US4878035A
Expired / Lapsed
US
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Hybrid frequency shift keying modulator and method
Assignee: Wavetek RF Products Inc
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Filing: 1988-05-27
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Granted: 1989-10-31
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Expires: 2008-05-27
Abstract
Abstract A hybrid frequency shift keying modulator and method produces binary FSK by simultaneously applying a digital modulating signal to the DDS section of a frequency synthesizer along with a coordinated analog modulating signal as direct frequency modulation of the accompanying PLL section. Low frequency performance is derived from the characteristics of the DDS modulation and the high frequency performance and accurate wave shape reproduction are derived from the modulation of the direct FM section.
Inventors
- 👤 John A. Vendely
- 👤 David M. Badger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:07
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10; H04L27/12
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
72 words
A frequency synthesizer including phase-locked loop and direct digital synthesis sections for generation of a synthesized RF output signal corresponding to a digitally coded input signal wherein the improvement comprises an FSK modulator comprising: means for modulating said phase-locked loop section in accordance with said input signal; means for deriving an FSK offset signal from said input signal; and means for applying said FSK offset signal to said direct digital synthesis section.
Claim 2
Dependent Claim
72 words
A frequency synthesizer including phase-locked loop and direct digital synthesis sections for generation of a synthesized RF output signal corresponding to a digitally coded input signal wherein the improvement comprises an FSK modulator comprising: means for modulating said phase-locked loop section in accordance with said input signal; means for deriving an FSK offset signal from said input signal; and means for applying said FSK offset signal to said direct digital synthesis section.
Claim 3
Dependent Claim
14 words
The frequency synthesizer of claim 1 wherein said modulating means comprises a summing circuit.
Claim 4
Dependent Claim
16 words
The frequency synthesizer of claim 2 wherein said modulating means further comprises an analog deviation register.
Claim 5
Dependent Claim
26 words
The frequency synthesizer of claim 3 wherein said modulating means further comprises a digital to analog converter receiving digital control signals from said analog deviation register.
Claim 6
Dependent Claim
15 words
The frequency synthesizer of claim 1 wherein said deriving means comprises a mode control circuit.
Claim 7
Dependent Claim
16 words
The frequency synthesizer of claim 1 wherein said deriving means comprises mark/space and center frequency registers.
Claim 8
Dependent Claim
14 words
The frequency synthesizer of claim 6 further comprising a return to center control circuit.
Claim 9
Dependent Claim
16 words
The frequency synthesizer of claim 5 further comprising an adder-subtractor responsive to said mode control circuit.
Claim 10
Dependent Claim
19 words
The frequency synthesizer of claim 8 further comprising a digital deviation register supplying digital control signals to said adder-subtractor.
Claim 11
Dependent Claim
22 words
The frequency synthesizer of claim 1 wherein said applying means comprises a latch circuit coupled to the output of said deriving means.
Claim 12
Dependent Claim
21 words
The frequency synthesizer of claim 10 further comprising a keying synchronizer circuit for supplying a clocking signal to said latch circuit.
Claim 13
Dependent Claim
21 words
The frequency synthesizer of claim 8 further comprising a center frequency register for supplying digital control signals to said adder-subtractor circuit.
Claim 14
Dependent Claim
31 words
The frequency synthesizer of claim 12 further comprising a return to center control circuit responsive to said mode control circuit for supplying a return to center signal to said adder-subtractor circuit.
Claim 15
Independent Claim
58 words
A method for generation of a synthesized RF output signal corresponding to a digitally coded input signal comprising the steps of: deriving analog and digital modulating signals from said input signal; modulating a PLL section of a signal generator with said analog modulating signal; and applying said digital modulating signal to a DDS section of said signal generator.
Claim 16
Independent Claim
58 words
A method for generation of a synthesized RF output signal corresponding to a digitally coded input signal comprising the steps of: deriving analog and digital modulating signals from said input signal; modulating a PLL section of a signal generator with said analog modulating signal; and applying said digital modulating signal to a DDS section of said signal generator.
Claim 17
Dependent Claim
20 words
The method of claim 14 wherein said step of deriving is carried by means of analog and digital deviation circuits.
Claim 18
Dependent Claim
28 words
The method of claim 14 wherein said step of modulating is carried out by inputting said analog modulating signal to a frequency modulation circuit in said PLL section.
Claim 19
Dependent Claim
27 words
The method of claim 14 wherein said step of applying is carried out by providing said digital modulating signal as parallel program data to said DDS section.
Claim 20
Dependent Claim
92 words
An FSK modulator for use in combination with a frequency synthesizer having PLL and DDS sections comprising: means for deriving analog and digital modulating signals from a digitally coded input signal; means for modulating said PLL section in accordance with said analog modulating signal; and means for applying said digital modulating signal to said DDS section; whereby high frequency response and wave shape reproduction of said input signal are maintained by modulation of said PLL section of said frequency synthesizer and low frequency response is maintained by modulation of said DDS section.
Claim 21
Dependent Claim
92 words
An FSK modulator for use in combination with a frequency synthesizer having PLL and DDS sections comprising: means for deriving analog and digital modulating signals from a digitally coded input signal; means for modulating said PLL section in accordance with said analog modulating signal; and means for applying said digital modulating signal to said DDS section; whereby high frequency response and wave shape reproduction of said input signal are maintained by modulation of said PLL section of said frequency synthesizer and low frequency response is maintained by modulation of said DDS section.
Claim 22
Dependent Claim
16 words
The FSK modulator of claim 18 wherein said deriving means comprises analog and digital deviation circuits.
Claim 23
Dependent Claim
20 words
The FSK modulator of claim 19 further comprising a return to center frequency circuit associated with said digital deviation circuit.
Claim 24
Dependent Claim
25 words
The FSK modulator of claim 18 wherein said modulating means comprises a frequency modulation circuit in said PLL section responsive to said analog modulating signal.
Claim 25
Dependent Claim
26 words
The FSK modulator of claim 18 wherein said applying means comprises a digital program data bus for providing said digital modulating signal to said DDS section.
Claim 26
Dependent Claim
14 words
The FSK modulator of claim 18 wherein said modulating means comprises a summing circuit.
Claim 27
Dependent Claim
16 words
The FSK modulator of claim 23 wherein said modulating means further comprises an analog deviation register.
Claim 28
Dependent Claim
26 words
The FSK modulator of claim 24 wherein said modulating means further comprises a digital to analog converter receiving digital control signals from said analog deviation register.
Claim 29
Dependent Claim
15 words
The FSK modulator of claim 24 wherein said deriving means comprises a mode control circuit.
Claim 30
Dependent Claim
16 words
The FSK modulator of claim 18 wherein said deriving means comprises mark/space and center frequency registers.
Claim 31
Dependent Claim
14 words
The FSK modulator of claim 27 further comprising a return to center control circuit.
Claim 32
Dependent Claim
16 words
The FSK modulator of claim 26 further comprising an adder-subtractor responsive to said mode control circuit.
Claim 33
Dependent Claim
19 words
The FSK modulator of claim 29 further comprising a digital deviation register supplying digital control signals to said adder-subtractor.
Claim 34
Dependent Claim
22 words
The FSK modulator of claim 18 wherein said applying means comprises a latch circuit coupled to the output of said deriving means.
Claim 35
Dependent Claim
21 words
The FSK modulator of claim 31 further comprising a keying synchronizer circuit for supplying a clocking signal to said latch circuit.
Claim 36
Dependent Claim
21 words
The FSK modulator of claim 29 further comprising a center frequency register for supplying digital control signals to said adder-subtractor circuit.
Claim 37
Dependent Claim
31 words
The FSK modulator of claim 33 further comprising a return to center control circuit responsive to said mode control circuit for supplying a return to center signal to said adder-subtractor circuit.
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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) | 1992-10-30 | 1993-05-01 | 1993-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-30 | 1997-05-01 | 1997-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-30 | 2001-05-01 | 2001-10-31 | $7700.00 | Window Closed / Lapsed |