| 摘要 |
<p>In the broadcasting system with code signalling, a multiplex signal is frequency modulated onto a main carrier by the transmitter. A sound-frequency information signal (9), a stereo information signal (13) which is modulated (11) onto a suppressed stereo auxiliary carrier (16, 17), a stereo pilot signal (15) with a frequency between the frequency spectra of the sound-frequency information signal and the modulated stereo information signal, and a binary code signal (23) are fed to the multiplexer (10). The code signal is modulated (20) onto an auxiliary carrier (18, 19) which lies outside the named frequency spectra, and the auxiliary carrier (18, 19) is a harmonic of a subharmonic of the stereo pilot signal and is derived from the same frequency source (14) as the stereo pilot signal. An unmodulated wave, which is necessary for detection of the code signal, is derived from the received stereo pilot signal by the receiver. In this way, perfect decoding of the code signal in the receiver is made possible with low receiving aerial voltages and without high-quality filters. <IMAGE></p> |
