UEbertragungssystem mit einer Sende- und einer Empfangsvorrichtung zur UEbertragung von Informationen in einem vorgeschriebenen Frequenzband und dafuer geeignete Sende- und Empfangsvorrichtungen

摘要

1277131 Automatic frequency and phase control PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 26 June 1969 [29 June 1968] 32372/69 Addition to 1201923 Heading H3A The invention relates to a signal transmission system in which as in the parent Specification, a periodic pulse pattern, non-correlated with the main information signal, is transmitted simultaneously with the information and in the same frequency band. In the receiver, according to the present invention, the combined signals, in which the main information signal comprises bivalent pulses, are applied to two parallel arranged channels, the first provided with a pulse restorer for restoring the main information signal and the second including a difference producer to which is applied the received signal and also the output of the pulse restorer, the output of the difference producer comprising the auxiliary periodic pulse pattern which is applied to the modulation device in the circuit for automatic phase control of the locally generated pulse pattern. In one embodiment the first channel includes a pulse restorer comprising a double limiter 92, the output from which is applied via the pulse regenerator 67 to the utilization circuits 68. The second channel comprises difference producer 93 to which the output of pulse restorer 92 is also fed via an automatic amplitude control circuit 95; the output of difference producer 93 is applied over filter 96 to the modulation device 19, the second input of which is derived from local pulse pattern generator 101, and the output of which controls the frequency of the pattern generator oscillator 161. The outputs of the double limiter 92 and difference producer 93 are combined in a product modulator 97 and applied over filter 98 to control the gain in the automatic amplitude control circuit 95. Alternatively, the output voltage of the difference producer 93 may be directly applied as a control voltage to the automatic amplitude control circuit 95, after rectification and filtering, or the amplitude control may be applied to the received signal. In a second embodiment (Fig. 3, not shown) the second input for the difference producer is derived from the pulse regenerator 67.