CN1285996A

CN1285996A - High difinition television vestigial sideband receiver

Info

Publication number: CN1285996A
Application number: CN98812863A
Authority: CN
Inventors: T·J·王
Original assignee: RCA Licensing Corp
Current assignee: Thomson Licensing SAS; RCA Licensing Corp
Priority date: 1997-10-31
Filing date: 1998-10-15
Publication date: 2001-02-28
Anticipated expiration: 2018-10-15
Also published as: CN1178485C; JP2001522206A; KR20010031338A; WO1999023822A1; AU1090099A; JP4149664B2; HK1035284A1; KR100540675B1

Abstract

System and apparatus for processing a received Vestigial Sideband (VSB) modulated datastream containing high definition video data represented by a VSB symbol constellation, said data having a data frame format constituted by a succession of data frames comprising a field sync component prefacing a plurality of data segments, apparatus comprising: an analog-to-digital converter (19) for converting said received VSB data stream to digital form; a digital demodulator (22) for demodulating an output signal from said converter to produce a demodulated signal; a digital phase control network (324-326) included in said demodulator; and a data reduction network (330, 332) included in said phase control network.

Description

High difinition television vestigial sideband receiver

The present invention relates to a kind of receiver system that is used to handle vestigial sideband modulation type high definition TV (HDTV) signal that proposes such as U.S. Major Leagues.

Restore data from the modulation signal that transmits digital information with sign format requires three functions usually in receiver: the timing recovery of sign synchronization, carrier wave recovers (frequency demodulation is to base band), and channel equalization.Timing recovery is one can make receiver clock (time base) and the synchronous processing procedure of transmitter clock by it.This allows received signal to be sampled in the best time, points to the relevant amplitude limit error of (decision-directed) processing to reduce with the judgement of receiving symbol value.It is a processing procedure that carrier wave recovers, and by this processing procedure, the radiofrequency signal of reception is being down-converted to a lower IF passband (for example near base band) back frequency displacement to base band, to allow the recovery of modulating baseband information.Adaptive channel equalizer is a processing procedure, and by this processing procedure, the situation about changing in the signal send channel and the influence of interference are compensated.This processing procedure adopts filter usually, and these filters are eliminated amplitude and the phase distortion that causes owing to the time dependent characteristic of the frequency of transmission channel, thereby improved sign determination ability is provided.

According to principle of the present invention, a kind of system that is used to handle the residual sideband that comprises high definition television information (VSB) modulation signal that is received comprises that one responds the digital demodulator of pilot signal component in high definition TV (HDTV) signal that is received.This digital demodulator comprises that one has the phase control loop of sampling microwave network under the data.

The accompanying drawing summary

Fig. 1 comprises the block diagram of the high-definition TV receiver part of device in accordance with the principles of the present invention.

Fig. 2 describes the data frame format that is used for according to the VSB modulation signal of HDTV system of U.S. Major Leagues.

The detailed structure of the digital demodulator/carrier recovery network in Fig. 3 presentation graphs 1.

The section synchronizing indicator in Fig. 4 presentation graphs 1 and the detailed structure of symbol clock recovery network.

Fig. 5 has described the signal waveform that helps to understand network operation shown in Figure 4.

Fig. 6 represents a kind of detailed structure of compensating network, and this network is used for eliminating the direct current biasing by the symbol data streams of the system handles of Fig. 1.

The detailed structure of NTSC co-channel interference detection network in the system of Fig. 7 presentation graphs 1.

Fig. 8 represents and the relevant frequency spectrum of network operation among Fig. 7.

In Fig. 1, the HDTV signal of terrestrial broadcasting analog input is by the fan-in network 14 that comprises rf tuning circuit and comprise that the IF processor 16 of two frequency conversion tuning devices of being used to produce intermediate frequency (IF) passband output signal and suitable automatic gain control (AGC) circuit handles.The signal that receives is to propose and the 8-VSB modulation signal of the carrier suppressed used in the U.S. as Major Leagues.This VSB signal is by one-dimensional data symbol cluster (constellation) expression, and wherein having only an axle to comprise will be by the quantized data of receiver recovery.For simplify this figure, do not illustrate be used to shown in the signal of functional block timing.

As described in the HDTV of the Major Leagues system specifications that came into force on April 14th, 1994, the VSB transmission system transmits the data with specified data frame format shown in Figure 2.The little pilot signal that is in the inhibition carrier frequency is added to transmission signals and is beneficial to realize carrier lock on vsb receiver.Referring to Fig. 2, each Frame comprises two fields, and wherein each comprises 313 sections of 832 multistage symbols.Each first section is called field synchronization segments, and 312 remaining sections are called data segment.Data segment generally includes the packet that meets MPEG.Each data segment comprises the section synchronization character of four symbols, then is 828 data symbols.The section of each comprises the section synchronization character of four symbols, then be the field synchronization component of the PN sequence of pseudo random number (PN) sequence that comprises 511 predetermined symbols and three 63 predetermined symbols, wherein one of the centre of the PN sequence of three 63 predetermined symbols is anti-phase in continuous field.VSB mode control signal (size of definition VSB symbol conformation) is the sequence of last 63PN then, is the symbol of 96 preservations and 12 symbols that duplicate from front surface field subsequently.

Continuation was converted to the numeric character data stream of sampling referring to Fig. 1 by analog to digital converter (ADC) 19 from the passband IF output signal of unit 16.The output of ADC19 sampling digital data stream, be demodulated to base band by all-digital demodulation device/carrier recovery network 22.This is to be undertaken by the little reference pilot carrier in the VSB data flow of response reception by all-digital phase-locked loop.Unit 22 produces will export I-phase demodulating symbol data streams in greater detail with reference to Fig. 3.

ADC19 comes over-sampling to import the VSB symbol data streams of 10.76 million symbol/seconds by the sampling clock that use doubles the 21.52MHz of receiving symbol rate, thereby the 21.52 million samples/sec data flow of crossing sampling of two sampling values of each symbol are provided.Use two sample values of this each symbol based on the processing of sample but not the processing based on symbol of symbol (sample value of each symbol) one by one can produce the favourable operation with follow-up signal processing capacity relevant with all DC compensation as will be discussed unit 26 and NTSC interference detector 30.

Synchronous and the symbol clock recovery network 24 of the section of being that is associated with ADC19 and demodulator 22.Network 24 detects and the repeating data section synchronized component of each Frame is separated with random data.Section be used to synchronously the to regenerate clock of 21.52MHz of correct phasing, it is used for by analog to digital converter 19 control datas stream symbol sampler.As what discuss in conjunction with Figure 4 and 5, network 24 helps using two symbol dependency basis quasi-modes of abbreviation to come detection segment synchronous with two relevant symbol data correlators.

As what will discuss with reference to figure 6, DC compensation unit 26 uses the adaptive tracing circuit, and the direct current biasing component that causes because of the pilot signal component is eliminated from the VSB signal of demodulation.Unit 28 detects the data fields synchronized component by the data segment of each reception is compared with the ideal field reference signal in the memory that is stored in receiver.Except field synchronization, field sync signal also is provided for the training signal of channel equalizer 34.

NTSC Interference Detection and inhibition are carried out unit 30 discussed in detail by reference Fig. 7 and 8.Afterwards, this signal is by channel equalizer 34 adaptive equalizations of operating with the compound mode of blindness (blind), training (training) and judgement directing mode.Equalizer 34 can be the type described in the article " the VSB modulation subsystem design that Major Leagues' digital television receiver is used " of people such as W.Bretl among the HDTV of Major Leagues system specifications and the August nineteen ninety-five IEEE Transactions on ConsumerE1ectronics.Equalizer 34 also can be the type of describing in people's such as Shiue the common unsettled U.S. Patent application (sequence number RCA88,947).The output stream of detector 30 down-converted to the sampling value/symbol data flow of (10.76 million symbol/second) before equalizer 34.This down-conversion can be realized by suitable following sampling microwave network (not shown in order to simplify accompanying drawing).

Equalizer 34 corrects channel distortions, but phase noise rotates the symbol cluster at random.Residual phase and gain noise in the output signal of Phase Tracking network 36 elimination equalizers 34 comprise the phase noise that is not had elimination by the carrier recovery network of front by the response pilot signal.The signal of this phasing is immediately by unit 40 formats, and by unit 42 release of an interleaves (deinterleaved).The Reed-Solomon error is proofreaied and correct by unit 44, and by unit 46 descramblings (releasing randomization).Afterwards, the data flow of decoding is carried out audio frequency, video and demonstration processing by unit 5.

Tuner 14, IF processor 16, field sync detector 28, equalizer 34, phase tracking loop 36, format decoder 40, deinterlacer 42, Reed-Solomon decoder 44 and descrambler 46 can adopt the circuit types of mentioning in the HDTV of the Major Leagues system specifications on April 4th, 1994 or above-mentioned people's such as Bretl the article.The circuit that is suitable for performance element 19 and 50 functions is widely known by the people.

Demodulation in the unit 22 is controlled (APC) ring by digital automatic phase and is carried out to realize that carrier wave recovers.Phase-locked loop uses weight of pilot frequency as the reference of initial acquisition and use common phase detectors in the phase place collection.Pilot signal embeds in the data flow that receives, and it comprises the data that present at random, are similar to the pattern of noise.Random data is not considered by the filtering operation of demodulator APC loop basically.The input signal of 10.76 million symbol/seconds of ADC19 is the signal that approaches base band, and the center of its VSB frequency spectrum is at 5.38MHz, and weight of pilot frequency is positioned at 2.69MHz.At 21.52MHz, input traffic is beneficial to by the ADC19 twice and crosses sampling.In the demodulated data stream from unit 22, weight of pilot frequency is arrived DC to downshift.

Fig. 3 represents the detailed structure of digital demodulator 22.From the 8-VSB modulation that comprises the very low frequency weight of pilot frequency of ADC19 and the data symbol data flow of over-sampling, be applied in the input of hilbert filter 320 and delay cell 322.Filter 320 is divided into " I " (homophase) and " Q " (90 ° of phase differences) component to the IF sampled data stream of input.Postpone 322 and present the delay of mating with hilbert filter 320.I and Q component are by using complex product musical instruments used in a Buddhist or Taoist mass 324 to rotate to base band in the APC ring.In case this loop is by synchronously, then the output of multiplier 324 is compound baseband signals.Data flow from the output I of multiplier 324 is used as actual demodulator output, and also is used for by using low pass filter 326 to obtain the weight of pilot frequency that is received data flow.The phase place that is used to obtain received signals from the data flow of multiplier 324 output Q.

In phase control loop, be applied to respectively on

low pass filter

326 and 328 from the I and the Q output signal of multiplier 324.

Filter

326 and 328 is Nyquist low pass filters that cut-off frequency is about 1MHz, and is used for reducing before being taken a sample under the data at 8: 1 by

unit

330 and 332 execution the bandwidth of signal.The Q signal of following sampling is by 336 filtering of automatic frequency control (AFC) filter.After filtering, Q signal by unit 338 amplitude limits to reduce the dynamic range requirement of phase detectors 340.Phase detectors 340 detect and proofread and correct and are applied to the I of its input and the phase difference between the Q signal, and produce by the output phase difference signal such as APC filter 344 filtering of second level low pass filter.The phase difference that unit 340 detects represent to expect near the difference on the frequency between the pilot signal frequency of the pilot signal frequency of direct current and reception.

If the pilot signal that receives is rendered as the frequency near direct current of expectation, then AFC unit 336 does not produce phase shift.Be input to the I of phase detectors 340 and the weight of pilot frequency of Q channel, will not depart from the phase relations of 90 degree each other mutually, thereby phase detectors 340 produce null values or near the phase error input signal of null value.Yet if the pilot signal that receives is rendered as wrong frequency, AFC unit 336 will produce phase shift.This will cause phase difference additional between the I of the input that is applied to phase detectors 340 and the Q channel pilot frequency signal.Detector 340 produces an output error value in response to this phase difference.

From the filtered phase error signal of filter 344 by taking a sample 1: 8 on the interpolater 346 with computing unit 330 and the 332 previous following samplings of carrying out, so that NCO 348 is operated in 21.52MHz.The output of interpolater 346 is applied to the control input of NCO 348, and its local regeneration is used for the pilot signal that demodulation is received data flow.NCO 348 comprises and being used for by response from the phase control signal of unit 340,344 and 346 and at the sine and the cosine check table of phase calibration regeneration pilot tone.The output Be Controlled of NCO 348, the phase error signal that makes detector 340 produce up to the I of multiplier 324 and Q signal output is actually till zero, thus the baseband I signal that indicates suitable demodulation is present in the output of multiplier 324.

In digital demodulator 22, in fact main signal processor comprises element 336,338,340 and 344.8: 1 times samplings that provided by

unit

330 and 332 help saving the processing power and the hardware of demodulator, and, promptly use the clock timing of the clock of 21.52MHz/8 or 2.69MHz rather than 21.52MHz and allow highly-efficient treatment by making APC loop element 336,338,340 and 344 a lower clock frequency timing.When digital signal processor (DSP) is used to implement network 22 particularly the phase-detection ring time, for example by requiring command code line still less pari passu, the result of described data conversion has improved software efficiency.The circulation of DSP can be used as other signal processing purpose.When special-purpose integrating circuit (ASIC) was used to implement network 22, the result of data conversion had reduced the requirement of hardware and power and has reduced the surf zone of integrating circuit.Demodulator utilizes weight of pilot frequency to realize that carrier wave recovers more favourable, and adopts the feedback processing of feed-forward process rather than use amplitude limiter decision data more complicated and consuming time.

The I channel data stream of demodulation is applied in the section that is shown specifically to Fig. 4 and Fig. 5 synchronously and symbol clock recovery unit 24.When repeating data section lock-out pulse was recovered by the random data pattern that is received data flow, section was used to the sampling clock of the 21.52MHz that doubles symbol rate of the suitable phasing used by regeneration control analog to digital converter 19 (Fig. 1) sampling operation synchronously and realizes that suitable symbol regularly.Fig. 5 has described ground station's signal of modulating for the 8-VSB according to the HDTV of Major Leagues standard and has had eight grades of synchronous (7 to+7) data segments of dependent segment.Section occurs in the beginning of each data segment synchronously and takies four mark spaces.Section is synchronously by the pattern 1-1-11 definition corresponding to from+5 to-5 section lock-out pulse width of cloth level.

Synchronously per 832 symbols of four sign fields occur once, but since data have at random and be similar to the characteristic of noise, so be difficult to be arranged in the VSB digital data stream of demodulation.Synchronous for detection segment under this condition, normally the I channel data stream of demodulation is applied to an input of data correlator, and the reference mode with 1-1-11 characteristic is applied to the reference input of this correlator, to compare with demodulating data.Correlator produces consistent with the reference mode reinforcement of per 832 characters.The data event of strengthening is by the accumulator accumulation relevant with this correlator.(not strengthening) at random of inserting relevantly then disappears with respect to the dependent segment synchronized component of strengthening.The network that is used for the section of recovery synchrodata of this mode for example can be known from people's such as the previously mentioned HDTV of Major Leagues standard and Bretl article.

Here as can be seen, although section generally is difficult to the location synchronously, it is difficult to detect when multipath (" ghost image ") exists especially.And, this shows that the latter two characteristics of segment synchronization pattern (amplitude rank) (11) is destroyed (corrupt) by the transmission distortion such as multipath easily, but preceding two characteristics (1-1) of segment synchronization pattern are difficult to especially but destroy.Can judge that in addition even preceding two amplitude responses (1-1) of segment synchronization pattern are destroyed, they generally also are to destroy in an identical manner, this just makes preceding two characteristics detect more easily by correlation technique.Thereby in disclosed system, be added to and be used for detection segment synchronization basic standard pattern on the correlator, preferably constitute by preceding two pattern levels (1-1) rather than by all four pattern levels (1-1-11).Like this, the reference mode of correlator preferably includes only two mark spaces.

In Fig. 4, be added to a signal input part and 832 symbol correlator 420 of phase detectors 410 from the over-sampling output stream of demodulator 22 (Fig. 1 and 3).Another signal input part of phase detectors 410 is from the relevant dependency basis quasi-mode generator 430 that comprises correlator 420, connect with the benchmark input end of correlator 420 and the data correlation process path receiving inputted signal of section integrator and accumulator 424.It is synchronous that in fact correlator 420 responds symbol coded data section.Reference mode generator 430 provides the reference mode 1-1 of simple abbreviation, thereby can allow to use better simply correlator network.This better simply reference mode is in synchronous detecting is handled, and particularly (confusion) obscured in unlikely generation under the condition of poor signal, and this is because used more reliable and more stable information.If four two destructions in relevant, disclosed system is also unlikely to be confused.In addition, significantly reduce the computing time of correlator 420.

The output of correlator 420 is by unit 424 integrations and accumulation.The section synchronizing generator 428 that comprises the comparator with predetermined threshold is by producing the section output of response unit 424 synchronously in reasonable time at interval corresponding to data segment sync in data flow.This situation takes place when surpassing predetermined level in the accumulation (section is external behavior synchronously) of the data event of strengthening.The synchronous phase place of the section that phase detectors 410 produce unit 428 compares with a section synchronous phase place that manifests in the demodulated data stream from unit 22, and produces the output phase error signal.This error signal is carried out low-pass filtering by automatic phase control (APC) filter 434, is applicable to generation to be controlled to be the signal that ACD19 provides the 21.52MHz VCXO (VCXO) 4366 that 21.52MHz crosses sampling clock.This sampling clock presents suitable timing when phase error signal is substantially zero by the APC effect.Symbol regularly (clock) recovers to finish in this point.The section that unit 428 produces also is applied to other decoder circuit that comprises automatic gain control (AGC) circuit (not shown) synchronously.

Because the weight of pilot frequency of the VSB signal medium and low frequency suppressed carrier that receives, so in demodulation output I symbol data, there is a direct current biasing from demodulator 22.This direct current biasing is relevant with each symbol and eliminated by compensating network 26 (Fig. 1) before further handling.I.e. ± 7 ± 5 ± 3 ± 1 the recovery of symmetrical symbols value of 8-VSB signal is convenient in the elimination that is transmitted the DC component of symbol.Figure 6 shows that the detailed structure of network 26, it is actually a direct current tracking feedback network.The device of the network 26 among Fig. 6 helps coming timing to double character rate, thereby eliminates DC component fast.This operation has promoted the quick convergence of receiver and its several independent particle systems, is used to be treated to the suitable operating condition of the received video data that shows usefulness with rapid generation.

In Fig. 6, comprise the input that the sampling demodulated data stream is added to subtractive combination device (subtractive combiner) 610 of crossing of useless direct current biasing.A reverse input end (-) of combiner 610, the control signal that produces by following output and receive the DC compensation voltages from DC voltage generator 616 according to combiner 610.Decay gradually with the sample rate that doubles character rate by feedback operation from the direct current biasing in the output signal of combiner 610.This direct current biasing is detected by unit 622 and by comparator 624 it is compared with a benchmark.The output of comparator 624 indicates the amplitude and the polarity of remaining direct current biasing, and is used for producing control signal by control-signals generator 626.Then, this control signal makes the amplitude and the polarity of the D. C. value of generator 616 incremental and demodulated data stream combination.This processing procedure is proceeded, until reach a kind of the stable state that D. C. value regulates no longer is provided by feedback operation unit 616 till.Generator 616 can provide the positive and negative DC offset value, and this can make that because of transmission-channel interference adding (just) direct current biasing on transmitter changes, and not only needs positive offset but also need negative offset like this on receiver.

Fig. 7 represents the detailed structure of NTSC co-channel interference detection network 30 shown in Figure 1.As what explained in the HDTV of the Major Leagues system specifications, the interference rejection of VSB transmission system is based on the frequency location of the solvent of the NTSC co-channel interference signal within the 6MHz television channel, and the periodicity trap of the base band comb filter of vsb receiver.These comb filter traps present high decay (zero) at the frequency location that disturbs high energy NTSC component.These components comprise the video carrier that is positioned at 1.25MHz from low wavestrip edge, are higher than the colour subcarrier that is positioned at 3.58MHz of video carrier frequency, and the sound carrier that is positioned at 4.5MHz on the video carrier frequency.

NTSC disturbs and is detected by circuit shown in Figure 7, and wherein signal-the interference plus noise of field synchronization pattern is measured at the input and output side of comb filter network, and these patterns are compared to each other.The reference field synchronous mode of Cai Yonging is programming and " ideal " version of the VSB signal field synchronous mode of reception that be local storage for this reason.

In Fig. 7, the I channel symbol data of over-sampling demodulation are added to NTSC and suppress an input of comb filter 710, the first input end of multiplexer 745, and an input of subtractive combination device 720.Comb filter 710 comprises a subtracter 712, and it deducts the sampling value that delay element 714 postpones from input I data, to produce the I channel symbol data flow of a pectination.The high energy that comb filter 710 is mentioned in front disturbs and produces significant amplitude fading or " zero " on the NTSC frequency.Be added to second input of multiplexer 745 from the pectination I data of filter 710.The delay element 714 of comb filter helps showing subsequently the 24-sampling of describing is postponed.

Programming 21.52 million sampling/second (doubling symbol rate) reference field synchronous mode, obtain from local storage in field synchronization interim of receiving data stream.The field synchronization reference mode is added to an input of NTSC band resistance comb filter 718, and the reverse input end (-) of combiner 720.Comb filter 718 is similar with comb filter 710, and also includes to be beneficial to and show the delay element that the 24-sampling postpones.Network among Fig. 7, particularly comb filter 710,718 and relevant delay network, clock is under the frequency of 21.52MHz.

In first error signal that the output of combiner 720 produces, be illustrated in poor between received field synchronous mode in the input traffic and the reference field synchronous mode.This error signal is by 722 squares of unit and by unit 724 integrations.In second error signal that the output of combiner 730 produces, be illustrated in poor between received field synchronous mode after filter 710 comb filterings and the reference field synchronous mode after filter 718 comb filterings.This second error signal is by 732 squares of unit and by unit 734 integrations.The energy of error signal is separately represented in

unit

722 and 732

output.Integrator

724 and 734 integral output signal are represented the not signal-interference plus noise amount of the received field synchronized component of comb filtering and comb filtering respectively.The signal of the representative energy of these integrations is added to the respective input of energy detector (comparator) 740 of the first and second error signal sizes of comparison integration.The output signal of detector 740 is added to the control input end of multiplexer 745, and one of input signal that makes it to be used to multiplexer 745 is provided as " data output " presents higher quality, and promptly having preferably, noise adds interference ratio.Thereby under the situation that significant NTSC cochannel disturbs, the comb filtering output signal of filter 710 will be from multiplexer 745 outputs, and unfiltered receiving symbol data flow will be exported when this interference is non-existent simultaneously.

The take a sample use of I channel data and field synchronization reference mode data of the mistake that postpones to use with 24-sampling in

comb filter

710 and 718 helps producing whole spectrum informations that relevant NTSC cochannel disturbs.This is beneficial to the more accurate NTSC interference analysis of generation and detection and comb filtering preferably.Particularly, 24 samplings in crossing the

comb filter

710 and 718 that sampling input data and related circuit timing use postpone to produce the frequency spectrum of comb filtering, and this frequency spectrum is not provided input traffic and destroys by the phase place and the amplitude aliasing effects of

operating comb filter

710 and 718 generations with the symbol rate of 10.76 million symbol/seconds by the symbol rate with 10.76 million symbol/seconds.Shown in Figure 8 at the final frequency spectrum that the output of

comb filter

710 and 718 produces, and comprise two near the 10.76MHz center but divide the full NTSC passband component of the comb filtering of opening with 10.76MHz.The decay trap disturbs the NTSC frequency to occur at described high energy.

Fig. 7 shows a kind of form of the NTSC co-channel interference detector that comprises element 722,724,732,734 and 740.But also can use the detector of other type.Thereby these elements can with four the input detectors be that so-called black box is represented, wherein this detector can be programmed with the requirement according to particular system and operate.In this case, four inputs are that two cross take a sample (two sampling value/symbols) that are connected with combiner 720 are imported, and two inputs of sampling excessively that link to each other with combiner 730, wherein the output particular importances of the filter 710 that is connected with the input of combiner 730.

As shown in Figure 8, the device of Fig. 7 can produce frequency spectrum clearly, and not owing to the relevant amplitude that causes than the last band edge of lower passband component and the frequency overlap of the following band edge of upper-passband component and the destruction (aliasing) of phase place.Therefore, the cochannel Interference Detection of element 720,722,724,730,732,734 and 740 execution are more accurate with the detection of system's execution of the comb filter with 12-sampling delay of the symbol rate processing input data of 10.76 million symbol/seconds than employing.Under latter event, amplitude and phase place are destroyed and may be produced near 5.38MHz, and wherein the passband component is overlapping up and down, and this moment, the passband component can not fine coupling and can not cancel this overlapping.This bad coupling may take place comprising under the situation of the signaling channel of multipath for example.The situation of this aliasing has reduced the effect of NTSC cochannel Interference Detection, and is avoided by system of the present disclosure.

Claims

1. be used for handling the received system that contains by the VSB modulated data stream of the high-definition video data of residual sideband (VSB) glossary of symbols group representation a kind of, described data have the data frame format (Fig. 2) that is made of a series of Frames, this Frame comprises the field synchronization component as the beginning of a plurality of data segments, and this device comprises:

-be used for above-mentioned received VSB data flow is converted to the analog to digital converter (19) of digital form;

-digital demodulator (22), the output signal that is used for the above-mentioned analog to digital converter of demodulation is to produce one by the signal of demodulation;

-be included in the digit phase control ring (324-326) in the above-mentioned demodulator; And

-be included in data conversion (data reduction) network (330,332) in the above-mentioned phase control ring.

2. according to the device of claim 1, it is characterized in that: described analog to digital converter (19) produces the digital data stream of sampled data, and it is crossed with the above-mentioned speed that is received the symbol rate multiple of data flow takes a sample.

3. according to the device of claim 1, it is characterized in that:

Described data manipulator (330,320) is a following sampling microwave network with the sampling coefficient (downsampling factor) that is associated down;

Described analog to digital converter (19) produces the digital data stream of sampled data, and it is crossed sampling with the above-mentioned speed that is received the symbol rate multiple of data flow; And

The part (336-344) of described phase control network (324-346) is operated on the speed that reduces in proportion with the above-mentioned coefficient of sampling down.

4. according to the device of claim 3, it is characterized in that the described coefficient of sampling down is 8: 1.

5. according to the device of claim 1, it is characterized in that described phase control network comprises:

-multiplier (324), it has respectively and to receive homophase that the restituted signal of 90 ° of phase differences each other uses and quadrature input, homophase (I) and quadrature (Q) output and a benchmark input end mutually mutually;

-phase detectors (340);

The following sampling microwave network (330-332) that above-mentioned homophase and the quadrature of the above-mentioned multiplier of-response exported mutually, be used for according to sampling coefficient under the data with exchanges data homophase and quadrature mutually multiplier output signal offer above-mentioned phase detectors; And

-reference signal is offered the control generator (348) of the said reference input of described multiplier.

6. according to the device of claim 5, it is characterized in that above-mentioned at least sampler (330,332) down and above-mentioned phase detectors (340) are operated on the speed that reduces in proportion with the above-mentioned coefficient of taking a sample down.

7. according to the device of claim 5, further comprise an interpolater (346), be used for the following sampled signal of above-mentioned phase detectors is provided the said reference input of above-mentioned oscillator.

8. according to the device of claim 1, it is characterized in that described phase control network comprises:

-multiplier (324), it has respectively homophase that " I " that receive 90 ° of phase differences each other and " Q " demodulating data use and quadrature input, I and Q data output end and a benchmark input end mutually;

-phase detectors (340);

-comprise that a low pass filter (326) reaches first path of sampling microwave network (330), is used for the I data of demodulation are coupled in an input of above-mentioned phase detectors (340);

-comprise that a low pass filter (328) reaches the alternate path of sampling microwave network (332), is used for the Q data of demodulation are coupled in another input of above-mentioned phase detectors;

-reference signal is offered the control generator (348) of the said reference input of above-mentioned multiplier; And

-interpolater (346) is used for the interpolation output signal of above-mentioned phase detectors is offered above-mentioned oscillator.

9. be used for handling the received system that contains by the VSB modulated data stream of the high-definition video data of residual sideband (VSB) glossary of symbols group representation a kind of, described data have the data frame format that is made of a series of Frames, this Frame comprises the field synchronization component as the beginning of a plurality of data segments, and a kind of signal processing method may further comprise the steps:

Above-mentioned received VSB data flow is converted to digital data stream;

The above-mentioned digital data stream of demodulation is flowed by demodulated data to produce one;

Digital data stream to above-mentioned demodulation carries out phase control, and wherein said phase control step comprises the step of the secondary sample signal being carried out phase control according to a data conversion coefficient.

10. according to the method for claim 9, it is characterized in that above-mentioned switch process crosses sampling with the above-mentioned speed that is received the symbol rate multiple of data flow to above-mentioned received data flow.

11., it is characterized in that the speed operation to reduce in proportion with above-mentioned data conversion coefficient at least in part of described phase control step according to the method for claim 9.

12., it is characterized in that above-mentioned sampling multiple excessively is 2 according to the method for claim 10.