KR960007201B1 - Hdtv transmitter receiver device - Google Patents

Abstract

The HDTV tranceiver for transmitting a TCM (Trellis Coded Modulation) signal as an 8VSB signal comprises: a transmitting means including a precoder means 29 for reducing an NTSC identical channel interference with an input of the TCM signal, and a first multiplexing means 32 for selecting either the TCM signal or the output signal from the precoder means 29 based on the presence of the NTSC identical channel interference so as to convert it to the 8VSB signal; and a receiving means including a postcom means 35 for reducing the NTSC identical channel interference from an A/D sampled signal; a second multiplexing means 37 for selecting either one of the A/D sampled signal and the output signal from the postcom means 35, a means 43 for determining whether the precoder means 29 is in use or not, and a postcom set storing means 45 for storing a postcom set signal 46 based on the output signal from the means 43 and outputting a signal for controlling the second multiplexing means 37, and a receiving means including the postcom set storing means 45.

Description

HTV Transceiver

1 is a block diagram of a conventional VSB transmitter.

2 is a block diagram of a conventional VSB receiver.

3 is a detailed configuration diagram of the precoder of FIG.

3 is a detailed configuration of the postcomb of FIG.

3 is a detailed block diagram of the digital postcoder of FIG.

4 is a block diagram of an HDTV transmitter according to the present invention.

5 is a block diagram of an HDTV receiver according to the present invention.

6 is a constellation diagram for calculating distance when no postcom is used.

7 is a constellation diagram for distance calculation in the case of using a postcom.

8 is a detailed block diagram of the fococoder of FIG.

8b is a detailed configuration diagram of the postcomb of FIG.

* Explanation of symbols for main parts of the drawings

1, 23: R-S encoder 2, 24, 27: interleaver

3, 29: precoder 4, 33: waveform mapper

5, 34: ADC, data segment and field synchronization generator

6: Postcom control unit 7, 35: Postcom

9, 14, 32, 37, 40c: multiplexer 10, 38: channel equalizer

11, 12, 43a: Slicer 13: Digital Postcoder

15, 39, 41: deinterleaver 16, 42: R-S decoder

17, 20, 22, 47, 49: adder 18, 19, 21, 25, 40b, 48, 50: delay

26, 40e: convolutional encoder 28: level mapper

40: Vita bee decoding system 43: Precoder use

45d: Postcomb set saver 40a: Streetmapper

40d: Vitaby Decoder 43b: Comparator

43c: Bit Error Rate Comparator

The present invention relates to an HDTV transceiver, and more particularly, to transmit a TCM (Trellis Coded Modulation) signal having a function of automatically switching between co-channel NTSC interference control by discriminating the presence and absence of co-channel NTSC interference to 8VSB. It is about HDTV transmitter and receiver.

In general, if there are co-channel NTSC stations in the neighborhood of HDTV stations and co-channel NISC interference occurs, pre-coders are used at the transmitting end and post-comb at the receiving end with the co-channel NTSC interference control filter. Use

1 is a configuration diagram of a conventional 4VSB transmitter, and FIG. 2 is a configuration diagram of a conventional 4VSB receiver.

A conventional 4VSB transmitter includes a R-S encoder (Reed-Solomon Encoder) 1, an interleaver 2, a precoder 3, and a 4VSB waveform mapper 4, as shown in FIG. The R-S encoder 1 performs an error correction R-S encoding function, and the inleaver 2 interpolates the signal output from the R-S encoder 1 in symbol units.

The precoder 3 precodes the signal output from the interleaver 2.

The 4VSB waveform mapper 4 converts the signal output from the precoder 3 into a voltage signal suitable for each level.

The formatted video, audio and auxiliary signals are R-S coded for error correction in the R-S encoder 1 and output to the interleaver 2.

The signal input to the interleaver 2 is interleaved in symbol units to make it easy to correct a burst error that may occur in a channel.

The signal processed by the interleaver 2 is input to the precoder 3, precoded, and then output to the 4VSB waveform mapper 4.

The signal input to the 4VSB waveform mapper 4 via the precoder 3 is converted into a voltage signal suitable for each level and transmitted.

The conventional 4VSB receiver has an analog / digital converter (ADC), a data segment and field synchronization generator 5, a postcomb controller 6, a postcomb 7, a multiplexer 9, as shown in FIG. 14), a channel equalizer 10, slicers 11 and 12, a digital post coder 13, a deinterleaver 15, and an RS decoder 16.

The ADC, the data segment and the field synchronization generator 5 perform A / D sampling on the input signal and generate a data segment synchronization signal and a field synchronization signal.

The postcomb 7 removes noise generated from co-channel NTSC interference in the signal output from the ADC and the data segment and the field synchronizer 5.

The multiplexer 9 selects and outputs from the ADC and the data segment and the signals output from the field synchronization generator 5 and the postcom 7 according to the signal output from the postcomb controller 6.

The channel equalizer 10 receives a signal output from the multiplexer 9 to remove ghost and intersymbol interference.

The slicers 11 and 12 slice the signals output from the channel equalizer 10.

The digital postcoder 13 digitally decodes the signal output from the slicer 12.

The multiplexer 14 selects and outputs signals output from the slicer 11 and the digital postcoder 13 according to the control of the post comb control unit 6.

The deinterleaver 15 deinterpolates the signal output from the multiplexer 14, and the R-S decoder 16 decodes the signal output from the deinterleaver 15.

The postcomb control section 6 controls the multiplexers 9 and 14 by determining the presence or absence of the synchronization channel NTSC interference using the signals output from the ADC and the data segment and the field synchronization generating section 5.

The received signal, which has passed through the tuner and the demodulation circuit, is input to the ADC, the data segment and the field synchronization generator 5, A / D sampled, and the data segment synchronization signal corresponding to the NTSC horizontal synchronization signal and the vertical synchronization of the NTSC. A data field synchronization signal corresponding to the above is generated.

The signal output from the ADC and the data segment and the field synchronizer 5 go through the postcom 7 and the channel equalizer 10 and the slicer 11 when there is co-channel NTSC interference, and there is no co-channel NTSC interference. In this case, the signal is output through the channel equalizer 10, the slicer 12, and the digital postcoder 13.

The presence or absence of co-channel NTSC interference is determined by the postcomb control section 6, which receives a known data field synchronization signal in the first line of each field and passes the postcomb 7 to reduce the 3 dB signal to noise ratio (SNR). Even if there is a problem, it is determined by comparing MSE (Mean Squ-are Error) whether it is better to eliminate co-channel NTSC interference or not to use postcom (7).

The postcom control section 6 controls the multiplexers 9 and 14 in accordance with the above determination.

The multiplexer 9 selects one of a signal passing through the postcom 7 and a signal not passing under the control of the postcom control unit 6 and outputs the signal to the channel equalizer 10. The input signal eliminates ghosts and inter-symbol-interference due to multiple paths generated during terrestrial broadcast transmission.

The slicers 11 and 12 slice in two or four levels according to the signals A / D converted by the ADC and the data segment and the field synchronization generator 5 to 8 bits or more.

The sliced signal from the slicer 12 is routed to the deinterleaver 15 through the digital postcoder 13.

The multiplexer 14 selects and outputs one of a signal passing through the slicer 11 and a signal passing through the slicer 12 and the digital postcoder 13 according to the control of the post comb control unit 6.

The signal output from the multiplexer 14 is deinterleaved by the deinterleaver 15 to be in a signal state before the interleaver 2 of the transmitter, and the signal output from the deinterleaver 15 is generated on the channel by the RS decoder 16. The error is corrected and output.

The operation of each block constituting the conventional 4VSB transceiver is described in detail as follows.

The RS encoder 1 adds and transmits the redundancy data indicating the position and value to the original data, and the RS decoder 16 uses the redundancy data when an error occurs in the transmitted original data. Correct it.

For example, if the original data is 147 bytes and 20 bytes of redundancy data are added for R-S coding, error correction capability for correcting 10 errors of the 147 bytes of data occurs.

The interleaver 2 and the deinterleaver 15 have a cluster error (Burst Er-ror) that may occur on a transmission, for example, when one of the lines appears as an error in the RS decoder 16 of the line where the cluster error occurred. For the purpose of correcting an error, for example, when the interleaver 2 of the transmitting end is changed in the direction of the line, it is received by the deinterleaver 15 of the receiving end in the original line direction again, so that the cluster error of one line is generated. The data is distributed over each line where no cluster error occurs, thereby improving error correction capability through error correction in the RS decoder 16.

For example, when one line of data is 147 bytes, when 147 bytes are distributed by 2 bytes in 73.5 lines, the cluster error can be corrected through error correction using the redundancy of the R-S decoder 16.

3 is a detailed block diagram of the precoder 3 of FIG. 1, FIG. 3 is a detailed block diagram of the postcomb 7 of FIG. 2, and FIG. 3 is a digital postcoder of FIG. 13 is a detailed configuration diagram.

The precoder 7 is configured to add and output the input signal and the signal delayed by the delayer 18 during the 12 symbol period by the modulo 4 adder 17 as shown in FIG.

The postcomb 7 is configured to calculate, in the adder 20, the difference between the input signal and the signal delayed in the delay 19 during the 12 symbol period as shown in FIG.

Therefore, if the input signal of the postcom 7 is 8 bits, the signal of 9 bits is output.

The digital postcoder 13 is configured to calculate, in the modulo 4 adder 22, the difference between the input signal and the signal delayed in the delayer 21 during the 12 symbol period as shown in FIG.

The digital postcoder 13 is configured in the same manner as the postcom 7 but becomes 2 bits because the input signal is passed through the slicer 12, and the signal delayed for the 12 symbol period is processed in the modulo 4 adder 22, The output signal also becomes 2 bits.

However, the conventional HDTV transceiver does not use TCM (Trellis Coded Modulation), which is recently used as a new technology, and thus does not provide the best performance.

In order to improve the above problems, an object of the present invention is to provide an HDTV transceiver for improving SNR gain by transmitting to 8VSB using Trellis Coded Modulation (TCM).

In order to achieve the above object, an embodiment of the present invention provides an HDTV that transmits a trellis coded modulated (TCM) signal to 8VSB. Transmitting means comprising a first multiplexing means for selecting the signal and the signal output from the precoder means and converting the signal into an 8VSB signal in accordance with the presence or absence of NTSC co-channel interference, and NTSC equal from the received and A / D sampled signal. Determining whether or not to use the postcom means, the second multiplexing means for selecting and outputting the A / D sampled signal and the signal output from the Fosccom means according to the presence or absence of NTSC co-channel interference Storing a signal output from the precoder use determining means and the precoder use determining means And post-comb set storing means for outputting a signal for controlling the second multiplexing means.

In addition, another embodiment for achieving the above object is RS encoding means 23 for re-solomon encoding a formatted signal, and a first interleaver to interpolate the signal output from the RS encoding means 23 ( Inter leaver) means 24, the first delay means 25 is delayed by inputting the MSB 1 bit of the signal output from the first interleaver means 24, LSB 1 of the signal output from the first interleaver means 24 A first convolutional encoding means 26 into which a bit is input and converted into two bits, a second interleaver means 27 for interpolating signals output from the first delay means 25 and the first convolutional encoding means 26, and A level mapper means 28 for converting a signal output from the second interleaver means 27 to a digital level, a precoder means 29 for precoding a signal output from the level mapper means 28, the precoder means From 29 and level mapper means 28 A transmission comprising a first multiplexing means 32 for selecting and outputting an output signal and an 8 VSB waveform mapper means 33 for converting and outputting a signal output from the first multiplexing means 32 to a corresponding voltage, respectively Means and a signal output from the ADC and the data segment and the field synchronizing means 34, the ADC and the data segment and the field synchronizing means 34, from which the received signal is input, A / D sampled, and the synchronizing signal is generated. A second multiplexing means 37 for selecting and outputting a signal output from the postcombing means 35, the postcombing means 35, the ADC and the data segment and the field synchronization generating means 34 as an input; A channel equalizing means 38 for removing ghost and intersymbol interference by inputting a signal output from the multiplexing means 37, and a signal output from the channel equalizing means 38 From the first deinterleaver means 39 for interpolating, the Viterbi decoding means 40 for vitata decoding the signal output from the first deinterleaver means 39, and the vittabi decoding means 40. And a second deinterleaver means 41 for reverse interleaving the output signal and a RS decode means 42 for RS decoding the signal output from the second deinterleaver means 41. It features.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

4 is a configuration diagram of the HDTV transmitter according to the present invention, and FIG. 5 is a configuration diagram of the HDTV receiver according to the present invention.

As shown in FIG. 4, the HDTV transmitter according to the present invention includes an RS encoder 23, an interleaver # 1 24, a delayer 25, a convolutional encoder 26, an interleaver # 2 27, and a level mapper. (28), a precoder 29, a path line 30, a multiplexer 32, and an 8VSB waveform mapper 33, each bit being 2 bits per symbol to convolutionally encode one LSB (Least Significant Bit) signal among the signals. After making 2 bits, all 3 bits are TCM and transmitted to 8 level VSB.

The R-S encoder 23 performs an error correction R-S encoding function, and the interleaver # 1 24 interpolates the signal output from the R-S encoder 23 in symbol units.

The delay unit 25 delays the MSB 1 bit of the signal output from the interleaver # 1 24, and the convolutional encoder 26 convolutionally encodes the LSB 1 bit of the signal output from the interleaver # 1 24 to make it 2 bits.

The interleaver # 2 (27) interpolates the signals output from the delay unit 25 and the convolutional encoder 26 by symbol unit.

The level mapper 28 converts to a digital level corresponding to the signal output from the interleaver # 2 27.

The precoder 29 precodes the signal output from the level mapper 28.

The multiplexer 32 selects and outputs signals from the level mapper 28 and the precoder 29 according to the precoder set signal 31.

The 8VSB waveform mapper 33 converts the signal output from the multiplexer 32 into a voltage corresponding to each level and outputs it.

The formatted audio, video and auxiliary signals are error-corrected R-S encoded by the R-S encoder 23 in byte units and output to the interleaver # 1 24.

Interleaver # 1 (24) interpolates the signal in symbol units of two bits, making it easy to correct cluster errors that may occur in the Viterbi Decoding System.

Since the signal processed by the interleaver # 1 (24) is 2 bits per symbol, the LSB 1 bit becomes 2 bits through the convolutional encoder 26 of 1/2 ratio, and the remaining 1 bit is delayed through the delay unit 25. do.

The 3-bit signal output from the delay unit 25 and the convolutional encoder 26 is easily interpolated in the symbol unit in the interleaver # 2 (27) to easily correct the cluster error that may occur in the channel.

The signal output from the interleaver # 2 (27) is input to a level mapper 28. The level mapper 28 is a digital level corresponding to an input signal of 3 bits, that is, 0, 1, 2, 3, Outputs one of 4, 5, 6 and 7.

The signal mapped from the level mapper 28 to the digital level by the TCM rule in which the LSB 2 bits are arranged so that the distance between two signals with the same maximum is maximum is transferred to the 8VSB waveform mapper 33 through the precoder 29. Or output to the 8VSB waveform mapper 33 through the path line 30 that does not go through the precoder 29, which is made by the operation of the multiplexer 32.

The multiplexer 32 is controlled by the precoder set signal 31. For example, when the precoder set signal is '1', a signal output from the precoder 29 is selected. The signal output through the path line 30 that does not pass through is selected.

The control of the precoder set signal may be implemented by a switch, which may be implemented by turning on / off the same channel NTSC interference.

The output signal of the multiplexer 41 is input to the 8VSB waveform mapper 33, converted into a voltage corresponding to each digital level, and transmitted.

In the HDTV receiver according to the present invention, as shown in FIG. 5, the ADC and the data segment and the field synchronizer 34, the postcomb 35, the path line 36, the multiplexer 37, the channel equalizer ( 38), Deinterleaver # 2 (39), Vitaby Decoding System (40), Deinterleaver # 1 (41), RS Decoder (42), Precoder Use Determinator (43), and Postcombination Storage (45) It is composed of The ADC data segment field synchronization generator 34 performs A / D and sampling of the input signal, and generates a data segment and a field synchronization signal.

The postcom 35 removes noise generated from co-channel NTSC interference in the signal output from the ADC and the data segment and the field synchronizer 34.

The multiplexer 37 selects and outputs from the ADC and the data segment and the signals output from the field synchronization generator 34 and the postcomb 35 according to the postcombine signal.

The channel equalizer 38 receives a signal output from the multiplexer 37 to remove ghost and intersymbol interference.

Deinterleaver # 2 39 deinterleaves the signal output from the channel equalizer 38. The vitabi decoding system 40 debits the signal output from the deinterleaver # 2 39.

The deinterleaver # 1 41 deinterleaves the signal output from the Vitaby decoding system 40, and the R-S decoder 42 decodes the signal output from the deinterleaver # 1 41. The precoder use discriminator 43 determines whether the precoder 29 of the transmitting end is used as a signal output from the vitabi decoding system 40 and outputs a postcom control signal.

The postcomset storage unit 45 stores the postcomset signal in accordance with the postcomb control signal output from the precoder use discriminator 54, and the distance mapper of the multiplexer 37 and the vitabi decoding system 40 A post-comset signal is output to 40a).

The Vitaby decoding system 40 is almost composed of a distance mapper 40a, a delay buffer 40b, a Vitaby decoder 40d, a multiplexer 40c, and a convolutional encoder 40e.

The distance mapper 40a outputs MSB 1 bit from four grid signals around the signal input from the deinterleaver # 2 39 in accordance with the postcomb set signal output from the postcomb set storage 45, and the surrounding 4 Outputs distance data from a lattice signal having LSB 2 bits of '00' among the lattice signals.

The vitabi decoder 40d performs vitabi decoding using the distance data output from the distance mapper 40a and outputs the result to the convolutional encoder 40e and the deinterleaver # 1 41.

The convolutional encoder 40e convolutionally encodes the data output from the Vitaby decoder 40d.

The delay buffer 40b delays one bit of the MSB from the signal output from the distance mapper 40a. The multiplexer 40c selects and outputs a signal output from the delay buffer 40b according to the signal output from the convolutional encoder 40e.

The precoder use discriminator 43 is composed of a slicer 43a, a comparator 43b, and a bit error rate comparator 43c.

The slicer 43a slices the signal output from the distance mapper 40a of the Vitaby decoding system 40.

The comparator 43b compares the signal output from the slicer 43a and the convolutional encoder 40e of the Vitaby decoding system 40 to detect the bit error.

The bit error rate comparator 43c calculates the bit error rate BER from the signal output from the comparator 43b and compares it with the threshold to output the postcom control signal.

The signal processed through the tuner, demodulator, and phase locked loop (PLL) is A / D sampled by the ADC and the data segment and field synchronization generator 34 to generate a data segment synchronization signal and a data field synchronization signal.

The signal output from the ADC and the data segment and the field synchronizer 34 is output to the channel equalizer 38 through the postcom 35 to reduce the interference of the NTSC co-channel when the precoder 29 is used at the transmitter. When the precoder 29 is not used at the transmitter because there is no interference of the same channel of NTSC, the signal is output to the channel equalizer 38 through the path line 36 without using the postcom 35.

The multiplexer 37 that selects the postcomb 35 and the path line 36 operates under the control of the postcombine signal 46. For example, if the postcombine signal 46 is "1", the post multiplexer 37 is selected. When the signal passing through the comb 35 is selected, and the post comb set signal 46 is "0", the path line 36 without using the post comb 35 is selected and output to the channel equalizer 38.

The signal output from the multiplexer 37 is output to the deinterleaver # 2 (39) by removing the ghost and inter-symbol-interference due to the multipath generated during the terrestrial broadcast transmission by the channel equalizer 38. do.

The signal output from the channel equalizer 38 is deinterleaved in the deinterleaver # 2 39 to restore the state before the interleaver # 2 39.

The signal output from the deinterleaver # 2 (27) is input to the vitabi decoding system 40 to decode which 2-bit symbol the data is.

That is, the signal output from the deinterleaver # 2 39 is input to the distance mapper 40a. The distance mapper 40a receives four signals around the input signal according to the postcomb set signal of the postcomb set storage 45. Finds one grid signal and outputs one bit of the MSB (most significant bit) of the grid signals to the delay buffer 40b, and calculates a distance between the input signal and four surrounding grid signals at the same time. Will be printed).

However, the case where the postcom 35 is used as a method of finding four peripheral grid signals is different from the case where the postcom 35 is not used, which is determined by the postcom set signal controlled by the postcomb set storage 45 or a switch. .

FIG. 6 is a constellation diagram for calculating distances between the input signal and four peripheral grid signals in the distance mapper when the postcom 35 is not used. FIG. 7 is an input signal from the distance mapper when the postcom 35 is used. This is a constellation diagram for distance calculation with four peripheral grid signals.

First, when the postcom 35 is not used, FIG. 6 is used. FIG. 6 shows that two signals having the same LSB 2 bits, for example, a distance between '000' and '100 according to the TCM signal set configuration rule. In this figure, the signal size is ± 7 for convenience, and the voltage level of the signal is -7, -5, -3, -1, 1, 3, 5, 7 and the digital level is 0, 1 Appears at level 8 of 2, 3, 4, 5, 6, 7.

The case where the input signal is '0' will be described as an example.

When the input signal is '0', the surrounding grid signals are 100, 001, 110, and 011. The MSB 1 bits of these four grid signals, that is, 1, 0, 1, 0 are output to the delay buffer 40b and LSB The distance from the grid signal corresponding to 2 bits, that is, 00, 01, 10, 11, that is, the distance from '1', which is a distance from '100', and the distance from '1', '110,' '3', which is the distance between '3' and '011', is output to the 1/2 ratio vitavita decoder 40d.

In the case of using the postcom 35, FIG. 7 is used. In FIG. 7, the signal has a maximum amplitude of ± 14, which is twice the size of FIG. -6, -4, -2, -0,2,4,6,8,18,12,14 and ± 14 with corresponding digital levels of 1, 2, 3, 4, 5, 6, 7, Appears at 15 levels of 0, 1, 2, 3, 4, 5, 6, 7.

Therefore, in the case of using the postcom 35, four peripheral grid signals are obtained based on FIG. 7 to obtain uncoded bits and distance data for vitabi decoding.

That is, the MSB 1 bit of the peripheral lattice signal is output to the delay buffer 40b, and the distance between the input signal and the peripheral lattice signal is obtained and output to the vitabi decoder 40d having a 1/2 ratio.

The bit rate decoder 40d having a half rate finds one bit of data before being encoded by the convolutional decoder 26 having a half rate of the transmitting end from the distance data output from the distance mapper 40a.

1-bit data output from the bit rate decoder 40d at 1/2 ratio is encoded by the convolutional encoder 40e of 1/2 ratio and output as 2 bits, 2-bit output from the convolutional encoder 40e at 1/2 ratio The data is used as a control signal for controlling the multiplexer 40c. That is, 2-bit data is controlled by the multiplexer 40c to select the MSB 1 bit corresponding to the lattice in which the two LSB bits of the four surrounding grid signals and the two bits output from the convolutional encoder 40e are selected to deinterleaver # 1 ( 41).

The 1-bit data output from the 1-bit data vitabi decoder 40d outputted from the multiplexer 37 is gathered to form a 2-bit symbol, and the 2-bit symbol signal is output to the deinterleaver # 1 41 again.

The 2-bit symbol signal outputted from the Vitaby decoding system 40 is deinterleaved by the deinterleaver # 1 (41) and made into a state before being interleaved by the interleaver # 1 (24) of the transmitting end, and is transmitted to the RS decoder 42. The signal input to the RS decoder 42 is error-corrected and output.

The control of the post-comb set signal 46 for controlling the multiplexer 40c and the distance mapper 40a is made of a switch, which can be controlled manually by turning it to '1' if it is on and '0' if it is off. The presence or absence discriminator 43 and the postcomb set storage unit 45 may be automatically adjusted.

The postcomb set storage unit 45 stores the postcomb set signal by controlling the output of the precoder use discriminator 54 and the postcom set enable signal, and stores the postcomb set signal with the multiplexer 37 and the bitavi. The output is output to the distance mapper 40a of the decoding system 40. If the output is '1', the multiplexer 47 selects the output of the postcomb 35.

If the post-comset signal is '1' at the receiver and the precoder 29 is used at the transmitter when the multiplexer 37 selects the post-computer 35, the error of the VATAVI decoding system 40 will be less. If not, there will be many errors, so the precoder use discriminator 43 checks the error rate of the Vitaby decoding system 40 and accordingly outputs a signal for postcom control to the postcomb set storage 45.

The detailed operation of the precoder use presence determiner 43 is as follows.

The slicer 43a slices the distance data output from the distance mapper 40a of the vitaby decoding system 40 and detects any one of 00, 01, 10, and 11, and detects the signal and the bitter detected by the slicer 43a. The output signal of the convolutional encoder 40e of the non-decoding system 40 is compared in the comparator 43b to obtain a bit error.

The bit error output from the comparator 43b is input to the bit error rate comparator 43c, and the bit error rate comparator 43c calculates a bit error rate BER indicating how much bit error occurs per unit time, and a threshold value. Compared with, the larger than the threshold difference, the postcom control signal is '1' indicating that there are many errors, indicating that the precoder 29 is not used.

Therefore, if the postcom set enable signal 44 indicating the enable of the postcom set signal is '1', the data value '1' stored in the postcombination store 45 is toggled to '0' and the multiplexer 40 ) Selects a route line 36 that does not use postcom.

That is, when the postcom enable signal 44 is '1' and the postcom control signal is '1', the postcom set signal 46 stored in the postcom set storage 45 is toggled.

At this time, the postcomb set storage unit 45 is configured as an E ² PROM which is stored even when the power is turned off.

The adjustment of the postcomb set enable signal 44 is by adjustment of the on / off switch or by the TV remote controller.

A comparison result of the bit error rate comparator 43c of the precoder use discriminator 43 indicates that if the bit error rate is less than the threshold value, the postcom control signal becomes '0', indicating that the current postcom control signal 46 is correct. Therefore, the post comb set signal 46 is not changed.

FIG. 8A is a detailed block diagram of the precoder 29 of FIG. 4, and FIG. 8B is a detailed block diagram of the postcom 35 of FIG.

The precoder 29 adds the delayed signal and the signal currently input through the delayer 48 and the delayer 48 to output a delayed signal for 12 signal periods as shown in FIG. A modulo 8 adder 47 is used.

The signal delayed during the 12 symbol period in the delayer 48 is added to the signal currently input in the adder 47 and output.

The postcomb 35 is an adder 49 for obtaining a difference between the delayed signal and the currently input signal through the delayer 50 and the delayer 50 for outputting a delayed signal during the symbol period as shown in FIG. It consists of

The delayed signal for the 12 symbol periods in the delayer 50 is determined by the difference from the signal currently input in the adder 49.

The present invention configured and operated as described above improves SNR gain of up to 5.23dB and at least 2.23dB by applying TCM to 4VSB and transmitting to 8VSB, thereby increasing the viewing distance and receiving high quality video.

Claims (14)

In an HDTV for transmitting a TCM (Trellis Coded Modulated) signal to 8VSB, a precoder means 29 for reducing NTSC co-channel interference as the input of the TCM signal is output from the TCM signal and the precoder means 29. Transmitting means comprising a first multiplexing means 32 which is selected according to the presence or absence of NTSC co-channel interference among the signals to be converted into an 8VSB signal, and reduces NTSC co-channel interference from the received A / D sampled signal. A second multiplexing means 37 and a precoder means 29 for selecting and outputting the A / D sampled signal and a signal output from the post comb means 35 according to the presence of NTSC co-channel interference. The post-comset signal 46 is stored according to the signal output from the precoder use determining means 43 and the signal output from the precoder use determining means 43 for Second multiplexing means for HDTV transmission and reception device, characterized in that consisting of a receiving means which comprises a post-comb set storage means (45) for outputting a signal to control (37). RS encoding means 23 for re-solomon encoding a formatted signal, first interleaver means 24 for interleaving a signal output from the RS encoding means 23, and the first interleaver The first delay means 25 is delayed by inputting the MSB 1 bit of the signal output from the means 24, the first convolutional code is converted into 2 bits by LSB 1 bit of the signal output from the first interleaver means 24 A second interleaver means 27 for interpolating signals output from the means 26, the first delay means 25 and the first convolutional code means 26, and a signal output from the second interleaver means 27. A level mapper means 28 for converting to a digital level, a precoder means 29 for precoding a signal output from the level mapper means 28, and an output from the precoder means 29 and a level mapper means 28 First multi to select and output from among the signals Transmitting means comprising a 8VSB waveform mapper means 33 by converting the signal output from the lexing means 32 and the first multiplexing means 32 into a corresponding voltage, respectively, and the received signal is input ADC and data segment and field synchronizing means 34, which are A / D sampled and generating synchronizing signals, and post comb means 35 for inputting signals output from the ADC and data segment and field synchronizing means 34; ) And a second multiplexing means 37 for selecting and outputting a signal output from the ADC, the data segment and the field dynamic generating means 34, and a signal output from the second multiplexing means 37 as input. Channel equalizing means 38 for removing interference, first deinterleaver means 39 for interleaving the signals output from the channel synchronization means 38, and first deinterleaver means 39 Viterbi decoding means 40 for vitaby decoding the signal outputted from the second, second deinterleaver means 41 for interleaving the signal output from the vitabi decoding means 40, and the second And a receiving means comprising RS decoding means (42) for RS decoding a signal output from the deinterleaver means (41). 3. The method according to claim 2, wherein the precoder use / determination means (43) and the precoder use are discriminated to determine whether or not the precoder means 29 is used as a signal output from the vitabi decoding means 40. Postcomb set storing means (45) for storing the postcomset signal (46) by means of a signal output from the means (43) and for outputting a signal for controlling the second multiplexing means (37) and the vitabi decoding means (40). HDTV transceiver, characterized in that further comprises a). 3. The precoder means (29) according to claim 1 or 2, wherein the precoder means (29) adds a delay means (48) for delaying an input signal for a 12 symbol period, and a signal and an input signal outputted from the delay means (48). HDTV transmission and reception device, characterized in that consisting of an addition means (47). The method of claim 1 or 2, wherein the postcombing means (35) calculates a difference between the delay means (50) for delaying the input signal during the 12 symbol period and the signal output from the delay means (50) and the input signal. HDTV transmitting and receiving device, characterized in that consisting of the addition means (49). The HDTV transceiver according to claim 1 or 2, wherein the first multiplexing means (32) is controlled by a precoder set signal which can be adjusted by a switch according to the presence or absence of NTSC equal channel interference. The apparatus of claim 1 or 2, wherein the second multiplexing means (37) is controlled by a postcomb set signal that can be controlled by a switch in accordance with the presence or absence of NTSC co-channel interference. The apparatus of claim 2, wherein the vitabi decoding means 40 finds a lattice signal around the input signal, outputs MSB 1 bit, and outputs distance data between the input signal and the surrounding lattice signal (4). 40a), the delay buffer means 40b for delaying the MSB 1 bit outputted from the distance mapper means 40a, and the distance data outputted from the distance mapper means 40a are inputted and encoded by the convolutional code means 26. 2/1 vitabi decoding means 40d which finds one bit before it becomes the second convolutional code means 40e and convolutional encoding of the signal output from the said 1/2 vitavita decoding means 40d, and the said 2 convolutional code And a third multiplexing means (40c) for selecting a signal output from the delay buffer means (40b) according to the signal output from the means (40e). 4. The HDTV transceiver as claimed in claim 1 or 3, wherein the postcomb set storage means (45) comprises an E ² PROM that can be stored even if power is not supplied. 4. The signal outputting apparatus according to claim 3, wherein the precoder use / determination means (43) is a slicing means (43a) for slicing a signal output from the vitabi decoding means (40) and a signal output from the sliding means (43a). And a bit error rate using the comparison means 43b for detecting an error and the signal output from the comparing means 43b by comparing with another signal output from the vitabi decoding means 40 and comparing with a set threshold. And a bit error rate comparing means (43c). 4. The HDTV transceiver as claimed in claim 1 or 3, wherein the postcom set enable signal for controlling the postcom set storage means (45) is controlled by a switch. 4. HDTV transceiver according to claim 1 or 3, characterized in that the postcom set enable signal for controlling the postcom storage means (45) is controlled by a remote controller. 10. The method according to claim 8, wherein the sounding distance mapper means 40a finds a master signal around the input signal according to the constellation (in accordance with FIG. 6) having a digital level of 8 levels when there is no NTSC co-channel interference. HDTV transceiver, characterized in that for outputting the distance data. The method of claim 8, wherein the distance mapper means (40a) is input according to the constellation (figure 6) in which the magnitude of the signal is twice that of the case of NTSC co-channel interference, and the digital level is 15 levels. And a grid signal surrounding the received signal and outputting distance data from the grid signal.