Patent US5303408A successfully refreshed from Google Patents.
US5303408A
Expired / Lapsed
US
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Squelch detector
Assignee: Motorola Solutions Inc
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Filing: 1992-04-03
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Granted: 1994-04-12
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Expires: 2012-04-03
Abstract
Abstract A communication device (100) having a receiver (106) and an audio output device (116) is provided. The communication device (100) includes a digital signal processor DSP (110) for measuring the level of signal energy in a first segment of the frequency spectrum of the received signal to dynamically establish a squelch threshold. The DSP (110) is also used to measure the level of signal energy in a second segment of the frequency spectrum of the received signal. The communication device (100) also includes audio gates (114). The audio gates (114) provides for the unmuting of the audio output device (116) when the signal energy contained in the second segment of the frequency spectrum of the received signal is below the squelch threshold.
Inventors
- 👤 Mansour Ghomeshi
- 👤 Chin P. Wong
- 👤 John W. Simmons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:14
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/1027; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/344
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
99 words
A communication device having an audio output device, comprising: receiver means for receiving a signal to produce a received signal having a frequency spectrum; a first means having a correlator and integrator and dump means for measuring a signal energy level in a first segment of the frequency spectrum of the received signal to determine a threshold; second means for measuring a signal energy level in a second segment of the frequency spectrum of the received signal; and third means for unmuting the audio output device when the signal level measured by the second means is below the threshold.
Claim 2
Dependent Claim
99 words
A communication device having an audio output device, comprising: receiver means for receiving a signal to produce a received signal having a frequency spectrum; a first means having a correlator and integrator and dump means for measuring a signal energy level in a first segment of the frequency spectrum of the received signal to determine a threshold; second means for measuring a signal energy level in a second segment of the frequency spectrum of the received signal; and third means for unmuting the audio output device when the signal level measured by the second means is below the threshold.
Claim 3
Dependent Claim
18 words
The communication device of claim 1, wherein the first means includes means for measuring low band signal energy.
Claim 4
Dependent Claim
18 words
The communication device of claim 1, wherein the second means includes means for measuring high band signal energy.
Claim 5
Dependent Claim
15 words
The communication device of claim 1, wherein the first means includes a digital signal processor.
Claim 6
Dependent Claim
14 words
The communication device of claim 1, wherein the third means includes an audio gate.
Claim 7
Dependent Claim
12 words
The communication device of claim 1, wherein the threshold includes a hysterisis.
Claim 8
Dependent Claim
31 words
The communication device of claim 1, wherein the third means includes means for muting the audio output device when the signal level measured by the second means is above the threshold.
Claim 9
Dependent Claim
122 words
In a radio communication device having an audio output device, a method for preventing low quality voice signals from reaching the audio output device, comprising the steps of: receiving a radio frequency signal to produce a received signal having a frequency spectrum; correlating to a first frequency segment of the frequency spectrum of the received signal; deriving a signal energy level in the first frequency segment to produce a threshold; monitoring a second frequency segment of the frequency spectrum of the received signal; sensing when the signal energy in the second frequency segment of the received signal is below the threshold; and unmuting the audio output device in response to the signal energy in the second frequency segment being below the threshold.
Claim 10
Dependent Claim
122 words
In a radio communication device having an audio output device, a method for preventing low quality voice signals from reaching the audio output device, comprising the steps of: receiving a radio frequency signal to produce a received signal having a frequency spectrum; correlating to a first frequency segment of the frequency spectrum of the received signal; deriving a signal energy level in the first frequency segment to produce a threshold; monitoring a second frequency segment of the frequency spectrum of the received signal; sensing when the signal energy in the second frequency segment of the received signal is below the threshold; and unmuting the audio output device in response to the signal energy in the second frequency segment being below the threshold.
Claim 11
Dependent Claim
14 words
The method of claim 8, wherein the first frequency segment includes low band audio.
Claim 12
Dependent Claim
14 words
The method of claim 8, wherein the second frequency segment includes high band noise.
Claim 13
Dependent Claim
49 words
The method of claim 8, further comprising the steps of: sensing when the signal energy in the second frequency segment of the received signal is above the threshold; and muting the audio output device in response to the signal energy in the second frequency segment being above the threshold.
Claim 14
Dependent Claim
143 words
A communication device having an audio output device, comprising: receiver means for receiving a radio frequency signal modulated with a digitized voice signal, the radio frequency signal having a frequency spectrum; processor means for recovering the digitized voice signal; means for converting the digitized voice signal to an analog signal; squelch means for sensing when to prevent the analog signal from reaching the audio output device, the squelch means comprising: a first means having a correlator integrator and dump means for measuring signal energy level in a first segment of the frequency spectrum of the received signal to establish a threshold; second means for measuring a signal energy level in a second segment of the frequency spectrum of the received signal; and third means for unmuting the audio output device when the signal level measured by the second means is below the threshold.
Claim 15
Dependent Claim
143 words
A communication device having an audio output device, comprising: receiver means for receiving a radio frequency signal modulated with a digitized voice signal, the radio frequency signal having a frequency spectrum; processor means for recovering the digitized voice signal; means for converting the digitized voice signal to an analog signal; squelch means for sensing when to prevent the analog signal from reaching the audio output device, the squelch means comprising: a first means having a correlator integrator and dump means for measuring signal energy level in a first segment of the frequency spectrum of the received signal to establish a threshold; second means for measuring a signal energy level in a second segment of the frequency spectrum of the received signal; and third means for unmuting the audio output device when the signal level measured by the second means is below the threshold.
Claim 16
Dependent Claim
17 words
The communication device of claim 12, further including means for correcting errors in the digitized voice signal.
Claim 17
Dependent Claim
80 words
A communication device having a squelch setting and an audio output device, comprising: receiver means for receiving a radio frequency signal to produce a received signal; correlator means for correlating a first segment of the received signal to dynamically produce a threshold based on the squelch setting; means for comparing signal energy in a second segment with the threshold; and means for unmuting the audio output device when the signal energy level in the second segment is below the threshold.
Claim 18
Dependent Claim
80 words
A communication device having a squelch setting and an audio output device, comprising: receiver means for receiving a radio frequency signal to produce a received signal; correlator means for correlating a first segment of the received signal to dynamically produce a threshold based on the squelch setting; means for comparing signal energy in a second segment with the threshold; and means for unmuting the audio output device when the signal energy level in the second segment is below the threshold.
Claim 19
Dependent Claim
17 words
The communication device of claim 14, wherein the means for comparing includes a "square and integrator" circuit.
Claim 20
Dependent Claim
16 words
The communication device of claim 14, wherein the means for comparing includes a digital signal processor.
Claim 21
Dependent Claim
12 words
The communication device of claim 14, wherein the threshold includes a hysterisis.
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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) | 1997-04-11 | 1997-10-11 | 1998-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-04-11 | 2001-10-11 | 2002-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-04-11 | 2005-10-11 | 2006-04-12 | $7700.00 | Window Closed / Lapsed |