12, -10, -8, -6, -4, - 2, 0, +2, +4, +6, +8, +101 +12 and +14 These levels of symbols are referred to as levels of "even" symbols and are detected by an even-level data transducer 24 to generate precoded symbols that decode results of 001, 010, 011, 100, 101, 110, 111, 000, 001, 010, 011, 100, 101, 110 and 111, respectively, The data transducers 22 and 24 can be the so-called 'big decision' type, as presumed to this point in the description, or it may be of the so-called type of "minor decision" used in the implementation of the Viterbi decoder. Arrays are possible in which the odd-level data transducer 22 and the even-level data transducer 24 are replaced by a simple data transducer, using multiplexer connections to change their place in the circuit and to provide polarization for modify their transduction ranges, but these arrangements are not preferred due to the complexity of the operation.

Synchronization and symbol matching circuits 16 are presumed in the foregoing description to be designed to suppress the direct bias component's input signal (the direct term of the system function as expressed in digital samples), such polarization component direct has a normalized level of +1.25 and appears in the signal of the real baseband supplied by the complex demodulator 14 due to the detection of the pilot carrier wave. Presently the symbol synchronization and matching circuits 16 are designed to preserve the direct polarizing component of their input signal, which somewhat amplifies the equalization filter in the circuits 16. Therefore, the levels of data transduction in the odd-level data transducer 22 they are balanced to take into account the direct bias component that accompanies the data steps in their input signal. Anticipating that the first linear combiner 202 is a subtractor filter, if the circuits 16 are designed to suppress or to preserve the direct term of the system function of its input signal it has no consequences with respect to the levels of data transduction in the torque level data transducer 24. However, if the differential delay provided by the first delay apparatus 201 is chosen so that the first linear combiner 202 is an adder, the data transduction levels in the data transducer of the level par 24 must be moved to take into account the double direct term that accompanies the steps of the data in its input signal. An intersymbol interference suppression wave filter 26 is used after the data transducers 22 and 24 to generate a response of the postcoder filter to the response of the precoding filter of the wave filter 20. The wave filter 26 includes a multiplexer of 3 inputs 261, a second linear combiner 262, and a second delay apparatus 263 with delay equal to that of the first delay apparatus 201 in the wave filter 20. The second linear combiner 262 is a module-8 adder if the first combiner linear 202 is a subtraction filter and is a subtraction filter of modulo-8 if the first linear combiner 202 in an adder. The first linear combiner 202 and the second linear combiner 262 can be constructed as read-only memories -respectively (ROM) to accelerate the linear combination operations sufficiently to support the speeds of the sample involved. The multiplexer output signal 261 supplies the response of the postcoder wave filter 26 and is delayed by a second delay apparatus 263. The second linear combiner 262 combines the precoded symbols by decoding the results of the even level data transducer 24 with the signal output of the second delay apparatus 263. The output signal of the multiplexer 261 reproduces one of the three signals applied to the multiplexer 261, which is selected in response to the first, second and third conditions of a supplied control signal of the multiplexer 261 from a controller 28. The first gateway of the multiplexer 261 receives ideal decoding results from symbols supplied from the memory within the controller 28 during times when the synchronization information of the DFS data field and the data segment synchronization information DSS from the channel I signal of the matched baseband are recovered by the data synchronization detection circuits 18. The controller 28 supplies the first condition of the multiplexer control signal to the multiplexer 261 during these times, conditioning the multiplexer 261 to supply, as final encoding results which are its output signals. , the ideal results of the decoding of symbols supplied from the memory inside the controller 28. The odd-numbered data transducer 22 provides intermediate decoding results of symbols as its output signal to the second input port of the multiplexer 261. The multiplexer 261 is conditioned by the second condition of the multiplexer control signal for reproducing the intermediate results of the symbol decoding in the final encoding results supplied by the multiplexer 261. The second linear combiner 262 supplies decoding results of the decoded symbols as its output signal to a third input gate of the multiplexer 261. The multiplexer 261 is conditioned by the third condition of the multiplexer control signal to reproduce the decoded results of the decoded symbols in the final encoding results from the multiplexer 261. Minor errors in the decoding results of the decoded symbols from the multiplexer filter. post-code wave 26 are reduced by the retro-feeding of the ideal decoding results of symbols supplied by the memory within the controller 28 during these times the data synchronization detection circuits 18 retrieve the synchronization information of the DSS and DFS data field . The output signal of the multiplexer 261 in the suppression wave filter ISI 26 comprises the final results of the decoding of symbols in 3 parallel bit groups, assembled by a data assembler 30 for application to a trellis decoder circuit or circuit 32. The trellis decoder circuitry 32 or circuitry conventionally uses twelve trellis decoders. The resulting trellis decoding is supplied from the circuitry 32 of the trellis decoder 32 to the de-multiplexing or de-interleaving circuitry for de-mutation. The bit regulation circuits 38 convert the output signal of the interstratified data 36 into bits of the data of the Reed Solomon error correction coding for the application to the circuits 38 of the Reed-Solomon decoder, which performs the Reed decoding. -Solomon for generating a corrected bitstream of the error supplied to a descrambler 40. The data descrambler 40 supplies the reproduced data to the receiver residue (not shown). The remainder of a receiver of the complete DTV signal will include a small separator, an audio decoder, an MPEG-2 decoder and so on. The remainder or remainder of a DTV signal receiver incorporated in a digital tape player / recorder will include circuits for converting the data to a form for recording.

An interference detector 44 of the shared channel or co-channel NTSC is used which is insensitive to the direct bias component of its input signal to detect the increase in the intensity of the interference artifacts of the shared channel NTSC in this input signal . Such input signal from the detector 44 is the signal from the baseband channel I in the receiver of the DTV signal of FIGURE 1. The interference detector 44 from the shared channel NTSC supplies the controller 28 with an indication of whether the interference of the The shared channel or co-channel NTSC is of sufficient intensity to cause an incorrigible error in the data transduction developed by the data transducer 22. If the detector 44 indicates that the interference of the additional NTSC channel is not so intense, the controller 28 will supply the second condition of the control signal of the multiplexer to the multiplexer 261 most of the time. The only times this does not happen are those times when the synchronization information of the DFS data field and the synchronization information of DSS data segments are retrieved by the data synchronization detection circuits 18, causing the controller 28 apply the first state or condition of the control signal of the multiplexer to the multiplexer 261. The multiplexer 261 is conditioned by the second state or condition of its multiplexer control signal to reproduce as its output signal the decoding results of symbols supplied in the interim from the odd-level data transducer 22. If the detector 44 indicates that the interference of the co-channel or shared channel NTSC is of sufficient intensity to cause an incorrigible error in the transduction of the data developed by the data transducer 22, the controller 28 will supply the third condition of the signal of the Multiplexer to multiplexer 261 most of the time. The only times in which this is not the case in those occasions when the synchronization information of the DFS data field or the synchronization information of DSS data segments are retrieved by the data synchronization detection circuits 18, causing the controller 28 applies the first state or condition of the control signal of the multiplexer to the multiplexer 261. This conditions the multiplexer 261 is conditioned by the third state or condition of its multiplexer control signal to reproduce as it sends output signals the results of the decoder of the symbol filtered by suppression of the ISI are provided as the secondary linear combination results from the secondary linear combiner 262. FIGURE 2 is a flow diagram showing how the equalization procedures are modified in the DTV signal receiver of FIGURE 1 depending on whether or not wave filtering is used to suppress the NTSC interference of the shared channel. The inventor notes that the presence of NTSC interference artifacts from the shared channel or co-channel in the coding of baseband symbols introduces errors in the calculation of the essential coefficients of the equalization filter unless the special measurements are taken at the calculations to cancel these artifacts. In an initial step SI, a complex demodulation of the digital television signals is continuously developed by the complex demodulator 14 in the receiver of the DTV signal of FIGURE 1, to separate a received signal from the baseband of the I channel and a received signal from the baseband of the Q channel in an orthogonal relationship with the received signal from the baseband of the I channel. In a decision step S2, which is also continuously developed by the interference detector of the shared channel NTSC 44 in the receiver of the DTV signal of FIGURE 1, this determines whether or not a significant amount of NTSC interference accompanies the signal received from the baseband of channel I. A significant amount of NTSC interference from the shared channel in a receiver of the DTV signal is that it causes the number of errors occurred during the trellis decoding to exceed to a significant degree the error correction capabilities of the decoding Two-dimensional Reed-Solomon that follows the trellis decoding. A substantial number of bit errors occur in the recently recovered data, under normally noisy reception conditions. The significant amount of NTSC interference of the shared channel in a receiver of the DTV signal of particular design was already determined by experiments in a prototype of the same. If, in decision step S2, no significant amount of NTSC interference of the shared channel is determined to accompany the signal received from the baseband of channel I, a step S3 of adjusting the essential weights of the digital equalization filter, in order to which matches its response to the baseband signal, and a subsequent step S4 of symbol decoding of the equalization filter response results from step S3 is developed. The step S3 of adjusting the weights of the core is done so that the equalization or digital equalization filter provides a response that conforms to the band-based signal of the channel I. The step S4 of the decoding of the response symbols of the equalization filter generates a decoding result of the symbol used in a step or step S5 of the trellis decoding of the result of the symbol decoding to correct the errors therein. Step S5 of the trellis decoding is followed by a step S6 of the Reed Solomon decoding to correct errors in the result of the trellis decoding and a step S7 to deform the results of the Reed-Solomon decoding. If in the decision of step S2 a significant amount of NTSC interference of the shared channel is determined to accompany the received signal from the baseband of the I channel, a step S8 of the wave filtering of the received signal of the baseband of the I channel to generate a filtered signal from the baseband of channel I a step S9 is developed, the essential or core weights of the digital equalization filter are adjusted to conform the response of the digital matching filter in cascade. A step S10 of the symbols decoding the response of such a cascade filter is developed and thereafter a step 11 of decoding the decoding response of the symbols is developed to obtain decoded results of the corrected symbols for use in step S5 of trellis or latticed decoding. Step S5 of the lattice decoding is still followed by step S6 of the Reed-Solomon decoding to correct errors in the result of the trellis decoding and the step S7 of deformed the results of the Reed-Solomon decoding. The sub-method used to adjust the essential weights of the digital equalization filter in step S3 to equalize the response of the digital equalization filter is similar to the adjustment of the essential weights of the digital equalization filter used in the prior art. The adjustment can be made by calculating the discrete Fourier transform (DFT) of the data field synchronization coding received a prescribed portion of this to determine the DTF of the DTV transmission channel. The DTF of the DTV transmission channel is normalized with respect to the largest term (s) to characterize the channel, and the essential weights of the digital equalization filter are selected to complement the "standardized DTF that characterizes the channel. This method of adjustment is described in more detail by CB Partel et al in US Patent No. 5,331,416 published July 19, 1994 and entitled "METHODS FOR OPERATING GHOST-CANCELLATION CIRCUITRY FOR TV RECEIVER OR VIDEO RECORDER", for example. This method is preferable for initial adjustment of the essential weights of the digital equalization filter because the initial adjustment is made more quickly by using the adaptive equalization.After the initial adjustment of the essential weights of the digital equalization filter, the methods of Adaptive Equalization An LMS block method is described for carrying out the matching adapted by J. Yang et al in the Norteame patent ricana No. 5, 648,987 published on July 15, 1997 and entitled "RAPID-UPDATA ADAPTIVE CHANNEL-EQUALIZATION FILTERING FOR DIGITAL RADIO RECEIVERS, SUCH AS HDTV RECEIVERS". A continuous LMS method for performing adaptive matching is described by A. L. R. Limberg in the application of the North American patent series No. 08 / 832,674 filed on April 4, 1997 and entitled "DYNAMICALLY ADAPTIVE EQUALIZER SYSTEM AND METHOD". In step S9 the DFT can be used to implement the sub-method by which the numerical or essential weights of the digital equalizer filter are adjusted to conform the response of the digital matching filter in cascade and the wave filter to an ideal response by such Cascade filter can be done using DFT, especially when the rapid initial equalization is developed before the change to adaptive equalization. The adjustment is made by calculating the discrete Fourier transform (DFT) of the synchronization encoding of the received data field or a prescribed portion of it, as the wave is filtered by the wave filter 20 to reject the artifacts and divide this by the DFT of the coding of the ideal data field synchronization prescribed portion of this, as well as the wave filtering, to determine the DFT of the DTV transmission channel. The DFT of the DTV transmission channel is then normalized with respect to the largest term (s) to characterize the channel, and the essential weights of the digital equalization filter are selected to complement the normalized DFT that characterizes the channel. After the initial adjustment of the essential weights of the digital equalization filter, adaptive equalization methods are preferably employed. These adaptive matching methods differ from those used when the interference artifacts of the shared NTSC channel are negligible in the number of possible valid signal conditions "is double, minus one, by using the wave filter 20 to reject the NTSC artifacts. FIGURE 3 shows a DTV signal receiver that differs from the DTV signal receiver of FIGURE 1 in that the Q-channel signal of the baseband, instead of the baseband I-channel signal, is applied to a radio frequency detector. interference of the shared channel NTSC 44 as its input signal The interference detector of the shared channel or co-channel NTSC 44 is used to detect the intensity of the artifacts arising from interference of the shared channel NTSC in the signal of the channel Q of the baseband The interference response of the shared channel interference detector NTSC 44 is sensitive to any direct bias component that may appear in the signal of the Q channel of the baseband during the time that the phase synchronization of the synchronous detector in the complex demodulator 14 is still established. So there is no change between the baseband signal and the filtered baseband signal when calculating the weighting coefficients for the equalization filtration in the circuits 16. Any polarization component that may appear in the Q channel signal of the baseband that follows the receiver of the DTV signal acquires a DTV signal (for example, due to a low phase synchronization during weak reception of the signal) will also not affect the detection response of the detector, channel interference shared NTSC 44. In the receiver of the DTV signal of FIGURE 3 the determination of whether or not a significant amount of NTSC interference of the shared channel accompanies the signal received from the baseband of channel I is deducted from the determination of whether or not a significant amount of NTSC interference from the shared channel 5 accompanies the signal received from the baseband of the Q channel. FIGURE 4 is a flow diagram that How the equalization procedures are modified in the signal receiver of FIGURE 3 depending on whether or not wave filtering is used that suppresses the NTSC interference of the shared channel. The flow chart of FIGURE 4 for the DTV signal receiver of FIGURE 3 differs from the flow chart of FIGURE 2 for the receiver of the DTV signal of FIGURE 1 where a decision step 'S02 determines whether or not replaces decision step S2 to determine whether or not a significant amount of NTSC interference from the shared channel accompanies the received signal from the baseband of channel I. FIGURE 5 is a schematic block diagram showing details of a portion of the receiver of the DTV signal of FIGURE 1 or of FIGURE 3 using a species 120 of the NTSC reject wave filter 20 and a species 126 of the post-coding wave filter 26. A subtraction filter 1202 serves as a first linear combiner in The reject wave filter NTSC 120, and an additive module-8 1262 serves as the second combiner in the post-encoder wave filter 126. The reject wave filter NTSC 120 uses a first delay apparatus 1201 exhibits a delay of twenty symbols, and the post-coding wave filter 126 uses a second delay apparatus 1263 also exhibits a delay of twenty symbols. The delay of 12 symbols displayed by each of the delaying devices 1201 and 1263 is enclosed in a delay cycle of the artifact of the analog TV video carrier wave at 59.75 times the analogue TV horizontal scan frequency fH The delay of 12 symbols approximates five cycles of the analog TV chrominance carrier wave artifact at 287.25 times fH. The delay of 12 symbols approaches six cycles of the artifact of the analog TV sound carrier wave at 345.75 times fH. This is the reason why the differentially combined response of subtraction filter 1202 to the audio carrier wave, to the video carrier wave and to frequencies close to the chrominance subcarrier wave differentially delayed by the first delay apparatus 1201 tends to reduce the interference of the additional channel. However, in parts of "a video signal where the edges through a horizontal scan line, - the amount of correlation in the analog TV video signal at such distances in the horizontal spatial direction is totally low. Species 1261 of the multiplexer 261 is controlled by a control signal of the multiplexer that is in its second condition over time when it is determined if there is insufficient interference of the shared channel NTSC to cause incorrigible error in the output signal of the data transducer 22 and that it is in its third condition over time when it is determined if there is sufficient interference of the shared channel NTSC to cause incorrigible error 5 in its output signal of the data transducer 22. The multiplexer 1261 is conditioned by its control signal which is in its third condition to feedback the results of the sum of the modulo-8 of the 10 adder 1262, delaying twenty symbols po r a delay apparatus 1263, to the adder 1262 as an adder. This is a modular accumulation procedure in which a simple error propagates as an operating error, with the error recurring every twenty symbols. The operating errors in the results that decode the postcoded symbols of the decoding wave filter 126 are separated by the multiplexer 1261 which is placed in its first condition for four symbols at the start of each segment, as well as during the entire segment containing field synchronization. When this control signal is in its first condition, the multiplexer 1261 reproduces as its ideal output signal that decodes results supplied by the memory in the controller 28. The introduction of ideal results that decode the symbols in the multiplexer 1261 signal for the operating error. Since there are 4 + 69 (12) symbols per data segment, the ideal results that decode the symbols that leaves four symbols in phase in each data segment, if no error can persist for a time greater than three data segments. FIGURE 6 is a schematic block diagram showing details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 using a NTSC 20 reject wave filter 220 species and a 226 species of the post-coding wave filter 26. The NTSC 220 reject filter uses a first delay apparatus 2201 that exhibits a delay of six symbols, and the post-encoder wave filter 226 uses a second delay apparatus 2263 that also exhibits a delay of six symbols. The delay of six symbols displayed by each of the 2201 and 2263 delay devices approach 0.5"cycle delays the artifact of the analog TV video carrier wave at 59.75 times the horizontal analog TV frequency fH, it approaches 2.5 cycles of the artifact of the analog TV chrominance subcarrier wave at 287.25 times FH and about 3 cycles of any artifact of the TV audio carrier wave at 345.75 times fH An 2202 adder serves as the first linear combiner in the reject wave filter NTSC 220, and a module subtractor-8 2262 that serves as the second linear combiner in the post-coding wave filter 226. Since the delay exhibited by the delay devices 2201 and 2263 is shorter than the delay exhibited by the delaying devices 1201 and 1263, although null near frequencies converted from frequencies of the analog TV carrier waves are thinner bands, are more likely to be in good anti-correlation in the signals additively combined by the adder 2202 to make it more likely that they are in good correlation in the signals differentially combined by the subtraction filter 1202. The artifacts converted of the frequencies near the analog TV video carrier wave and the chroma subcarrier are trapped in the filter over wider reject frequency bands in the NTSC 220 reject wave filter than in the response of the wave filter with NTSC rejection 120. The artifacts of the NTSC sound carrier wave are trapped in the filter by the NSTC reject wave filter 220. However, if the sound carrier wave of the shared channel that interferes with the analog TV signal has been eliminated by the SAW filtering or by a sound trap in the 12-amp IF chain, the little rejection of the sound from the wave filter 220 is not a problem. The responses for synchronization peaks are reduced in duration using the NTSC 220 reject filter of FIGURE 6 instead of the reject NTSC 120 wave filter of FIGURE 5, thus there is a substantially reduced tendency to overcome the correction of the error in the trellis or trellis that decodes the Reed-Solomon coding. A 2261 sort of multiplexer 261 is controlled by a multiplexer control signal that is in its second condition most of the time when it is determined if there is insufficient interference of the shared NTSC channel to cause an incorrigible error in the output signal of the transducer. data 22 and that is in its third condition more than the time when this is determined if there is insufficient interference of the shared channel NTSC to cause an incorrigible error in the output signal of the data transducer 22. The multiplexer 2261 is conditioned by its control signal which is in its third condition to feedback the results of the sum of module-8 of adder 2262 that delays six symbols by the delay apparatus 2263, to adder 2262 as a summand. This is a modular accumulation procedure in which a simple error propagates as an operating error, with the error recurring every twenty symbols. The operating errors in the results that decode the symbols filtered by ISI suppression of the wave filter 226 by suppression ISI are separated by the multiplexer 2261 which is placed in its first condition for four symbols at the start of each segment, as well as during the entire segment that contains field synchronization. When this control signal is in its first condition, the multiplexer 2261 reproduces as its output signal the decoding results of the ideal symbols, supplied by the memory in the controller 28. The introduction of ideal results that decode the symbols in the signal output of multiplexer 2261 stops any malfunction. Since there are 4 + 138 (6) symbols per data segment, the ideal results that decode the symbols that leaves four symbols in phase in each data segment, if no error can persist for a longer time than three data segments. The probability of a protected period of the error of operation in the post-encoding wave filter 226 is substantially smaller in the post-encoding wave filter 126, although the error recurs more frequently and affects the double than as many of the twelve interlaced trellis codes. FIGURE 7 is a schematic block diagram showing details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 using a 320 species of the NTSC 20 reject filter and a 326 wave filter species postcoding 26. The NTSC 320 reject wave filter uses a first delay apparatus 3201 that exhibits a delay of 1368 symbols, such a delay being substantially equal to the time of two horizontal scan lines of an analog TV signal, and the filter of 326 post-coding wave uses a second delay apparatus 3263 that also exhibits delay. The first linear combiner in the reject wave filter NTSC 320 is a subtractor 3202, and the second linear combiner in the supersession wave filter 326 of ISI is an additive 3262 of the module-8. A sort 3261 of the multiplexer 261 is controlled by a control signal of the multiplexer which is in its second condition most of the time when this is determined if there is insufficient interference of the shared NTSC channel to cause incorrigible error in the output signal of the transducer. data 22. The control signal of the multiplexer is in its third condition most of the time 'when it is determined if there is insufficient interference of the shared NTSC channel to cause an incorrigible error in the output signal of the data transducer 22. The receiver of The DTV signal preferably contains circuits for detecting the change between alternate scan lines in the interference of the shared channel NTSC, so the controller 28 may refuse to supply the control signal of the third condition of the multiplexer 3261 under such conditions. The multiplexer 3261 is conditioned by its control signal which is in its third feedback condition of the sum results of the module-8 of the adder 3262, which delays 1368 symbols by the delay apparatus 3263, to the adder 3262 as an addend. This is a modular accumulation procedure in which a simple error propagates as an operating error, with the error recurring every 1368 symbols. This duration of the coded symbol is larger than the duration for the Reed-Son code block, so a simple operating error is easily corrected during Reed Son decoding. The operating errors in the results that decode the filtered ISI suppression symbols of the ISI suppression wave filter 326 are separated by the multiplexer 3261 which is placed in its first condition for four symbols at the start of each segment, as well as during the entire segment that contains field synchronization. When this control signal is in its first condition, the multiplexer 3261 reproduces as its ideal output signal that decodes results supplied by the memory in the controller 28. The introduction of ideal results that decode the symbols in the multiplexer 3267 signal stops the operating error. The duration of 16.67 milliseconds of an NTSC video field exhibits the transmission intensity loss phase versus the duration of 24.19 milliseconds of a DTV data field, so the DTV data segment containing the field synchronization eventually scans the light rectangle of NTSC image. The 525 lines in the luminous rectangle each contain 684 time symbols, for a total of 359,100 time symbols. Since this is somewhat less than 432 times the 832 time symbols in a DTV data segment that contains field synchronization, one can reasonably ask oneself that performance error of duration greater than 432 data fields can be erased by the 3261 multiplexer that reproduces ideal results that decode symbols during the synchronization of the field containing the DTV data segments. There is also the loss of transmission intensity phase between the data segments, for the initial code groups from which the ideal results decode the symbols that are suitable, and the NTSC video scanning lines. One can estimate 359,100 time symbols which is 89,775 consecutive data segments. Since there are 313 data segments per data field, one wonders with reasonable confidence that an operating error whose duration error exceeds 287 data fields can be erased by the multiplexer 3261 that reproduces ideal results that decode symbols during the start of the coding of the groups. The two sources of elimination of operating errors are reasonably independent of each other, thus operating errors of duration greater than two hundred or the data fields are totally unlikely. Further, if the interference of the shared channel goes down once when the operating errors recur, they condition the multiplexer 3261 to reproduce the response of the data transducer 22 as its output signal, the error can be corrected more quickly than it could otherwise be. case. The NTSC reject 320 filter of FIGURE 7 is quite good at eliminating "the demodulation artifacts generated in response to horizontal analog TV sync pulses, as well as eliminating any of the demodulation artifacts generated in response to synchronization pulses and analog TV vertical equalization pulses These devices are the interference of the shared channel with the highest energy Except where there is a change of scan line to scan line in the video content of the analog TV signal over the In the period of two scan lines, the NTSC 320 reject wave filter provides reasonably good elimination of this video content despite its color.The elimination of the FM audio carrier wave of the analogue TV signal is reasonably good, in if it is eliminated by a consecutive rejection filter in the synchronization and equalization circuits 16. The artifacts of most analog TV color sync pulses are removed in the NTSC 320 reject wave filter response, as well. In addition, the filtering provided by the NTSC 320 reject wave filter is Orthogonal to the interference rejection formed within the trellis decoding procedures FIGURE 8 is a schematic block diagram showing details of a portion of the DTV signal receiver. of FIGURE 1 or FIGURE 3 using a type 420 of the NTSC 20 reject filter and a 426 species of the post-encoding wave filter 26. The reject NTSC 420 filter uses a first delay apparatus 4201 which exhibits a delay of 179,208 symbols, such a delay is substantially equal to the time of 262 horizontal scan lines of a TV analog signal, and the post-coding wave filter 426 uses a second delay apparatus 4261 that also exhibits delay. as the first linear combiner in the NTSC reject wave filter 420, and a subtraction filter of the module-8 4262 serves as the second linear combiner in the 426 suppression wave filter ISI. A species 4261 of the multiplexer 261 is controlled by a multiplexer control signal that is in its second condition over time when it is determined if there is insufficient interference of the shared NTSC channel to cause incorrigible error in the output signal of the data transducer. 22 and that is in its third condition over time when this is determined if there is insufficient interference of the shared channel NTSC to cause incorrigible error in the output signal of the data transducer 22. The DTV signal receiver preferably contains circuits to detect change between 15 scan lines alternated in the interference of the shared channel "NTSC, so the controller 28 may refuse to supply the control signal of the third condition of the multiplexer 3261 under such conditions. The multiplexer 4261 is conditioned by its control signal which is in its third feedback condition of the results of the module-8 of the adder 4262, which delays 179,208 symbols by the delay apparatus 4263, to the adder 4262 as an addend. This is a modular accumulation procedure in which a simple error propagates as an operating error, with the recurring error every 179,208 symbols. This duration of the coded symbol is larger than the duration for the Reed Solomon code block, so a simple operating error is easily corrected during Reed Solomon decoding. The operating errors in the results that decode the postcoded symbols of the post-code wave filter 426 are separated by the multiplexer 4261 which is placed in its first condition for four symbols at the start of each segment, as well as during the entire segment containing field synchronization. When this control signal is in its first condition, the multiplexer 4261 reproduces as its output signal the ideal decoding results supplied "by the memory in the controller 28. The introduction of ideal results that decode the symbols in the output signal of the Multiplexer 4261 stops the operating error The maximum number of data fields required to clear the operating error in the output signal of the multiplexer 4261 is substantially assumed to be the same as that required to clear the operating error in the output signal of the multiplexer 4261. multiplexer 3261. However, the number of times the error recurs in this period is smaller by the factor of 131. The NTSC reject filter 420 of FIGURE 8 removes more demodulation artifacts generated in response to synchronization pulses horizontal analog TV, as well as eliminate any of the demodulation artifacts generated in response to the synchronization pulses and vertical analogue TV equalization pulses. These artifacts are the interference of the shared channel with greater energy. Also, the NTSC 420 reject filter eliminates artifacts that originate from the video content of the analog TV signal that does not change from field to field or line to line, get rid of stationary patterns regardless of their horizontal or horizontal spatial frequency. color. Artifacts of higher color TV sync pulses are eliminated in the reject wave filter response 420, too. FIGURE 8 is a schematic block diagram showing details of a portion of the DTV signal receiver of FIGURE 1 or FIGURE 3 using a 520 species of the NTSC 20 reject filter and a 526 wave filter species Pos encoding 26. The NTSC 520 reject wave filter uses a first delay apparatus 5201 which exhibits a delay of 718,200 symbols, such delay is substantially equal to the period of two pulse cycles of a TV analog signal, and the filter of post-coding wave 526 uses a second delay apparatus 5261 which also exhibits delay. A subtraction filter 5202 serves as the first linear combiner in the reject wave filter NTSC 520, and an additive of the module-8 5262 serves as the second linear combiner in the post-encryption wave filter 526. A 5261 sort of multiplexer 261 is controlled by a control signal of the multiplexer that is in its second condition most of the time when it is determined if there is insufficient interference of the shared channel NTSC to cause an incorrigible error in the output signal of the data transducer 22 and that is in its third condition over time when it is determined if there is sufficient interference from the shared channel NTSC to cause an incorrigible error in the output signal of the data transducer 22. The DTV signal receiver preferably contains circuits to detect alternation between alternate scan lines - in the interference of the shared channel NTSC, so the controller 28 may refuse to supply the control signal of the third condition of the multiplexer 5261 under such conditions. The multiplexer 5261 is conditioned by its control signal which is in its third feedback condition of the results of the module 8 of the adder 5262, which delays 718,200 symbols by the delay apparatus 5263, to the adder 5262 as an addend. This is a modular accumulation procedure in which a simple error propagates as an operating error, with the error recurring every 718,200 symbols. This duration of the coded symbol is larger than the duration for the Reed Solomon code block, so a simple operating error is easily corrected during Reed Solomon decoding. The operating errors in the results that decode the symbols filtered by ISI suppression of the ISI suppression wave filter 526 are separated by multiplexer 5261 which is placed in its first condition for four symbols at the start of each segment, as well as during the segment totality that contains field synchronization. When this control signal is in its "first condition, the multiplexer 5261 reproduces as its ideal output signal that it decodes results supplied by the memory in the controller 28. The introduction ideal results that decode the symbols in the signal of the multiplexer 5261 stops the operating error The maximum number of data fields required to clear the operating error in the output signal of multiplexer 5261 is assumed to be substantially the same as that required to clear the operating error in the output signal of multiplexer 3261. However, the number of times the error recurs in this period is less by the factor of 525. The NTSC reject 520 filter of FIGURE 9 removes all the demodulation artifacts generated in response to vertical TV synchronization pulses analogue, as well as eliminating all demodulation artifacts generated in response to the pulses of horizontal analog TV synchronization. These artifacts are the interference of the shared channel with greater energy. Also, the NTSC 520 reject wave filter eliminates artifacts that originate from the video content of the TV analog signal that does not change from field to field or line to line, get rid of stationary patterns despite their spatial or color frequencies . The artifacts of all the color TV sync pulses are eliminated in the response of the NTSC reject filter 420, as well. FIGURE 10 shows a general form of the shared channel interference detector 44 comprising the DTV signal receivers of FIGURES 1 and 3. A node 440 receives the input signal for the detector 44, such an input signal can be matched to the channel base signal of channel I or channel Q of the symbol synchronizing circuits 16 of the DTV signal receiver of FIGURE 1, the baseband signal of the equalized Q channel supplied from circuits 16 of the DTV signal receiver of FIGURE 3, the baseband signal of the channel I supplied without the equalization of the complex demodulator 14 of a modified DTV signal receiver of FIGURE 1, or a baseband signal of the Q channel supplied without equalization of the complex demodulator 14 of a receiver of modified DTV signal of FIGURE 3. In a wave filter with NTSC rejection within the detector 44 a third delay apparatus 441 differentially delays the input signal applied to the node 440 for g to input signals adding for a digital subtraction filter 442, the sum of the output signal of which is a response of the NTSC reject wave filter in which the artifacts originating from the synchronous detection of said shared channel are reinforced which interferes with the analogue television signal. In an NTSC selection wave filter within the detector 44 fourth delay apparatus 443 differentially delays the input signal applied to the node 440 to generate input signals by adding a digital subtraction filter 444, the sum of the signal of such is a response of the wave filter with NTSC selection in which the artifacts originating from the synchronous detection of said shared channel that interfere in the analog television signal are eliminated. A direct term of the characteristic system that originates from the synchronous detection of the pilot carrier wave appear to be of similar intensity in both wave filter responses with NTSC R rejection and in the wave filter response with NTSC selection. The amplitude of the response R of the wave filter with NTSC rejection from the subtractor 442 is detected by an amplitude detector 445, and the amplitude of the response S of the wave filter with NTSC selection of the subtracter 444 is detected by an amplitude detector. 446, and the results of the amplitude detection by the amplitude sensors 445 and 446 are compared by an amplitude comparator 447. The amplitude comparator 447 supplies an output bit indicative of whether or not the amplitude detector response 445 is substantially it needs the response of the amplitude detector 446. This output bit is used to select between the first and second operation condition of the multiplexer 261. For example, this output bit from the amplitude comparator 447 may be one of the two bits of the amplitude comparator 447. control that supplies the controller 28 to the multiplexer 261 in the suppression wave filter ISI of FIGURE 1 or FIGURE 3. The other control bit which is indicative or whether or not the signal is supplied from the controller 28 is reproduced in the response of the multiplexer 261. The amplitude sensors 445 and 446 may, by way of example, be envelope detectors with a constant time equal to several sample intervals. of data, so the differences in the data components of their input signals tend to average the low values assuming that these components are random. The amplitude differences in the erratic noise that accompanies the difference of the output signals of the subtraction filters 442 and 444 tend to be averaged as zero. Accordingly, when the amplitude comparator 447 indicates that the amplitude detection responses of the amplitude detectors 445 and 446 indicate that these responses differ more than a prescribed amount, this is indicative that the artifacts of any shared channel interfering with the analog television signal are close to a significant level for the baseband signal of the matched I channel applied to the odd-level data transducer 22. The errors in decoding the symbol made by simply transducing the baseband signal of the channel I are correctable by the error correction codes of trellis and Reed-Solomon, while large artifacts of the NTSC signal of the co-channel or shared channel are kept below the significant level. The artifacts of the NTSC co-channel interference are rejected in the response R of the wave filter of the subtractor 442, and the artifacts of the NTSC interference of the co-channel are selected in the response S of the wave filter of the subtractor 444. When the amplitude of the response of the S-wave filter is substantially larger than the amplitude of the R-response of the wave filter, this difference can then be assumed to be caused by the presence of interference artifacts of the shared channel NTSC at node 440 This output bit supplied by the amplitude comparator 447 for this condition is conditioned to the multiplexer 261 not to be operable in its second condition, by means of that not selecting the interim symbol that decodes results of the odd-level data transducer 22 for that it appears as a final symbol that decodes the results of multiplexer 261. When1 the amplitude of the response S of the wave filter is not substantially larger than the amplitude of the response R of the wave filter, this absence of the difference can then be assumed to indicate the absence of interference artifacts from the shared channel NTSC at node 440. This output bit supplied by the amplitude comparator 447 for this condition conditions the multiplexer 261 is not operable in its third condition, so as not to de-select the encoding of the filtered ISI suppression symbol that results from the second linear combiner 262 to appear as a decoding of the final symbol resulting from the multiplexer 261. The 6-symbol delay device 1443 is used as the fourth delay device 443 in the preferred embodiments of the co-channel NTSC interference detector 44 shown in Figures 11-14. FIGURE 11 shows a species 144 of the shared channel interference detector NTSC of FIGURE 10 particularly well suited for use with the symbols decoding apparatus of FIGURE 5. A third delay apparatus 1441 provides a differential delay of 12 symbols between the input signals of the minuend and subtracting for the subtractor 442 in a wave filter that removes the artifacts from the NTSC interference of the co-channel that accompany the baseband signal supplied to the node 440. These artifacts may have arisen of the components of analog TV signals at frequencies that approximate the frequencies of the video carrier wave, the color subcarrier and the audio subcarrier. In certain less preferred embodiments of the invention, the third delay device 441 is chosen to have a delay of slightly more p less than the duration of a horizontal scanning line of NTSC, to suppress the artifacts of the NTSC interference of the channel that have emerged from the analog TV signal components at frequencies that approximate the frequencies of the video carrier and the color subcarrier. FIGURE 12 shows a species 344 of the shared channel interference detector NTSC 44 of FIGURE 10 particularly well supplied for use with the symbol decoding apparatus of FIGURE 7. In the interference detector 344 of the shared NTSC channel, a third delay device 3441 of 1368 symbols provides differential delay of 2 video lines in the wave filter with NTSC selection used to suppress the interference artifacts of the NTSC shared channel. FIGURE 13 shows a species 444 of the shared channel interference detector NTSC of FIGURE 10 particularly well supplied for use with the symbol decoding apparatus of FIGURE 8. In the interference detector 444 of the shared channel NTSC, a third 4441 delay device, a delay apparatus of 179,208 symbols provides differential duration delay of 262 video lines in the NTSC reject wave filter used to suppress interference artifacts from the shared NTSC channel. FIGURE 14 shows a species 544 of the shared channel interference detector NTSC of FIGURE 10 particularly well supplied for use with the symbol decoding apparatus of FIGURE 9. In the interference detector 544 of the shared NTSC channel, an apparatus of delay 5441 of 718,200 symbols providing differential delay of 2 video pulse cycle duration is used as the third wavelength delay device with NTSC selection used to suppress co-channel or shared channel NTSC interference artifacts. Figure 15 shows how certain species 044 of the NTSC interference detector 44 of the co-channel of Figure 5 can share the fourth delay 443 as a portion of the first delay in certain species 020 of the NTSC reject wave filter 20. The remaining portion 0201 of the first delay is cascaded with the fourth delay portion 443 to differentially delay the input signal supplied to the node 440 to generate minuend input signals and subtracting for a digital subtractor 0202. The subtractor 0202 serves as the first linear combiner of the NTSC reject wave filter 020. The difference output signal of the subtractor 0202 supplies the NTSC reject wave filter response to the amplitude detector 445 as its input signal, in addition to supplying that response of the NTSC reject wave filter to the data transducer 24 of the same level and its input signal. The third delay 441 is provided by the cascade elements 443 and 0201 which also provide the first delay in the NTSC reject wave filter 020.; and the subtractor 442 is provided by the subtractor 0262 in the NTSC reject wave filter 020. Thus, in FIGURE 15 the elements 441 and 442 are subsumed in the NTSC reject wave filter 020 and do not appear separately. The interference of intersymbols introduced by the NTSC reject wave filter 020 is suppressed by a sort 026 of the suppression wave filter ISI using a digital subtractor 0262 of module 8 as the second linear combiner. Figure 16 shows an alternative general form 46, the co-channel NTSC interference detector can take on the DTV signal receivers of FIGS. 1 and 3. A node 460 receives the input signal for the interference detector 46 NTSC co-channel. The input signal may be the Q channel baseband signal or the equalized I channel provided from the symbol synchronizer circuitry 16, as in the DTV signal receivers of FIGS. 1 and 3 respectively. This signal may instead be the baseband signal of the Q channel or channel I, supplied without the equalization or equalization of the complex demodulator 14 in a modification of the DTV signal receiver of FIGURE 1 or FIGURE 3. In a NTSC reject wave filter within the detector 46 a fifth delay device 461 differentially delays the input signal applied to the node 460 to generate summing input signals for a digital addiver 462. The sum output signal of subtractor 462 is an R response of the NTSC reject wave filter in which the artifacts arising from the synchronous detection of the co-channel or shared channel analog television signal are suppressed. . In an NTSC selection wave filter within the detector 46 a sixth delay device 463 differentially delays the input signal applied to the node 460 for general adder input signals for a digital adder 464. The summation output signal of the adder 464 is an S response of the NTSC selection wave filter in which the artifacts arising from the synchronous detection of the co-channel interference analog television signal are reinforced. In the co-channel NTSC interference detector 46 the direct term of the system characteristic arising from the synchronous detection of the pilot carrier wave is reinforced in both the response R of the NTSC reject wave filter and the response S of the NTSC selection wave filter, instead of being suppressed as in the co-channel NTSC interference detector 44. The amplitude of the response R of the NTSC reject wave filter from the adder 462 is detected by the amplitude detector 465, and the amplitude of the response S of the NTSC selection wave filter of the addend 464 is detected by the detector 466 of amplitude. An amplitude comparator 467 compares the results of the amplitude detection by the amplitude sensors 465 and 466 to generate an output bit indicative of whether or not the response of the amplitude detector 466 substantially exceeds the response of the amplitude detector 465. This output bit is used to select between the second and third operating states 261 of the multiplexer. For example, this output bit of the amplitude comparator 467 may be one of two control days that the controller 28 supplies to the multiplexer 261 in the ISI suppression wave filter 26 of FIGURE 1 or FIGURE 3. The other The control bit is indicative of whether or not the supplied signal from the controller 28 is to be reproduced in response 261 of the multiplexer. The amplitude sensors 465 and 466 can, by way of example, be envelope detectors with a time constant equal to several data sample intervals, so that the differences in the data components of their input signals tend to average a low value assuming that these data components are randomized. The amplitude differences in the random noise and the direct terms accompanying the sum output signals or the addifiers 462 and 464 tend to averaging zero as well. According to this, when the amplitude comparator 467 indicates that the amplitude detection responses of the amplitude sensors 465 and 466 differ more than a prescribed amount, this is also indicative that the artifacts of any co-channel interference analog television signal are above a significant level in the baseband signal supplied to node 460. This significant level corresponds to the significant level for the equalized channel I baseband signal applied to the odd level data transducer 22. The errors in the decoding of the symbols made simply by the transduction of the data of the baseband signals of channel I are correctable - by the coding of the error correction of trellis and Reed-Solomon, while as artifacts of the co-channel NTSC signal remain below the significant level. The artifacts of the co-channel NTSC interference are rejected in the response R of the wave filter from the subtractor 462, and the artifacts of the co-channel NTSC interference are selected from the response S of the wave filter from the subtractor 464. When the amplitude of the S-response of the wave filter is substantially larger than the amplitude of the R-response of the wave filter, it can be assumed then that this difference is caused by the presence of NTSC interference artifacts from the wave filter. -channel in the signal at the node 460. The output bit supplied by the amplitude comparator 467 for this condition, conditions the multiplexer 261 not to be operable in its second state, thereby deselecting the decoding of the intermediate symbols resulting from the transducer 22 of the odd level data appearing as decoding results of final symbols resulting from multiplexer 261. When the amplitude of the response The S wave filter is not substantially larger than the amplitude of the R response of the wave filter, this lack of difference can be considered as indicative of the absence of artifacts from the NTSC interference of the co-channel signal in the node 460. The output bits provided by the amplitude comparator 467 for this condition, conditions the multiplexer 261 not to be operable in its third stage, thus deselecting the decoding results of the filtered symbols by suppression of the secondary linear combiner 262 appearing as the final symbol decoding results of multiplexer 261. FIG. 17 shows a kind 244 of the NTSC interference detector 46 of the co-channel of FIGURE 16 particularly well suited for use with the decoding apparatus of FIG. symbols of FIGURE 6. A fifth delay device 2461 provides differential delay of 6 symbols between the input signals of the sum Adder 462 in a wave filter that suppresses artifacts from the NTSC interference of the co-channel that accompanies the baseband signal supplied to node 460. These artifacts may have arisen from the components of the analog TV signal at frequencies that approximate the frequencies of the video carrier wave and the color subcarrier wave. A sixth delay device 2463 provides 12 symbol differential delay between the summing input signals for the 464 adder in a wave filter that reinforces the NTSC interference artifacts of the co-channel arising from the frequencies close to the wave video carrier and color subcarrier and accompanying the baseband signal supplied to node 460. FIGURE 18 shows a modification of the DTV signal receiver of FIGURE 1 as described so far, constructed in accordance with a Further aspect of the invention as for using a plurality of even-level data transducers A24, B24 and C24 operated in parallel. Each of these data transducers is preceded by a respective NTSC reject wave filter and succeeded by a respective ISI suppression wave filter. The even-level data transducer A24 converts the response of an NTSC reject filter A20 of a first type to the first decoding results of the precoded symbols for the application to an ISI suppression wave filter A26 of a first type. The even-level data transducer B24 converts the response of a NTSC reject filter B20 of a second type to a second result of decoding of wave-filtered symbols for the application to an ISI suppression wave filter B26 of a second type. The even-level data transducer C24 converts the response of a NTSC reject filter C20 of a third type to a third result of symbol decoding filtered by wave for the application to an ISI suppression wave filter C26 of a third kind. The odd-level data transducer 22 supplies decoding results of intermediate symbols to the A26 wave filters, B26 and C26 for suppression of ISI. The prefixes A, B and C in the identification numbers for the elements of FIGURE 18 are different integers corresponding to the respective integers 1,2,3,4 and 5 when the portions of the receiver are used as shown in FIGURES 5, 6, 7, 8 and 9. A co-channel interference detector A44 of a first type determines from the channel Q signal how effective the NTSC reject filter A20 of the first type will be in reducing interference of the co-channel of an analog TV signal in the signal of the equalized or equalized current channel I. A co-channel interference detector B44 of a second type determines from the Q-channel signal how effective the NTSC reject filter C20 of the third type will be in reducing the co-channel interference of an analog TV signal in the Channel I signal equalized or equalized present. The suppression of the pilot carrier wave in the Q-channel signal facilitates interference detectors A44, B44 and C44 of the co-channel to provide indications of the relative effectiveness of the NTSC reject wave filters A20, B20 and C20. The decoding selection circuitry 90 of the symbols generates a better estimate of the correct symbol decoding for the application to the data assembler 30. This best estimate is generated by selecting between the ideal decoding results of the symbols from the controller 28, the decoding results of the symbols in the intermediate of the odd-level data transducer 22, and the results of the decoding of the symbols filtered by suppression of ISI of the A26, B26 and C26 wave filters of ISI suppression. The symbol decoding selection circuitry 90 responds to the indications of effectiveness from the co-channel interference detectors A44, B44 and C44 to formulate this best estimate unless the controller 28 supplies additional symbol selection information to the circuitry. 90 decoding selection of the symbols. The information of selection of the additional symbols supplied from the controller 28 includes indications of when the synchronization of the codes occurs, which indications condition that the best estimate is estimated based on the ideal decoding results of the symbols of the controller 28. The best The estimated decoding results of the symbols are used to correct the summation procedures in the 'A26, B26 and C26 wave filters of adjustment in the preferred modes of the DTV signal receiver of FIGURE 18. If the interference detectors A44 , B44 and C44 of the co-channel indicate all the substantial lack of artifacts of the NTSC interference of the co-channel at other times than when the synchronization of the codes occurs, the decoding circuitry 90 of the decoding of the symbols responds for select the decoding results of the intermediate symbol of the transducer 22 of the data of ni Odd vel as the best estimate of the correct decoding results of the symbols. This minimizes the effect of Johnson noise in decoding the symbol. If at least one of the interference detectors A44, B44 and C44 of the co-channel indicate substantial NTSC interference artifacts of the co-channel at times different from when code synchronization occurs, the decoding selection circuitry 90 of the symbols responds to select the results of decoding of filtered symbols with ISI suppression of the A26, B26 or C26 wave filter of ISI suppression following one of the NTSC reject wave filters A20, B20 and C20 that best suppress "artifacts of Co-channel NTSC interference as determined by co-channel interference detectors A44, B44 and C44 High-energy demodulation artifacts generated in response to analog TV synchronization pulses or pulses, equalization or equalization pulses and solor pulses are suppressed when the NTSC reject wave filter A20 is combined with video frames additively. Also, artifacts that arise from the video content of the analog TV signal that does not change in two frames or frames are suppressed, are freed from stationary patterns irrespective of their spatial color frequency. The co-channel interference detector A44 of FIGURE 14 is used in conjunction with the symbol decoding circuitry of FIGURE 9. The remaining problem of suppressing the demodulation artifacts primarily affects the suppression of those demodulation artifacts that arise from the frame to frame difference in certain pixel locations within the frame of analog TV signal lines. These demodulation artifacts can be suppressed by intra-frame filtering techniques. The circuitry of the NTSC reject wave filter B20 and the ISS suppression wave filter B26 can be chosen to suppress the remaining demodulation artifacts by mapping to the horizontal direction. The circuitry of the NTSC reject wave filter C20 and the ISI suppression wave filter C26 can be chosen to suppress the remaining demodulation artifacts by remaining correlated in the vertical direction. Consider how such a decision can be implemented additionally.

It is assumed that the carrier wave of the sound of an analog TV signal of co-channel interference is suppressed by the SAW filtering or a sound trap in the IF amplifier chain 12. It is then advantageous to choose that the circuitry of the NTSC reject wave filter B20 and the IS2 suppression wave filter B26 be of the types such as the NTSC rejection wave 220 filter circuit and the deletion wave 226 filter. of ISI of FIGURE 6. This is because the correlation between the video components of only six symbols away from each other is usually better than the correlation between the twelve symbols of video components away from each other. The interference detector B44 of the co-channel of FIGURE 17 is used in conjunction with the symbol decoding circuitry of FIGURE 6. The optimum choice of the circuitry of the CTS reject wave filter C20 and the C26 wave filter of Suppression of ISI is less direct. "The NTSC signal of co-channel interference is inter-linked by the field, so the choice can be made if the current scan line in the NTSC reject C20 wave filter is going to be combined with the scan line more in the same field or with the spatially closest line in the preceding field, the choice of the closest exploration line temporarily in the same field is generally the best choice, since cuts between fields are less likely they are destroyers of NTSC rejection by the C20 wave filter With such choice, the NTSC reject C20 wave filter circuitry and the ISI suppression C26 wave filter are of similar types to the wave filter circuitry NTSC rejection 320 and the ISI suppression wave filter 326 of FIG. 7. The co-channel interference detector C44 of FIGURE 12 is used in conjunction with the symbol decoding circuitry of FIGURE 7. With the other choice, the circuitry of the NTSC reject C20 wave filter and the C26 ISI suppression wave filter are of the types such as the NTSC reject wave filter 420 filter and the filter Wave Suppression Waveform 426 of Figure 8. The co-channel interference detector C44 of Figure 13 is used in conjunction with the symbol decoding circuitry of Figure 8. FIGURE 19 shows modifications of the signal receiver of DTV of FIGURE 18 in which the co-channel interference detectors A44, B44 and C44 detect the presence of co-channel NTSC interference artifacts in the Q-channel baseband DTV signal, instead of that the interference artifacts in the baseband DTV signal of channel I. Detect the presence of co-channel NTSC interference artifacts in the baseband DTV signal of channel I, as was done in the signal receiver DTV of FIGURE 18, advantageously allows to the co-channel interference detectors A44, B44 and C44 share the delay elements with the NTSC reject A20, B20 and C20 wave filters. Someone skilled in the art of DTV receiver design will realize with the above description designing other embodiments of the invention, and the claims that follow will be constructed to include such embodiments of the invention within their scope. For example, ISI deletion filtration forms other than those specifically described can be used in embodiments of the invention. Another form of ISI suppression filtration is described by Citta and Sgrignoli in U.S. Patent No. 5,087,975 issued February 11, 1992 and "entitled" VSB HDTV TRANSMISSION SYSTEM WITH REDUCED INTERFERENCE OF THE NTSC CO-CHANNEL ".

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property:

Claims (11)

1. CLAIMS 1. A digital television signal receiver for digital television signals these are received as the amplitude modulation with residual sideband of a carrier wave and which are apt to be accompanied sometimes by a shared channel that interferes with the analogue television signal of undesirable intensities, said receiver of the digital television signal is characterized in that it includes; amplification circuits for supplying a modulated amplitude digital television signal with residual sideband; demodulation circuits responsive to said digital television signal of modulated amplitude with residual sideband to supply at least one signal from the baseband; an apparatus that decodes symbols for symbols that decode a baseband signal from channel I to generate symbol decoding results, the symbol decoding apparatus is connected to receiving the baseband signal from channel I as a input signal of the demodulation circuit, and the decoding apparatus of the symbol includes a selectively operable filter to suppress any artifacts from a shared channel that interferes with the analog television signal that accompanies the band signal of the channel I base to disconnect the symbol, the filter is operable when and only when the apparatus decoding the symbol receives a signal indicating the existence of a significant amount of interference of the shared channel NTSC; the error correction circuit for correcting errors in symbols that decode results from the apparatus decoding the symbol; an interference detector of the shared channel connected to receive an additional baseband input signal from the demodulation circuit, said interference detector of the shared channel which is of a type insensitive to the direct termination of the system function of the signal from the base band is received as its input signal and comprises: a first wave filter combining said input signal of the additional base band with itself subjected to a first amount of differential delay to generate a first response of the wave filter, in which the artifacts originating from the synchronous detection of said shared channel interfering with the analog television signal are eliminated, and, a second additive combination wave filter said another input signal from the baseband itself is subjected to a second amount of differential delay to generate a second response of the wave filter, in the which reinforces the artifacts that originate from the synchronous detection of said shared channel that interferes with the analog television signal, and in which the direct term of the characteristic system that originates from the synchronous detection of the carrier is similar to that in the first response of the wave filter; a first amplitude detector for detecting the amplitude of said first response of the first wave filter to generate a first response of the amplitude detection; a second amplitude detector for detecting the amplitude of said second wave filter response to generate a second response of the amplitude detection; and an amplitude comparator for comparing said first and second responses of the amplitude detection and indicating, when and only when said first and second amplitude detection responses differ more than a prescribed amount, supplying the signal indicating that the quantity exists. Significant NTSC interference of the shared channel.
2. 2. The digital television signal receiver according to claim 1, characterized in that the demodulation circuit comprises: a response of the complex demodulator to the digital television signal of modulated amplitude with residual amplified sideband, to supply the signal of the baseband of channel 1 used in applying to said symbol decoding apparatus its said input signal, and to supply "the baseband signal of the Q channel containing additional artifacts- of any shared channel that interferes with the analog television signal.
3. 3. The digital television signal receiver according to claim 2, characterized in that said baseband signal of the Q channel of said complex demodulator is used when applying said additional baseband signal to the interference detector of the shared channel as its signal of entry.
4. 4. The digital television signal receiver according to claim 2, characterized in that said baseband signal of channel I of said complex demodulator is used when applying said additional signal of the baseband to said interference detector of the shared channel as its entrance sign.
5. 5. The digital television signal receiver, according to claim 1, characterized in that said first combination wave filter is of a type for the differential combination of said input signal the base band with itself subject to said first amount of delay differential to generate the first response of the combination wave filter, and wherein the second filter is of a type for the differential combination of said baseband input signal with itself subject to said second amount of differential delay to generate said response of the combination wave filter.
6. 6. The digital television signal receiver according to claim 5, characterized in that said second amount of differential delay is six symbol epochs.
7. 7. The digital television signal receiver according to claim 6, characterized in that said first amount of differential delay is twenty symbol epochs.
8. 8. The digital television signal receiver according to claim 6, characterized in that said first amount of differential delay is 1368 times of symbols or the duration of two NTSC video scanning lines.
9. 9. The digital television signal receiver according to claim 6, characterized in that said first amount of differential delay is 179,208 times of symbols or the duration of 262 NTSC video scan lines.
10. 10. The digital television signal receiver according to claim 6, characterized in that said first amount of differential delay is 710,200 symbol times of two NTSC video structures.
11. 11. The digital television signal receiver according to claim 1, characterized in that said first combination wave filter is of a type of audio combination said input signal of the additional base band with itself is subjected to said first amount of differential delay for generating said first response of the combination wave filter, and wherein said second combination wave filter is of a type of audio combination said additional baseband input signal with itself is subject to said second amount of differential delay to generate the second response of the combination wave filter. 12-. The digital television signal receiver, according to claim 11, characterized in that said first amount of differential delay is six symbol epochs. 13. The digital television signal receiver according to claim 12, characterized in that said second amount of differential delay is twenty symbol epochs. 14. A digital television signal receiver for digital television signals these are received as the amplitude modulation with residual sideband of a carrier wave and that are apt to be accompanied sometimes by a shared channel that interferes with the analogue television signal of undesirable intensities, said receiver of the digital television signal, characterized in that it includes: amplification circuits for supplying a digital television signal of modulated amplitude with residual sideband; demodulation circuits responsive to said digital amplitude modulated television signal with residual sideband to supply at least one signal from the baseband, an apparatus that decodes symbols connected to receive, as an input signal from said demodulation circuits, a baseband signal from channel I that contains artifacts from any shared channel that interferes with the analog television signal; a first data transducer included in said apparatus that decodes symbols for the decoding of symbols of said baseband signal of channel I to generate the first results of symbol decoding; a first wave filter included in said symbol decoder apparatus for combining the baseband signal of channel I with itself to hold a first amount of differential delay to generate a first response of the wave filter, in which they are eliminated the artifacts that originate from the synchronous detection of said shared channel that interferes with the "analog television signal; a second data transducer included in said apparatus that decodes symbols for the decoding of symbols of said wave filter response that lasts two times to generate the second results of symbol decoding; a second wave filter included in said symbol decoding apparatus for combining decoded results of selected symbols with the selected results of the decoding of results with the final decoding results of symbols that are subjected to a second amount of delay to generate said results At the end of the symbol decoding, said selected decoded symbol results correspond to said final results of the symbol decoding during the first times and to said second results of the symbol decoding during the second times, said first and second amounts of delay each it has the same number of times of symbols as the other; error correction circuits connected to correct errors in the final results of the symbol decoding, said error correction circuits are able to correct errors in said first results of decoding symbols as said final results of the symbol decoding provided and when the artifacts of any shared channel that interfere with the analog television signal are of less intensity in said signal of the baseband of channel 1 than said undesirable intensities; Y an interference detector of the shared channel connected to receive another input signal from the baseband from said demodulation circuits, said interference detector of the shared channel which is of a type insensitive to the direct termination of the function of the signal system of the Baseband this is received as your input signal and comprises: a third wave filter that differentially combines said other baseband input signal with itself to clamp to a third amount of differential delay to generate a third response of the wave filter, in which the artifacts originating from the synchronous detection of said shared channel that interferes with the analog television signal, and where they are eliminated; a fourth wave filter that differentially combines said other input signal from the baseband with itself to hold a fourth amount of differential delay to generate a fourth response of the wave filter, in which the artifacts originating from the synchronous detection of said shared channel that interferes with the analog television signal, and wherein the direct term of the characteristic system originating from the synchronous detection of the carrier is similar to that in said response of the first wave filter; a first amplitude detector for detecting the amplitude of said third wave filter response to generate a first response of the amplitude detection; a second amplitude detector for detecting the amplitude of said response of the fourth wave filter to generate a second response of the amplitude detection; Y an amplitude comparator for comparing said first and second responses of the amplitude detection and indicating, when and only when said first and second responses of the amplitude detection differ more than a prescribed amount, this shared channel interfering with the analog signal of The television in said baseband signal of channel I is of sufficient intensity that said error correction circuits may be unable to consistently correct errors in the first symbol decoding results of said first data transducer, the resulting indication that is supplied said second wave filter as a command to select otherwise said first result of the symbol decoding as said final result of the symbol decoding. 15. The digital television signal receiver according to claim 14, characterized in that said demodulation circuits comprise a complex demodulator responsive to said digital television signal of modulated amplitude with residual amplified sideband ", to supply the signal of the baseband of the channel I used when applying to said symbol decoding apparatus its input signal, and for supplying the baseband signal of the Q channel containing other artifacts of any shared channel that interferes with the analog television signal. 16. The digital television signal receiver according to claim 15, characterized in that said baseband signal of the Q channel of said complex demodulator is used to apply said other signal of the baseband to said interference detector of the shared channel as its signal of entry. 18. The digital television signal receiver of claim 16, characterized in that said baseband signal of channel I of said complex demodulator is used when applying said other signal of the baseband to said interference detector of the shared channel as its signal of entry. 19. The digital television signal receiver according to claim 15, characterized in that said second wave filter at three prescribed times selects an ideal result of the symbol decoding as said final result of the symbol decoding, wherein said second time is it sometimes obtains said third time when said amplitude comparator supplies said second wave filter with said command to select otherwise the first result of the symbol decoding as said final result of the symbol decoding, and where said first times are obtained at times in addition to said second and third times. 20. The digital television signal receiver according to claim 14, characterized in that the third wave filter is of a type that differentially combines the input signal of the additional baseband with itself when subjected to the first amount of differential delay to generate the response of the third wave filter, and wherein the fourth wave filter is of a type for differential combination of the input signal of the additional baseband with itself when subjected to the second amount of delay differential to generate the fourth response of the wave filter. 21. The digital television signal receiver according to claim 20, characterized in that said fourth amount of differential delay is six symbol epochs. 22. The digital television signal receiver according to claim 21, characterized in that the first, second and third amounts of differential delay are twenty symbol epochs. 23. The digital television signal receiver according to claim 21, characterized in that the first, second and third amounts of differential delay are of times of 1368 symbols or the duration of two NTSC video scanning lines. 24. The digital television signal receiver according to claim 21, characterized in that the first, second and third amounts of differential delay are each of 179,208 time symbols or the duration of 262 NTSG video scan lines. 25. The digital television signal receiver according to claim 21, characterized in that said first, second and third amounts of differential delay is 718,200 time symbols or the duration of two NTSC video pulse cycles. 26. A digital television signal receiver according to claim 14, characterized in that the first wave filter is of a type to additively combine the input signal of the additional baseband with itself when subjected to the first amount of delay differential to generate the response of the first wave filter, and wherein the second wave filter is of one type to additively combine the input signal of the additional baseband with itself when subjected to the second amount of differential delay for generate the response of the second wave filter. 27. The digital television signal receiver according to claim 26, characterized in that the first amount of differential delay is six symbol epochs. 28. The digital television signal receiver according to claim 27, characterized in that the second amount of differential delay is twenty symbol epochs. SUMMARY OF THE INVENTION A first wave filter differentially combines a baseband signal of the Q or I channel supplied as an input signal to an interference detector of the shared channel NTSC for a DTV receiver with this signal being subjected to a first amount of differential delay, for generate a first response of the wave filter in which artifacts that are generated from the synchronous detection of the shared channel that interfere with the analog television signal are eliminated, but a direct term is reinforced attributable to the pilot carrier wave that is detected synchronously . The detector includes a second wave filter that differentially combines the input signal with this signal is subjected to a second amount of differential delay to generate a second wave filter response in which the shared channel artifacts. they are reinforced as well as the direct term attributable to the pilot carrier wave that is detected synchronously. The amplitudes of the first and second responses of the wave filter are detected by the first and second amplitude detectors, respectively. An amplitude comparator compares the first and second response of the amplitude detection and indicates, when and only when the first and second responses of the amplitude detection differ more than a prescribed amount, that the interfering shared channel is of sufficient intensity to be reprehensible