US 5,710,710 AGranted

Frequency counter with reduced false correlations

AssigneeOptoelectronics Co., Ltd.

InventorsWilliam P. Owen, Judd Sheets

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Abstract

An improved frequency counter for more reliably reading the frequency of low level signals by employing a method of separating the desired signal from undesirable noise related signals, wherein the frequency counter comprises signal input amplifier circuitry, a frequency modulator circuit for phase shifting the self-oscillation frequency of the undesired signal to isolate it from the valid signal, a prescaler circuit, a frequency or pulse counter driven by the output of the prescaler, and a correlator circuit for differentiating the self-oscillation frequencies from the main signal frequency so as to reduce false correlations between the self-oscillation, or noise, and valid signals.

Claims19

Dependent claims

A frequency counter for accurately determining the frequency of a valid periodic RF input signal of interest, said frequency counter distinguishing the frequency count of said valid periodic RF input signal from undesired self-oscillations, said frequency counter comprising:

(a) signal input means for receiving successive signal samples, the signal samples including the valid periodic RF input signal and the undesired self-oscillations;
(b) frequency measuring means, electrically associated with said signal input means, for measuring the frequency of the signal samples over a predetermined period of time so as to obtain a plurality of frequency counts;
(c) means for separating the signal samples to obtain successive frequency counts and to facilitate isolation of the valid periodic RF input signal from the undesired self-oscillations, said separating means being in electrical communication with said signal input means and said frequency measuring means,;
(d) correlating means, electrically communicated with said frequency measuring means and said separating means, for calculating a difference in frequency measurements between said successive frequency counts and for comparing said difference in said frequency counts to a preselected value, wherein a valid periodic RF input signal is deemed measured when said preselected value exceeds said difference;
and
(e) frequency display means, electrically associated with said correlating means, for displaying said frequency measurement of said valid periodic RF input signal.

3 more elements

A frequency counter for determining the frequency of a valid low-level periodic RF input signal of interest having self-oscillations, said frequency counter distinguishing the frequency count of said main periodic RF input from the frequency count of the self-oscillation, said frequency counter comprising:

(a) signal input means for receiving signal samples, the signal samples including a at least a first signal sample and a second signal sample;
(b) frequency measuring means, electrically associated with said signal input means, for measuring the frequency of said signal samples, including the first signal sample and the second signal sample, so as to obtain at least a first frequency count and a second frequency count corresponding to said first and second signal samples;
(c) modulator means, in electrical communication with said signal input means, for selectively shifting the phase of the second signal sample received, when said modulator means is enabled and prior to measuring the frequency count of the second signal sample, so as to facilitate isolation of the valid periodic RF signal input from the undesired self-oscillations;
(d) correlating means, electrically associated with said frequency measuring means and said modulator means, for calculating a difference between said first frequency count and said second frequency count and for comparing said difference to a preselected value;
and
(e) frequency display means, electrically associated with said correlating means, for displaying frequency counts when said difference is less than said preselected value.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/561,692Filed 22 Nov 1995 · continuation in part
Priority: 21 Sep 1994
Granted: 20 Jan 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G01R 23/10
Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage: by converting frequency…
G01R 23/02
Arrangements for measuring frequencies; Arrangements for analysing frequency spectra: arrangements for measuring frequency, e.g. pulse repetition…
G01R
Measuring electric variables

Family

Serial310,228Parent of this continuation-in-part · filed 21 Sep 1994
US 5,471,402 AParent of this continuation-in-part
US 5,710,710 AThis patent

From the US filing history. Foreign family members aren’t listed.

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