Varying bandwidth digital signal detector

A communication receiver comprising:

• means for receiving a plurality of signals each having a distinct carrier modulated by an information signal including a signal having a first carrier signal modulated by a first information signal, each information signal having a plurality of levels and transitions between the levels occurring at predetermined intervals,
• means responsive to the received signal for demodulating the received signal to form a baseband signal including a component corresponding to the first information signal,
• means for detecting the levels of the baseband signal between the transitions of the first information signal,
• means responsive to the detected levels of the baseband signal for synchronizing the demodulating means to the first carrier frequency, and
• means responsive to the detected levels of the baseband signal for synchronizing the detecting means to the transitions of the first information signal,
• the detecting means including:
• means for limiting the baseband signal from the demodulating means to a first bandwidth at the transition instants of the first information signal and to a second narrower bandwidth between the transitions of the first information signal, and
• means for sampling the baseband signal from the bandwidth limiting means during the second narrower bandwidth of the baseband signal.

A communication system for exchanging information signals over a plurality of channels comprising:

• a plurality of transmitters each responsive to an information signal having a plurality of levels and transitions between the levels occurring at predetermined intervals for generating a prescribed band signal having a distinct carrier modulated by the information signal, the prescribed bands forming a set of overlapping frequency band channels, and
• at least one receiver comprising:
• means for receiving the set of overlapping frequency band channel signals including a signal having a first carrier signal modulated by a first information signal,
• means responsive to the received signals for forming a demodulated signal including a component corresponding to the first information signal,
• means for detecting the levels of the demodulated signal between the transitions of the first information signal,
• means responsive to the detected levels of the demodulated signal for synchronizing the demodulated signal forming means to the first carrier frequency, and
• means responsive to the detected levels of the demodulated signal for synchronizing the detecting means to the transitions of the first information signal,
• the detecting means including:
• means for restricting the demodulated signal to a first bandwidth at the transition instants of the first information signal and to a second narrower bandwidth between the transitions of the first information signal, and
• means for sampling the demodulated signal from the bandwidth limiting means during the second narrower bandwidth of the demodulated signal to form a signal corresponding to the first information signal.