US4100376A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pilot tone demodulator
Assignee: Raytheon Co
•
Filing: 1977-01-03
•
Granted: 1978-07-11
•
Expires: 1997-01-03
Abstract
Abstract A communication system for inphase and quadrature modulation of low frequency signals wherein the modulated signal frequency bands lie close to a carrier, the system including a pilot tone having a fixed frequency ratio to the carrier, the system further including a demodulator employing the pilot tone in a phase locked loop for synthesizing a coarse replica of the carrier, a filter incorporating inphase and quadrature channels utilizing the coarse carrier for extracting the actual carrier from the modulated signal spectrum and synchronous detection of the signals by means of the extracted carrier.
Inventors
- 👤 Saul L. Woythaler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:46
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/30; H04B1/302
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
176 words
A demodulator of a signal bearing data operative with a pilot tone lying outside the spectrum of said data signal, said demodulator comprising: phase lock means for providing a first signal which is phase locked to said pilot tone, said phase lock means including frequency synthesizing means for generating a carrier reference signal having a frequency proportional to the frequency of said pilot tone; means coupled to said reference signal for filtering said data signal to extract a carrier therefrom, the frequency of said reference signal approximating the frequency of said carrier, said filtering means including means for mixing said data signal with said reference signal to produce a first lower frequency signal, means for filtering said first lower frequency signal and means for mixing said first lower frequency signal with said reference signal to provide a first component of said carrier; and means coupled to said filtering means for providing signals bearing inphase and quadrature relationships to said reference signal, and means coupled to said inphase and quadrature signals for synchronously detecting said data signal.
Claim 2
Dependent Claim
176 words
A demodulator of a signal bearing data operative with a pilot tone lying outside the spectrum of said data signal, said demodulator comprising: phase lock means for providing a first signal which is phase locked to said pilot tone, said phase lock means including frequency synthesizing means for generating a carrier reference signal having a frequency proportional to the frequency of said pilot tone; means coupled to said reference signal for filtering said data signal to extract a carrier therefrom, the frequency of said reference signal approximating the frequency of said carrier, said filtering means including means for mixing said data signal with said reference signal to produce a first lower frequency signal, means for filtering said first lower frequency signal and means for mixing said first lower frequency signal with said reference signal to provide a first component of said carrier; and means coupled to said filtering means for providing signals bearing inphase and quadrature relationships to said reference signal, and means coupled to said inphase and quadrature signals for synchronously detecting said data signal.
Claim 3
Dependent Claim
118 words
A system according to claim 1 wherein said synthesizing means includes means coupled to said reference signal for shifting the phase of said reference signal by 90° to produce a second signal, said filtering means including means coupled to said phase shifting means for mixing said second signal with said data signal to produce a second lower frequency signal, a low pass filter for filtering said second lower frequency signal, means coupled to said low pass filter for mixing said second lower frequency signal with said second signal to produce a second component of said carrier in quadrature with said first component of said carrier, and means for summing together said first and second components of said carrier.
Claim 4
Independent Claim
232 words
A system for communicating a data bearing signal, said system including a pilot tone positioned outside a spectrum of said data signal, said system comprising: a frequency synthesizer for synthesizing a carrier signal and a pilot tone signal which bear a fixed frequency ratio, said synthesizing means including means for selecting a frequency bearing a fixed frequency ratio to the frequency of said carrier, means for selecting said ratio, and means for combining a signal at said frequency with said carrier to produce said pilot tone; means coupled to a source of data and to said carrier for modulating said carrier with inphase and quadrature portions of said data; means for transmitting the sum of said inphase and quadrature modulated components of said carrier with said pilot tone; means for receiving said sum, said receiving means including a phase locked loop producing a signal which is phase locked to said pilot tone and a first reference signal which is at a fixed frequency ratio to said pilot tone, means for multiplying said sum by inphase and quadrature components of said first reference signal to produce inphase and quadrature products of said multiplication, means for filtering said products, means coupled to said filtering means for producing inphase and quadrature carrier reference signals, and means coupled to said produced inphase and quadrature carrier reference signals for synchronously detecting said sum to extract said data.
Claim 5
Independent Claim
232 words
A system for communicating a data bearing signal, said system including a pilot tone positioned outside a spectrum of said data signal, said system comprising: a frequency synthesizer for synthesizing a carrier signal and a pilot tone signal which bear a fixed frequency ratio, said synthesizing means including means for selecting a frequency bearing a fixed frequency ratio to the frequency of said carrier, means for selecting said ratio, and means for combining a signal at said frequency with said carrier to produce said pilot tone; means coupled to a source of data and to said carrier for modulating said carrier with inphase and quadrature portions of said data; means for transmitting the sum of said inphase and quadrature modulated components of said carrier with said pilot tone; means for receiving said sum, said receiving means including a phase locked loop producing a signal which is phase locked to said pilot tone and a first reference signal which is at a fixed frequency ratio to said pilot tone, means for multiplying said sum by inphase and quadrature components of said first reference signal to produce inphase and quadrature products of said multiplication, means for filtering said products, means coupled to said filtering means for producing inphase and quadrature carrier reference signals, and means coupled to said produced inphase and quadrature carrier reference signals for synchronously detecting said sum to extract said data.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |