US3761825A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multipath simulator for modulated r.f. carrier signals
Assignee: United States Department of the Navy
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Filing: 1972-06-14
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Granted: 1973-09-25
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Expires: 1992-06-14
Abstract
Abstract A multipath simulator which delays a baseband signal and then translates this delay to the modulated RF signal. This is done by producing a difference signal which is the difference between the delayed and undelayed baseband signals. The undelayed baseband signal first modulates the RF carrier directly. This modulated RF carrier is then divided into two branches. The difference signal is then used to modify the modulation on one of these branches to make it appear as if it had been modulated by the delayed baseband signal. The linear sum of these two RF signals is a signal which simulates the effects of multipath on modulated RF carrier signals.
Inventors
- 👤 E Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:42
CPC Classifications
H; H04; H04B; H04B17/00; H04B17/0082; H04B17/0087
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
99 words
A circuit for simulating the effects of multipath as baseband frequencies comprising: means for filtering the baseband signal prior to modulation; means for generating a carrier signal; means for modulating the carrier signal with the output of said filtering means; means for splitting the output of the modulating means into a direct path signal and at least one indirect path signal; means for modifying the modulation on the indirect path signal to produce a delayed replica of the direct path signal; and means for summing the direct path signal and the indirect path signal to produce the multipath signal.
Claim 2
Dependent Claim
99 words
A circuit for simulating the effects of multipath as baseband frequencies comprising: means for filtering the baseband signal prior to modulation; means for generating a carrier signal; means for modulating the carrier signal with the output of said filtering means; means for splitting the output of the modulating means into a direct path signal and at least one indirect path signal; means for modifying the modulation on the indirect path signal to produce a delayed replica of the direct path signal; and means for summing the direct path signal and the indirect path signal to produce the multipath signal.
Claim 3
Dependent Claim
75 words
The circuit of claim 1 wherein said means for modifying the modulation on the indirect path signal comprises: a linear modulator inserted in the indirect signal path; means connected to the filtering means for splitting the baseband signal into first and second originals; means for delaying the second signal; means for producing a difference signal by subtracting the delayed signal from said first signal; and means for applying said difference signal to said linear modulator.
Claim 4
Dependent Claim
14 words
The circuit of claim 2 wherein said linear modulator is a linear phase modulator.
Claim 5
Dependent Claim
15 words
The circuit of claim 3 wherein said carrier signal generating means is a PM generator.
Claim 6
Dependent Claim
31 words
The circuit of claim 3 wherein said carrier signal generating means is a FM generator; and said means for applying said difference signal to said linear phase modulator is an integrator.
Claim 7
Dependent Claim
25 words
The circuit of claim 2 wherein: said linear modulating means is a linear AM modulator; and said carrier signal generating means is an AM generator.
Claim 8
Dependent Claim
73 words
The circuit of claim 1 including: means for splitting the output of the modulating means into a plurality of indirect path signals; a plurality of means for modifying the modulation on each indirect path signal to produce different delayEd replica of the direct path signal from each indirect path signal; and said summing means includes means for summing the plurality of indirect signals with the direct path signal to produce a multipath signal.
Claim 9
Dependent Claim
42 words
The circuit of claim 2 wherein: said second signal is derived from the input to said filtering means; said delaying means is a digital delay; second filtering means are inserted between said digital delay; and said means for producing a difference signal.
Claim 10
Dependent Claim
98 words
The circuit of claim 1 further comprising: a first frequency mixing means inserted into the direct path signal; a fixed frequency oscillator connected to the first frequency mixer; said means for modulating the indirect path signal comprises; a second frequency mixing means inserted into the indirect path signal; means connected to the filtering means for splitting the base-band signal into first and second signals; means for delaying the second signal; means for producing a difference signal by subtracting the delayed signal from the first signal; and means for applying the difference signal to said second frequency mixing means.
Claim 11
Dependent Claim
33 words
The circuit of claim 9 wherein said carrier signal generating means is a FM generator; and said means for applying the difference signal to said second frequency mixer is a voltage controlled oscillator.
Claim 12
Dependent Claim
36 words
The circuit of claim 9 wherein said carrier signal generating means is a PM generator; and said means for applying the difference signal to said second frequency multiplier comprises a differentiator and a voltage controlled oscillator.
Claim 13
Dependent Claim
40 words
The circuit of claim 9 including: a voltage controlled oscillator as the means for applying the difference signal to the second frequency multiplier; and means for phase locking the voltage controlled oscillator to the frequency of the fixed frequency oscillator.
Claim 14
Dependent Claim
69 words
The circuit of claim 12 wherein said phase locking means comprises: a frequency mixer connected to the outputs of the voltage controlled oscillator and the fixed frequency oscillator; a pair of frequency dividers are provided between the outputs of the voltage controlled oscillator and fixed frequency oscillator respectively; and a loop filter is connected between the output of the frequency mixer and an input of the voltage controlled oscillator.
Claim 15
Dependent Claim
14 words
The circuit of claim 13 including means for inserting a differential doppler simulating signal.
Claim 16
Dependent Claim
23 words
The circuit of claim 14 wherein said differential doppler simulating means is inserted between the fixed frequency oscillator and said first frequency mixer.
Claim 17
Dependent Claim
12 words
The circuit of claim 13 including means for simulating polarization diversity signals.
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) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |