Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1986-06-12
1989-04-11
Groody, James J.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358167, 455223, 375 1, H04N 708
Patent
active
048211206
ABSTRACT:
In a receiver for the reception of satellite television signals sub-carrier signals carrying, for example, data are recovered from the demodulated television signal and themselves demodulated to provide data outputs. Prior to the second demodulation, each sub-carrier signal is averaged to improve its signal-to-noise, ratio, thereby taking advantage of the relatively small basic bandwidth of the sub-carrier signal to enable satisfactory reception of the signal in poor reception conditions when the received signal is too weak to obtain an acceptable television picture signal. Impulse noise in the received signal is reduced prior to averaging. To avoid intermodulation products being generated by the transmission and reception of several sub-carriers together, direct sequence modulation of the transmitted sub-carriers can be used to spread their power over a wider frequency band. A code lock loop circuit is then used in the receiver to recover the original narrow band signals, which are subsequently averaged to obtain the advantage in signal-to-noise ratio.
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Devon County Council
Groody James J.
Kostak Victor R.
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