Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Patent
1987-12-15
1989-12-19
Blum, Theodore M.
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
342375, 342382, G01S 124
Patent
active
048885932
ABSTRACT:
A direction finding method and apparatus for a radio signal source, modulated by a digital information signal and existing in a heavy interference environment, is based on cyclic crosscorrelation. The direction finding technique exploits the second order periodicity of a transmitted signal having digital modulation, whereby the technique is immune to narrow-band interference. Radio frequency signals are received by two spaced antennas, and the signal of interest can be considered as a cyclostationary process. The signal time of arrival difference between the two antennas is determined using a cyclic crosscorrelation method. This is implemented by sending the electrical signals, developed by the antennas, through a variable delay device, then to a balanced mixer. The composite signal from the mixer is sent to a band-pass filter whose center frequency is equal to the baud rate of the signal of interest. The output energy of the filter is proportional to that portion of the cyclic crosscorrelation function where the cyclic frequency corresponds to the baud rate. With the use of a peak detector, which finds the peak values of the cyclic crosscorrelation function, the time difference of arrival between the two antennas is determined. This, in turn, determines a line of position to the radio source.
REFERENCES:
patent: 3196439 (1965-07-01), Byatt
patent: 3870998 (1975-03-01), Dewey et al.
patent: 4000466 (1976-12-01), Scouten et al.
patent: 4198634 (1980-04-01), Jernigan et al.
patent: 4204655 (1980-05-01), Gulick et al.
patent: 4486757 (1984-12-01), Ghose et al.
patent: 4638321 (1987-01-01), Drogin
Boyles et al., "Cycloergodic Properties of Discrete-Parameter Nonstationary Stochastic Processes", IEEE Transactions on Information Theory, vol. IT-29, No. 1, Jan. 1983, pp. 105-114.
Friedman Joseph S.
King John P.
Pride, III Joseph P.
Blum Theodore M.
Signal Science, Inc.
LandOfFree
Time difference of arrival geolocation method, etc. does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Time difference of arrival geolocation method, etc., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Time difference of arrival geolocation method, etc. will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1905293