| 摘要 |
A television signal transmission system comprises a main end unit 10 which includes a pair of SAW filters 22, 24 with the same delay, where one filter 22 has amplitude and normalized phase frequency response characteristics which continually vary between approximately -6 dB and 180 degrees at the picture carrier wave frequency and between zero dB and zero degrees at the sound carrier wave frequency in the television signal, and the second filter 24 has essentially flat amplitude and normalized phase response between the picture carrier wave and the sound carrier wave frequencies. A radio frequency video signal is supplied to both filters 22, 24, where the output power from the first filter 22 is selected for transmission during at least part of the horizontal blanking interval in the television signal and at other times the output power is selected from the second filter 24 for transmission. The transmitted signal is received by a decoder 66 which includes a two-phase stable phase modulation detector 80 and third and fourth SAW filters 72, 74 which have response characteristics which are complementary to those of the filters 22, 24 in the main end. The received signal is supplied to both the third and fourth SAW filters 72, 74, the outputs of which are selectively connected to an output terminal 84 as response to the phase modulation detector 80 for recreating the received signal. <IMAGE>
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