KR20060070391A - A digital multimedia signal receiver for processing a single carrier modulated signal and a multi carrier modulated signal and a receiving method thereof - Google Patents

Abstract

The present invention relates to a digital multimedia signal receiver and a method of receiving the same. The digital multimedia receiver according to the present invention includes a tuner for tuning a received multimedia signal to a corresponding band, an analog to digital converter for converting a tuned signal output from the tuner into a digital signal, and a signal of a digital signal output from an analog to digital converter. An automatic gain control unit for measuring the characteristic, controlling the gain of the tuned signal output from the tuner according to the measured signal characteristic and the modulation mode instruction, and demodulating and outputting the digital signal output from the analog-to-digital converter according to the modulation mode instruction It includes a demodulator. Thereby, a digital multimedia receiver and a method of receiving the same are provided which can process both a single carrier modulated signal and a multicarrier modulated signal with a simple structure.

Single, multi, carrier, digital, multimedia, broadcasting

Description

A digital multimedia signal receiver for processing a single carrier modulated signal and a multi carrier modulated signal and a receiving method

1 is a block diagram showing the configuration of a conventional multi-carrier digital broadcast receiver;

2 is a block diagram showing the configuration of a conventional single carrier digital broadcast receiver;

3 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a first embodiment of the present invention;

4 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to the first embodiment of the present invention shown in FIG.

5 is a block diagram showing a configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a second embodiment of the present invention;

6 is a flowchart provided to explain an automatic gain control method performed in the digital multimedia receiver according to the second embodiment of the present invention shown in FIG.

7 is a block diagram showing the structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a third embodiment of the present invention;

8 is a block diagram showing a configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fourth embodiment of the present invention;

9 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to the fourth embodiment of the present invention shown in FIG. 8;

10 is a block diagram showing the structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fifth embodiment of the present invention;

11 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a sixth embodiment of the present invention;

12 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to a sixth embodiment of the present invention shown in FIG. 11;

13 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a seventh embodiment of the present invention;

14 is a flowchart provided to explain a digital multimedia reception method performed in a digital multimedia receiver according to a seventh embodiment of the present invention shown in FIG. 13;

FIG. 15 is a block diagram illustrating a configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to an eighth embodiment of the present invention.

The present invention relates to a digital multimedia receiver and a digital multimedia receiving method, and more particularly, to a digital multimedia receiver and a digital multimedia receiving method capable of processing a multi-carrier modulated signal and a single carrier modulated signal.

 With the advent of the multimedia communication and broadcasting era, countries around the world are digitizing analog broadcasts. In particular, in advanced countries such as the United States, Europe, and Japan, digital broadcasting systems have already been developed and put into practical use. Due to this rapid development, different standards for digital broadcasting have been proposed in each country.

On December 24, 1996, the US Federal Communications Commission (ATC) approved the Advanced Television Systems Committee (ATSC) digital TV standard as the next generation TV broadcast standard. Terrestrial broadcasters shall comply with the ATSC standard for video / audio compression protocols, packet data transmission structures, and modulation and transmission systems. However, the protocol for the video format was not specified and was reserved by the industry.

The ATSC digital TV standard is intended for high-quality video, audio, and additional data transmission in the 6 MHz band using single carrier VSB, supporting both terrestrial broadcast mode and high-speed cable broadcast mode. At the heart of this approach is the 8-VSB approach, which modulates the digital signal by complementing the existing analog BSB approach.

In Europe, a coded orthogonal frequency division multiplexing (COFDM) system has been adopted as the DVB-T (Digital Video Broadcasting Terrestrial) standard, which has advantages in high frequency efficiency and interference prevention.

In addition, digital multimedia broadcasting techniques using various modulation methods have been proposed, and these techniques can be classified into a multi-carrier technique and a single-carrier technique. Thus, conventional digital multimedia receivers are classified into multi-carrier digital receivers and single-carrier digital receivers.

 1 is a block diagram illustrating a multi-carrier digital broadcast receiver according to the prior art.

Conventional multi-carrier digital broadcast receivers include a tuner (110) for receiving a multi-carrier modulated digital multimedia signal, an AD converter (120) for converting an output signal from the tuner (110) into a digital signal, and an AD converter (120). Synchronization unit 130 for performing timing recovery and carrier recovery for the digital signal, FFT unit 140 for performing Fast Fourier Transform (FFT) on the output signal from the synchronization unit 130, FFT unit Equalizer 150 for equalizing the output signal from 140, Quadrature Amplitude Modulation (QAM) symbol detector 160 for performing symbol detection on the equalized output, and transmitted for the output signal from symbol detector 160 An FEC unit 170 that performs forward error correction and a descrambler 180 that descrambles an output signal from the FEC unit 170 to obtain an MPEG stream.

2 is a block diagram showing a single carrier digital broadcast receiver according to the prior art.

A conventional single carrier digital broadcast receiver includes a tuner 210 for receiving a single carrier modulated digital multimedia signal, an AD converter 220 for converting an output signal from the tuner 210 into a digital signal, and performing timing recovery and carrier recovery. An equalizer 240, an equalizer 240 that equalizes the output signal from the synchronizer 230, an offset quadrature amplitude modulation (OQAM) or a QAM symbol detector that performs symbol detection on the output from the equalizer 240 250, an FEC unit 260 that performs transmission error correction on the output signal from the equalizer 240, and a descrambler 270 that descrambles the output signal from the FEC unit 260 to obtain an MPEG stream. ).

The discussion of single carrier and multicarrier transmission systems continues for a long time and the results of the discussion are still unclear. Both transmission methods have advantages and disadvantages. Therefore, it is preferable that each broadcasting station selects an appropriate transmission scheme for a specific situation or broadcasting environment. In this case there is a need for a digital TV receiver capable of decoding single carrier and multicarrier modulated broadcast signals for watching DTV programs from broadcasters using different transmission techniques.

As is known, a receiver according to the prior art cannot simultaneously receive a multicarrier modulated signal and a single carrier modulated signal, and a conventional receiver cannot operate in a different digital broadcasting system.

Accordingly, an object of the present invention is to provide a digital multimedia receiver and a method of receiving the same, capable of receiving both a single carrier modulated signal and a multicarrier modulated signal.

In accordance with another aspect of the present invention, a digital multimedia receiver includes: a tuner for tuning a received multimedia signal into a corresponding band, an analog-digital converter for converting the tuned signal output from the tuner into a digital signal, and the output from the analog-digital converter. An automatic gain control unit for measuring a signal characteristic of a digital signal and controlling a gain of the tuned signal output from the tuner according to the measured signal characteristic and modulation mode indication and from the analog-digital converter according to the modulation mode indication And a demodulator for demodulating and outputting the output digital signal.

Here, the automatic gain control unit is preferably an RF automatic gain control unit or an IF automatic gain control unit.

On the other hand, the digital multimedia reception method according to the present invention, (a) tuning the received multimedia signal, (b) converting the tuned signal into a digital signal, (c) measuring the signal characteristics of the digital signal And (d) controlling the gain of the tuned signal in accordance with the measured signal characteristic and modulation mode indication.

Here, in the step (d), it is preferable to control the gain of the tuned signal according to the RF automatic gain control mode or the IF automatic gain control mode.

Hereinafter, with reference to the accompanying drawings illustrating the present invention.

3 is a block diagram of a receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a first embodiment of the present invention.

Referring to FIG. 3, the receiver includes a tuner 310, an analog-to-digital converter (AD converter) 320, a demodulator 330, a selector 340, and a common channel decoder 360.

The tuner 310 tunes the received multimedia signal to the corresponding band. Here, the multimedia signal is a single carrier modulated signal or a multicarrier modulated signal. The AD converter 320 converts the tuning signal input from the tuner 310 into a digital signal. The demodulator 330 includes a first demodulator 331 for demodulating and outputting a single carrier modulated signal and a second demodulator 332 for demodulating and outputting a multicarrier modulated signal. When the digital signal is input to the demodulator 330, only one of the two demodulators is operated so that the signal corresponding to the modulation mode of the multimedia signal input from the AD converter 320 can be demodulated. The selector 340 selects a valid signal from the demodulated signals output from the demodulator 330 according to the modulation mode indication. The common channel decoder 360 decodes and outputs a demodulated signal input from the demodulator.

In the demodulator 330, the digital signal is processed in the first demodulator 331 and the second demodulator 332. Either one or both demodulators are activated to process the signal, and the appropriate output is selected for post processing. For example, when the input digital signal is a single carrier modulated signal, the first demodulator 331 operates to output a single carrier demodulated signal. When the input digital signal is a multicarrier modulated signal, the second demodulator 332 operates to output the multicarrier demodulated signal.

The selector 340 receives a modulation mode indication indicating a modulation mode of a signal input to the demodulator 330, and outputs signals from the first demodulator 331 and the second demodulator 332 according to the modulation mode indication. Choose one. In more detail, when the input digital signal is a single carrier modulated signal, the selector 340 selects a demodulated signal output from the first demodulator 331. When the input digital signal is a multicarrier modulated signal, the selector 340 selects a demodulated signal output from the second demodulator 332.

The common channel decoder 360 used in both the single carrier transmission mode and the multicarrier transmission mode is connected to the demodulator. A Reed-Solomon (RS) block decoder or a low-density-parity-check (LDPC) decoder may be used as the common channel decoder.

An operation of the digital multimedia receiver according to the first embodiment of the present invention will be described with reference to FIGS. 3 and 4.

4 is a flowchart provided to explain a digital multimedia signal receiving method performed in a digital multimedia receiver according to the first embodiment of the present invention shown in FIG.

The tuner 310 tunes the received signal to the corresponding band (S410). Subsequently, the AD converter 320 digitizes the tuning signal output from the tuner 310 and outputs a digital signal (S420).

The demodulator 330 demodulates the digital signal output from the AD converter 320 and outputs demodulated signals (S430). Here, only one or all of the demodulators in the demodulator 330 are operated for signal processing, and an appropriate output is selected for post processing. More specifically, when the signal is a single carrier modulated signal, the first demodulator 331 operates to output the single carrier demodulated signal. When the signal is a multicarrier modulated signal, the second demodulator 332 operates to output the multicarrier demodulated signal.

A valid signal among the demodulated signals output from the demodulator 330 is selected by the selector 340 according to the modulation mode indication (S440). When the selector 340 knows that the digital signal input to the demodulator 330 is a single carrier modulation mode signal by the modulation mode indication, the selector 340 demodulates the output from the first demodulator 331. Select the signal. When the selector 340 learns that the digital signal input to the demodulator 330 is a multicarrier modulated signal according to the modulation mode command, the selector 340 receives the demodulated signal output from the second demodulator 332. Choose.

Subsequently, the demodulated signal output from the selector 340 is decoded and output by the common channel decoder 360 (S450).

According to the multimedia receiver having the above structure and the method of receiving the same, both the single carrier modulated signal and the multicarrier modulated signal can be processed by determining the modulation mode of the received multimedia signal. Therefore, the receiver can be simply implemented in hardware, and the performance of the receiver is improved.

5 is a block diagram of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a second embodiment of the present invention.

As shown in FIG. 5, the receiver includes a tuner 510, an AD converter 520, and an automatic gain controller for controlling a gain of a tuning signal input to the AD converter 520 according to a modulation mode indication. ) And a demodulator 540.

The structure of the digital multimedia receiver shown in FIG. 5 is similar to that of FIG. 5 does not show a selector and a decoder. Also, the tuner 510 and the AD converter 520 perform the same functions as the tuner 310 and the AD converter 320 of FIG. 3. Therefore, detailed description thereof will be omitted.

The single carrier modulated signal and the multicarrier modulated signal have different PERR (Peak to Average Powef Patio) characteristics. The multicarrier modulated signal has a relatively large PARR characteristic compared to the single carrier modulated signal. Automatic gain control (AGC) algorithms for the two modulation modes are different. In the receiver, only one AGC is used. Therefore, in the receiver for processing the single carrier modulated signal and the multicarrier modulated signal, the automatic gain control unit 530 employs an algorithm according to the modulation mode indication indicating the modulation mode of the signal.

The automatic gain control unit 530 measures signal characteristics such as average power or average magnitude of the digital signal output from the AD converter 520, and gains a tuning signal output from the tuner 510 and input to the AD converter 520. Is adjusted according to the AGC algorithm corresponding to the modulation mode. As a result, the amplitude of the signal output from the tuner 510 falls within the proper operating range of the AD converter 520. For example, due to the PARR difference, the target power for the AGC in the multi-carrier mode is set to have a value less than the target power for the AGC in the single carrier mode. In this manner, the AD converter 520 operates appropriately in response to the modulation mode of the multimedia signal.

The automatic gain control unit 530 may be implemented as a radio frequency (RF) AGC or an intermediate frequency (IF) AGC.

6 is a flowchart provided to explain an automatic gain control method performed in the digital multimedia receiver of FIG. 5 according to the second embodiment of the present invention.

The tuner 510 tunes the received signal (S610).

Thereafter, the AD converter 520 converts the tuning signal output from the tuner 510 into a digital signal (S620).

The automatic gain control unit 530 measures the average power of the digital signal input from the AD converter 520 (S630).

The automatic gain control unit 530 controls the gain of the signal input from the tuner 510 to the ADC 520 based on the measurement result and the modulation mode indication (S640).

According to the digital multimedia receiver and the receiving method of the present invention having the above structure, the single carrier modulated signal and the multicarrier modulated signal can be processed by determining the modulation mode of the received multimedia signal. In addition, the gain of the tuner of the receiver is controlled corresponding to the modulation mode of the received multimedia signal. Therefore, the receiver can be simply implemented in hardware, and the reception performance of the receiver is greatly improved.

FIG. 7 is a block diagram illustrating a structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a third embodiment of the present invention.

The digital multimedia receiver illustrated in FIG. 7 includes a tuner 710, an AD converter 720, a synchronizer 730, a demodulator 740, and a channel decoder 760.

Tuner 710 tunes the received multimedia signal to an intermediate frequency signal. The AD converter 720 converts the tuned analog signal into a digital signal through sampling and quantization.

The synchronizer 730 synchronizes the digital signal converted by the AD converter 720 using the modulation mode indication. The synchronization unit 730 includes a timing recovery block 730T and a carrier recovery block 730C.

While the carrier recovery block 730C compensates for the frequency and phase offsets, the timing recovery block 730T compensates for the timing offset of the digital signal input from the AD converter 720 and converts the sampling rate.

The timing recovery block 730T includes a resampling unit 731 and a timing error detector 732. Here, the timing error detection unit 732 detects an output signal of the resampling unit 733 to calculate a timing error based on the modulation mode indication, provides timing error information to the resampling unit 731, and timing error. The sampling rate is converted using the timing error information input from the detector 732. In addition, the resampling unit 731 may include a decimator and an interpolator for decimation and interpolation. Since the timing error detection algorithm is different in the single carrier modulation mode and the multicarrier modulation mode, and the algorithms for the two modulation modes can be implemented in the timing error detection unit, the timing error detection unit 732 selects a corresponding algorithm based on the modulation mode indication. Choose. In this case, the timing error information is determined in accordance with the modulation mode indication.

The carrier recovery block 730C includes a mixer 733 and a frequency offset estimator 734. Here, the frequency offset estimator 734 detects the output signal of the mixer 733, estimates the frequency offset based on the modulation mode indication, and provides the frequency offset information to the mixer 733. The mixer 733 may adjust the frequency offset of the signal output from the resampling unit 731 based on the frequency offset information estimated from the frequency offset estimator 734 to generate a signal synchronized with the input of the demodulator 740. To compensate. Similar to timing error detection, the frequency offset estimation algorithms of the single carrier modulation mode and the multicarrier modulation mode are implemented in the frequency offset estimator, and the frequency offset estimator 734 selects the corresponding algorithm based on the modulation mode indication. That is, estimated frequency offset information is generated according to the modulation mode indication.

The demodulator 740 demodulates the synchronization signal input from the synchronizer 730 based on the modulation mode indication.

The channel decoder 760 decodes and outputs a demodulated signal.

As can be appreciated from the foregoing, the digital multimedia receiver according to the present invention performs synchronization based on the modulation mode indication.

According to the structure of the receiver of FIG. 7, timing recovery occurs immediately before carrier recovery. However, timing recovery block 730T can be positioned differently, as long as timing recovery is performed before actually demodulation is performed. That is, the positions of the timing recovery block 730T and the carrier recovery block 730C may be exchanged.

The demodulation mode indication may be received from a mode detector (not shown).

By using the digital multimedia receiver of the structure shown in FIG. 7, the timing offset and the frequency offset can be compensated based on the single carrier modulation mode and the multicarrier modulation mode. Thus, the receiver can operate properly for both single carrier and multicarrier transmission modes.

Receive filters are commonly used in digital multimedia receivers to reduce internal symbol interference and added noise. Due to the different spectral characteristics, systems for single carrier modulation mode and multicarrier modulation mode should have unique bandwidths.

 Receive filters are commonly used in digital multimedia receivers to reduce internal symbol interference and added noise. Due to the different spectral characteristics, systems for single-carrier modulation mode and multi-carrier modulation mode must have unique bandwidths. In order to use only one common receive filter in the digital multimedia receiver to handle the single carrier modulation mode and the multicarrier modulation mode, the characteristics of the receive filter must be changed by applying another predetermined coefficient set. To this end, the filter coefficient set of the common receive filter used in the single carrier modulation mode and the multicarrier modulation mode should be updated according to the modulation mode.

8 is a block diagram showing the configuration of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fourth embodiment of the present invention. Referring to FIG. 8, the digital multimedia receiver 800 includes a tuner 810, an AD converter 820, a filter coefficient unit 830, a reception filter 840, a demodulator 850, and a channel decoder 870. do.

The tuner 810 tunes (down-converts) the multimedia signal received via the antenna.

The AD converter 820 converts the signal output from the tuner 810 into a digital signal through sampling, quantization, and encoding.

The filter coefficient unit 830 provides a set of coefficients according to the modulation mode indication. The filter coefficient unit 830 includes a filter coefficient memory 831 and a filter coefficient uploader 832.

The filter coefficient memory 831 stores two filter coefficient sets corresponding to the single carrier modulation mode and the multicarrier modulation mode, respectively. The filter coefficient uploader 832 reads the filter coefficient set from the filter coefficient memory 831 and uploads the filter coefficient set to the receiving filter 840 according to the modulation mode indication.

The reception filter 840 filters the digital signal input from the AD converter 820 according to the filter coefficient set provided by the filter coefficient unit 830 corresponding to the single carrier modulation mode or the multicarrier modulation mode. The reception filter 840 may be a Square-Root Raised Cosine (SRRC) filter. The SRRC filter used as a filter to match the transmit SRRC filter maximizes the signal-to-noise ratio by matching the signal.

The demodulator 850 demodulates the digital signal filtered by the reception filter 840 according to the modulation mode indication.

The demodulator 850 includes a first switch 851, a first quadrature amplitude modulation (QAM) demodulator 852, an FFT unit 853, a second QAM demodulator 854, and a second switch 855.

The first switch 851 selects one of the first QAM demodulator 852 and the FFT unit 853 according to the modulation mode indication. More specifically, if the modulation mode indication is a single carrier modulation mode indication, that is, if the signal filtered by the receive filter 840 is a single carrier modulation mode indication, the first switch 851 selects the first QAM demodulator 852. do. The first QAM demodulator 852 demodulates the signal filtered by the reception filter 840. The first QAM demodulator 852 may use an offset quadrature amplitude modulation (OQAM) demodulator or a QAM demodulator. If the modulation mode indication is a multicarrier modulation mode indication, that is, if the signal filtered by the reception filter 840 is a multicarrier modulation mode, the first switch 851 selects the FFT unit 853. The FFT unit 853 performs Fast Fourier Tansformation on the filtered signal input from the reception filter 840. The second QAM demodulator 854 demodulates the fast Fourier transformed signal from the FFT unit 853.

The second switch 855 selects one of the first QAM demodulator 852 and the second QAM demodulator 854 according to the modulation mode indication. More specifically, when the modulation mode indication is a single carrier modulation mode indication, the second switch 855 selects the output signal of the second QAM demodulator 852 and outputs it to the channel decoder 870, wherein the modulation mode indication is multi-modal. In the case of the carrier modulation mode indication, the second switch 855 selects the output signal of the second QAM demodulator 854 and outputs it to the channel decoder 870.

Channel decoder 870 decodes the demodulated signal input from demodulators 852 and 854.

On the other hand, the first switch 851 can be omitted. In this case, only one or both of second QAM demodulator 852 and second QAM demodulator 854 operate. In more detail, the signal output from the reception filter 840 is simultaneously input to the second QAM demodulator 852 and the FFT unit 853, and only one of the first QAM demodulator 852 and the FFT unit 853 is provided. Or both can work.

An operation procedure of the digital multimedia receiver of FIG. 8 will be described in detail with reference to FIG. 9. FIG. 9 is a flowchart provided to explain a digital multimedia reception method performed in the digital multimedia receiver of FIG. 8 according to the fourth embodiment of the present invention.

Referring to FIG. 9, first, a received signal is tuned (down-converted) (S910). Subsequently, the tuned signal is converted into a digital signal (S920).

Subsequently, the digital signal is filtered according to the modulation mode indication (S930). More specifically, a filter coefficient set is provided according to the modulation mode indication, and the digital signal is filtered based on the provided filter coefficient set.

The filtered signal is demodulated according to the modulation mode indication (S940). More specifically, if the modulation mode indication is a single carrier modulation mode indication, then the filtered signal is demodulated by OQAM demodulation, and when the modulation mode indication is a multicarrier modulation mode indication, the filtered signal is subjected to fast Fourier transform and QAM demodulation. Demodulated by

Finally, the demodulated signal is decoded (S960).

Since the common filter is used in both the single carrier modulated signal mode and the multicarrier modulated signal mode, the implementation of the digital multimedia receiver is simple and the processing performance of the digital multimedia receiver is improved.

10 is a block diagram illustrating a structure of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a fifth embodiment of the present invention.

The digital multimedia receiver 1000 shown in FIG. 10 includes a tuner 1010, an AD converter 1020, a synchronizer 1030, a demodulator 1040, a selector 1050, and a channel decoder 1070. .

The tuner 1010 tunes the received multimedia signal to the corresponding band. The AD converter 1020 converts the tuned analog signal into a digital signal through sampling and quantization.

The synchronizer 1030 performs synchronization on the digital signal converted by the AD converter 1020 and moves the signal to the baseband using a modulation mode indication.

The demodulator 1040 demodulates the synchronization signal input from the synchronizer 1030. The demodulator 1040 includes a first demodulation block 1041 and a second demodulation block 1042. The first demodulation block 1041 and the second demodulation block 1042 demodulate the received single carrier modulated signal and the multicarrier modulated signal, respectively. Based on the modulation mode indication, one or both of the two demodulation blocks corresponding to the modulation mode are operated and an appropriate output is selected for post processing.

The first demodulation block 1041 demodulates the equalized signal input from the first equalizer 1043 and the first equalizer 1043 for equalizing the synchronized single carrier modulated signal input from the synchronizer 1030. OQAM unit 1044 for. The first equalizer 1043 further includes a first equalization filter 1043a and a coefficient updater 1043b. Here, the OQAM unit 1044 may be implemented by either a QAM demodulator or an offset QAM demodulator.

The first equalization filter 1043a performs equalization of the synchronization signal input from the synchronization unit 1030 using the equalization coefficients provided by the coefficient updater 1043b. The coefficient updater 1043b calculates and estimates equalization coefficients by using a synchronization signal input from the synchronization unit 1030, an output of the first equalization filter 1043a, and a reference signal. The reference signal may be a predetermined value such as field sync or segment sync defined in the ATSC standard or a decision value by actual data. The reference signal may be calculated from the signal demodulated by the OQAM unit 1044.

In the single carrier modulation mode, the first equalization filter 1043a equalizes the synchronization signal input from the synchronizer 1030 using the equalization coefficient provided by the coefficient updater 1043b. The output of the equalization filter 1043a is input to the OQAM unit 1044 and demodulated. The demodulated signal from the OQAM unit 1044 is input to the selection unit 1050. The coefficient updater 1043b detects the synchronization signal, the output of the first equalization filter, and the reference signal input from the synchronization unit 1030, updates the equalization coefficients, and provides equalization coefficient information to the equalization filter 1043a.

Equalization coefficients vary depending on the equalization algorithm used. Thus, the implementation of the coefficient updater 1043b depends on the type of equalization filter used. Among existing algorithms for equalization of a single carrier modulated signal, a Decision Feedback Equalizer (DFE) algorithm is widely used. When processing a single carrier modulated signal, using the DFE filter improves the performance of the proposed demodulator.

On the other hand, the second demodulation block 1042 includes an FFT unit 1045 for converting the synchronized multicarrier modulated signal from the time domain to the frequency domain, a second equalizer 1046 for equalizing the converted signal, and an equalizer. And a QAM unit 1047 for demodulating the equalized signal at 1046. The second equalizer 1046 further includes a second equalization filter 1046a and a channel estimator 1046b.

In the multi-carrier modulation mode, channel estimator 1046b is a time domain reference, such as a PN (Pseudo Noise) sequence inserted between the OFDM symbols or the pilot subcarriers embedded in the OFDM symbol, input from the synchronizer 1030. The estimation using the synchronization signal having the signals is performed, and the channel estimation information is provided to the second equalization filter 1046a. The FFT unit 1045 converts the synchronization signal input from the synchronization unit 1030. The second equalization filter 1046a equalizes the fast Fourier transformed transform signal by using the channel estimation information input from the channel estimator 1046b. The QAM unit 1047 inputs the modulation signal generated by demodulating the equalization signal of the second equalization filter 1046a in the QAM mode to the selection unit 1050.

The selector 1050 selects an output signal corresponding to the modulation mode indication from the output signals of the OQAM unit 1044 and the QAM unit 1047 and outputs the output signal to the channel decoder 1070.

The channel decoder 1070 decodes the demodulated signal and outputs it. Here, a low density parity check (LDPC) decoder may be used as the channel decoder.

Accordingly, the demodulator shown in FIG. 10 may demodulate the received single carrier modulated signal and the multicarrier modulated signal.

According to the structure of the demodulator shown in FIG. 10, channel distortion may be compensated based on the single carrier modulation mode and the multicarrier modulation mode. Thus, the performance of the digital multimedia receiver for two modulation modes can be improved, and channel errors can be reduced.

In order to reduce the manufacturing cost of a digital multimedia receiver capable of processing single carrier modulated signals and multicarrier modulated signals, a common AD converter may be used. However, due to the unique characteristics of both modulation modes, the symbol rates of the single carrier modulation mode and the multicarrier modulation mode are different. Therefore, in the signal processing path of the digital multimedia receiver, the output of the common AD converter must be decimated at different sample rates to be suitable for the single carrier modulation mode and the multicarrier modulation mode.

For example, assume that the sample rate of the AD converter is r1, and the symbol rates of the single carrier transmission mode and the multicarrier transmission mode are r2 and r3, respectively. The decimating ratio N: 1 of the single carrier transmission mode is equal to r1: r2, and the decimating ratio M: 1 of the multicarrier transmission mode is equal to r1: r3. Since r3 will be less than r2, M is greater than N.

11 is a block diagram of a digital multimedia receiver for processing a single carrier modulation mode signal and a multicarrier modulation mode signal according to a sixth embodiment of the present invention.

Referring to FIG. 11, the digital multimedia receiver includes a tuner 1110, an AD converter 1120, a decimator 1130, a demodulator 1140, and a channel decoder 1160.

The tuner 1110 tunes (down-converts) the multimedia signal received through the antenna.

The AD converter 1120 converts the signal tuned from the tuner 1110 into a digital signal through sampling, quantization, and encoding.

The decimation unit 1130 decimates the digital signal input from the AD converter 1120 according to the modulation mode instruction.

The first switch 1131 selects one of the first decimator 1132 and the second decimator 1133 according to the modulation mode indication. More specifically, if the modulation mode indication is a single carrier modulation mode indication, the first switch 1131 selects the first decimator 1132, and the first decimator 1132 passes through the first switch 1131. Receive a digital signal. The first decimator 1132 decimates the digital signal input from the AD converter 1120 at a ratio of N: 1. When the modulation mode indication is a multi-carrier modulation mode indication, the first switch 1131 selects the second decimator 1133, and the second decimator 1133 receives the digital signal passing through the first switch 1131. Receive. The second decimator 1133 decimates the output of the AD converter 1120 at a ratio of M: 1. Here, N and M are predetermined to correspond to the single carrier modulation mode and the multicarrier modulation mode, respectively.

The demodulator 1140 demodulates the decimation signal output from the decimation unit 1130. The demodulator 1140 includes an OQAM demodulator 1141, an FFT unit 1142, a QAM demodulator 1143, and a second switch 1144. Here, the OQAM demodulator 1141 may be implemented by either a QAM demodulator or an offset QAM demodulator.

The OQAM demodulator 1141 demodulates the signal decimated by the first decimator 1132. The FFT unit 1142 performs fast Fourier transform on the decimated signal input from the second decimator 1133. The QAM demodulator 1143 demodulates the fast Fourier transformed converted signal input from the FFT unit 1142.

Since the function of the second switch 1144 is the same as that of the second switch 955 of FIG. 9, a detailed description thereof will be omitted.

The channel decoder 1160 decodes a signal input from the demodulator 1140.

In addition, similarly to FIG. 9, the first switch 1131 may be omitted.

Referring to FIG. 12, the operation of the digital multimedia receiver illustrated in FIG. 11 will be described in detail. 12 is a flowchart provided to explain a digital multimedia reception method performed in the digital multimedia receiver shown in FIG. 11 according to the sixth embodiment of the present invention.

Referring to FIG. 12, the received multimedia signal is tuned (down-converted) (S1210). The down-converted signal is converted into a digital signal (S1220). The digital signal is decimated according to the modulation mode indication (S1230). More specifically, if the modulation mode indication is a single carrier modulation mode indication, the digital signal is decimated at a ratio of N: 1, and if the modulation mode indication is a multicarrier modulation mode indication, the digital signal is deciphered at a ratio of M: 1. Is displayed. Here, N and M are predetermined to correspond to the single carrier modulation mode and the multicarrier modulation mode, respectively.

The decimated signal is demodulated according to the modulation mode indication (S1240). More specifically, if the modulation mode indication is a single carrier modulation mode indication, the decimated signal is demodulated by (offset) QAM demodulation, and if the modulation mode indication is a multicarrier modulation mode indication, the decimated signal is a fast Fourier transform and Demodulated by QAM demodulation.

Finally, the demodulated signal is decoded (S1260).

Since the sample rates are converted in proportion to the symbol rates of the single carrier modulated signal and the multicarrier modulated signal by the decimators, only one AD converter is used in the digital multimedia receiver. Therefore, the digital multimedia receiver can be simply implemented in hardware, and the single carrier modulated signal and the multicarrier modulated signal can be properly processed.

By using the data interleaver, the efficiency of error correction coding can be improved. The data interleaver spreads burst errors. Depending on the modulation mode, the data frame formats are different. Thus, the parameters defining the functionality of the data interleaver are different for the single carrier modulation mode and the multicarrier modulation mode. Therefore, in the DTV receiver, the parameter for the deinterleaver must be changed according to different modulation modes. In addition, the excellent error correction capability enables the LDPC code to be used in the single carrier modulation mode and the multicarrier modulation mode.

13 is a block diagram of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to a seventh embodiment of the present invention.

Referring to FIG. 13, the digital multimedia receiver includes a tuner 1310, an AD converter 1320, a demodulator 1330, a deinterleaver 1340, and an LDPC decoder 1350.

The tuner 1310 tunes (down-converts) the multimedia signal received through the antenna.

The AD converter 1320 converts a digital signal from a tuned signal input from the tuner 1310 through sampling and quantization.

The demodulator 1330 demodulates the digital signal input from the AD converter 1320 according to the modulation mode instruction. The demodulator 1330 includes a first switch 1331, an OQAM demodulator 1332, an FFT unit 1333, a QAM demodulator 1334, and a second switch 1335. Here, the OQAM demodulator 1332 may be implemented by either a QAM demodulator or an offset QAM demodulator.

The first switch 1351 selects one of the OQAM demodulator 1352 and the FFT unit 1353 according to the modulation mode indication. More specifically, when the modulation mode indication is a single carrier modulation mode indication, that is, when the multimedia signal is a single carrier modulation mode signal, the first switch 1351 selects the OQAM demodulator 1352. The OQAM demodulator 1352 demodulates the digital signal input from the AD converter 1320. When the modulation mode indication is a multicarrier modulation mode indication, that is, when the multimedia signal is a multicarrier modulation mode signal, the first switch 1351 selects the FFT unit 1353. The FFT unit 1353 performs fast Fourier transform on the digital signal input from the AD converter 1320. The QAM demodulator 1354 demodulates the fast Fourier transformed signal input from the FFT unit 1353.

The deinterleaver 1340 deinterleaves the modulated signal according to the modulation mode indication. More specifically, the function of the deinterleaver is determined by the parameters of the deinterleaver. The deinterleaver having the same structure may deinterleave the single carrier modulated signal and the multicarrier modulated signal by using parameters corresponding to the single carrier modulation mode and the multicarrier modulation mode. That is, other deinterleaving parameters corresponding to the two modulation modes are applied to the deinterleaver 1340 according to the modulation mode indication.

As such, only one deinterleaver is used to process single carrier modulated signals and multicarrier modulated signals. Therefore, the parameters of the deinterleaver 1340 should be determined according to the modulation mode indication.

A channel decoder 1350, such as an LDPC decoder or an RS block decoder, decodes the deinterleaving signal input from the deinterleaver 1340.

In addition, similarly to the case of FIG. 9, the first switch 1531 may be omitted.

14 is a flowchart provided to explain a digital multimedia reception method performed in the digital multimedia receiver shown in FIG. 13 according to the seventh embodiment of the present invention.

Referring to FIG. 14, in step S1410, the received signal is down converted. In operation S1420, the down converted signal is converted into a digital signal.

In step S1430, the digital signal is demodulated according to the modulation mode indication. More specifically, when the modulation mode indication is a single carrier modulation mode indication, the digital signal is demodulated by OQAM demodulation, and when the modulation mode indication is a multicarrier modulation mode indication, the digital signal is demodulated by FFT and QAM demodulation. .

In operation S1440, the demodulated signal is deinterleaved according to the modulation mode indication. In this case, the deinterleaving parameters are determined and applied according to the modulation mode indication.

Finally, in step S1450, channel decoding is performed on the deinterleaved signal.

Since only one deinterleaver is used for the single carrier modulation mode signal and the multicarrier modulation mode signal, the digital multimedia receiver can be easily implemented.

15 is a block diagram of a digital multimedia receiver for processing a single carrier modulated signal and a multicarrier modulated signal according to an eighth embodiment of the present invention.

15, a digital multimedia receiver includes a tuner 1510 for tuning a received signal to a corresponding band, an AD converter 1520 for converting a tuned signal input from the tuner 1510 into a digital signal, and an AD converter ( A demodulator 1530 for demodulating a digital signal input from 1520, a symbol demapper 1540 for demapping a demodulated signal input from demodulator 1530, and a symbol demapper And an LDPC decoder 1560 for decoding and outputting a signal output from the 1540.

In digital multimedia transmission systems where transmission of a high resolution A / V bit stream is required in the absence of substantial error, it is important to use powerful error correction coding to reduce the bit error rate. LDPC codes, a form of error correction coding, possess excellent error correction capabilities. Therefore, the LDPC code can be combined with a digital multimedia transmission system corresponding to the single carrier modulation mode and the multicarrier modulation mode.

In the case where the LDPC encoder is used in the transmitter to improve the error correction capability, the decoder of the receiver should correspondingly use the LDPC decoder. In this case, improved decoding performance can be obtained.

The OQAM symbol demapper is used as the symbol demapper 1540. In this case, the digital multimedia receiver is used to process single carrier modulated signals.

The QAM symbol demapper is used as the symbol demapper 1540. In this case, the digital multimedia receiver is used to process the multicarrier modulated signal.

According to the receiver, an improved error correction capability can be obtained.

As described above, according to the present invention, the digital multimedia receiver has a simple structure and processes both the single carrier modulated signal and the multicarrier modulated signal and has excellent performance.

Further, according to the present invention, the decoding performance of the digital multimedia receiver is greatly improved by using the LDPC decoder.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications that fall within the scope of the claims.

Claims (4)

A tuner for tuning the received multimedia signal into a corresponding band; An analog-digital converter for converting the tuned signal output from the tuner into a digital signal; An automatic gain control unit for measuring signal characteristics of the digital signal output from the analog-digital converter and controlling gain of the tuned signal output from the tuner according to the measured signal characteristics and modulation mode indication; And And a demodulator for demodulating and outputting the digital signal output from the analog-to-digital converter according to the modulation mode indication. The method of claim 1, And the automatic gain control unit is an RF automatic gain control unit or an IF automatic gain control unit. (a) tuning the received multimedia signal; (b) converting the tuned signal into a digital signal; (c) measuring signal characteristics of the digital signal; And (d) controlling the gain of the tuned signal according to the measured signal characteristic and modulation mode indication. The method of claim 3, wherein In step (d),  And controlling the gain of the tuned signal according to an RF auto gain control mode or an IF auto gain control mode.

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