US3914693A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Calibration test apparatus
Assignee: Boeing North American Inc
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Filing: 1974-07-10
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Granted: 1975-10-21
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Expires: 1994-07-10
Abstract
Abstract A test device for calibrating an FM transmitter as to its frequency deviation with a given frequency test tone input signal of a predetermined amplitude. The device operates by supplying the test tone to a microwave transmitter and mixing a signal representative of the output of the transmitter with a locally generated signal of nearly the same frequency and low pass filtering the output of the mixer. This output is then monitored for a null condition as a frequency deviation adjusting mechanism in the transmitter is adjusted to produce a null output from the low pass filter.
Inventors
- 👤 Gilbert M Ohlen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:40
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/06
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
162 words
The method of calibrating a frequency deviation adjustable frequency modulated transmitter for frequency deviation when the transmitter includes output means for providing an automatic frequency control (AFC) test signal directly indicative in frequency of the carrier frequency of the signal to be transmitted comprising the steps of: generating a first signal of a predetermined amplitude and a first frequency; applying the first signal to the frequency modulated transmitter for frequency modulating the carrier output thereof; generating a second signal of a second frequency, the frequency of said second signal differing from the frequency of the AFC test signal by a lessor amount than said first frequency; mixing the test signal and said second signal; lowpass filtering the mixed test and second signals to pass only the difference frequency signal; measuring the amplitude of the signal passed by filtering; and adjusting the frequency Deviation of said transmitter until a first minimum amplitude measurement is obtained at which point the transmitter deviation is calibrated.
Claim 2
Independent Claim
162 words
The method of calibrating a frequency deviation adjustable frequency modulated transmitter for frequency deviation when the transmitter includes output means for providing an automatic frequency control (AFC) test signal directly indicative in frequency of the carrier frequency of the signal to be transmitted comprising the steps of: generating a first signal of a predetermined amplitude and a first frequency; applying the first signal to the frequency modulated transmitter for frequency modulating the carrier output thereof; generating a second signal of a second frequency, the frequency of said second signal differing from the frequency of the AFC test signal by a lessor amount than said first frequency; mixing the test signal and said second signal; lowpass filtering the mixed test and second signals to pass only the difference frequency signal; measuring the amplitude of the signal passed by filtering; and adjusting the frequency Deviation of said transmitter until a first minimum amplitude measurement is obtained at which point the transmitter deviation is calibrated.
Claim 3
Dependent Claim
209 words
Apparatus for calibrating a frequency deviation adjustable frequency modulated transmitter for frequency deviation comprising, in combination: transmitter means including output means for providing an automatic frequency control (AFC) test signal directly indicative in frequency of the carrier frequency of the signal to be transmitted and including input means; test tone means for generating a first signal of a predetermined amplitude and a first frequency; means connecting said test tone means to said input means of said transmitter means for frequency modulating the carrier output thereof; oscillator means for generating a second signal of a second frequency, the frequency of said second signal differing from the frequency of the AFC test signal by a lessor amount than said first frequency; mixing means for mixing the test signal and said second signal connected to said transmitter means and to said oscillator means; filter means connected to said mixing means, for lowpass filtering the mixed test and second signals to pass only the difference frequency signals; and measuring means for providing an indication of the amplitude of the signal passed by filter means, the adjustment of a frequency deviation adjustment means of said transmitter, until a first minimum amplitude indication is obtained, representing the point at which the transmitter deviation is calibrated.
Claim 4
Dependent Claim
209 words
Apparatus for calibrating a frequency deviation adjustable frequency modulated transmitter for frequency deviation comprising, in combination: transmitter means including output means for providing an automatic frequency control (AFC) test signal directly indicative in frequency of the carrier frequency of the signal to be transmitted and including input means; test tone means for generating a first signal of a predetermined amplitude and a first frequency; means connecting said test tone means to said input means of said transmitter means for frequency modulating the carrier output thereof; oscillator means for generating a second signal of a second frequency, the frequency of said second signal differing from the frequency of the AFC test signal by a lessor amount than said first frequency; mixing means for mixing the test signal and said second signal connected to said transmitter means and to said oscillator means; filter means connected to said mixing means, for lowpass filtering the mixed test and second signals to pass only the difference frequency signals; and measuring means for providing an indication of the amplitude of the signal passed by filter means, the adjustment of a frequency deviation adjustment means of said transmitter, until a first minimum amplitude indication is obtained, representing the point at which the transmitter deviation is calibrated.
References Cited (Backward Citations)
US2293022A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-20 | 1979-04-21 | 1979-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-20 | 1983-04-21 | 1983-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-20 | 1987-04-21 | 1987-10-21 | $7700.00 | Window Closed / Lapsed |