US3838338A
Expired / Lapsed
US
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Frequency measurements
Assignee: FLANN MICROWAVE INSTR Ltd
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Filing: 1973-10-09
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Granted: 1974-09-24
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Expires: 1993-10-09
Abstract
Abstract This invention relates to a method of and an apparatus for automatically measuring the frequency of an input signal, particularly where the frequency of the signal to be measured lies above the upper limit of direct-counting frequency counters. The input signal to be measured is mixed simultaneously with a first reference signal and a number of consecutive harmonics thereof. A lowest beat frequency is extracted from the resulting beat frequencies. In order to obtain a value for the number of the nearest harmonic and to determine whether the input signal lies above or below this nearest harmonic, the first reference signal is increased and decreased by a known increment to obtain respective further lowest beat frequencies. The set of lowest beat frequencies is processed to compute the value of the frequency of the input signal. There are regions midway between adjacent harmonics where input signals cannot be measured, and thus to provide a continuous measurement range including these regions and also to provide a check on a measurement obtained with respect to the first reference signal, a further reference signal is used instead of the first reference signal and the measurement procedure is performed with another set of lowest beat frequencies. If required, further reference signals may be used to extend the measurement range.
Inventors
- 👤 K Khoury
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:19
CPC Classifications
G; G01; G01R; G01R23/00
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
335 words
Apparatus for automatically measuring the frequency of an input signal, and comprising generating means for generating a reference signal having a preselected frequency, and a number of consecutive harmonics thereof, mixing means for mixing an input signal with the reference signal and each of the consecutive harmonics, and processing means for measuring a resulting beat frequency; and wherein the generating means is arranged to generate at least two sets of reference signals and their harmonics, a first set of which being based on the preselected frequencies F1, F2 and F3 where F1 F2 - Delta F F3 + Delta F, and a second set of which being based on the p reselected frequencies F4, F5 and F6 where F4 - F5 - delta F F6 + delta F, Delta F and delta F being preselected increments, and each of the reference signals being generated simultaneously with its harmonics; wherein the mixing means is arranged, for each of the reference signals of the sets, to mix the input signal with a respective reference signal and its harmonics simultaneously; wherein the apparatus includes filtering means having a preselected cut-off frequency equal to less than half the difference between adjacent harmonics in order to extract a respective one of the resulting beat frequencies and to reject unseparable beat frequencies which arise where an input signal lies in a region disposed centrally between two adjacent harmonics; wherein the processing means is responsive to the respective extracted beat frequencies for a set of the reference signals for providing the value of the number of the harmonic of a selected one of the reference signals of the set, said harmonic being the nearest harmonic to the input signal, the value of the extracted beat frequency, and the sign of the difference between the input signal and said nearest harmonic; and wherein F1, F4, Delta F, delta F and the cut-off frequency of the filtering means are selected such that a continuous measurement range extends over a selected number of the harmonics.
Claim 2
Dependent Claim
335 words
Apparatus for automatically measuring the frequency of an input signal, and comprising generating means for generating a reference signal having a preselected frequency, and a number of consecutive harmonics thereof, mixing means for mixing an input signal with the reference signal and each of the consecutive harmonics, and processing means for measuring a resulting beat frequency; and wherein the generating means is arranged to generate at least two sets of reference signals and their harmonics, a first set of which being based on the preselected frequencies F1, F2 and F3 where F1 F2 - Delta F F3 + Delta F, and a second set of which being based on the p reselected frequencies F4, F5 and F6 where F4 - F5 - delta F F6 + delta F, Delta F and delta F being preselected increments, and each of the reference signals being generated simultaneously with its harmonics; wherein the mixing means is arranged, for each of the reference signals of the sets, to mix the input signal with a respective reference signal and its harmonics simultaneously; wherein the apparatus includes filtering means having a preselected cut-off frequency equal to less than half the difference between adjacent harmonics in order to extract a respective one of the resulting beat frequencies and to reject unseparable beat frequencies which arise where an input signal lies in a region disposed centrally between two adjacent harmonics; wherein the processing means is responsive to the respective extracted beat frequencies for a set of the reference signals for providing the value of the number of the harmonic of a selected one of the reference signals of the set, said harmonic being the nearest harmonic to the input signal, the value of the extracted beat frequency, and the sign of the difference between the input signal and said nearest harmonic; and wherein F1, F4, Delta F, delta F and the cut-off frequency of the filtering means are selected such that a continuous measurement range extends over a selected number of the harmonics.
Claim 3
Dependent Claim
55 words
An apparatus as recited in claim 1 wherein the generating means is arranged to generate each of the reference signals of each of the sets simultaneously, the mixing means comprises respective individual mixers, the filtering means comprises respective individual filters, and the processing means is arranged to accept the respective extracted beat frequencies in parallel.
Claim 4
Dependent Claim
64 words
An apparatus as recited in claim 1 wherein the generating means is arranged to generate each of the reFerence signals of each of the sets simultaneously, the mixing means comprises at least one mixer, but fewer mixers than generated reference signals, and wherein there is provided multiplexing means for switching a mixer to receive in turn each of a plurality of generated reference signals.
Claim 5
Dependent Claim
48 words
An apparatus as recited in claim 3 wherein the processing means is arranged to control the multiplexing means such that the processing means receives the lowest beat frequencies for the sets of reference signals in synchronism with the processing of the lowest beat frequencies by the processing means.
Claim 6
Dependent Claim
57 words
An apparatus as recited in claim 1 wherein the generating means comprises a single controllable generator arranged to generate sequentially each of the reference signals of each of the sets, the mixing means comprises a single mixer, the filtering means comprises a single filter, and the processing means is arranged to accept the extracted beat frequencies serially.
Claim 7
Dependent Claim
41 words
An apparatus as recited in claim 5 wherein the processing means is arranged to control the controllable generator such as to generate the sets of reference signals in synchronism with the processing of the extracted beat frequencies by the processing means.
Claim 8
Dependent Claim
34 words
An apparatus as recited in claim 6 wherein the processing means is arranged to provide an indication if the input signal cannot be measured with respect to any of said sets of reference signals.
Claim 9
Dependent Claim
23 words
An apparatus as recited in claim 1 wherein the processing means is arranged to compute and read-out the value of the input signal.
Claim 10
Dependent Claim
22 words
An apparatus as recited in claim 1 wherein the generating means is arranged such that Delta F is equal to delta F.
Claim 11
Dependent Claim
51 words
An apparatus as claimed in claim 1 wherein the processing means is arranged to process the extracted beat frequencies from two of the sets of reference signals and to select for read-out the processed data having a lower value of the number of the nearest harmonic of the corresponding reference signal.
Claim 12
Independent Claim
260 words
An apparatus for automatically measuring the frequency of an input signal, and comprising controllable generating means for generating one at a time of six reference signals which form two sets F1 to F3 and F4 to F6, where F1 F2 - Delta F F3 + Delta F and F4 F5 - Delta F F6 + Delta F, Delta F being a preselected increment, the generating means being arranged to generate a reference signal simultaneously with a number of consecutive harmonics of the generated reference signal; mixing means for mixing an input signal with a generated reference signal and its harmonics; filtering means for providing at an output an extracted lowest beat frequency from the resulting beat frequencies, the filtering means having a cut-off frequency less than half the frequency of the lowest reference signal whereby ambiguity is avoided where an input signal lies approximately midway between adjacent harmonics; and processing means responsive to the output of the filtering means for processing the lowest beat frequencies, the processing means being arranged to control the controllable generating means to generate preselected reference signals in accordance with a predetermined schedule in order to provide a sufficient number of lowest beat frequencies for processing, the processing means being also arranged to display one of the computed frequency of the input signal and an indication that the input signal lies outside the measurement range of the apparatus; F1, F4, F and the cut-off frequency of the filtering means being interrelated such that a continuous measurement range extends over a selected number of the consecutive harmonics.
Claim 13
Independent Claim
260 words
An apparatus for automatically measuring the frequency of an input signal, and comprising controllable generating means for generating one at a time of six reference signals which form two sets F1 to F3 and F4 to F6, where F1 F2 - Delta F F3 + Delta F and F4 F5 - Delta F F6 + Delta F, Delta F being a preselected increment, the generating means being arranged to generate a reference signal simultaneously with a number of consecutive harmonics of the generated reference signal; mixing means for mixing an input signal with a generated reference signal and its harmonics; filtering means for providing at an output an extracted lowest beat frequency from the resulting beat frequencies, the filtering means having a cut-off frequency less than half the frequency of the lowest reference signal whereby ambiguity is avoided where an input signal lies approximately midway between adjacent harmonics; and processing means responsive to the output of the filtering means for processing the lowest beat frequencies, the processing means being arranged to control the controllable generating means to generate preselected reference signals in accordance with a predetermined schedule in order to provide a sufficient number of lowest beat frequencies for processing, the processing means being also arranged to display one of the computed frequency of the input signal and an indication that the input signal lies outside the measurement range of the apparatus; F1, F4, F and the cut-off frequency of the filtering means being interrelated such that a continuous measurement range extends over a selected number of the consecutive harmonics.
Claim 14
Independent Claim
296 words
A method of automatically measuring the frequency of an input signal, and comprising the steps of generating a reference signal having a preselected frequency, and a number of consecutive harmonics thereof, mixing an input signal with the reference signal and each of the consecutive harmonics, and measuring a resulting beat frequency; the method being characterised by the step of generating at least two sets of reference signals and their harmonics, a first set of which being based on the preselected frequencies F1, F2 and F3 where F1 F2 - Delta F F3 + Delta F, and a second set of which being based on the preselected frequencies F4, F5 and F6 where F4 - F5 -delta F F6 + delta F, Delta F and delta F being preselected increments, and each of the reference signals being generated simultaneously with its harmonics; by the step of mixing, for each of the reference signals of the sets, the input signal with a respective reference signal and its harmonics simultaneously; by the step of extracting the respective lowest beat frequencies provided that the input signal lies outside a respective predetermined region disposed centrally between the respective neighbouring harmonics; and by the step of processing the respective extracted beat frequencies for a set of the reference signals for providing the value of the number of the harmonic of a selected one of the reference signals of the set, said harmonic being the nearest harmonic to the input signal, the value of the extracted beat frequency, and the sign of the difference between the input signal and said nearest harmonic; and by the step of preselecting F1, F4, Delta F, delta F and the respective predetermined regions such that a continuous measurement range extends over a selected number of the harmonics.
Claim 15
Independent Claim
296 words
A method of automatically measuring the frequency of an input signal, and comprising the steps of generating a reference signal having a preselected frequency, and a number of consecutive harmonics thereof, mixing an input signal with the reference signal and each of the consecutive harmonics, and measuring a resulting beat frequency; the method being characterised by the step of generating at least two sets of reference signals and their harmonics, a first set of which being based on the preselected frequencies F1, F2 and F3 where F1 F2 - Delta F F3 + Delta F, and a second set of which being based on the preselected frequencies F4, F5 and F6 where F4 - F5 -delta F F6 + delta F, Delta F and delta F being preselected increments, and each of the reference signals being generated simultaneously with its harmonics; by the step of mixing, for each of the reference signals of the sets, the input signal with a respective reference signal and its harmonics simultaneously; by the step of extracting the respective lowest beat frequencies provided that the input signal lies outside a respective predetermined region disposed centrally between the respective neighbouring harmonics; and by the step of processing the respective extracted beat frequencies for a set of the reference signals for providing the value of the number of the harmonic of a selected one of the reference signals of the set, said harmonic being the nearest harmonic to the input signal, the value of the extracted beat frequency, and the sign of the difference between the input signal and said nearest harmonic; and by the step of preselecting F1, F4, Delta F, delta F and the respective predetermined regions such that a continuous measurement range extends over a selected number of the harmonics.
Claim 16
Dependent Claim
54 words
A method as recited in claim 12 wherein the generating step comprises simultaneously generating the respective reference signals; the mixing step comprises simultaneously and respectively mixing the input signal with the reference signals; the respective lowest beat frequencies are extracted simultaneously; and the processing step comprises accepting the respective lowest beat frequencies in parallel.
Claim 17
Dependent Claim
60 words
A method as recited in claim 12 wherein the generating step comprises simultaneously generating the respective reference signals; the mixing step is performed by means of at least one mixer, but fewer mixers than generated reference signals; and including the step of switching at least one mixer to receive in turn each of an associated plurality of generated reference signals.
Claim 18
Dependent Claim
41 words
A method as recited in claim 12 wherein the generating step comprises sequentially generating the reference signals; the mixing step is performed sequentially by means of a single mixer; and the processing step comprises accepting the respective lowest beat frequencies serially.
Claim 19
Dependent Claim
24 words
A method as recited in claim 15 wherein he generating step comprises generating the sets of reference signals in synchronism with the processing step.
Claim 20
Dependent Claim
32 words
A method as recited in claim 16 and including the step of providing an indication if the input signal cannot be measured with respect to any of said sets of reference signals.
Claim 21
Dependent Claim
21 words
A method as recited in claim 12 and including the step of computing and reading-out the value of the input signal.
Claim 22
Dependent Claim
25 words
A method as recited in claim 12 wherein the generating step comprises generating the reference frequencies such that Delta F is equal to delta F.
Claim 23
Dependent Claim
48 words
A method as recited in claim 12 wherein the processing step comprises processing the lowest beat frequencies from teo of the sets of reference signals, and selecting for read-out the processed data having a lower value of the number of the nearest harmonic of the corresponding reference signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |