Importance

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Abstract

A phase jitter detector that is ideally suited for use in combination with tone receivers (e.g., tone-to-pulse converters) to provide a speech immune tone detection system or in a measuring instrument to provide a direct measurement of the signal-to-noise ratio (SNR) of a signal is disclosed. In either application, the phase jitter detector can be implemented in either phase locked loop or digital logic form. Regardless of how implemented, the phase jitter detector determines the phase jitter of an incoming signal by first squaring the signal (by passing the incoming signal through a high gain amplifier that limits the signal, for example). After squaring, the phase jitter of the squared signal is determined by: (1) determining the phase deviation of each cycle of the squared signal with respect to the average frequency of the squared signal over a predetermined number of cycles; and (2) combining the phase deviation and the predetermined number of cycles information to determine phase jitter. In tone detection system applications, the phase jitter information is used to control whether or not a tone receiver is to complete a tone conversiono sequence. In SNR measuring applications, the phase jitter information is converted into SNR form and displayed.

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First Claim