US 4,790,013 AGranted

Receiver capable of quickly establishing stable frame synchronization

AssigneeNEC Corporation

InventorKouzou Kage

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Abstract

In a receiver responsive to an input signal comprising information signals following frame synchronization signals, respectively, frame synchronization is established by a frame synchronization pulse generator (56) with reference to both of the information signals and the frame synchronization signals. A discriminator (57) discriminates between the information signals and other spurious signals by monitoring descrambled digital signals produced by a descrambler (47) in response to the information signals or by monitoring reproduced analog signals into which the descrambled digital signals are converted by a digital to analog converter (51). The monitoring is carried out within silent parts interposed between information parts of either the descrambled digital signals or the reproduced analog signals. The information signals are discriminated either by a preselected pattern inevitably appearing in the silent parts of the descrambled digital signals or by amplitudes of the silent parts of the reproduced analog signals. Alternatively, the information signals may be discriminated by detecting the autocorrelation of the reproduced analog signals.

Claims9

Dependent claims

A receiver responsive to an input signal comprising a plurality of frames, each frame to include information signals following frame synchronization signals, for producing a reproduction of said information signals with frame synchronization established, said receiver including a signal producing means responsive to said input signal for producing a succession of digital signals conveying the respective information signals and signal converting means for converting said digital signals into said reproduction, wherein the improvement comprises:

monitoring means for monitoring a predetermined one of said succession of digital signals and said reproduction of said information signals to produce a result signal indicative of whether or not said information signals are produced in response to said input signal;
and
frame synchronization establishing means responsive to said input signal and said result signal for establishing said frame synchronization, said frame synchronization establishing means including means to monitor said result signal and said frame synchronization signals of said input signal over a plurality of said frames to keep said frame synchronization even in the absence of said frame synchronization signals. PG,35

Dependencies are inferred from the claim text.