The DSC-HDTV interference rejection system

Using a precoding technique to reduce the BER penalty of an M-QAM channel in hybrid AM-VSB/M-QAM subcarrier multiplexed lightwave systems

“…We note that the only penalty of the precoding technique is the 3 dB degradation in SNR [4]. This is because that the equivalent noise power after the comb filter is…”

“…A modification of Fig.l(c) by utilizing modulo reductions [4], shown in Fig.1(d), can avoid all the above disadvantages and still retain the operation of the comb filtering. The output of the precoder is now confined to the same range of the input data by a modulo operator.…”

“…This technique was previously adopted by digital spectrum-compatible high definition television broadcast system to reject co-channel NTSC visual, color, and aural carriers [4], and can be realized in an M-QAM modem by digital signal processing techniques. We have modified the precoding technique in [41 to reject discrete interferences located at fixed frequencies such as 6n+l.25 MHz where composite-triple beat (CTB) occurs (n is an integer), and (6n+1.25)±1.25 and (6n+1.25)±O.75…”

Using precoding technique to reduce the BER penalty of an M-QAM channel in hybrid AM-VSB/M-QAM subcarrier multiplexed lightwave systems

“…A modification of Fig. 1(c) by utilizing modulo reductions [4], shown in Fig. 1(d), can avoid all the above disadvantages and still retain the operation of the comb filtering.…”

“…In this letter, we propose a novel precoding technique to solve the problem. This technique was previously adopted by digital spectrum-compatible high definition television broadcast system to reject cochannel NTSC visual, color, and aural carriers [4], and can be realized in an -QAM modem by digital signal processing techniques. We have modified the precoding technique in [4] to reject discrete interferences located at fixed frequencies such as 6 1.25 MHz where composite-triple beat (CTB) occurs (n is an integer), and (6 1.25) 1.25 and (6 1.25) 0.75 MHz where composite second-order (CSO) beat occurs [5].…”