US4910467A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for decoding a quadrature modulated signal
Assignee: Motorola Solutions Inc
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Filing: 1988-11-02
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Granted: 1990-03-20
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Expires: 2008-11-02
Abstract
Abstract A method of demodulating a quadrature modulated signal includes first receiving the signal. The rf signal is then quadrature demodulated to produce in-phase and quadrature signals. One of these signals is filtered to produce a correction signal which is used for phase and amplitude correction. Both of the demodulated signals are again quadrature demodulated to produce the output signals. The second demodulation can be accomplished utilizing a correlation decoder. The applied correlation pulse includes a subcarrier component.
Inventors
- 👤 Clifford D. Leitch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:05
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/38
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
102 words
A method of demodulating a quadrature modulated RF signal having a pilot carrier comprising the steps of: receiving the RF signal; mixing the received signal with a local oscillator signal to produce an inphase signal; mixing the received signal with a quadrature local oscillator signal to produce a quadrature signal; low pass filtering at least on one of said in-phase and quadrature signals to obtain the pilot carrier signal, applying the pilot carrier signal to the in-phase and quadrature signals to provide correction of the signals, and quadrature demodulating both of the corrected in-phase and quadrature signals to provide the output signals.
Claim 2
Independent Claim
102 words
A method of demodulating a quadrature modulated RF signal having a pilot carrier comprising the steps of: receiving the RF signal; mixing the received signal with a local oscillator signal to produce an inphase signal; mixing the received signal with a quadrature local oscillator signal to produce a quadrature signal; low pass filtering at least on one of said in-phase and quadrature signals to obtain the pilot carrier signal, applying the pilot carrier signal to the in-phase and quadrature signals to provide correction of the signals, and quadrature demodulating both of the corrected in-phase and quadrature signals to provide the output signals.
Claim 3
Dependent Claim
46 words
A method of demodulating a quadrature modulated RF signal as defined in claim 1, including the steps of deriving a bit sync signal from the received signal, and applying the bit sync signal to delay the in-phase and quadrature signals prior to demodulation of the signals.
Claim 4
Independent Claim
67 words
A method of demodulating a quadrature modulated RF signal comprising the steps of: receiving the RF signal; mixing the received signal with a local oscillator signal to produce an in-phase baseband signal; mixing the received signal with a quadrature local oscillator signal to produce a quadrature baseband signal; and correlation detecting each of the baseband signals with correlation pulses including a subcarrier component to decode the signals.
Claim 5
Independent Claim
67 words
A method of demodulating a quadrature modulated RF signal comprising the steps of: receiving the RF signal; mixing the received signal with a local oscillator signal to produce an in-phase baseband signal; mixing the received signal with a quadrature local oscillator signal to produce a quadrature baseband signal; and correlation detecting each of the baseband signals with correlation pulses including a subcarrier component to decode the signals.
Claim 6
Dependent Claim
51 words
A method of demodulating a quadrature modulated RF signal as defined in claim 3, including the steps of low pass filtering at least one of said baseband signals to recover a pilot carrier signal, and applying the recovered pilot carrier signal to the baseband signals to provide phase and amplitude correction.
Claim 7
Dependent Claim
46 words
A method of demodulating a quadrature modulated RF signal as defined in claim 4, including the steps of deriving a bit sync signal from the received signal, and applying the bit sync signal to delay the in-phase and quadrature signals prior to applying the correlation pulses.
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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) | 1993-03-19 | 1993-09-18 | 1994-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-19 | 1997-09-18 | 1998-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-19 | 2001-09-18 | 2002-03-20 | $7700.00 | Window Closed / Lapsed |