Patent US4922549A successfully refreshed from Google Patents.
US4922549A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital FM squelch detector
Assignee: Motorola Solutions Inc
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Filing: 1988-10-27
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Granted: 1990-05-01
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Expires: 2008-10-27
Abstract
Abstract A method is disclosed for determining when a frequency-modulated expected information signal resides at a predetermined channel. The method is based on determining a value based on the frequency deviation of the received signal, and then comparing the value with a threshold based on the expected information signal. The method is particularly well-suited for use as a squelch detector in digital FM radios.
Inventors
- 👤 Mark J. Johnson
- 👤 Francis R. Yester, Jr.
- 👤 Steven C. Jasper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:48
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/344; H04B1/16
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
123 words
A method of determining when a frequency-modulated expected information signal resides at a predetermined channel comprising the steps of: (a) providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; (b) determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and (c) comparing said value with a threshold based at least in part on a characteristic of said expected information signal. wherein said received IF signal includes quadrature components and said step of determining a value for said received IF signal includes determining the number of times at least one quadrature component of said received IF signal at least substantially equals a first predetermined number.
Claim 2
Independent Claim
123 words
A method of determining when a frequency-modulated expected information signal resides at a predetermined channel comprising the steps of: (a) providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; (b) determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and (c) comparing said value with a threshold based at least in part on a characteristic of said expected information signal. wherein said received IF signal includes quadrature components and said step of determining a value for said received IF signal includes determining the number of times at least one quadrature component of said received IF signal at least substantially equals a first predetermined number.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said first predetermined number equals zero.
Claim 4
Dependent Claim
17 words
The method of claim 2 including the step of squelching a radio responsive to said comparing step.
Claim 5
Dependent Claim
19 words
The method of claim 3 wherein said received IF signal is in the form of a digital bit stream.
Claim 6
Independent Claim
144 words
A method of determining when a frequency-modulated expected information signal resides at a predetermined channel, comprising the steps of: (a) providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; (b) determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and (c) comparing said value with a threshold based at least in part on a characteristic of said expected information signal. wherein said received IF signal includes quadrature components and said step of determining a value for said received IF signal includes determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and the number of times a second quadrature component of said received IF signal at least substantially equals a second predetermined number.
Claim 7
Independent Claim
144 words
A method of determining when a frequency-modulated expected information signal resides at a predetermined channel, comprising the steps of: (a) providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; (b) determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and (c) comparing said value with a threshold based at least in part on a characteristic of said expected information signal. wherein said received IF signal includes quadrature components and said step of determining a value for said received IF signal includes determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and the number of times a second quadrature component of said received IF signal at least substantially equals a second predetermined number.
Claim 8
Dependent Claim
17 words
The method of claim 5 wherein said first predetermined number and said second predetermined number equal zero.
Claim 9
Dependent Claim
17 words
The method of claim 6 including the step of squelching a radio responsive to said comparing step.
Claim 10
Dependent Claim
19 words
The method of claim 7 wherein said received IF signal is in the form of a digital bit stream.
Claim 11
Independent Claim
145 words
A method of determining when a frequency-modulated expected information signal resides at a predetermined channel, comprising the steps of: (a) providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; (b) determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and (c) comparing said value with a threshold based at least in part on a characteristic of said expected information signal, wherein said received IF signal includes quadrature components and said step of determining a value for said received IF signal includes determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and a second quadrature component of said received IF signal at least substantially equals a second predetermined number at substantially the same time.
Claim 12
Independent Claim
145 words
A method of determining when a frequency-modulated expected information signal resides at a predetermined channel, comprising the steps of: (a) providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; (b) determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and (c) comparing said value with a threshold based at least in part on a characteristic of said expected information signal, wherein said received IF signal includes quadrature components and said step of determining a value for said received IF signal includes determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and a second quadrature component of said received IF signal at least substantially equals a second predetermined number at substantially the same time.
Claim 13
Dependent Claim
17 words
The method of claim 9 wherein said first predetermined number and said second predetermined number equal zero.
Claim 14
Dependent Claim
17 words
The method of claim 10 including the step of squelching a radio responsive to said comparing step.
Claim 15
Dependent Claim
19 words
The method of claim 11 wherein said received IF signal is in the form of a digital bit stream.
Claim 16
Dependent Claim
146 words
A radio having signal determining means for determining when a frequency-modulated expected information signal resides at a predetermined channel, said signal determining means comprising: receiving means for providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; value determining means responsive to said receiving means for determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and comparing means responsive to said value determining means for comparing said value with a threshold based at least in part on a characteristic of said expected information signal, wherein said received IF signal includes quadrature components and said value determining means includes means responsive to said receiving means for determining the number of times at least one quadrature component of said received IF signal at least substantially equals a first predetermined number.
Claim 17
Dependent Claim
146 words
A radio having signal determining means for determining when a frequency-modulated expected information signal resides at a predetermined channel, said signal determining means comprising: receiving means for providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; value determining means responsive to said receiving means for determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and comparing means responsive to said value determining means for comparing said value with a threshold based at least in part on a characteristic of said expected information signal, wherein said received IF signal includes quadrature components and said value determining means includes means responsive to said receiving means for determining the number of times at least one quadrature component of said received IF signal at least substantially equals a first predetermined number.
Claim 18
Dependent Claim
12 words
The radio of claim 13 wherein said first predetermined number equals zero.
Claim 19
Dependent Claim
17 words
The radio of claim 14 including squelching means responsive to said comparing means for squelching said radio.
Claim 20
Dependent Claim
19 words
The radio of claim 15 wherein said received IF signal is in the form of a digital bit stream.
Claim 21
Dependent Claim
167 words
A radio having signal determining means for determining when a frequency-modulated expected information signal resides at a predetermined channel, said signal determining means comprising: receiving means for providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; value determining means responsive to said receiving means for determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and comparing means responsive to said value determining means for comparing said value with a threshold based at least in part on a characteristic of said expected information signal, wherein said received IF signal includes quadrature components and said value determining means includes means responsive to said receiving means for determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and the number of times a second quadrature component of said received IF signal at least substantially equals a second predetermined number.
Claim 22
Dependent Claim
167 words
A radio having signal determining means for determining when a frequency-modulated expected information signal resides at a predetermined channel, said signal determining means comprising: receiving means for providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; value determining means responsive to said receiving means for determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and comparing means responsive to said value determining means for comparing said value with a threshold based at least in part on a characteristic of said expected information signal, wherein said received IF signal includes quadrature components and said value determining means includes means responsive to said receiving means for determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and the number of times a second quadrature component of said received IF signal at least substantially equals a second predetermined number.
Claim 23
Dependent Claim
17 words
The radio of claim 17 wherein said first predetermined number and said second predetermined number equal zero.
Claim 24
Dependent Claim
17 words
The radio of claim 18 including squelching means responsive to said comparing means for squelching said radio.
Claim 25
Dependent Claim
19 words
The radio of claim 19 wherein said received IF signal is in the form of a digital bit stream.
Claim 26
Dependent Claim
168 words
A radio having signal determining means for determining when a frequency-modulated expected information signal resides at a predetermined channel, said signal determining means comprising: receiving means for providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; value determining means responsive to said receiving means for determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and comparing means responsive to said value determining means for comparing said value with a threshold based at least in part on a characteristic of said expected information signal. wherein said received IF signal includes quadrature components and said value determining means includes means responsive to said receiving means for determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and a second quadrature component of said received IF signal at least substantially equals a second predetermined number at substantially the same time.
Claim 27
Dependent Claim
168 words
A radio having signal determining means for determining when a frequency-modulated expected information signal resides at a predetermined channel, said signal determining means comprising: receiving means for providing a received IF signal from said predetermined channel, said received IF signal being frequency-modulated; value determining means responsive to said receiving means for determining a value for said received IF signal based at least in part on the frequency deviation of said received IF signal; and comparing means responsive to said value determining means for comparing said value with a threshold based at least in part on a characteristic of said expected information signal. wherein said received IF signal includes quadrature components and said value determining means includes means responsive to said receiving means for determining the number of times a first quadrature component of said received IF signal at least substantially equals a first predetermined number and a second quadrature component of said received IF signal at least substantially equals a second predetermined number at substantially the same time.
Claim 28
Dependent Claim
17 words
The radio of claim 21 wherein said first predetermined number and said second predetermined number equal zero.
Claim 29
Dependent Claim
17 words
The radio of claim 22 including squelching means responsive to said comparing means for squelching said radio.
Claim 30
Dependent Claim
19 words
The radio of claim 23 wherein said received IF signal is in the form of a digital bit stream.
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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) | 1993-04-30 | 1993-10-30 | 1994-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-30 | 1997-10-30 | 1998-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-30 | 2001-10-30 | 2002-05-01 | $7700.00 | Window Closed / Lapsed |