US3602819A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sensitivity or noise level measurement circuit and method
Assignee: AT&T Inc
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Filing: 1969-05-07
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Granted: 1971-08-31
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Expires: 1989-05-07
Abstract
Abstract A device, such as a receiver, amplifier, active filter, etc. is tested for sensitivity or noise level by modulating an input signal source and switching the output of the device between two terminals in synchronism. Following signal detection and integration, the output of one of the terminals is connected to one side of a null detector while the output of the other terminal is connected through a resistance network and then to the other side of a null detector. The resistor network is adjusted so that when the input signal source is reduced to a level such that the output signal of the device is equal to the noise level within the device, the null detector indicates a null. The input signal level in dbm at this point is equal to the sensitivity of the device.
Inventors
- 👤 Richard W Abbott
- 👤 Samuel S Montgomery
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:36
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/26
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
274 words
A circuit for measuring the sensitivity of a radio device, comprising: means for applying a signal to the input of said device; means for varying and for indicating the power level of the signal applied to the input of said device; switching means connected to the output of said device for alternately connecting the output signal from said device to a first and a second sampling path; means for interrupting said input signal and for actuating said switching means in synchronism to connect the output of the device to said first sampling path when the input signal is absent and to said second sampling path when the input signal is present; means for detecting and integrating the signals impressed upon the respective first and second sampling paths; first and second variable resistances connected in series in said second sampling path; means having a First input connected to the first sampling path and a second input connected to the second variable resistance for indicating the relative magnitude of signals applied to the first and second inputs thereof; means for shorting said first variable resistance during a calibration step; said second variable resistance being adjusted so that there are equal signal magnitudes applied to the first and second inputs of said indicating means when said shorting means is operated and no signals are applied to the input of the device; and said first variable resistance being adjusted so that equal signals are applied to the first and second inputs of said indicating means when the magnitude of the signal on the second sapling path is twice the magnitude of the signal on the first sampling path.
Claim 2
Dependent Claim
274 words
A circuit for measuring the sensitivity of a radio device, comprising: means for applying a signal to the input of said device; means for varying and for indicating the power level of the signal applied to the input of said device; switching means connected to the output of said device for alternately connecting the output signal from said device to a first and a second sampling path; means for interrupting said input signal and for actuating said switching means in synchronism to connect the output of the device to said first sampling path when the input signal is absent and to said second sampling path when the input signal is present; means for detecting and integrating the signals impressed upon the respective first and second sampling paths; first and second variable resistances connected in series in said second sampling path; means having a First input connected to the first sampling path and a second input connected to the second variable resistance for indicating the relative magnitude of signals applied to the first and second inputs thereof; means for shorting said first variable resistance during a calibration step; said second variable resistance being adjusted so that there are equal signal magnitudes applied to the first and second inputs of said indicating means when said shorting means is operated and no signals are applied to the input of the device; and said first variable resistance being adjusted so that equal signals are applied to the first and second inputs of said indicating means when the magnitude of the signal on the second sapling path is twice the magnitude of the signal on the first sampling path.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |