US3813672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatically controlled digital vhf direction finder
Assignee: Individual
•
Filing: 1972-08-07
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Granted: 1974-05-28
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Expires: 1992-08-07
Abstract
Abstract An automatically controlled digital VHF direction finding apparatus provided with two parallel antennae alternatively connected by a switch to a common receiving channel which produces an output signal to control the generation of a digital signal representing the phase difference between voltages induced in the antennae due to their being separated in space. The time interval is determined between two voltage points of equal value in the voltage generated in one antenna and between a given voltage point of the voltage generated in said one antenna and a voltage point of equal voltage of the voltage generated in the other antenna. A third antenna can be employed to increase the base of operation and for purposes of providing an error correcting signal, a cable of fixed length can be introduced into the circuits to provide a known increase of transit time.
Inventors
- 👤 W Weisser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:12
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/46; G01S3/48
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
177 words
Apparatus for determining the direction of arrival of electromagnetic waves comprising at least two receiving antennas spaced apart at a distance less than half the wave length of the electromagnetic waves, said waves generating voltages of different phases in said antennas, a single receiver channel means, said channel means having an output; an electrically controlled switch coupled between the antennas and said receiver channel means, said switch alternatively coupling the antennas to the receiver channel means; means to determine sequential phase reference points on the voltage generated in said receiver channel means; control means for the switch connected to the output of the receiver channel means and operating the switch to change over between said antennas immediately after each second determined phase reference point of the voltage generated in the receiver channel means; and an electronic digital time measuring means, the output of the receiver channel means being further connected to said electronic digital time measuring means to measure the time interval between each two reference phase points in the output voltage of the receiver channel means.
Claim 2
Dependent Claim
177 words
Apparatus for determining the direction of arrival of electromagnetic waves comprising at least two receiving antennas spaced apart at a distance less than half the wave length of the electromagnetic waves, said waves generating voltages of different phases in said antennas, a single receiver channel means, said channel means having an output; an electrically controlled switch coupled between the antennas and said receiver channel means, said switch alternatively coupling the antennas to the receiver channel means; means to determine sequential phase reference points on the voltage generated in said receiver channel means; control means for the switch connected to the output of the receiver channel means and operating the switch to change over between said antennas immediately after each second determined phase reference point of the voltage generated in the receiver channel means; and an electronic digital time measuring means, the output of the receiver channel means being further connected to said electronic digital time measuring means to measure the time interval between each two reference phase points in the output voltage of the receiver channel means.
Claim 3
Dependent Claim
21 words
Apparatus as claimed in claim 1 comprising means for extending the measured time interval to reduce interference resulting from transient phenomena.
Claim 4
Dependent Claim
33 words
Apparatus as claimed in claim 1 comprising a third antenna for rotating electrically the base of the measuring means in order to extend the single-valued working range to an azimuth angle of 360*.
References Cited (Backward Citations)
US2284475A
Cited
US3663956A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |