SYSTEM AND PROCESS FOR LOCATING SOURCES OF RADIATION

• US 3,864,681 A
• Filed: 02/28/1973
• Issued: 02/04/1975
• Est. Priority Date: 02/28/1973
• Status: Expired due to Term

• Current Assignee: George A. Olive
• Original Assignee: George A. Olive
• Inventors: Olive, George A.
• Primary Examiner(s): Farley, Richard A.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/336,409
• Time in Patent Office: 706 Days
• Field of Search: 343/112R,112TC,112C 235/150.27
• US Class Current: 342/457
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders

Abstract

A vehicle location system is provided for determining the coordinate location of a vehicle through radio transmission radiation from the vehicle and the system includes a plurality of receiver sites at known coordinate locations each having antennacoupler means providing first and second signals whose phase difference is approximately linearly related to the azimuth angle of the receiver signal from the radiation source. The first and second signals are processed at each receiver site to translate the frequency of the signals to a lower frequency and to remove the common frequency variations therefrom. Thereafter, the signals are passed through a phase detector which provides a binary output expression which is linearly related to the phase difference between the first and second signals. The binary expressions from each of the respective receiver sites are then processed through an electronic data processing means which is programmed to determine the coordinates of the radiation source from the plurality of the binary expressions.

Claims

1. A vehicle location system for determining the coordinate location of a vehicle through radio transmission radiation from the vehicle comprising:

a plurality of receiver sites at known coordinate locations each having antenna-coupler means providing means prOviding first and second signals whose phase difference is approximately linearly related to the azimuth angle of the received signal from the radiation source;

phase detector means for each receiver site responsive to the first and second signals to provide a binary expression linearly related to the phase difference between the first and second signals; and

electronic data processing means programed to determine the coordinates of the radiation source from the plurality of binary expressions.

2. The vehicle location system of claim 1 further including signal processing means for each receiver site for translating the signal frequency of the first and second signals to a lower frequency and removing the common frequency variations therefrom prior to passage of such signals to the phase detector.

3. The vehicle location system of claim 2 wherein the signal processing means includes a first mixing device having the first signal as its first input;

signal generating means providing a signal as the first output of the signal processing means and the second input to the first mixing device; and

a second mixing device having its first input the difference output from the first mixer and its second input the second signal to provide a second difference output from the signal processing device in which the frequency variations are removed and which differs from the first output only by the initial phase difference, the first and second outputs being the inputs to the phase detector.

4. The vehicle location system of claim 1 wherein the phase detector means includes first gate generating means having the first and second signals as its input and providing a first gating signal of duration indication of the phase difference of the first and second signals;

and first counter means responsive to the presence of first gating signal to provide a numeric count linearly related to the phase difference between the first and second input signals.

5. The vehicle location system of claim 4 wherein the phase detector further includes delay means delaying the second signal a predetermined phase shift;

a third gate generating means having the first signal and second delayed input signal as its inputs and providing a third gating signal of duration indicative of the phase difference of the first and second delayed input signals;

second counter means responsive to the presence of the third gate signal to provide a numeric count linearly related to the phase difference between the first and second delayed signals;

means for detecting when the first and second signals are at or approaching a coincidence condition and providing a fourth gating signal upon the occurrence of a coincidence condition; and

counter gate means responsive to the presence or absence of the fourth gating signal to select the count in either the first or second counter means as the binary expression to be applied to the data processing means depending upon the occurrence of a coincidence condition.

6. The vehicle location system of claim 1 wherein the electronic data processing means includes data storage means for receiving and storing the binary expressions for recall;

and electronic digital signal processing means programed to sequentially (1) recall from the data storage the binary expressions from predetermined chosen receiver sites;

(2) calculate an approximate coordinate location for the radiation source;

(3) choose the best receiver sites for coordinate determination based upon the established approximate coordinate location;

(4) recall from data storage the binary expressions for the chosen receiver sites; and

(5) determine an accurate location of the radiation source from the binary expressions from the chosen receiver sites.

7. The vehicle location receiving system of claim 6 further including at least one remote fixed radiation source whose coordinates are known and wherein the signal processing means is (6) preprogramed With a known binary expression representing a known azimuth angle for each receiver site in respect to the fixed radiation source and is further programed to (7) periodically initiate signal radiation from the fixed radiation source (8) recall the resultant binary expressions from data storage and compare the preprogramed binary expression for each receiver site and (9) to automatically reprogram to calculate the correct azimuth angle for any receiver site binary expression differing from the preprogramed binary expression for that site.

8. The vehicle location system of claim 1 further including means at each receiver site to store the binary expressions;

means at predetermined receiver sites to notify the data storage means that binary expressions have been determined; and

interrogator means within the data storage means to sequentially interrogate each receiver site to transmit the binary expression to the data storage means.

9. The process of determining the coordination location of a vehicle through radio transmission radiation from the vehicle comprising the steps of:

receiving the transmission radiation at a plurality of sites of known coordinate locations by means of antenna-coupler means generating first and second signals whose phase difference is approximately linearly related to the azimuth angle of the received signal from the radiation source;

processing the first and second signals to translate the frequency thereof to a lower frequency and to remove the common frequency variations therefrom;

utilizing the phase difference between the first and second signals to provide a gating signal to control a binary counter to provide a binary count linearly related to the phase difference between the first and second signals; and

processing the binary counts from the receivers of the plurality of sites in a digital computer programed to determine the coordinates of the radiation source based upon the known coordinate locations of the respective receiver sites.

10. A system for determining the coordinate location of an unknown radiation source from a plurality of binary expressions each derived from the received radiation at a given receiver site of a plurality of receiver sites and each linearly related to the azimuth angle of the radiation source from the given receiver site whose coordinates are known comprising:

data storage means for receiving and storing the binary expressions for recall; and

electronic digital signal processing means programed to sequentially (1) recall from the data storage means the binary expressions from predetermined chosen receiver sites;

(2) calculate an approximate coordinate location of the radiation source;

(3) choose the best receiver sites for coordinate determination based upon the established approximate coordinate location;

(4) recalling from data storage the binary expressions from the chosen receiver sites; and

(5) determining the accurate location of the radiation source from the binary expressions from the chosen receiver sites.

11. The system of claim 10 further including at least one remote radiation source whose coordinates are known and wherein the signal processing means is (6) preprogramed with a known binary expression representing a known azimuth angle in respect to the fixed radiation source and is further programed to periodically (7) initiate signal radiation from the fixed radiation source (8) recall the resultant binary expressions from data storage and compare the preprogramed binary expression for each receiver site and (9) to automatically reprogram to calculate the correct azimuth angle for any receiver site binary expression differing from the preprogramed binary expression for that site.

12. The system of claim 10 further including means at each receiver site to store the binary expressions;

means at predetermined receiver sites to notify the data storage means that binary Expressions have been determined; and

interrogator means within the data storage means to sequentially interrogate each receiver site to transmit the binary expression to the data storage means.

13. A method for determining the coordinate location of an unknown radiation source from a plurality of binary expressions each derived from the received radiation at a given receiver site of a plurality of receiver sites and each linearly related to the azimuth angle of the radiation source from the given receiver site whose coordinates are known comprising the steps of:

receiving and storing the binary expressions from each receiver site in a data storage means; and

programing an electronic digital signal processing means to (1) recall the binary expressions from data storage from predetermined chosen receiver sites;

(2) calculating an approximate coordinate location of the radiation source;

(3) chosing the best receiver sites for coordinate determination based upon the established approximate coordinate location;

(4) recalling from data storage the binary expressions for the chosen receiver sites; and

(5) calculating an accurate location of the radiation source from the binary expressions from the chosen receiver sites.