Television channel selector - used on network distribution system permits use of wide-band receivers

摘要

A selector for television signals distributed on a network system and interposed between the main transmission cable and the receiver has a variable-frequency band-pass filter, a transposing modulator, a fixed frequency band-pass filter (34) and an attenuator. Vision pass-band shaping occurs so that the vision carrier is attenuated to half amplitude whilst preserving the sound signal. The characteristics of the selector shape the response so that a wide-band receiver can accept the narrow-band selected signals. In addition, if the transposed channel is chosen in the 41-68 MHz Band, the filter is easy to manufacture.