US4410890A
Expired / Lapsed
US
⏱️ 0.0 years remaining
VHF Directional receiver
Assignee: Federal Communications Commission
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Filing: 1981-05-06
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Granted: 1983-10-18
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Expires: 2001-05-06
Abstract
Abstract A miniature handheld receiver contained in a metal shielding enclosure incorporating a slot type directional antenna as a part of the structure such that when the antenna is aligned with a radio frequency signal of interest, a null is produced in the signal level. The antenna is coupled to receiver circuitry which includes an oscillator used to FM modulate the signal by tone injection when an unmodulated carrier is present, an FM detector for demodulating the RF signal, an audio amplifier for amplifying the demodulated audio and an acoustically coupled earphone to prevent stray RF pickup from the earphone cord.
Inventors
- 👤 Stevan A. Davis
- 👤 Arthur Luedtke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:13
CPC Classifications
H; H01; H01Q; H01Q13/00; H01Q13/10; G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/38; G01S3/40
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
85 words
A small handheld directional receiver particularly suited for use by operators in public areas for covert location of radiation sources at VHF frequencies consisting of: an integral directional nonresonant slot antenna with very short effective height connected to FM receiving circuitry completely shielded by a metal housing, said receiving circuitry having a selectable modulation means for adding FM Modulation to unmodulated received signals, with audio output being proportional to the strength of a received signal and coupled to said operator's ear through a non-metallic means.
Claim 2
Dependent Claim
85 words
A small handheld directional receiver particularly suited for use by operators in public areas for covert location of radiation sources at VHF frequencies consisting of: an integral directional nonresonant slot antenna with very short effective height connected to FM receiving circuitry completely shielded by a metal housing, said receiving circuitry having a selectable modulation means for adding FM Modulation to unmodulated received signals, with audio output being proportional to the strength of a received signal and coupled to said operator's ear through a non-metallic means.
Claim 3
Dependent Claim
43 words
The directional receiver of claim 1 wherein said modulation means consists of an audio oscillator coupled to local oscillator of said receiver in such a manner as to cause a small symmetrical shift in the local oscillator frequency at an audio frequency rate.
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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) | 1986-10-17 | 1987-04-18 | 1987-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-17 | 1991-04-18 | 1991-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-17 | 1995-04-18 | 1995-10-18 | $7700.00 | Window Closed / Lapsed |