Digital television system

Abstract

Disclosed is a digital television system carrying out modulation/demodulation by VSB(vestigial side band) . A VSB transmitter includes an additional error correction encoder designed in a manner that a signal mapping of a TCM encoder is considered, a multiplexer(MUX), a TCM encoder operating in a manner corresponding to state transition processes of the additional error correction encoder, and a signal transmission part including an RF converter. And, A VSB receiver includes a signal receiver part receiving a signal transmitted from the transmitter, a TCM decoder, a signal processing part including a derandomizer, and an additional error correction decoder part.

What is claimed is:  
     
         1 . A VSB transmitter comprising: an additional error correction encoder carrying out state transition processes on additional data inputted to correct an error and designed for a TCM coding to be considered wherein the TCM coding will be carried out later; 
 a multiplexer multiplexing the additional data and ATSC data wherein the additional and ATSC data are inputted thereto;    a TCM encoder operating in a manner corresponding to the state transition processes of the additional error correction encoder and encoding the ATSC and additional data outputted from the multiplexer; and    a signal transmission part converting the ATSC and additional data outputted from the TCM encoder into an RF(radio frequency) signal and transmitting the RF signal to a receiver.    
     
     
         2 . The VSB transmitter of  claim 1 , further comprising a randomizer, an RS encoder, and an interleaver which are connected in order between the multiplexer and the TCM encoder in series.  
     
     
         3 . The VSB transmitter of  claim 1 , wherein the randomizer processes the ATSC data only.  
     
     
         4 . The VSB transmitter of  claim 1 , the signal transmission part comprising: 
 a VSB modulator VSB-modulating an output signal of the TCM encoder;    an RF converter converting an output signal of the VSB modulator into an RF signal and outputting the RF signal; and    a transmission antenna transmitting an output of the RF converter to a receiver side.    
     
     
         5 . The VSB transmitter of  claim 1 , wherein the additional error correction encoder uses a convolutional encoding method.  
     
     
         6 . The VSB transmitter of  claim 1 , the TCM encoder comprising: 
 a precoder preceding the inputted data; and    a signal path selection part making the inputted data go by way of or avoid the precoder in accordance with whether the inputted data are the additional data or the ATSC data.    
     
     
         7 . The VSB transmitter of  claim 1 , wherein whether the inputted data goes by way of or avoid the precoder depends on what kind of the additional error correction encoder is.  
     
     
         8 . The VSB transmitter of  claim 1 , wherein the ATSC data includes audio data and video data to be transmitted by a VSB method.  
     
     
         9 . A VSB transmitter comprising: 
 an additional error correction encoder encoding additional data for error correction;    a multiplexer multiplexing the additional data outputted from the additional error correction encoder and ATSC data inputted thereto;    a randomizer bypassing the additional data in the data outputted from the multiplexer and randomizing the ATSC data only;    an RS encoder adding a parity to the additional data and ATSC data outputted from the randomizer;    an interleaver interleaving the additional and ATSC data outputted from the RS encoder;    a TCM encoder bypassing the additional data in the data outputted from the interleaver and encoding the ATSC data only;    a VSB modulator modulating the additional and ATSC data outputted from the TCM encoder; and    an RF converter RF-converting the additional and ATSC data outputted from the VSB modulator.    
     
     
         10 . The VSB transmitter of  claim 9 , the TCM encoder comprising: 
 a precoder outputting a second switch input signal by preceding a first input bit as a first switch input signal;    an inverter outputting a third switch input signal by inverting the second switch input signal;    a comparator providing a switching control signal by comparing the first and second switch input signals each other;    a switch selectively outputting one of the first to third switch input signals as a first output signal; and    an encoder encoding a second input bit as a second output signal so as to output a third output signal.    
     
     
         11 . The VSB transmitter of  claim 10 , wherein the comparator provides the switching control signal so that the comparator, when the first input bit as the first switch input signal is equivalent to the second input signal, outputs the second switch input signal as the first output signal and that the comparator, when the first switch input signal is different from the second switch input signal, outputs the third switch input signal as the first output signal.  
     
     
         12 . The VSB transmitter of  claim 10 , the precoder comprising: 
 an adder outputting the second switch input signal by adding the first input bit and a delayed signal each other; and    a delayer providing the adder with a signal attained by delaying an output signal of the adder for a predetermined time.    
     
     
         13 . A VSB receiver comprising: 
 a signal receiver part tuning additional data and ATSC data received from a VSB transmitter;    a TCM decoder decoding the ATSC and additional data to output a soft signal;    a signal processing part carrying out a hard decision on the ATSC data having a from of the soft signal outputted from the TCM decoder; and    an additional error correction decoder part decoding the additional data having the form of the soft signal outputted from the TCM decoder for error correction.    
     
     
         14 . The VSB receiver of  claim 13 , the signal processing part comprising: 
 a limiter limiting the ATSC data outputted from the TCM decoder;    an RS decoder decoding an output signal of the limiter; and    a derandomizer derandomizing an output signal of the RS decoder.    
     
     
         15 . A VSB receiver comprising: 
 an RF tuner tuning RF signal transmitted from a VSB transmitter;    a VSB demodulator demodulating IF signal outputted from the RF tuner;    a TCM decoder decoding ATSC data and additional data;    a deinterleaver deinterleaving soft output of the TCM decoder;    a limiter carrying out a hard decision on the soft-outputted ATSC data;    an RS decoder decoding the hard-outputted ATSC data;    a derandomizer derandomizing the ATSC data having passed through the RS decoder; and    an additional error correction decoder part carrying out an error correction on the soft-outputted additional data.    
     
     
         16 . The VSB receiver of  claim 15 , further comprising an RS parity removal part between the deinterleaver and the additional error correction decoder part to remove a parity of the additional data.