CN1193524C - Demodulation device for subcarrier frequency signals - Google Patents

Demodulation device for subcarrier frequency signals Download PDF

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CN1193524C
CN1193524C CNB001344307A CN00134430A CN1193524C CN 1193524 C CN1193524 C CN 1193524C CN B001344307 A CNB001344307 A CN B001344307A CN 00134430 A CN00134430 A CN 00134430A CN 1193524 C CN1193524 C CN 1193524C
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aforementioned
signal
phase error
circuit
frequency signals
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CN1311575A (en
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藤原卓
井户纯
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2676—Blind, i.e. without using known symbols
    • H04L27/2678—Blind, i.e. without using known symbols using cyclostationarities, e.g. cyclic prefix or postfix
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0044—Control loops for carrier regulation
    • H04L2027/0053—Closed loops
    • H04L2027/0059—Closed loops more than two phases
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0044—Control loops for carrier regulation
    • H04L2027/0063—Elements of loops
    • H04L2027/0067—Phase error detectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0044—Control loops for carrier regulation
    • H04L2027/0071—Control of loops
    • H04L2027/0075—Error weighting

Abstract

A sub-carrier-frequency signal demodulating apparatus detects phase error by correlating a guard interval with a corresponding part of an effective symbol period. Each such error detection period is partitioned into sub-periods, a separate phase error value is obtained for each sub-period, and these phase error values are weighted, giving generally higher weights to sub-periods with higher correlation values. The weighted phase error values are then recombined to obtain a final phase error signal. The partitioning and weighting enable the phase error to be detected with consistent accuracy, even if the signal is received on a multipath channel.

Description

Demodulation device for subcarrier frequency signals
Technical field
The present invention relates to the modulation signal that for example transmits by the OFDM mode is carried out using in the demodulated received machine; more particularly; phase error signal for the correlation institute computing during the protection of disposing by the decline during protection interim in during using according to a symbol of the digital modulation signals that is transmitted by the OFDM mode and the corresponding therewith significant character is transcribed at interval; the reference signal synchronous detection subcarrier frequency signals of control subcarrier frequency, the demodulation device for subcarrier frequency signals that the subcarrier frequency signals that subcarrier frequency signals is carried out using in the demodulated received machine carries out demodulation.
Background technology
Use description of drawings that the modulation signal according to the orthogonal frequency-division multiplex transmission system transmission is carried out the demodulated received machine.
Figure 10 is the structured flowchart of OFDM receiver that receives the modulation signal of OFDM (OFDM) transmission means.
In OFDM receiver 50, reception antenna 40 is installed.Reception antenna 40 is connected with the main carrier frequency signal demodulation unit 30 of OFDM receiver 50 inside.The modulation signal of the OFDM transmission means that is received by antenna 40 is input in the main carrier signal demodulating unit 30 and carries out a demodulation according to the reference signal of main carrier frequency, from main carrier frequency signal demodulation unit 30 output subcarrier frequency signals BS, this subcarrier frequency signals BS carries out secondary demodulation by subcarrier frequency signals demodulating unit 30 according to the reference signal SS of subcarrier frequency signals, from subcarrier frequency signals demodulating unit 20 output restituted signal DS.
If foregoing is carried out interpolation, then subcarrier frequency can be considered as intermediate frequency (IF), and subcarrier frequency signals BS also can be considered as intermediate frequency signal or IF signal.In addition, subcarrier frequency signals BS is the summation of digitally having modulated a plurality of subcarrier frequency signals, its subcarrier signal be the frequency with reference signal SS be the center the empty termly standard width of a room in an old-style house of frequency every signal.
Among Figure 10, the 2nd, multiplier, the 4th, the delay circuit during the significant character, the 5th, according to the phase error detection circuit of correlation properties detected phase error, the 9th, the loop filter of Gain Adjustable, the 10th, can carry out the oscillating circuit of FREQUENCY CONTROL according to Numerical Control, SS is the output signal corresponding to the Numerical Control oscillating circuit 10 of the phase error signal input vibration of sampling time N, is the reference signal of being taken advantage of the subcarrier frequency on the subcarrier frequency signals BS by multiplier 2.
Secondly, the action of existing subcarrier frequency signals demodulating unit 20 shown in Figure 10 is described.
If receiver 50 receives the modulation signal of OFDM transmission means, then subcarrier frequency signals is input to multiplier 2 in the subcarrier frequency signals demodulating unit 20 from main carrier frequency signal demodulation unit 30, does not revise the restituted signal DS of phase error under initial condition from multiplier 2 outputs.This restituted signal DS and this restituted signal DS with significant character during the signal that postponed during the significant character of delay circuit 4 be input to phase error detection circuit 5 together.In phase error detection circuit 5, output phase error signal after the correlation properties of two signals of detection input.Phase error signal is input to loop filter 9, and the phase error signal of being got rid of high-frequency noise by loop filter 9 is input to Numerical Control oscillating circuit 10.
Here, be corresponding to COS θ (N) and the SIN θ (N) (θ (N)=Δ θ (N)+Δ θ (N+1)) of the output signal Δ θ (N) of the loop filter 9 of sampling time N arbitrarily from the reference signal S of Numerical Control oscillating circuit 10 output.
Reduce phase error signal ES from the reference signal SS of this Numerical Control oscillating circuit 10 outputs because vibration is controlled to be, therefore the multiply each other phase error of the restituted signal DS that obtains of subcarrier frequency signals BS and reference signal SS is reduced by multiplier 2.
Phase error signal ES is by in phase error detection circuit 5, detect restituted signal DS and restituted signal 3 has been postponed correlation properties between the signal of length considerable part during the significant character in this signal, generate according to the phase error of its correlation detection restituted signal.Among Figure 10, be input to during the restituted signal DS of delay circuit 4 is delayed significant character during the significant character length considerable part and export later on.In phase error detection circuit 5, the correlation properties between the signal that detects the restituted signal DS that delayed time and the restituted signal DS that is not delayed generate also output phase error signal ES according to the value of its correlation properties.The high-frequency noise of being got rid of the radio-frequency component etc. of phase error signal ES from phase error detection circuit 5 output phase error signal ES by loop filter 9 outputs to Numerical Control oscillating circuit 10.
Like this, in subcarrier frequency signals demodulating unit 20, implement synchronous detection.The roughly action of synchronous detection is as follows.Generate phase error signal ES according to restituted signal DS, by the frequency of oscillation of phase error signal ES control from the reference signal SS of the subcarrier frequency of Numerical Control oscillating circuit 10 outputs.By multiplier 2 the reference signal SS of subcarrier frequency signals BS and the subcarrier frequency output restituted signal DS that multiplies each other.When the phase error of the reference signal SS of subcarrier frequency signals BS and subcarrier frequency was big, the value of phase error signal also strengthened.
Yet, existing demodulation device for subcarrier frequency signals 20 shown in Figure 10 is in order to obtain phase error according to restituted signal DS with the correlation properties that this restituted signal DS has been postponed the signal of the scheduled time, receive under the situation of the restituted signal (multidiameter ripple restituted signal) that receives by the multipath transmission path delay, add multidiameter ripple restituted signal for the restituted signal that receives by the common transmission path that has connected emitter and receiver with shortest path, the correlation properties of obtaining in phase error detection circuit 5 according to the influence of its multidiameter ripple restituted signal also change.
Specifically; since during the protection in the restituted signal is transcribed at interval with the significant character of multidiameter ripple restituted signal during the part (non-protection transcribe at interval during) of the tight front of protection during transcribing at interval do not have correlation, the correlation till initially the finishing during suitable with time of delay of multidiameter ripple in during therefore the protection from restituted signal is transcribed at interval reduces.In addition; further postponed do not have correlation during the protection in postponing during the significant character in the restituted signal of multidiameter ripple during the significant character is transcribed at interval as the delay protection interim of the protection interim during the significant character that has been delayed and multidiameter ripple restituted signal, the correlation reduction between therefore till being delayed of using of coherent detection finished during initial suitable with the time of delay of multipath transmission ripple in interim of delay protection during the significant character the restituted signal.The problem of the precision deterioration of detected phase error will take place in its result.
Summary of the invention
The present invention produces in view of above-mentioned existing problem, even purpose is to provide when having the delay ripple that transmits through the multidiameter path, the precision that also suppresses detected phase error worsens, stably the demodulation device for subcarrier frequency signals of detected phase error.
In order to achieve the above object; according to a kind of demodulation device for subcarrier frequency signals of the present invention; this demodulation device for subcarrier frequency signals has and receives the subcarrier signal include during the significant character that has been spaced apart by protection; generate phase error signal and restituted signal; carry out the oscillating circuit of the generation reference signal of FREQUENCY CONTROL according to aforementioned phase error signal; by using the 1st multiplier of aforementioned reference signal generating solution tonal signal, it is characterized in that possessing:
Receive one and aforementioned restituted signal of aforementioned auxiliary carrier frequency signaling as non-inhibit signal, make aforementioned non-inhibit signal postpone length during the significant character in the subcarrier frequency signals, output is as the delay circuit of the inhibit signal that postpones the result;
Aforementioned inhibit signal in detecting between a protection interim detection period partly in the aforementioned auxiliary carrier frequency signaling and the correlation properties between the aforementioned non-inhibit signal, being divided between aforementioned detection period between a plurality of secondary detection periods, corresponding between the aforementioned auxiliary detection period, the phase error detection circuit of error amount takes place to cut apart based on a plurality of the 1st phase places of aforementioned correlation properties;
Receive aforementioned the 1st phase place and cut apart error amount, the weight coefficient circuit of a plurality of weight coefficients of computing correspondence;
Carry out multiplying the 2nd multiplier that a plurality of the 2nd phase places are cut apart error amount takes place by aforementioned the 1st phase place being cut apart error amount with corresponding weight coefficient; Cut apart on the error amount in above-mentioned a plurality of the 2nd phase places and to implement the computing circuit that computing obtains aforementioned phase error signal.
As an opinion of the present invention, the weight coefficient circuit is cut apart the aforementioned weight coefficient of scale operation of the amplitude of error amount according to aforementioned the 1st phase place.
As another opinion of the present invention, the aforementioned weight coefficient of scale operation that the power that the weight coefficient circuit is cut apart the amplitude of error amount according to aforementioned the 1st phase place is taken advantage of.
As another opinion of the present invention, computing circuit is cut apart the aforementioned phase error signal of average acquisition of error amount by aforementioned the 2nd phase place of computing.
As another opinion of the present invention, the aforementioned phase error signal of average acquisition that the power that computing circuit is cut apart error amount by aforementioned the 2nd phase place of computing is taken advantage of.
As another opinion of the present invention, delay circuit and aforementioned phase error detection circuit receive the aforementioned restituted signal as aforementioned non-inhibit signal, and aforementioned the 1st multiplier is gone into aforementioned reference signal in that the aforementioned auxiliary carrier frequency signaling is superior.The frequency of oscillator is controlled by the reference signal of having used feedback control system.
As another opinion of the present invention, delay circuit and aforementioned phase error detection circuit receive the aforementioned auxiliary carrier signal as aforementioned non-inhibit signal, and aforementioned the 1st multiplier is gone into aforementioned reference signal in that the aforementioned auxiliary carrier frequency signaling is superior.The frequency of oscillator is controlled by the reference signal of having used feedforward control system.
As another opinion of the present invention, delay circuit and aforementioned phase error detection circuit receive the aforementioned auxiliary carrier signal as aforementioned non-inhibit signal, and aforementioned the 1st multiplier is gone into aforementioned reference signal in that aforementioned inhibit signal is superior.The frequency of oscillator is controlled by the reference signal of having used feedforward control system.
Subcarrier frequency signals for example is an OFDM signal.
Demodulation device for subcarrier frequency signals of the present invention can also be between aforementioned computing circuit and aforementioned oscillating circuit the linkloop filter, remove high-frequency noise from aforementioned phase error signal.
Description of drawings
Fig. 1 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 1.
Fig. 2 (a)～(g) is the sequential chart that the restituted signal DS etc. of the phase error detection circuit 5 that is input to Fig. 1 is shown.
Fig. 3 is that the amplification time axle illustrates Fig. 2 (c), (e), (f), (g) signal the time, has illustrated in (h) the sequential chart during the segmentation of having segmented between the correlation properties detection period.
Fig. 4 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 2.
Fig. 5 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 3.
Fig. 6 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 4.
Fig. 7 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 5.
Fig. 8 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 6.
Fig. 9 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 7.
Figure 10 shows the block diagram of the structure of the existing subcarrier frequency signals modulating device in the OFDM receiver.
Embodiment
Below, according to illustrated example explanation the present invention.In addition, in Fig. 1～Fig. 9, for Figure 10 and shown in the identical symbol of part mark of existing demodulation device for subcarrier frequency signals identical function.
Example 1
Fig. 1 is the block diagram that illustrates as the structure of the demodulation device for subcarrier frequency signals of the invention process form 1.
Among Fig. 1, the 21st, as the subcarrier frequency signals demodulating unit of the demodulation device for subcarrier frequency signals of this example, BS is a subcarrier frequency signals, 2 is the 1st multipliers, DS is a restituted signal, the 4th, the delay circuit during the significant character, the 5th, during having segmented during each coherent detection, detect the phase error detection circuit of each phase error according to correlation properties, the 6th, computing is for the phase place in during having segmented during the coherent detection each is cut apart the weight coefficient circuit that error amount carries out the weight coefficient of multiplying, 7 is the 2nd multipliers, the 8th, the computing circuit of the signal during each segmentation that computing has been weighted, the 9th, the loop filter of Gain Adjustable, the 10th, can carry out the oscillating circuit of FREQUENCY CONTROL by Numerical Control, SS is the reference signal from 10 outputs of Numerical Control oscillating circuit, and ES is the phase error signal from computing circuit 8 outputs.
The 1st multiplier 2 is corresponding to phase error Δ θ (N), by at the superior reference signal SS that goes into from 10 outputs of Numerical Control oscillating circuit of subcarrier frequency signals BS, revises the phase error output restituted signal DS of subcarrier frequency signals BS.The correlation properties of the output signal of delay circuit 4 during phase error detection circuit 5 detections and the significant character; detect the 1st phase error of restituted signal according to the value of its correlation properties, the value of the 1st phase error is cut apart error amount as the 1st phase place of having cut apart in during the segmentation of about definite value N (N is the integer more than 2 and is the total little number of pulse of the clock signal used in than the protection interim during the aforementioned symbol).Weight coefficient circuit 6 is cut apart error amount computing and output according to the 1st phase place and is used for cutting apart error amount by the 2nd multiplier 7 corresponding to the 1st phase place and carries out a plurality of weight coefficients corresponding to the weighting of the influence of multidiameter ripple respectively.Error amount is superior goes into weight coefficient to the 2nd multiplier 7 by cutting apart in the 1st phase place, cuts apart in each the 1st phase place to be weighted back output the 2nd phase place on the error amount and to cut apart error amount.Computing circuit 8 is cut apart error amount according to each the 2nd phase place, and for example by applying computing such as addition, output is as the phase error signal ES of the 2nd phase error.Loop filter 9 for example has the filter that more than one frequency characteristic can change gain different the time at least, exporting after the output addition of each filter.
Secondly, action in the subcarrier frequency signals demodulating unit 21 of this example shown in Figure 1 is described with reference to Figure 10.
If OFDM receiver 50 receives the modulation signal of OFDM transmission means, then subcarrier frequency signals BS is input to the 1st multiplier 2 in the subcarrier frequency signals demodulating unit 21 from subcarrier frequency signals demodulating unit 20.
Here, in subcarrier frequency signals demodulating unit 21, implement synchronous detection, identical as the roughly action of synchronous detection with the action in the existing subcarrier frequency signals demodulating unit 20 shown in Figure 10.
Under the initial condition of subcarrier frequency signals demodulating unit 21, do not revise the restituted signal DS of phase error from 2 outputs of the 1st multiplier.This restituted signal DD and restituted signal DS by significant character during delay circuit 4 signal that postponed part during the significant character be input to phase error detection circuit 5 together.In phase error detection circuit 5, output phase error signal after the correlation properties of two signals of detection input.This phase error signal ES makes decline synchronised during protection interim and the significant character corresponding with it, exports.
Cut apart back output during each that segmented between the correlation properties detection period from the phase error signal of phase error detection circuit 5 output.That is, phase error detection circuit 5 the segmentation that is divided into 1～N during the correlation detection during, detect and output phase error according to detected correlation during each segmentation.
Weight coefficient circuit 6 according to phase error detection circuit 5 each the segmentation during the output valve computing for each the segmentation during weight coefficient.For example, for strengthening weight coefficient during the strong segmentation of correlation, during the segmentation a little less than the correlation, promptly, for since demodulation through the signal (multidiameter ripple restituted signal) of the delay ripple (multidiameter ripple) beyond the shortest path in the multipath wait influence the reduction of phase error detection precision during reduce weight coefficient, suppress of the influence of multidiameter ripple thus for restituted signal.
Each weight coefficient corresponding to each output of phase error detection circuit 5 from weight coefficient circuit 6 output is taken advantage of in each output of phase error circuit 5 by the 2nd multiplier 7, be weighted for the phase error signal during each segmentation.The signal from 7 outputs of the 2nd multiplier that computing circuit 8 inputs are all by carrying out computing according to each input signal, is exported final phase error signal ES.
The output of computing circuit 8 is the loop filter 9 that phase error signal ES is input to Gain Adjustable.The phase error signal of being got rid of high-frequency noise by loop filter 9 is input to Numerical Control oscillating circuit 10.
10 outputs of Numerical Control oscillating circuit are corresponding to COS θ (N) and the SIN θ (N) (θ (N)=Δ θ (N)+Δ θ (N+1)) of the output signal Δ θ (N) of the loop filter 9 of convenience sampling moment N, that is, output is as the reference signal SS that has been reproduced the signal of subcarrier frequency.By the reference signal SS from these Numerical Control oscillating circuit 10 outputs being carried out the restituted signal DS that phase error has been revised in multiplication acquisition mutually with subcarrier frequency signals BS by the 1st multiplier 2.
Here, the signal that has postponed above-mentioned restituted signal DS is described and the restituted signal DS that do not have to postpone between the detection method of correlation properties.
Fig. 2 is the sequential chart that the restituted signal DS etc. of the phase error detection circuit 5 that is input to Fig. 1 is shown.
Fig. 2 (a) illustrates the restituted signal DS that is not delayed, and ST0, ST1, ST2 illustrate during the symbol as the signal unit of transmission signals.In ST0 during the symbol (below, be designated as ST0), has ES0 during protection interim GI0 (below, be designated as GI0) and the significant character (below, be designated as ES0).In addition, the decline from ES0 to the front side be equivalent to GI0 during, RG0 during becoming protection and transcribing at interval (below, be designated as RG0).Equally, ST1 during symbol is among the ST2; have each protection interim GI1, GI2 (below, be designated as GI1; GI2); with ES1 during the significant character, ES2 (below, be designated as ES1; ES2); in addition, the RG1 (below, be designated as RG1) during the front side becomes protection and transcribes at interval of the decline during significant character the ES1.
Fig. 2 (b) has been illustrated in delay that the correlation properties function uses in the detecting signal of restituted signal DS, DL0, DL1, DL2 illustrate as with the ES0 of each Fig. 2 (a), ES1, the ES2 timing period during quite.DG0, DG1 are the GI0 of each Fig. 2 (a), the GI1 timing period DL0 that delayed time, the delay protection interim of DL1.
As described above, the ST0～ST2 as the modulation unit of the modulation signal that is transmitted by the OFDM mode is made of GI0～GI2 and ES0～ES2.Interfere received signal by the inhibit signal of multipath synchronously and in order to prevent for what obtain signal between transmitter and the receiver, the start-up portion of ST0～ST2 is provided with protection interim GI0～GI2 during each symbol.In addition, ES0～ES2 is actually and comprises by during the communication data of demodulation during the significant character, and last a part of RG0～RG2 transcribes each protection interim GI0～GI2 of correspondence in this period among ST0～ST2 during its symbol.
Fig. 2 (a) GI0, restituted signal among the GI1 is owing to be the RG0 that has transcribed Fig. 2 (a), the signal of the restituted signal among the RG1, so the restituted signal among the GI0 and the restituted signal among the RG0 be identical content, restituted signal and the restituted signal among the RG1 among the GI1 are identical contents.Thereby the restituted signal and the restituted signal among the RG0 that GI0 have been postponed among the DG0 of timing period DL0 are identical contents, and the restituted signal and the restituted signal among the RG1 that GI1 have been postponed among the DG1 of timing period LD1 are identical contents.Wherein, DG0 and RG0 or DG1 and RG1 are not limited to synchronously.
Here, shown in Fig. 2 (c), DT0 between the correlation properties detection period is set, DT1 (below, be designated as DT0, DT1) make RG0 or RG1 become identical during, detect the content of the restituted signal among the RG0 among the DT0 and the correlation properties of the content of the restituted signal among the DG0, the correlation properties of the content of the restituted signal among the RG1 among the detection DT1 and the content of the restituted signal among the DG1.Owing to can detect restituted signal and the phase deviation amount of the restituted signal among the DG0 the RG0 from the value of detected correlation properties, i.e. phase error, so from phase error detection circuit 5 output phase error signals.
Like this, can the detected phase error, and this point also can be carried out mathematical proof.For example, at Paul H.Moose, " A Technique for Orthogonal FrequencyDivision Multiplexing Frequency Offset Correction " IEEE TRANSON COMMUNICATIONS, VoL.42, NO.10, OCTOBER 1994, show the principle of existing modulation signal by demodulation device for subcarrier frequency signals demodulation OFDM mode with mathematical formulae.
Here, phase error is asked in the skew of frequency of utilization.At first, N in i the symbol of the ofdm signal that comprises frequency shift (FS) δ F sampling is designated as SN.Be positioned under the protection situation of interim the autocorrelation performance function R N that definition is represented with formula (1) at n.
[formula 1]
R N = 1 2 E [ s n * s n + N ] · · · ( 1 )
In the formula, E (x) is the desired value of x, and x* is the conjugate complex number of x.In addition, N is FFT (high speed Fourier transform) size.
When having frequency shift (FS), if ignore noise, then sn+N uses sn and ε F frequency shift (FS), shows as following formula (2).
[formula 2]
s n+N＝s nexp[j2πδfN] …(2)
Formula (2) is updated in the formula (1), can obtains following formula (3).
[formula 3]
R N = 1 2 E [ | s n | 2 ] exp [ j 2 ] πδfN ] · · · ( 3 )
Here, suppose the calculating of the approximate desired value E (x) of time average among the enough protections of the energy interim GI, then formula (1) can be expressed as following formula (4).
[formula 4]
R N = 1 2 N 8 Σ n = - N 8 - 1 s n * s n + N · · · ( 4 )
Thereby, by the complex data that obtains from formula (4), extract phase component wherein, shown in following formula (5), can infer frequency shift (FS) δ f.
[formula 5]
δf = 1 2 πN tan - 1 [ Im [ R N ] Re [ R N ] ] · · · ( 5 )
Shown in following formula (6), can ask phase error δ θ from the formula (5) of this frequency shift (FS) δ f.
[formula 6]
δθ = tan - 1 [ Im [ R N ] Re [ R N ] ] · · · ( 6 )
From as can be known above; by shown in formula (1)～formula (4); ask the back-page correlation properties during the protection interim significant character corresponding, shown in formula (5)～formula (6),, can detect the phase error of restituted signal with mathematical formulae from wherein extracting phase component with it.
Fig. 2 (d)～(g) is the sequential chart that the relation of above-mentioned multidiameter ripple restituted signal and common restituted signal is shown.
Fig. 2 (b) illustrates multidiameter ripple restituted signal, (e) the superior and the subordinate illustrate the restituted signal and the multidiameter ripple restituted signal of (a) overlappingly, (f) correlation properties in illustrating between the correlation properties detection period of (c) taken place conversion during with correlation properties do not change during, the restituted signal that the restituted signal that (g) the superior and the subordinate illustrate overlappingly that the coherent detection of (b) uses has been delayed and multidiameter ripple restituted signal have been delayed.
MS0～MS2 during each symbol in the multidiameter ripple restituted signal shown in Fig. 2 (d) since through the delay path in the multipath transmission path (below, be designated as the multipath transmission path), therefore for ST0 during each symbol in the common restituted signal shown in (a)～ST2 difference timing period dt.For this reason, for the RG0 in the restituted signal in the common path of process shown in the upper level of Fig. 2 (e), the MEOB (during in the multidiameter ripple restituted signal of above-mentioned RG0) in the restituted signal in the process multidiameter path shown in the next stage of Fig. 2 (e) is timing period dt also.Thereby, RG0 from restituted signal initially to during the dt, promptly, for DT0a during the variation of the correlation properties shown in Fig. 2 (f), be subjected to influence through the ME0a in the restituted signal in multidiameter path (during in the multidiameter ripple restituted signal of non-RG0 part among the ES0 during the significant character).Equally, for DT0b during the variation of the correlation properties shown in Fig. 2 (f), be subjected to influence through the ME0b in the restituted signal in multidiameter path.Here, because RG0 and ME0b are the same signals that is in the relation of delay, therefore have correlation, but RG0 and ME0a there is not correlation.
On the other hand, for the restituted signal in the common path of process shown in the upper level of Fig. 2 (g) coherent detection with in DG0 in the signal that has been delayed, shown in the next stage of Fig. 2 (g) through the restituted signal in multidiameter path coherent detection with in the signal that has been delayed MI0 (corresponding to coherent detection with in the multidiameter ripple restituted signal that has been delayed above-mentioned DG0 during) also timing period dt.Thereby, from coherent detection with in the restituted signal that has been delayed DG0 initially to during the dt, promptly, DT0a during changing for the correlation properties shown in Fig. 2 (f), be subjected to through the restituted signal in multidiameter path coherent detection with in the influence of MD01b (in the multidiameter ripple restituted signal of the non-RG0 part during corresponding to significant character among the ES0 during) in the signal that has been delayed.Equally, DT0b during changing for the correlation properties shown in Fig. 2 (f), be subjected to through the restituted signal in multidiameter path coherent detection with in the influence of MI0 in the signal that has been delayed.Here, DG0 and MI0 are owing to be that therefore the same signal that is in the relation of postponing has correlation, but DG0 and MD0b do not have correlation.
Thereby, because RG0 and ME0a do not have correlation, therefore the RG0 from restituted signal initially to during correlation the dt do not reduce, because DG0 and MD0b do not have correlation, therefore from restituted signal coherent detection with in the signal that has been delayed DG0 initially to during correlation the dt do not reduce, its result, for example, in existing subcarrier frequency signals demodulating unit 20 shown in Figure 10, the precision of detected phase error worsens.
In this example, detect RG0 from Fig. 2 initially to during the dt and from DG0 initially to during the dt, by reducing the weighting during it, make the precision of final phase error not worsen.
Fig. 3 is that the amplification time axle illustrates Fig. 2 (c), (e), (f), (g) signal the time, has illustrated in (h) the sequential chart during the segmentation of having segmented between the correlation properties detection period.
(c) of Fig. 3 (e)～(g) is the figure that amplifies the time shaft of the respective signal show Fig. 2, (h) illustrate by the phase error detection circuit 5 of this example the symbol that has segmented between the correlation properties detection period during.Preferably carry out careful cutting apart during this segmentation; yet can not be thinner owing to detect relevant ability than the wavelength of clock signal, therefore in this example, be taken as during the segmentation that is divided into predetermined value N (N is the integer 2 or more and is the total little number of pulse than employed clock signal in the protection interim during the symbol).
Like this, by segmenting between the correlation properties detection period, dt during can specificly having passed through that the subcarrier frequency signals in multidiameter path postpones, thereby, subcarrier frequency signals through the multidiameter path is joined on the subcarrier signal that has passed through common path DT0a during the correlation properties during can specificly reducing as correlation change.
In this example, use weight coefficient circuit 6, than the lowland set change for correlation properties during the weight coefficient of DT0a, establish weight coefficient than the highland for DT0b during the correlation properties conversion.So, in computing circuit 8, in the final phase error signal of institute's computing, reduce influence through the subcarrier frequency signals in multidiameter path.
As described above, the demodulation device for subcarrier frequency signals 21 of this example possess be divided into during several segmentations between the correlation properties detection period and during each segmentation output the 1st phase place cut apart the phase error detection circuit 5 of error amount, computing is used for cutting apart in the 1st phase place the weight coefficient circuit 6 of the weight coefficient that is weighted on the error amount, multiply by corresponding weight coefficient respectively and export the 2nd multiplier 7 that the 2nd phase place is cut apart error amount for cut apart error amount as the 1st phase place of the output of phase error detection circuit 5, computing the 2nd phase place is cut apart the computing circuit 8 of error amount, be divided between a correlation properties detection period during several segmentations owing to constitute, cut apart error amount and be weighted respectively for the phase place in during each segmentation, computing result's the value of the phase error during this each segmentation that has been weighted export as final phase error signal, the regeneration of carrying out subcarrier frequency signals according to phase error signal generates reference signal, the synchronous detection subcarrier frequency signals, even therefore under the situation of the inhibit signal that has process multidiameter path, also can suppress by this inhibit signal a little less than for correlation during influence, the precision that suppresses detected phase error worsens, stably the detected phase error.
Example 2
Fig. 4 is the block diagram that illustrates as the demodulation device for subcarrier frequency signals of the invention process form 2.In addition, in following Fig. 4～Fig. 9, for the identical symbol of part mark of the demodulation device for subcarrier frequency signals identical function of the 1st example shown in Figure 1, and the repetitive description thereof will be omitted.
Among Fig. 4, the 12nd, each the 1st phase place during each segmentation of phase error detection circuit 5 output is cut apart error amount and is detected peaked maximum value detecting circuit, and the 13rd, the normalization circuit of normalization and computing weight coefficient is carried out in the output of the maximum that detects according to maximum value detecting circuit 12 during each segmentation of phase error detection circuit 5.
Below, the action of the subcarrier frequency signals demodulating unit 22 of this example is described.
The subcarrier frequency signals demodulating unit 22 of this example is not from revising the restituted signal DS of phase error in initial condition from multiplier 2 output, and to cut apart the action of error amount identical with example 1 to exporting each the 1st phase place of having been segmented by phase error detection circuit 5.
Weight coefficient circuit 6 according to each the 1st phase place of phase error detection circuit 5 cut apart the error amount computing for each the segmentation during weight coefficient.In this example, cut apart error amount as each the 1st phase place of the output of phase error detection circuit 5 and be input to maximum value detecting circuit 12, the maximum phase error that becomes that each the 1st phase place is cut apart in the error amount detects and is maximum.Detected maximum for example is taken as 1 by normalization circuit 13 each the 1st phase place is cut apart error amount and carry out normalization, the weight coefficient of its normalization result during as each segmentation.By being cut apart error amount, each the 1st phase place carries out normalization, for strengthening weight coefficient during the strong segmentation of correlation, for the segmentation interval a little less than the correlation, promptly since through the inhibit signal in multidiameter path make that the phase error detection precision reduces during reduce weight coefficient.
By cutting apart error amount from each the 1st phase place of each weight coefficients of weight coefficient circuit 6 outputs and phase error detection circuit 5 and carry out multiplying cut apart error amount corresponding to each the 1st phase place of phase error detection circuit 5, cut apart error amount for each the 1st phase place and be weighted as the 2nd phase place and cut apart error amount by the 2nd multiplier 7.In computing circuit 8, input is cut apart error amount from each the 2nd phase place of all the 2nd multiplier 7 outputs, and for example by computings such as enforcement additions, output is as the phase error signal ES of the 2nd phase error for each input signal.Following action is identical with example 1.
By such setting weight coefficient, can suppress with other during compare phase error less during, that is, since the multidiameter ripple influence correlation weak during phase error detection the time amplitude.Thereby, can suppress the influence in the segmentation interval of weakening by the inhibit signal correlation of having passed through the multidiameter path.
As discussed above, the subcarrier frequency signals demodulating unit 22 of this example calculates the weight coefficient of computing in weight coefficient circuit 6 owing to constitute the ratio of the amplitude that uses maximum value detecting circuit 12 and normalization circuit 13 to cut apart error amount according to the 1st phase place, therefore be fairly simple circuit structure, even under the situation of the delay ripple that has process multidiameter path, also can than the 1st example further suppress since the multidiameter signal correlation weaken during influence, the precision that can suppress detected phase error worsens, stably the detected phase error.
Example 3
Fig. 5 is the block diagram that illustrates as the demodulation device for subcarrier frequency signals of the invention process form 3.
In the subcarrier frequency signals demodulating unit 23 of this example, setting for the weight coefficient in the weight coefficient circuit 6 shown in Figure 1, constitute each the 1st phase place power of cutting apart the error amount amplitude of input during each segmentation taken advantage of and compare, its comparative result normalization and carry out computing.
Among Fig. 5, the 14th, carry out the Power raising circuit that power is taken advantage of cutting apart error amount from interval the 1st phase place of exporting of each segmentation of phase error detection circuit 5, the 12nd, detect peaked maximum value detecting circuit from each output of Power raising circuit 14, the 13rd, the normalization circuit of normalization and computing weight coefficient is carried out in the output during each segmentation of Power raising circuit 14 according to maximum value detecting circuit 12 detected maximums.
Below, the action of the subcarrier frequency signals demodulating unit 23 of this example is described.
It is identical with example 1 that the 1st phase place that the subcarrier frequency signals demodulating unit 23 of this example has been segmented by phase error detection circuit 5 from the restituted signal DS that do not revise phase error in initial condition from multiplier 2 output to output is cut apart the action of error amount.
Weight coefficient circuit 6 according to each the 1st phase place of phase error detection circuit 5 cut apart the error amount computing for each the segmentation during weight coefficient.In this example, each the 1st phase place of phase error detection circuit 5 is cut apart error amount and is input to each Power raising circuit 14, calculates power value of taking advantage of that each the 1st phase place is cut apart error amount by each Power raising circuit 14.The output of each Power raising circuit 14 is imported into maximum value detecting circuit 12, becomes maximum phase error detection and is maximum.Detected maximum for example is taken as 1 carries out normalization, the weight coefficient during its normalization result is segmented as each by normalization circuit 13 power value of taking advantage of of phase error during each segmentation.By the power value of taking advantage of normalization of the phase error during each is segmented, for strengthening weighting system during the strong segmentation of correlation.During the segmentation a little less than the correlation, that is, and by reducing weight coefficient during the inhibit signal phase error detection precision reduction of passing through the multidiameter path.
By the 2nd multiplier 7 from 6 outputs of weight coefficient circuit corresponding to each weight coefficient of each output of phase error detection circuit 5 with cut apart error amount as each the 1st phase place of the output of phase error detection circuit 5 and carry out multiplying, cut apart error signal for each the 1st phase place during each segmentation and be weighted as the 2nd phase place and cut apart error amount.In computing circuit 8, input is cut apart error amount from each the 2nd phase place of all the 2nd multiplier 7 outputs, and by each input signal is carried out computing, output is as the phase error signal ES of the 2nd phase error.Following action is identical with example 1.
By such setting weight coefficient, can suppress with other during compare the 1st phase place cut apart error amount less during, that is, since the multidiameter ripple influence that correlation weakens during the amplitude of phase error detection value.Thereby, the influence during the segmentation that can suppress to weaken by the inhibit signal correlation of having passed through the multidiameter path.
As discussed above, the subcarrier frequency signals detecting unit of this example is owing to constitute by Power raising circuit 14, maximum value detecting circuit 12 and normalization circuit 13 are cut apart ratio that the power of the amplitude of error amount takes advantage of according to the 1st phase place and are calculated weight coefficient by 6 computings of weight coefficient circuit, therefore can further adjust the ratio of weight coefficient than the 2nd example, it is fairly simple circuit structure, even under the situation of the delay ripple that has process multidiameter path, also can further suppress since the multidiameter signal correlation weaken during influence, the precision that can suppress detected phase error worsens, stably the detected phase error.
Example 4
Fig. 6 is the block diagram that illustrates as the demodulation device for subcarrier frequency signals of the invention process form 4.
In the subcarrier frequency signals demodulating unit 24 of this example, make in computing circuit shown in Figure 18, carry out by weight coefficient circuit 6 and 7 weightings of the 2nd multiplier each the 2nd phase place cut apart error amount and average computing.
Among Fig. 6, the 15th, computing is cut apart the average average circuit of error amount as each the 2nd phase place of the output of the 2nd multiplier 7, is arranged in the computing circuit 8.
Below, the action of the subcarrier frequency signals demodulating unit 24 of this example is described.
The subcarrier frequency signals demodulating unit 24 of this example is identical with example 1 to cut apart the action that error amount is weighted by weight coefficient circuit 6 and the 2nd multiplier 7 each the 1st phase place during for each segmentation from the restituted signal DS that do not revise phase error in initial condition from multiplier 2 output.
Computing circuit 8 inputs are cut apart error amount from each the 2nd phase place of all the 2nd multiplier 7 outputs, and by each input signal is carried out computing, output is as the phase error signal ES of the 2nd phase error.
Here, the computing circuit 8 of this example is owing to be averaging circuit 15, if each the 2nd phase place of therefore all conduct the 2nd multiplier 7 output signals is cut apart error amount and is input in the average circuit 15, calculating mean value in average circuit 15 then, its mean value as the phase error signal ES of the 2nd phase error from average circuit 15 outputs.Following action is identical with example 1.
By the mean value of such each phase error signal of computing, can suppress the influence during the segmentation that the inhibit signal correlation through the multidiameter path weakens.
As described above, the subcarrier frequency signals demodulating unit 24 of this example constitutes computing circuit 8 by average circuit 15, each the 2nd phase place of having carried out weighting by computing in computing circuit 8 is cut apart average acquisition the 2nd phase difference value of error amount, therefore be fairly simple circuit structure, even under the situation of the delay ripple that has process multidiameter path, also can further suppress by the multidiameter signal correlation weaken during influence, the precision that suppresses detected phase error worsens, stably the detected phase error.
Example 5
Fig. 7 is the block diagram that illustrates as the demodulation device for subcarrier frequency signals of the invention process form 5.
This example in carrier frequency signaling demodulating unit 25, in computing circuit shown in Figure 18, carry out by weight coefficient circuit 6 and 7 weightings of the 2nd multiplier each the 2nd phase place cut apart error amount and carry out power and take advantage of average calculating operation.
Among Fig. 7, the 16th, the power that computing is cut apart error amount as the 2nd phase place of the output of the 2nd multiplier 7 takes advantage of average power to take advantage of average circuit, is arranged in the computing circuit 8.
Below, the action of the subcarrier frequency signals demodulating unit 25 of this example is described.
The subcarrier frequency signals demodulating unit 25 of this example is identical with example 1 to cut apart the action that error amount is weighted by weight coefficient circuit 6 and the 2nd multiplier 7 each the 1st phase place during for each segmentation from the restituted signal DS that do not revise phase error in initial condition from multiplier 2 output.
Computing circuit 8 inputs are cut apart error amount by each the 2nd phase place of all the 2nd multiplier 7 outputs, and by each input signal of computing, output is as the phase error signal of the 2nd phase error.
Here, because the computing circuit 8 of this example is that power is taken advantage of average circuit 16, therefore, be input to power and take advantage of in the average circuit 16 if all cut apart error amount as each the 2nd phase place of the output signal of the 2nd multiplier 7, then take advantage of in the average circuit 16 and calculate power and take advantage of mean value, take advantage of its power mean value to take advantage of average circuit 16 outputs from power as final phase error signal at power.Following action is identical with example 1.
Take advantage of mean value by the power that each the 2nd phase place of such computing is cut apart error amount, the influence during the segmentation that can suppress to weaken by inhibit signal correlation through the multidiameter path.
As discussed above, the subcarrier frequency signals demodulating unit 25 of this example is owing to take advantage of average circuit 16 to constitute computing circuit 8 with power, carry out the power that each the 2nd phase place of weighting cuts apart error amount by computing in computing circuit 8 and taken advantage of average acquisition the 2nd phase error, therefore can further adjust the ratio of strengthening than example shown in Figure 64, it is simple circuit configuration, even under the situation of the delay ripple that has process multidiameter path, also can further suppress since the multidiameter signal correlation weaken during influence, the precision that can suppress detected phase error worsens, stably the detected phase error.
Example 6
Fig. 8 is the block diagram that illustrates as the demodulation device for subcarrier frequency signals of the invention process form 6.
In the subcarrier frequency signals demodulating unit 26 of this example, the configuration different with above-mentioned example 1 adopted in the configuration of the 1st multiplier 2 of the phase error output restituted signal DS that revises subcarrier frequency signals BS.More particularly, in example 1, disposed the 1st multiplier 2 make from being reproduced of Numerical Control oscillating circuit 10 outputs the reference signal SS as the signal of subcarrier frequency feed back, and in this example, dispose the 1st multiplier 2 and make reference signal SS is feedovered.That is, the 1st multiplier 2 is configured to not delay circuit 4 and phase error detection circuit 5 outputs during significant character of its output, but exports as restituted signal DS.
Below, the action of the subcarrier frequency signals demodulating unit 26 of this example is described.
The subcarrier frequency signals BS of the subcarrier frequency signals demodulating unit 26 of this example is directly inputted to phase error detection circuit 5, simultaneously, also is directly inputted to delay circuit 4 during the significant character.And the signal that has been postponed part during the significant character by delay circuit during the significant character 4 is input to phase error detection circuit 5.In addition, later by the action that phase error detection circuit 5 is implemented, up to by identical carry out the action of restituted signal DS that the phase multiplication obtained revising phase error from the reference signal SS of numerically-controlled oscillator 10 outputs and subcarrier frequency signals BS with example 1 by the 1st multiplier 2.
By not being to be taken as feedback circuit but to be taken as feed forward circuit, can shorten convergence time to the synchro detection circuits in the subcarrier frequency signals demodulating unit 26 like this.
As described above, the subcarrier frequency signals demodulating unit 26 of this example is owing to be taken as feed forward circuit to synchro detection circuit, therefore be fairly simple circuit structure, even under the situation of the delay ripple that has process multidiameter path, also can suppress since the multidiameter signal correlation weaken during influence, the precision that can suppress detected phase error worsens, detected phase error stably, and then can also shorten convergence time.
Example 7
Fig. 9 is the block diagram that illustrates as the demodulation device for subcarrier frequency signals of the invention process form 7.
In the subcarrier frequency signals demodulating unit 27 of this example, the configuration of the 1st multiplier 2 of the phase error output restituted signal DS that revises subcarrier frequency signals BS is taken as the configuration different with above-mentioned example 1.More particularly, in example 1, dispose the 1st multiplier 2 suitable make from the regeneration of Numerical Control oscillating circuit 10 outputs the reference signal SS as the signal of subcarrier frequency feed back, and in this example, dispose the 1st multiplier 2 makes reference signal SS back level of delay circuit 4 during significant character is feedovered.That is, the 1st multiplier 2 is arranged such that the output of delay circuit 4 during the input significant character, simultaneously, is configured to not delay circuit 4 and phase error detection circuit 5 outputs during significant character of its output, and exports as restituted signal DS.
Below, the action of the subcarrier frequency signals demodulating unit 27 of this example is described.
The subcarrier frequency signals BS of the subcarrier frequency signals demodulating unit 27 of this example is directly inputted to phase error detection circuit 5, simultaneously, also is directly inputted to delay circuit 4 during the significant character.And the signal that has been postponed part during the significant character by delay circuit during the significant character 4 is input to phase error detection circuit 5, simultaneously, also is input to the 1st multiplier 2.In addition, later by the action that phase error signal testing circuit 5 is implemented, up to by identical carry out the action of restituted signal DS that the phase multiplication obtained revising phase error from the reference signal SS of Numerical Control oscillator 10 outputs and subcarrier frequency signals BS with example 1 by the 1st multiplier 2.
By not being to be taken as feedback circuit but to be taken as feed forward circuit like this, can shorten convergence time to the synchro detection circuits in the subcarrier frequency signals demodulating unit 27.
As discussed above, the subcarrier frequency signals demodulating unit 27 of this example is owing to synchro detection circuit being taken as the feed forward circuit that the signal of part during the significant character of having been delayed time by delay circuit during the significant character 4 is input to the 1st multiplier 2, therefore be fairly simple circuit structure, even under the situation of the delay ripple that has process multidiameter path, also can suppress since the multidiameter signal correlation weaken during influence, the precision that can suppress detected phase error worsens, detected phase error stably, and can shorten convergence time, can can access the more high-precision demodulation device for subcarrier frequency signals that stably moves for carrying out phase error corrections during the actual symbol of detected phase error.
In addition, the subcarrier frequency signals demodulating unit of above-mentioned each example has been recorded and narrated the situation of the receiver of use OFDM (OFDM) mode, yet, for example also can be assembled into a part of circuit of digital television receiver demodulating unit.
Kind, the connection status of the various circuit of the formation subcarrier frequency signals demodulating unit that illustrated in above-mentioned each example in the demodulation device for subcarrier frequency signals of the present invention in addition, or kind, control method of being connected to the main signal unit of subcarrier frequency signals demodulating unit etc. are not limited to the content that illustrated in the aforementioned example.
As overall opinion of the present invention, at the subcarrier frequency letter of demodulation subcarrier frequency signals In number demodulating equipment and since possess ask for the detected phase error protection interim and and its During the correlation properties of the rear section during the corresponding significant character, dividing between the correlation properties detection period Cut to during several segmentations, cut apart error amount for the 1st phase place of each subdivided interval and carry out Weighting is asked device as the 2nd phase error to its operation values, therefore plays and can suppress Because during the subcarrier frequency signals phase place coherent detection that has postponed through multi-path transmission paths In correlation weaken during impact, can prevent the deterioration of phase error detection precision, Can make the effect of having stable behavior.
As an opinion of the present invention, possess between the correlation properties detection period owing to constitute Be divided into several subdivided intervals, cut apart error amount for the 1st phase place of each subdivided interval and advance Row adds temporary, according to the dress of the scale operation weight coefficient of the amplitude of each the 1st phase error Putting, is fairly simple circuit structure therefore, can talk about and can suppress because through multipath Transmission path delay the subcarrier frequency signals coherent detection during in correlation weaken Impact during this time can prevent the deterioration of phase error detection precision, can make having stable behavior Effect.
As another opinion of the present invention, possess the correlation properties detection period owing to constitute Between be divided into several the segmentation during, for each the segmentation during in the 1st phase place cut apart error When value was weighted, the scale operation of taking advantage of according to the power of the amplitude of each the 1st phase error added Therefore the device of weight coefficient can further be adjusted the ratio of weighting, can talk about and can advance One step suppresses because the subcarrier frequency signals coherent detection that has postponed through multi-path transmission paths Correlation during this time weaken during impact, prevent the deterioration of phase error detection precision, Make the more stable effect of action.
As another opinion of the present invention, possess the correlation properties detection period owing to constitute Between be divided into several the segmentation during, for each the segmentation during the 1st phase place cut apart error amount Being weighted, its mean value is asked device as the 2nd phase error, therefore is relatively letter Single circuit structure can play and suppress owing to postponed through multi-path transmission paths Correlation in during the subcarrier frequency signals coherent detection weaken during impact, can prevent End the deterioration of phase error detection precision, make the effect of having stable behavior.
As another opinion of the present invention, possess the correlation properties detection period owing to constitute Between be divided into several the segmentation during, for each the segmentation during the 1st phase place cut apart error amount Be weighted, take advantage of its power mean value to ask device as the 2nd phase error, therefore can Further the ratio of amplitude modulation weighting can be talked about and can suppress because through multi-path transmission paths Correlation in during the subcarrier frequency signals coherent detection that has postponed weaken during shadow Ring, can prevent the deterioration of phase error detection precision, can make the more stable effect of action.
As another opinion of the present invention, owing to consist of reponse system so that according to restituted signal Determine phase error, therefore can talk about the effect of revising reliably phase error with restituted signal Really.
As another opinion of the present invention, owing to consist of feedforward system so that according to subcarrier frequently Therefore rate signal deciding phase error is fairly simple circuit structure, even there is process In the situation of the delay ripple in multidiameter path, also can suppress because multidiameter signal correction Property weaken during impact, can talk about the precision that can suppress detected phase error Worsen, detected phase error stably, and then can shorten the effect of convergence time.
As another opinion of the present invention, owing to consist of feedforward system so that according to subcarrier frequently Rate signal deciding phase error obtains the demodulation letter according to the subcarrier frequency signals that has been delayed Number, be fairly simple circuit structure therefore, even there be prolonging through the multidiameter path Late in the situation of ripple, also can suppress since the multidiameter signal correlation weaken during shadow Ring, can talk about the precision that suppresses detected phase error and worsen, can stably detect Phase error, and then, convergence time can be shortened, for having detected substantial phase error Symbol can carry out phase error corrections, can make with higher precision the effect of having stable behavior.
As another opinion of the present invention, subcarrier frequency signals is orthogonal frequency division multiplexing transmission Signal can be talked about the strict frequency in the demodulation of satisfying OFDM signal The effect that control requires.
As another opinion of the present invention, because demodulation device for subcarrier frequency signals possesses ring Therefore path filter can talk about the effect that can remove from phase error signal high-frequency noise Really.

Claims (10)

1. demodulation device for subcarrier frequency signals; this demodulation device for subcarrier frequency signals has and receives the subcarrier signal include during the significant character that has been spaced apart by protection; generate phase error signal and restituted signal; carry out the oscillating circuit of the generation reference signal of FREQUENCY CONTROL according to aforementioned phase error signal; by using the 1st multiplier of aforementioned reference signal generating solution tonal signal, it is characterized in that possessing:
Receive one and aforementioned restituted signal of aforementioned auxiliary carrier frequency signaling as non-inhibit signal, make aforementioned non-inhibit signal postpone length during the significant character in the subcarrier frequency signals, output is as the delay circuit of the inhibit signal that postpones the result;
Aforementioned inhibit signal in detecting between a protection interim detection period partly in the aforementioned auxiliary carrier frequency signaling and the correlation properties between the aforementioned non-inhibit signal, being divided between aforementioned detection period between a plurality of secondary detection periods, corresponding between the aforementioned auxiliary detection period, the phase error detection circuit of error amount takes place to cut apart based on a plurality of the 1st phase places of aforementioned correlation properties;
Receive aforementioned the 1st phase place and cut apart error amount, the weight coefficient circuit of a plurality of weight coefficients of computing correspondence;
Carry out multiplying the 2nd multiplier that a plurality of the 2nd phase places are cut apart error amount takes place by aforementioned the 1st phase place being cut apart error amount with corresponding weight coefficient; Cut apart on the error amount in above-mentioned a plurality of the 2nd phase places and to implement the computing circuit that computing obtains aforementioned phase error signal.
2. the demodulation device for subcarrier frequency signals described in claim 1 is characterized in that:
Aforementioned weight coefficient circuit is according to the aforementioned weight coefficient of the scale operation of the amplitude of aforementioned phase error.
3. the demodulation device for subcarrier frequency signals described in claim 1 is characterized in that:
The aforementioned weight coefficient of scale operation that aforementioned weight coefficient circuit is taken advantage of according to the power of the amplitude of aforementioned phase error.
4. the demodulation device for subcarrier frequency signals described in claim 1 is characterized in that:
Aforementioned computing circuit is cut apart the aforementioned phase error signal of average acquisition of error amount by aforementioned the 2nd phase place of computing.
5. the demodulation device for subcarrier frequency signals described in claim 1 is characterized in that:
The aforementioned phase error signal of average acquisition that the power that aforementioned computing circuit is cut apart error amount by aforementioned the 2nd phase place of computing is taken advantage of.
6. the demodulation device for subcarrier frequency signals described in claim 1 is characterized in that:
The aforementioned auxiliary carrier frequency signaling is an OFDM signal.
7. the demodulation device for subcarrier frequency signals described in claim 1 is characterized in that:
Between aforementioned computing circuit and aforementioned oscillating circuit, be connected the loop filter of removing high-frequency noise from aforementioned phase error signal.
8. the demodulation device for subcarrier frequency signals described in each of claim 1～7 is characterized in that:
Aforementioned delay circuit and aforementioned phase error detection circuit receive the aforementioned restituted signal as aforementioned non-inhibit signal, and aforementioned the 1st multiplier is gone into aforementioned reference signal in that aforementioned restituted signal is superior.
9. the demodulation device for subcarrier frequency signals described in each of claim 1～7 is characterized in that:
Aforementioned delay circuit and aforementioned phase error detection circuit receive the aforementioned auxiliary carrier frequency signaling as aforementioned non-inhibit signal, and aforementioned the 1st multiplier is gone into aforementioned reference signal in that the aforementioned auxiliary carrier frequency signaling is superior.
10. the subcarrier frequency signals described in each of claim 1～7 is separated the system device, it is characterized in that:
Aforementioned delay circuit and aforementioned phase error detection circuit receive the aforementioned auxiliary carrier signal as aforementioned non-inhibit signal, and aforementioned the 1st multiplier is gone into aforementioned reference signal in that aforementioned time delayed signal is superior.
CNB001344307A 2000-02-28 2000-11-30 Demodulation device for subcarrier frequency signals Expired - Fee Related CN1193524C (en)

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