US5115514A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measuring and controlling signal feedback between the transmit and receive antennas of a communications booster
Assignee: Allen Telecom LLC
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Filing: 1988-08-12
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Granted: 1992-05-19
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Expires: 2008-08-12
Abstract
Abstract A cellular communication system booster has plural narrowband and wideband channels each having down mixers, local oscillators, IF filters, and amplifiers for amplifying communication signals. On a narrowband channel preferably not in use, and preferably in a time-multiplexed manner, a reference signal of known signal strength is substituted at the output amplifier in lieu of a normal communications signal. When this amplified reference signal is broadcast at the output antenna a portion of the signal is feed back to the input antenna due to imperfect isolation between the antennas. This feedback signal is measured by a Radio Signal Strength Indicator (RSSI) circuit at the point of its receipt into the IF filter of the narrowband channel. The measured signal strength serves as a measurement of signal isolation/feedback between the antennas. A microprocessor receiving the measurement and knowledgeable of the reference signal strength controls the gain of the channel amplifier so as to maintain the feedback signal 10 dB below the reference signal, thereby preventing RF signal feedback oscillation. In different embodiments the reference signal may be derived from an injection oscillator or, alternatively, from an actual communication signal upon another communications channel. Isolation/feedback measurements are typically stepped across multiple channels spanning the entire communications frequency band, thereby providing measurement and appropriate control at all frequencies and operational conditions.
Inventors
- 👤 Samuel A. Leslie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:56
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/155; H04B7/15564; H04B7/15578; H04B7/24; H04B7/26; H04B7/2603; H04B7/2606; H04W; H04W16/00; H04W16/24; H04W16/26
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
139 words
An apparatus for measuring feedback in an adjustable gain booster usable in a radiotelephone system, the booster having at least one adjustable gain amplifier and being capable of receiving signals at an input port and transmitting amplified signals corresponding thereto from an output port, the apparatus comprising: means for storing a list of signal channels to be measured; means for transmitting signals from the output port corresponding to said list; means for measuring a parameter value of each said transmitted signal; means for receiving signals at the input port, corresponding to said transmitted signals; means for measuring a parameter value of each received signal which corresponds to one of the transmitted signals; and means for processing said two parameter values associated with each said transmitted signal including means for forming an isolation indicium therefrom for each said transmitted signal.
Claim 2
Independent Claim
139 words
An apparatus for measuring feedback in an adjustable gain booster usable in a radiotelephone system, the booster having at least one adjustable gain amplifier and being capable of receiving signals at an input port and transmitting amplified signals corresponding thereto from an output port, the apparatus comprising: means for storing a list of signal channels to be measured; means for transmitting signals from the output port corresponding to said list; means for measuring a parameter value of each said transmitted signal; means for receiving signals at the input port, corresponding to said transmitted signals; means for measuring a parameter value of each received signal which corresponds to one of the transmitted signals; and means for processing said two parameter values associated with each said transmitted signal including means for forming an isolation indicium therefrom for each said transmitted signal.
Claim 3
Dependent Claim
27 words
An apparatus as in claim 1, including means for adjusting the gain of at least one amplifier of the booster in response to said formed isolation indicia.
Claim 4
Dependent Claim
39 words
An apparatus as in claim 1, including means for selecting a minimal isolation indicium and means for adjusting the gain of said at least one adjustable gain amplifier of the booster in response to said selected minimal isolation indicium.
Claim 5
Dependent Claim
31 words
An apparatus as in claim 3 including means for adjusting said gain so as to have a value on the order of 10 dB less than said selected minimal isolation indicium.
Claim 6
Dependent Claim
24 words
An apparatus as in claim 1 including means, coupled to said processing means, for generating a reference signal for transmission from the output port.
Claim 7
Dependent Claim
30 words
An apparatus as in claim 5 with said received signal measuring means including means for measuring a field strength parameter of a received signal corresponding to said transmitted reference signal.
Claim 8
Dependent Claim
22 words
An apparatus as in claim 6 including means for forming said isolation indicium from said received signal and said transmitted reference signal.
Claim 9
Independent Claim
114 words
A method of measuring feedback in an adjustable gain booster usable in a radiotelephone system, the booster having at least one adjustable gain amplifier and being capable of receiving signals at an input port and transmitting amplified signals corresponding thereto from an output port, the method comprising: storing a list of signal channels to be measured; transmitting signals from the output port corresponding to the list; determining a parameter value of each transmitted signal; receiving at the input port signals corresponding to the transmitted signals; measuring a parameter value for each received signal; processing the two parameter values associated with each transmitted signal and forming an isolation indicium therefrom for each such transmitted signal.
Claim 10
Independent Claim
114 words
A method of measuring feedback in an adjustable gain booster usable in a radiotelephone system, the booster having at least one adjustable gain amplifier and being capable of receiving signals at an input port and transmitting amplified signals corresponding thereto from an output port, the method comprising: storing a list of signal channels to be measured; transmitting signals from the output port corresponding to the list; determining a parameter value of each transmitted signal; receiving at the input port signals corresponding to the transmitted signals; measuring a parameter value for each received signal; processing the two parameter values associated with each transmitted signal and forming an isolation indicium therefrom for each such transmitted signal.
Claim 11
Dependent Claim
28 words
A method as in claim 8 including adjusting the gain of said at least one adjustable gain amplifier of the booster in response to the formed isolation indicia.
Claim 12
Dependent Claim
30 words
A method as in claim 8 including selecting a minimal isolation indicium and adjusting the gain of said at least one adjustable gain amplifier in response to the selected indicium.
Claim 13
Dependent Claim
29 words
A method as in claim 10 including adjusting the gain so as to have a value on the order of 10 dB less than the selected minimal isolation indicium.
Claim 14
Dependent Claim
17 words
A method as in claim 8 including generating a reference signal for transmission from the output port.
Claim 15
Dependent Claim
17 words
A method as in claim 12 including measuring the received signal corresponding to the transmitted reference signal.
Claim 16
Dependent Claim
21 words
A method as in claim 13 including forming the isolation indicium from the measured received signal and the transmitted reference signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-05-19 | 1995-11-18 | 1996-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-05-19 | 1999-11-18 | 2000-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-05-19 | 2003-11-18 | 2004-05-19 | $7700.00 | Window Closed / Lapsed |