Adaptive signal quality measurement circuit for PSK and FSK demodulators

Abstract

In a demodulator for an antipodal data stream, such as a PSK or FSK demodulator, a signal quality measuring circuit having a high dynamic range. Any signal quality parameter can be measured, such as BER and E.sub.b /N.sub.o. The number of zero crossings in a certain error gate is compared with the total scaled number of zero crossings in the sampling interval. These values are translated into a quantitative measure of signal quality by means of a pre-established table of values obtained during calibration of the instrument. The wide dynamic range of the circuit is achieved by using several gates of various widths. The gates are derived from a bit synchronizer; the system functions without the necessity for superimposing upon the data stream any coding information as is common with BER measurement devices of the prior art.

Dependencies are inferred from the claim text.