CN1798282B - Digital multimedia receiver - Google Patents
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- CN1798282B CN1798282B CN2004101014332A CN200410101433A CN1798282B CN 1798282 B CN1798282 B CN 1798282B CN 2004101014332 A CN2004101014332 A CN 2004101014332A CN 200410101433 A CN200410101433 A CN 200410101433A CN 1798282 B CN1798282 B CN 1798282B
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Abstract
The invention consists of an ADC, a synchronizing unit used to synchronize the digital signal from the ADC in order to generate a synchronous signal in term of instruction of modulation mode, a demodulator used to demodulate the synchronous signal in term of the instruction of the modulation mode, and a channel decoder used to decode the demodulated signal and to output the decoded signal. The synchronizing unit includes a time recovery module for use in compensating the time offset and a carrier recovery module used to compensating the frequency error.
Description
Technical field
The present invention relates to a kind of digital multimedia receiver, relate in particular to a kind of receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation.
Background technology
In multimedia communication and broadcasting epoch, digitlization is all being carried out with the broadcasting of analogue type in countries in the world, especially in the developed country such as the U.S., and states such as Europe and Japan, digit broadcasting system is utilized by exploitation and input.Along with its fast development, in different countries, it was suggested the different standard that is used for digital broadcasting.
On December 24th, 1996, FCC (FCC) has proposed Advanced Television Systems Committee (ATSC) digital television standard as television broadcasting standard of future generation.All terrestrial broadcasting operators must abide by the ATSC standard about the standard of video/audio compression, packet data transmission structure and modulation and transmission system.Only about the standard of video format not by concrete regulation, but leave the industry decision for.
ATSC numeral TV standard utilizes single carrier VSB mode on the bandwidth of 6MHz, to transmit high-quality video, audio frequency and additional data, and supports terrestrial broadcasting pattern and high data rate cablecast pattern simultaneously.The main aspect of this mode is to have the 8-VSB modulator approach of improved form of the existing analogue type VSB mode of conduct of digital signal modulation capability.
In Europe, for its high frequency efficiency and antijamming capability and with COFDM (COFDM) system applies in DVB-T (digital video broadcast-terrestrial).
Other uses the data transmission scheme of different modulator approaches can be divided into multi-carrier scheme and single-carrier scheme.Thus, the conventional digital multi-media receiver can be divided into multi-carrier digital multi-media receiver and single carrier digital multimedia receiver.
Fig. 1 is the schematic block diagram of the conventional digital multi-media receiver of the expression signal that is used to handle multi-carrier modulation.
This traditional multi-carrier digital multi-media receiver comprises: tuner 110 is used for the multi-media signal of the tuning multi-carrier modulation that receives; ADC (analog to digital converter) 120, being used for the conversion of signals from tuner 110 outputs is digital signal; Lock unit 130 is used for the signal from ADC 120 is carried out timing recovery and carrier wave recovery; Fast Fourier transform (FFT) unit 140 is used for the signal from lock unit 130 outputs is carried out FFT; Balanced unit 150 is used for the signal of 140 outputs from the FFT unit is carried out equilibrium; QAM (quadrature amplitude modulation) symbol detection unit 160 is used for symbol detection is carried out in the output of equalizer; Preceding paragraph error correction (FEC) unit 170 is used for the signal from symbol detection unit 160 outputs is carried out the preceding paragraph error correction; With descrambler 180, be used for the signal of 170 outputs from the FEC unit is carried out descrambling to obtain mpeg stream.
Fig. 2 is the schematic block diagram that expression is used for the conventional digital multi-media receiver of processing single-carrier modulated signals.
This conventional single carrier digital multimedia receiver comprises: tuner 210 is used to receive the multi-media signal of single-carrier modulated; ADC 220, and being used for the conversion of signals from tuner 210 outputs is digital signal; (SYNC) unit 230 is used for carrying out and regularly recovers and the carrier wave recovery synchronously; Balanced unit 240 is used for the signal from lock unit 230 outputs is carried out equilibrium; (biasing) QAM symbol detection unit 250 is used for symbol detection is carried out in the output of balanced unit 240; FEC unit 260 is used for the signal of symbol detection unit 250 outputs is carried out the preceding paragraph error correction; With descrambler 270, be used for the signal of FEC unit 260 outputs is carried out descrambling to obtain mpeg stream.
So to the performance of single carrier transmitting system well still the performance of multicarrier transmission systems have permanent dispute well, but do not have concrete result.These two kinds of schemes all have merits and demerits separately.Therefore, the expectation broadcasting station allows from multiple transmission plan, to select to be fit to the transmission plan of its specific needs and broadcast environment.In this case, need be able to receive the decode the receiver of the broadcast singal of single carrier and multi-carrier modulation, to watch DTV (DTV) program from the broadcasting station of using different transmission schemes.
As everyone knows, traditional digital multimedia receiver can not receive the signal of single-carrier modulated signals and multi-carrier modulation simultaneously, and there are a lot of inconvenience in this.
Summary of the invention
One side of the present invention is to solve the problems referred to above and/or shortcoming at least.
The invention provides a kind of receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation.
The said receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation comprises; Be used on the multimedia of tuning reception tuner to corresponding wave band; Be used for tuning analog signal conversion is the ADC of digital signal; Be used to use the modulating mode indication synchronously from the digital signal of ADC to produce the lock unit of synchronizing signal; Be used to use the demodulating unit of the synchronous signal of modulating mode indication demodulation lock unit and be used for through the signal decoding of demodulating unit demodulation and the channel decoder of output result signal.
The lock unit of digital multimedia receiver can comprise the timing recovery block that is used to use modulating mode to indicate and compensates from the timing error of the digital signal of ADC; With the output signal frequency error that is used to use modulating mode to indicate and compensates timing recovery block to produce the carrier recovery block of synchronizing signal.
Timing recovery block comprises sampling unit, first loop filter and Timing Error Detector (TED) again.Sampling unit receives the digital signal from ADC again; TED detects the output signal of sampling unit based on modulating mode indication calculating timing error again; Its output signal is fed to first loop filter; First loop filter carries out filtering to the output signal of TED, and sampling unit uses the timing slip of the timing error estimation compensation of the warp first loop filter filtering from the digital signal of ADC again.
Carrier recovery block comprises blender, NC0 unit, second loop filter and frequency error estimator (FEE).Mixer mixing is the output signal of sampling unit again; The output signal of FEE detection mixer and based on skew of modulating mode indication estimated frequency and phase deviation; Second loop filter carries out filtering to the output signal of FEE; The NC0 unit will be converted into the phase value corresponding N C0 value of phase value and output and conversion by the frequency shift (FS) of the second loop filter filtering and phase deviation, and the NC0 value that blender uses the NC0 unit to provide compensates output signal frequency skew and the phase deviation of sampling unit with the input of generation synchronizing signal as demodulating unit again.
On the other hand, the lock unit of digital multimedia receiver can comprise, is used to use modulating mode to indicate and compensates the carrier recovery block from the output signal frequency error of the timing recovery block of the digital signal of ADC; With the timing recovery block of the output signal that is used to use modulating mode to indicate and compensates carrier recovery block with the timing error that produces synchronizing signal.
Carrier recovery block comprises blender, NC0 unit, second loop filter and frequency error estimator (FEE).Mixer mixing is from the digital signal of ADC; The output signal of FEE detection mixer and based on skew of modulating mode indication estimated frequency and phase deviation; Second loop filter carries out filtering to the output signal of FEE; The NC0 unit will convert phase value and output and the phase value corresponding N C0 value of changing into by the frequency shift (FS) and the phase deviation of the second loop filter filtering, and the NC0 value that blender uses the NC0 unit to provide compensates frequency shift (FS) and phase deviation from the digital signal of ADC.
Timing recovery block comprises sampling unit, first loop filter and Timing Error Detector (TED) again.Sampling unit receives the output signal of blender again; TED detects the output signal of sampling unit based on modulating mode indication calculating timing error again; Its output signal is fed to first loop filter; First loop filter carries out filtering to the output signal of TED, and the sampling unit use produces the input of synchronizing signal as demodulating unit through the timing slip of the output signal of the timing error estimation compensation blender of the first loop filter filtering again.
Preferably, channel decoder is the LDPC decoder.
Description of drawings
Through the following description of embodiment being carried out below in conjunction with accompanying drawing, above-mentioned and other purposes of the present invention and advantage will become apparent, wherein:
Fig. 1 is the schematic block diagram of the conventional digital multi-media receiver of the expression signal that is used to handle multi-carrier modulation;
Fig. 2 is the schematic block diagram that expression is used for the conventional digital multi-media receiver of processing single-carrier modulated signals;
Fig. 3 is the block diagram of expression according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of first embodiment of the invention;
Fig. 4 is the flow chart of the digital multimedia signal method of reseptance carried out in the digital multimedia receiver shown in Figure 3 of expression according to first embodiment of the invention;
Fig. 5 is the block diagram of expression according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of second embodiment of the invention;
Fig. 6 is the flow chart of the auto gain control method of execution during expression receives according to the digital multimedia shown in Fig. 5 of second embodiment of the invention;
Fig. 7 is the block diagram of expression according to the structure of the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of third embodiment of the invention;
Fig. 8 is the block diagram of demonstration according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of fourth embodiment of the invention;
Fig. 9 is the flow chart according to the digital multimedia method of reseptance of in digital multimedia receiver shown in Figure 8, carrying out of fourth embodiment of the invention;
Figure 10 is the block diagram of expression according to the structure of the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of fifth embodiment of the invention;
Figure 11 is the block diagram of demonstration according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of sixth embodiment of the invention;
Figure 12 is the flow chart according to the digital multimedia method of reseptance of in the digital multimedia receiver shown in Figure 11, carrying out of sixth embodiment of the invention;
Figure 13 is the block diagram of demonstration according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of seventh embodiment of the invention;
Figure 14 is the flow chart according to the digital multimedia method of reseptance of in digital multimedia receiver shown in Figure 13, carrying out of seventh embodiment of the invention; With
Figure 15 is the block diagram of expression according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals or multi-carrier modulation of eighth embodiment of the invention.
Embodiment
Now, will describe embodiments of the invention in detail, its example is enumerated in the accompanying drawings, and wherein identical label is represented identical parts all the time.Embodiment is described with reference to the accompanying drawings to explain the present invention.
Fig. 3 is the block diagram according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of first embodiment of the invention.
With reference to Fig. 3, this digital multimedia receiver comprises: tuner 310, be used for the multi-media signal that receives be tuned to corresponding band, wherein, multi-media signal is the signal of single-carrier modulated signals or multi-carrier modulation; ADC (analog-digital converter) 320, being used in the future, the tuning conversion of signals of self-tuner 310 is a digital signal; Demodulating unit 330; Comprise the demodulator 331 and the demodulator 332 that is used for the signal demodulation and the output of multi-carrier modulation that are used for single-carrier modulated signals demodulation and output; Wherein, When digital signal was imported into demodulating unit 330, one or two in two demodulators will be from digital demodulation signal and the output of ADC320; Selector 340 is used for being selected effective signal what export from demodulating unit 330 by the signal of demodulation according to the modulating mode indication; With shared channel decoder 350, be used for select from the signal decoding of the demodulation of demodulating unit 330 outputs and the signal that output obtains.
In demodulating unit 330, one or two operation in demodulator 331 and the demodulator 332 is also handled the digital signal of importing.If input signal is a single-carrier modulated signals, then demodulator 331 moves the also signal of output single carrier demodulation correctly.If digital signal is the signal of multi-carrier modulation, then the signal of multicarrier demodulation is also correctly exported in demodulator 332 operations.
Selector 340 reception indications are input to the modulating mode indication of the modulating mode of the signal in the demodulating unit 340, and according to one in the signal of this modulating mode indication selection output from demodulator 331 and demodulator 332.In more detail, if this digital signal is a single-carrier modulated signals, then selector 340 is selected from the signal of the demodulation of demodulator 331 outputs.If this digital signal is the signal of multi-carrier modulation, then selector 340 is selected from the signal of the demodulation of demodulator 332 outputs.
The shared channel decoder 350 that is used to single carrier transmission pattern and multi-carrier transmission pattern is connected in demodulating unit 330 through selector 340, and RS block decoder and LDPC decoder can be used as shared channel decoder 350.
Now, will the operation according to the digital multimedia receiver of first embodiment of the invention be described with reference to Fig. 3 and Fig. 4.
Fig. 4 is the flow chart of the digital multimedia signal method of reseptance of execution in receiving according to the digital multimedia shown in Fig. 3 of first embodiment of the invention.
At step S410, tuner 310 arrives corresponding band with the signal tuning that receives.Then, at step S420, ADC 320 is the tuning signal digitalized and output digital signal of self-tuner 310 in the future.
At step S430, demodulating unit 330 will and be exported the signal of demodulation from the digital demodulation signal of ADC 320.Here, one or two in the demodulator can processing digital signal in the demodulating unit 330.Specifically, if the signal of input is a single-carrier modulated signals, then demodulator 331 is also exported the digital signal demodulation correctly of input under single carrier mode.If the signal of input is the signal of multi-carrier modulation, then demodulator 332 is also exported the digital signal demodulation correctly of input under multi-carrier mode.
At step S440, selector 340 is always selected effective signal according to the modulating mode indication in the signal of demodulation unit 330.If selector 340 learns that according to the pattern modulation intelligence digital signal that is input to demodulating unit 330 is a single-carrier modulated signals, then selector 340 is selected from the signal of the demodulation of demodulator 331 outputs.If select 340 to learn that according to modulating mode indication the digital signal that is input to demodulating unit 330 is the signal of multi-carrier modulation, then selector 340 is selected from the signal of the demodulation of demodulator 332 outputs.
At step S450, shared channel decoder 350 will be from the signal decoding and the output of the demodulation of selector 340.
The digital multimedia receiver with said structure and the method for reseptance of the application of the invention can be through the modulating modes of the multi-media signal confirming to receive, and the signal of single-carrier modulated signals and multi-carrier modulation all can be processed.Thereby the hardware of this receiver is realized being simplified, and the receptivity of receiver is enhanced.
Fig. 5 is the block diagram of expression according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of second embodiment of the invention.
As shown in Figure 5; This digital multimedia receiver comprises: tuner 510; ADC 520; Be used for indicating the AGC (automatic gain controller) 530 of the gain of controlling the tuning signal that is input to ADC 520 and being used for the demodulating unit 540 that indication is carried out demodulation to digital signal according to modulating mode according to modulating mode.
The structural similarity of the structure of digital multimedia receiver shown in Figure 5 and receiver shown in Figure 3.In order to simplify, selector and decoder are not shown among Fig. 5.In addition, the tuner 310 among tuner 510 and ADC 520 and Fig. 3 is identical with the function of ADC 320, and therefore, the abridged is to their detailed description.
The signal of single-carrier modulated signals and multi-carrier modulation has different PAPR (peak-to-average power ratio) characteristic, and the signal of multi-carrier modulation is compared with single-carrier modulated signals has big relatively PAPR.The AGC algorithm that is used for these two kinds of modulating modes is also inequality.In above-mentioned receiver; Only used an AGC; Therefore, at the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation, AGC 530 should indicate according to the modulating mode of the modulating mode of indicating multi-media signal and adopt corresponding algorithm.
The characteristics of signals that AGC 530 measures from the digital signal of ADC 520 like average power or average amplitude (magnitude); And according to adjusting the gain that is input to the tuning signal of ADC 520 subsequently from tuner 510 with the corresponding AGC algorithm of modulating mode; Thereby, from the amplitude of the signal of tuner 510 output within the suitable opereating specification of ADC 520.For example, because the difference of PAPR, the target power that is used for the AGC of multi-carrier mode is set to the low value of target power than the AGC of single carrier mode.Like this, ADC 520 and true(-)running corresponding with the modulating mode of multi-media signal.
AGC 530 is RF (radio frequency) AGC or IF (intermediate frequency) AGC.
Fig. 6 is the flow chart of the auto gain control method carried out in the digital multimedia receiver of representing according to a second embodiment of the present invention shown in Figure 5.
At step S610, the tuner 510 tuning multi-media signals that receive.
At step S620, ADC 520 will be a digital signal from the tuning conversion of signals of tuner 510 outputs.
At step S630, the characteristics of signals that AGC 530 measures from the digital signal of ADC 520 like average power and average amplitude.
At step S640, AGC 530 indicates according to the result who measures and modulating mode and controls the gain that is input to the signal of ADC 520 from tuner 510.
Through use have said structure according to digital multimedia receiver of the present invention and auto gain control method, can come the signal of processing single-carrier modulated signals and multi-carrier modulation through the modulating mode of the multi-media signal confirming to receive.In addition, according to the modulating mode of the multi-media signal that receives can receiver control the gain of tuner.Thereby the realization of the hardware of receiver is simplified, and the receptivity of receiver is enhanced.
Fig. 7 is the block diagram of expression according to the structure of the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of third embodiment of the invention.
Digital multimedia receiver shown in Figure 7 comprises tuner 710, ADC 720, lock unit 730, demodulating unit 740 and channel decoder 750.
Timing recovery block 730T comprises sampling unit 731, first loop filter 732 and Timing Error Detector (TED) 733 again.At this, the output signal that TED733 detects sampling unit 731 again calculates timing error to indicate based on modulating mode, and its output signal is fed to first loop filter 732.The output signal of 732 couples of TED 733 of first loop filter carries out filtering, is fed to sampling unit 731 again through the signal of first loop filter 732 filtering.Sampling unit 731 uses through the timing error of first loop filter, 732 filtering and estimates to compensate the timing slip from the digital signal of ADC 720 again.And sampling unit 731 can comprise withdrawal device and the interpolation device that is respectively applied for extraction and interpolation again.Because different for the timing error detection algorithm of single-carrier modulated pattern and multi-carrier modulation pattern, so realize in TED 733 for the algorithm of said two kinds of patterns, TED 733 is based on the corresponding algorithm of modulating mode indication selection.In such cases, timing error information is by modulating mode indication decision.
Demodulating unit 740 will be from the synchronous signal demodulation of lock unit 730 based on modulating mode indication.
Can find out that from above description digital multimedia receiver according to the present invention is indicated based on modulating mode and carried out synchronously.
According to the receiver structure of Fig. 7, regularly recover to recover to take place once the back carrier wave takes place.Yet in fact, timing recovery block 730T can place different positions, takes place before demodulation as long as regularly recover.That is to say that the position of timing recovery block 730T and carrier recovery block 730C can exchange.
The modulating mode indication can receive from the mode detector (not shown).
Through using the structure of digital multimedia receiver shown in Figure 7, can be based on single-carrier modulated pattern and multi-carrier modulation pattern compensation timing slip and frequency shift (FS).Therefore, receiver can correctly be operated single-carrier modulated pattern and multi-carrier modulation pattern.
Receiving filter is used in the digital multimedia receiver usually, to reduce inter symbol interference and additional noise.The system that is used for single-carrier modulated pattern and multi-carrier modulation pattern should have different bandwidth owing to different spectral characteristics.In order in digital multimedia receiver, only to use a shared receiving filter with processing single-carrier modulated pattern and multi-carrier modulation pattern, the characteristic of receiving filter should be changed through using different pre-determined factor collection.For this reason, the filter coefficient set that is used for the shared receiving filter of single-carrier modulated pattern and multi-carrier modulation pattern should be updated according to modulating mode.
Fig. 8 is the block diagram of demonstration according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of fourth embodiment of the invention.
With reference to Fig. 8, this digital multimedia receiver comprises tuner 810, ADC 820, filter coefficient unit 830, receiving filter 840, demodulating unit 850 and channel decoder 860.
The multi-media signal that tuner 810 tuning (down conversion) receives through antenna.
Receiving filter 840 according to by filter coefficient storage 831 that provide with single-carrier modulated pattern or the corresponding filter coefficient set of multi-carrier modulation pattern, will be from the digital signal filter of ADC 820.Receiving filter 840 can be square root raised cosine (SRRC) filter.Being used as the SRRC filter that is complementary with transmitting terminal SRRC filter maximizes signal to noise ratio through matched signal.
Demodulating unit 850 indicates the digital signal of demodulation by receiving filter 840 filtering according to modulating mode.Demodulating unit 850 comprises first switch 851, OQAM demodulator 852, FFT unit 853, qam demodulator 854 and second switch 855.
In addition, first switch 851 can be omitted.In this case, one of OQAM demodulator 852 and qam demodulator 854 or both work.At length, be input to OQAM demodulator 852 and FFT unit 853 simultaneously by the signal of receiving filter 840 filtering, one of OQAM demodulator 852 and FFT unit 853 or both are allowed to work.
In addition, in the present embodiment, demodulator 852 also can be a qam demodulator.
To describe the operating process of the digital multimedia receiver shown in Fig. 8 now with reference to Fig. 9 in detail.Fig. 9 is the flow chart according to the digital multimedia method of reseptance of in digital multimedia receiver shown in Figure 8, carrying out of fourth embodiment of the invention.
With reference to Fig. 9, in step S910, the signal that receives is by tuning (down conversion).In step S920, the signal of tuning (down conversion) is converted into digital signal.
In step S930, this digital signal is indicated by filtering according to modulating mode.More particularly, filter coefficient set is provided according to modulating mode indication, and based on this filter coefficient set with digital signal filter.
In step S940, filtered digital signal is indicated by demodulation according to modulating mode.At length; If the modulating mode indication is the indication of single-carrier modulated pattern; So filtered signal is separated through OQAM and is transferred by demodulation, if the modulating mode indication is the indication of multi-carrier modulation pattern, so filtered signal is separated through FFT and QAM and transferred by demodulation.
At last, in step S950, the signal after the demodulation is decoded.
In addition, in step S940, if the modulating mode indication is the indication of single-carrier modulated pattern, so filtered signal also can be separated through QAM and transfer by demodulation.
Because shared filter is used for the signal of single-carrier modulated signals and multi-carrier modulation, so the realization of digital multimedia receiver is simplified, and the handling property of digital multimedia receiver is enhanced.
Figure 10 is the block diagram of expression according to the structure of the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of fifth embodiment of the invention.
Digital multimedia receiver shown in Figure 10 comprises tuner 1010, ADC 1020, lock unit 1030, demodulating unit 1040, selector 1050 and channel decoder 1060.
The multi-media signal of 1010 pairs of receptions of tuner be tuned to corresponding wave band.ADC 1020 will be a digital signal through tuning analog signal conversion through sampling and quantification.
The first equalization filter 1043a uses the equalizing coefficient that is provided by coefficient update device 1043b to carrying out equilibrium from lock unit 1030 synchronous signals.Coefficient update device 1043b uses from lock unit 1030 synchronous signal, the output of equalizer and the estimation that reference signal is carried out the calculating of equalizing coefficient.
In the single-carrier modulated pattern, the first equalization filter 1043a uses the equalizing coefficient that is provided by coefficient update device 1043b to carrying out equilibrium from lock unit 1030 synchronous signals.The output of the first equalization filter 1043a is imported into OQAM unit 1044 and therein by demodulation.The signal of 1044 demodulation is imported into selector 1050 for you to choose from the OQAM unit.Coefficient update device 1043b detects from lock unit 1030 synchronous signal, equalizers and exports and reference signal, and upgrades equalizing coefficient, and equalizing coefficient information is offered equalization filter 1043a.
At this, prearranged signal is used as reference signal like the PN sequence.If first balanced unit 1043 is in direct judgment model (decision-directed mode), OQAM demodulation output is used as reference signal so.
Equalizing coefficient is according to employed equalization algorithm and difference.Therefore the realization of coefficient update device 1043b is by the kind decision of employed equalization filter.At the existing algorithm that is used for the equilibrium of single-carrier modulated signals, for example in linear equalization, frequency domain equalization and the decision feedback equalization (decision-feedbackequalization), use the DFE algorithm better.When processing single-carrier modulated signals, the use of DFE filter provides the more performance of the demodulating equipment of proposition.
On the other hand; Second demodulation block 1042 comprises the FFT unit that is used for the signal of synchronous multi-carrier modulation is transformed into from time domain frequency domain; Be used for second balanced unit 1046 of the balanced signal of changing and be used for the QAM unit 1047 of demodulation from the signal of second balanced unit, 1046 equilibriums.Second balanced unit 1046 further comprises the second equalization filter 1046a and channel estimator 1046b.
In the multi-carrier modulation pattern; Channel estimator 1046b uses reference signal to estimate; In such cases, the PN sequence of from the synchronous signal of lock unit 1030, extracting is used as reference signal, and channel estimating information is offered the second equalization filter 1046a.FFT unit 1045 FFT conversion is from the synchronous signal of lock unit 1030.The second equalization filter 1046a uses the signal from the balanced FFT conversion of channel estimating information of channel estimator 1046b.QAM unit 1047, is selected for indicating according to modulating mode with the input as selector 1050 of the signal that produces demodulation with the balanced signal of the QAM pattern demodulation second equalization filter 1046a.
In fact, other prearranged signal can be used as reference signal like pilot sub-carrier.Pilot sub-carrier is detected from the output of FFT unit 1045.
Thus, demodulating unit shown in Figure 10 has the ability of equalizing signal, but the signal of the single-carrier modulated signals of demodulate reception and multi-carrier modulation.
Use the demodulating unit shown in Figure 10 can be based on single-carrier modulated pattern and multi-carrier modulation pattern compensation channel distortion.Thereby, can improve the performance of the digital multimedia receiver that is used for these two kinds of patterns, and reduce channel errors.
Can processing single-carrier modulated signals and the cost of the digital multimedia receiver of the signal of multi-carrier modulation in order to reduce, can use a shared ADC.But because the unique character of single-carrier modulated pattern and multi-carrier modulation pattern, the symbol-rate of these two kinds of modulating modes is different.Therefore, in the processing path of digital multimedia receiver, the output of shared ADC should be extracted to being suitable for the different symbol-rate of single-carrier modulated pattern and multi-carrier modulation pattern.
For example, the sample rate of supposing ADC is r1, and the symbol-rate of single-carrier modulated pattern and multi-carrier modulation pattern is respectively r2 and r3.The extraction yield N:1 of single-carrier modulated pattern equals r1:r2, and the extraction yield M:1 of multi-carrier modulation pattern equals r1:r3.Because r3 is less than r2, M is greater than N.
Figure 11 is the block diagram of demonstration according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of sixth embodiment of the invention.
With reference to Figure 11, this digital multimedia receiver comprises tuner 1110, ADC 1120, extracting unit 1130, demodulating unit 1140 and channel decoder 1150.
The multi-media signal that tuner 1110 tuning (down conversion) receives through antenna.
ADC 1120 will be a digital signal by tuner 1110 tuning conversion of signals through sampling, quantification and coding.
Extracting unit 1130 is according to the digital signal of modulating mode indication extraction from ADC 1120.Extracting unit 1130 comprises first switch 1131, first withdrawal device 1132 and second withdrawal device 1133.
First switch 1131 is according to one in modulating mode indication selection first withdrawal device 1132 and second withdrawal device 1133.More particularly, if the modulating mode indication is the indication of single-carrier modulated pattern, first switch 1131 is selected the digital signal that first withdrawal device, 1132, the first withdrawal devices 1132 receive through first switch 1131 so.First withdrawal device 1132 extracts the digital signal from ADC 1120 with N:1.If the modulating mode indication is the indication of multi-carrier modulation pattern, first switch 1131 is selected the digital signal that second withdrawal device, 1133, the second withdrawal devices 1133 receive through first switch 1131 so.Second withdrawal device 1133 extracts the digital signal from ADC 1120 with M:1.Here, come predetermined respectively N and M corresponding to single-carrier modulated pattern and multi-carrier modulation pattern.
The signal that demodulating unit 1140 demodulation are extracted by extracting unit 1130.Demodulating unit 1140 comprises OQAM demodulator 1141, FFT unit 1142, qam demodulator 1143 and second switch 1144.
OQAM demodulator 1141 will be by the signal demodulation of first withdrawal device, 1132 extractions.The 1142 pairs of signals that extracted by second withdrawal device 1133 in FFT unit are carried out the FFT conversion, and qam demodulator 1143 will be by the signal demodulation of FFT unit 1142 FFT conversion.
Second switch 1144 is indicated one that selects in OQAM demodulator 1141 and the qam demodulator 1143 according to modulating mode.The function of the second switch 855 among the function of second switch 1144 and Fig. 8 is identical, has therefore omitted the detailed description to it.
Channel decoder 1150 decodings are by the signal of demodulating unit 1140 demodulation.Channel decoder 1150 can be the LDPC decoder.
In addition, similar with Fig. 8, first switch 1131 can omit.
In addition, in the present embodiment, demodulator 1141 also can be a qam demodulator.
To describe the operating process of the digital multimedia receiver shown in Figure 11 now with reference to Figure 12 in detail.Figure 12 is the flow chart according to the digital multimedia method of reseptance of in the digital multimedia receiver shown in Figure 11, carrying out of sixth embodiment of the invention.
With reference to Figure 12, in step S1210, the signal that receives is by tuning (down conversion).In step S1220, the signal of tuning (down conversion) is converted into digital signal.
In step S1230, digital signal is indicated according to modulating mode and is extracted.At length, if the modulating mode indication is the indication of single-carrier modulated pattern, digital signal is extracted with N:1 so, if the modulating mode indication is the indication of multi-carrier modulation pattern, digital signal is extracted with M:1 so.Here, come predetermined respectively N and M corresponding to single-carrier modulated pattern and multi-carrier modulation pattern.
In step S1240, the signal after the extraction is by demodulation.More particularly, if the modulating mode indication is the indication of single-carrier modulated pattern, the signal after N:1 extracts so passes through the OQAM demodulation by demodulation.If modulating mode indication is the indication of multi-carrier modulation pattern, the signal after M:1 extracts so through FFT conversion and QAM demodulation by demodulation.
At last, in step S1250, the signal after the demodulation is decoded.
In addition, in step S1240, if the modulating mode indication is the indication of single-carrier modulated pattern, the signal after N:1 extracts so also can be through the QAM demodulation by demodulation.
Because withdrawal device is changed the symbol-rate of the signal of sample rate and single-carrier modulated signals and multi-carrier modulation respectively pro rata, so only use a shared ADC at digital multimedia receiver.Therefore, the hardware of digital multimedia receiver is realized being simplified, and the signal of single-carrier modulated signals and multi-carrier modulation can correctly be handled.
Can improve the efficient of error correction coding through using data interleaver.Data interleaver has been disperseed burst error.Because according to different modulating modes, data frame structure is different, can be different so limit the parameter of data interleaver function, and to be used for single-carrier modulated pattern and multi-carrier modulation pattern.Therefore, in digital multimedia receiver, the parameter that is used for deinterleaver should change according to different modulating modes.In addition, the LDPC sign indicating number is because its super error ability can be used for single-carrier modulated pattern and multi-carrier modulation pattern.
Figure 13 is the block diagram of demonstration according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals and multi-carrier modulation of seventh embodiment of the invention.
With reference to Figure 13, this digital multimedia receiver comprises tuner 1310, ADC 1320, demodulating unit 1330, deinterleaver 1340 and LDPC decoder 1350.
The multi-media signal that tuner 1310 tuning (down conversion) receives through antenna.
Therefore, have only a deinterleaver to be used for the signal of processing single-carrier modulated signals and multi-carrier modulation.Therefore, the parameter of deinterleaver 1340 should be indicated according to modulating mode and is determined.
The signal decoding that LDPC decoder 1350 will be deinterleaved by deinterleaver 1340.LDPC decoder 1350 also can be replaced by the decoder of other type.
In addition, similar with the situation of Fig. 9, first switch 1331 can omit.
In addition, in the present embodiment, demodulator 1332 also can be a qam demodulator.
Figure 14 is the flow chart according to the digital multimedia method of reseptance of in digital multimedia receiver shown in Figure 13, carrying out of seventh embodiment of the invention.
With reference to Figure 14, in step S1410, the signal that receives is by down conversion.In step S1420, the signal of down conversion is converted into digital signal.
In step S1430, this digital signal is indicated by demodulation according to modulating mode.At length; If the modulating mode indication is the indication of single-carrier modulated pattern; This digital signal is separated through OQAM and is transferred by demodulation so, if the modulating mode indication is the indication of multi-carrier modulation pattern, this digital signal is separated through FFT conversion and QAM and transferred by demodulation so.
In step S1440, deinterleave according to the signal of modulating mode indication with demodulation.In this case, indication comes definite and applies the parameter that deinterleaves according to modulating mode.
At last, in step S1450, the signal after the demodulation is decoded by LDPC.
In addition, in step S1430, if the modulating mode indication is the indication of single-carrier modulated pattern, this digital signal also can be separated through QAM and transferred by demodulation so.
Owing to have only a deinterleaver to be used for the signal of single-carrier modulated signals and multi-carrier modulation, so the realization of digital multimedia receiver is simplified.In addition, because in digital multimedia receiver, used the LDPC decoder with super error ability, the handling property of digital multimedia receiver is enhanced.
Figure 15 is the block diagram of expression according to the digital multimedia receiver of the signal that is used for processing single-carrier modulated signals or multi-carrier modulation of eighth embodiment of the invention.
With reference to Figure 15, digital multimedia receiver comprises: tuner 1510, be used for the multi-media signal that receives be tuned to corresponding band; ADC 1520, and being used for the tuning conversion of signals from tuner 1510 outputs is digital signal; Demodulator 1530 is used for the digital signal of demodulation from ADC 1520; Code element is removed mapper 1540, is used for the signal of the demodulation of exporting from demodulator 1530 is gone mapping; With LDPC decoder 1550, be used for the signal decoding that removes mapper 1540 from code element is also exported the signal that obtains.
In the digital multimedia transmission system of the bit stream that requires the video/audio of transmission of high-definition under error-free situation, use powerful error correcting code extremely important to reduce bit error rate.The LDPC sign indicating number has stronger error correcting capability as a kind of error correcting code, and therefore, the LDPC sign indicating number can combine with the digital multimedia transmission system corresponding to single-carrier modulated pattern or multi-carrier modulation pattern.
Use under the situation of LDPC encoder with the raising error correcting capability at the digital multimedia transmitter, in receiver, should correspondingly use the LDPC decoder.In this case, can improved receptivity.
When the multi-media signal that receives was single-carrier modulated signals, it was that the OQAM code element goes mapper or QAM code element to remove mapper that code element is removed mapper 1540.
When the multi-media signal that receives was the signal of multi-carrier modulation, it was that the QAM code element is removed mapper that code element is removed mapper 1540.
Through using above-mentioned receiver, can improved error correcting capability.
As stated, according to an aspect of the present invention, digital multimedia receiver can processing single-carrier modulated signals and the signal of multi-carrier modulation, and has the structure of simplification and high receptivity.
According to a further aspect in the invention, through using the LDPC decoder, the decoding performance that digital multimedia receives significantly improves.
Though represent with reference to specific embodiment and described the present invention, it should be appreciated by those skilled in the art, under the situation that does not break away from the spirit and scope of the present invention that are defined by the following claims, can carry out the modification of various forms and details to it.
Claims (6)
1. digital multimedia receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation comprises:
Tuner, the multi-media signal that is used for tuning reception is to corresponding wave band;
ADC, being used for tuning analog signal conversion is digital signal;
Lock unit, be used to use the modulating mode indication synchronously from the digital signal of ADC to produce synchronizing signal;
Demodulating unit is used to use the synchronous signal of modulating mode indication demodulation lock unit; With
Channel decoder is used for through the signal decoding of demodulating unit demodulation and export the signal of gained,
Wherein, lock unit comprises: timing recovery block is used to use modulating mode to indicate and compensates the timing error from the digital signal of ADC; Carrier recovery block, the output signal frequency error that is used to use modulating mode to indicate and compensates timing recovery block is to produce synchronizing signal.
2. digital multimedia receiver as claimed in claim 1, wherein:
Timing recovery block comprises sampling unit, first loop filter and Timing Error Detector (TED) again,
Sampling unit receives the digital signal from ADC again; TED detects the output signal of sampling unit based on modulating mode indication calculating timing error again; Its output signal is fed to first loop filter; First loop filter carries out filtering to the output signal of TED, and sampling unit uses the timing slip of the timing error estimation compensation of the warp first loop filter filtering from the digital signal of ADC again; With
Carrier recovery block comprises blender, NCO unit, second loop filter and frequency error estimator (FEE),
Mixer mixing is the output signal of sampling unit again; The output signal of FEE detection mixer and based on skew of modulating mode indication estimated frequency and phase deviation; Second loop filter carries out filtering to the output signal of FEE; The NCO unit will be converted into the phase value corresponding N CO value of phase value and output and conversion by the frequency shift (FS) of the second loop filter filtering and phase deviation, and the nco value that blender uses the NCO unit to provide compensates output signal frequency skew and the phase deviation of sampling unit with the input of generation synchronizing signal as demodulating unit again.
3. according to claim 1 or claim 2 digital multimedia receiver, wherein, channel decoder is the LDPC decoder.
4. digital multimedia receiver that is used for the signal of processing single-carrier modulated signals and multi-carrier modulation comprises:
Tuner, the multi-media signal that is used for tuning reception is to corresponding wave band;
ADC, being used for tuning analog signal conversion is digital signal;
Lock unit, be used to use the modulating mode indication synchronously from the digital signal of ADC to produce synchronizing signal;
Demodulating unit is used to use the synchronous signal of modulating mode indication demodulation lock unit; With
Channel decoder is used for through the signal decoding of demodulating unit demodulation and export the signal of gained,
Wherein, lock unit comprises: carrier recovery block is used to use modulating mode to indicate and compensates the output signal frequency error from the timing recovery block of the digital signal of ADC; Timing recovery block, the timing error of output signal that is used to use modulating mode to indicate and compensates carrier recovery block is to produce synchronizing signal.
5. digital multimedia receiver as claimed in claim 4, wherein:
Carrier recovery block comprises blender, NCO unit, second loop filter and frequency error estimator (FEE),
Mixer mixing is from the digital signal of ADC; The output signal of FEE detection mixer and based on skew of modulating mode indication estimated frequency and phase deviation; Second loop filter carries out filtering to the output signal of FEE; The NCO unit will convert phase value and output and the phase value corresponding N CO value of changing into by the frequency shift (FS) and the phase deviation of the second loop filter filtering, and the nco value that blender uses the NCO unit to provide compensates frequency shift (FS) and phase deviation from the digital signal of ADC; With
Timing recovery block comprises sampling unit, first loop filter and Timing Error Detector (TED) again,
Sampling unit receives the output signal of blender again; TED detects the output signal of sampling unit based on modulating mode indication calculating timing error again; Its output signal is fed to first loop filter; First loop filter carries out filtering to the output signal of TED, and the timing slip of the output signal of the timing error estimation compensation blender of the sampling unit use warp first loop filter filtering is to produce the input of synchronizing signal as demodulating unit again.
6. like claim 4 or 5 described digital multimedia receivers, wherein, channel decoder is the LDPC decoder.
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