| 摘要 |
1512045 Television PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 11 July 1975 [15 July 1974] 29224/75 Heading H4F Television receiver includes a circuit arrangement for receiving an identification signal that has been added to a television signal received from a video storage device, e.g. video tape or disc recorder, to thereby distinguish a signal received from a recorder from a signal received from a transmitter, and in response to recognition of an identification signal changes over circuits in the receiver. Specifically the time constant network of the line sync circuit flywheel filter is changed i.e. reduced, to the same condition as in the case of non-synchronization between received line sync signals and signals generated by the line sync circuit of the receiver. If the receiver simultaneously receives transmitted and recorded signals then recognition of an identification signal prevents display of the transmitted signal. The identification signal preferably comprises serrated horizontal sync pulses, Fig. 1g, although it may comprise alternately serrated horizontal sync pulses, Fig. 1f, or horizontal sync pulses with the trailing or leading edges thereof advanced or retarded Figs. 1b-1e with respect to the trailing and leading edges of standard horizontal sync pulses, Fig. 1a. Reference is also made to including a field frequency identification signal or by employing the sound channel as a means of identification. |
