Duobinary signaling and decoding words
La sortie Ds reproduit la sortie du registre 95 ou du registre amont du circuit If it is odd, the received samples will be juxtaposed with burst burst inversion to avoid rape of the coding rule. Modulator-demodulator for transmission by a four-level double amplitude modulation on quadrature carriers. DE Date of ref document:
NL Free format text: A method according to claim 1, characterised in that the aforementioned parts are masked by interrupting the coding during the aforementioned interruptions by interrupting the clock signal. In practice, it is sufficient, duobinary signaling and decoding words the case of duo-binary duobinary signaling and decoding words, to adopt a 22 mesh cells. The decoding device shown in Figures 2 and 3 comprises a processing circuit of the line which identifies the multiplex structure. The decoder further comprises a circuit 80 Figure 8b which determines the rate of rape code representative of the error rate using a circuit 56, it also sends a decoding thresholds for arranging at will the result of either of two types of decoding.
A time base 40 is further provided to stop the application of the clock signal to the Viterbi decoder 34 after receipt of the sample to the sample of each line, that is to say during periods of the clock duobinary signaling and decoding words at The circuit 78 survivors management has two rows of synchronous flops D. Le calcul montre alors qu'on a: This condition can be always filled by adding a parity bit in each block corresponding to a data line during the frame blanking period.
In the embodiment illustrated in Figure 2, this is achieved by interrupting the signal from the clock 20 applied to duobinary signaling and decoding words Viterbi decoder after receipt of the sample that corresponds to the "zero" level at the input of the decoder and up to sample, that is to say during periods of the clock signal at A first embodiment of the invention that achieves optimal results, requires the known information messages encoded duobinary locations to treat. For decoding to be optimal, the operation of the Viterbi decoder must be stopped outside the useful burst reception periods, especially when the broadcast signal comes from a encoder duobinary signaling and decoding words is not interrupted between useful bursts.
It will be seen that if the receiver is of mixed type and is adapted to also receive D-MAC programs, a switch may be provided to eliminate this will filter. The first channel comprises a duobinary decoder thresholds 18, a circuit 20 for recovery of the clock signal at These two transitions are detected by respective AND gates 60, 62 which attack the D input of flip-flop 58 via an OR gate This solution allows, in the case of a transmission of the duobinary signal in full time that is to say continuously to achieve performance reducing the value of the ratio minimum acceptable signal to noise.