US4397034A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low probability of intercept transmitting apparatus
Assignee: Unisys Corp
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Filing: 1981-03-26
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Granted: 1983-08-02
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Expires: 2001-03-26
Abstract
Abstract A system for transmitting desired information is provided which has a very low probability of being intercepted. The system combines a well known narrow bandwidth directional antenna for limiting the interception of the main beam information signal with a novel random noise generated signal which guarantees that the sidelobe signals which also contain the desired information cannot be distinguished as information signals.
Inventors
- 👤 Benjamin V. Cox
- 👤 Billie M. Spencer
- 👤 John W. Zscheile, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:13
CPC Classifications
H; H04; H04K; H04K1/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
125 words
A low probability of intercept transmitting apparatus, comprising: a source of data information, a local oscillator adapted to provide a carrier frequency, a first modulator coupled to said local oscillator and to said data information for providing a main modulated data signal, a directional antenna coupled to said main modulated data signal for transmitting main data signals and producing a desirable main beam signal and undesirable sidelobe signals, a source of random noise signals having the same statistical waveform characteristics as said data information, a second modulator coupled to said local oscillator and to said random noise signals for providing a random modulated masking signal, and an omni-directional antenna colocated with said directional antenna for transmitting said masking signal and for masking said sidelobe signals.
Claim 2
Dependent Claim
125 words
A low probability of intercept transmitting apparatus, comprising: a source of data information, a local oscillator adapted to provide a carrier frequency, a first modulator coupled to said local oscillator and to said data information for providing a main modulated data signal, a directional antenna coupled to said main modulated data signal for transmitting main data signals and producing a desirable main beam signal and undesirable sidelobe signals, a source of random noise signals having the same statistical waveform characteristics as said data information, a second modulator coupled to said local oscillator and to said random noise signals for providing a random modulated masking signal, and an omni-directional antenna colocated with said directional antenna for transmitting said masking signal and for masking said sidelobe signals.
Claim 3
Dependent Claim
78 words
A low probability of intercept transmitting apparatus as set forth in claim 1 which further comprises: a first amplifier coupled between said first modulator and said directional antenna, a second amplifier coupled between said second modulator and said omni-directional antenna, said second amplifier providing an output signal on said omni-directional antenna which is greater than the maximum sidelobe signal, whereby the signal to noise ratio of said sidelobe signal to said masking signal is less than zero decibels.
Claim 4
Dependent Claim
42 words
A low probability of intercept transmitting apparatus as set forth in claim 2 wherein the output from said first amplifier multiplied by the gain of said main beam signal from said directional antenna provides adequate signal strength to accommodate a remote receiver.
Claim 5
Dependent Claim
43 words
A low probability of intercept transmitting apparatus as set forth in claim 2 wherein the output from said second amplifier multiplied by the gain of said omni-directional antenna is less than the main beam signal and greater than the maximum undesirable sidelobe signal.
Claim 6
Dependent Claim
39 words
A low probability of intercept transmitting apparatus as set forth in claim 1 wherein said data source provides coded digital signals and said random signal source provides means for independently generating random signals which emulate said coded digital signals.
Claim 7
Dependent Claim
23 words
A low probability of intercept transmitting apparatus as set forth in claim 1 wherein said omni-directional antenna includes a plurality of omni-directional antennas.
Claim 8
Dependent Claim
34 words
A low probability of intercept transmitting apparatus as set forth in claim 6 wherein said plurality of omni-directional antennas are placed in the near proximity to said directional antenna to serve as decoy sources.
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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) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |