US 5,815,117 A · Digital direction finding receiver

Abstract

The invention is embodied in a digital direction finding receiver having N frequency channels spanning a frequency band of the receiver and capable of receiving signals simultaneously from a plurality of antennas spaced from one another, one of the antennas including a reference location antenna. The receiver of the invention includes a plurality of analog-to-digital converters having their analog inputs connected to respective ones of the antennas, a reference source capable of outputting a reference digital signal containing at least a local frequency component within a selected one of the N frequency channels, a plurality of digital down converter modules, each one of the digital down converter modules having a reference input connected to the reference source and a signal input connected to the digital output of a respective one of the analog-to-digital converters, each the digital down converter modules including a multiplier for producing at an output of the digital down converter a product of the reference signal and the signal from the respective one of the antennas, and a digital phase detector having plural phase detector signal inputs connected to the outputs of remaining ones of the digital down converters, the phase detector detecting phase angles of signals on each of the phase detector signal inputs relative to a corresponding signal received at the reference antenna.

Claims19

Dependent claims

A digital direction finding receiver having N frequency channels spanning a frequency band of said receiver, said receiver capable of receiving signals simultaneously from a plurality of antennas spaced from one another, one of said antennas comprising a reference location antenna, said receiver comprising:

a plurality of analog-to-digital converters having their analog inputs connected to respective ones of said antennas;
a reference source capable of outputting a reference digital signal containing at least a local frequency component within a selected one of said N frequency channels;
a plurality of digital down converter modules, each one of said digital down converter modules having a reference input connected to said reference source and a signal input connected to the digital output of a respective one of said analog-to-digital converters, each said digital down converter modules comprising a multiplier for producing at an output of said digital down converter a product of said reference signal and the signal from the respective one of said antennas;
and
a digital phase detector having plural phase detector signal inputs connected to the outputs of remaining ones of said digital down converters, said phase detector detecting phase angles of signals on each of said phase detector signal inputs relative to a corresponding signal received at said reference antenna.

2 more elements

A parameter encoder system including a direction finding receiver capable of receiving signals simultaneously from a plurality of antennas spaced from one another including a reference location antenna, for identifying selected parameters including angle of arrival of a digitally sampled incoming signal lying within a receiver bandwidth, wherein said receiver bandwidth is divided into plural contiguous frequency channels, each channel having a channel bandwidth, whereby said incoming signal is divided into plural channelized signals lying in respective ones of said plural frequency channels, said parameter encoder comprises plural channel processors connected to receive respective ones of said channelized signals, each of said channel processors comprising:

Fourier transform means for producing a frequency value and an amplitude value for each sample of the respective channelized signal;
a channel arbitrator comprising:
comparator means for comparing said amplitude value with a predetermined threshold, comparing said amplitude value with the corresponding amplitude values of adjacent ones of said channels and comparing said frequency value with corresponding frequency values of adjacent ones of said channels;
processor means for sensing whether a detected signal lies in said respective channel based upon at least one of:
(a) determination of a corresponding amplitudes values of said respective channel and its adjacent neighbor channels relative to said predetermined threshold,
(b) determination of predominance of said frequency value over corresponding frequency values of adjacent neighbor channels,
(c) determination of a difference between said frequency value and that of an adjacent neighbor channel exceeding a predetermined frequency threshold;
a plurality of analog-to-digital converters having their analog inputs connected to respective ones of said antennas;
a reference source capable of outputting a reference digital signal containing at least a local frequency component within one of said N frequency channels identified by said processor means of said channel arbitrator;
a plurality of digital down converter modules, each one of said digital down converter modules having a reference input connected to said reference source and a signal input connected to the digital output of a respective one of said analog-to-digital converters, each said digital down converter modules comprising a multiplier for producing at an output of said digital down converter a product of said reference signal and the signal from the respective one of said antennas;
and
a digital phase detector having plural phase detector signal inputs connected to the outputs of remaining ones of said digital down converters, said phase detector detecting phase angles of signals on each of said phase detector signal inputs relative to a corresponding signal received at said reference antenna.

9 more elements

Dependencies are inferred from the claim text.

Digital direction finding receiver

Life of this patent

Digital direction finding receiver

Life of this patent

Abstract

Claims19