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Rai Radiotelevisione Italiana

Paolo D'Amato

Rolando Salvadorini

Mario Cominetti

In order to improve the quality of color television signals for broadcasting via satellite, the signals are transmitted on two of the channels available for transmission via satellite according to the rules established by CCIR. In the case of transmission by means of a compatible system, the NTSC, or SECAM signal is transmitted on the first of the two channels and on the second channel there are transmitted the baseband R-Y and B-Y signals at from 0 to about 3 MHz sequentially on alternate lines and up to the limit of the video band the high frequency components of the luminance signal. In the case of transmission by means of a non-compatible system, there is transmitted on the first channel the luminance information in the whole available band and on the second channel the chrominance information R-Y and B-Y in the whole available band according to the following two alternatives: (1) the information is transmitted by means of a time division multiplex in which the first half of the active line is transmitted in one of the chrominance components and the second half in the other component; (2) the information is transmitted by means of a frequency sharing multiplex in which one of the components is transmitted in baseband, i.e. from 0 to about 3 MHz, and the other component is transmitted on an amplitude modulated subcarrier with single side band or vestigial band.

Method of transmitting and receiving color television signals on two

A method for reducing the probability of the loss of a character in a digital transmission employing biphase coding which comprises the steps of identifying the bits out-of-code, that is the bits which don't correspond to the two biphase code configurations; complementing the logic value said bits are given by the demodulator, if there is parity error; inhibiting a character not comprising out-of-code bits, but in which parity error occurs or if two or more out-of-code bits are present in the character. The circuit implementing the method comprises shift register means for storing the information bits and control signals identifying the out-of-code bits; parity check means; complementing means for complementing the logic state which are given by the demodulator to the out-of-code bits, said complementing means being conditioned by the simultaneous occurrence of the out-of-code bit and the parity error in a character; logic means for inhibiting the character in presence of parity error alone or of two or more out-of-code bits.

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Turin, Italy

Paolo D'Amato