US 12,422,522 B2 · Real-time detection and parameter estimation of radar signals in time varying noisy environments

Abstract

Radar signal detection and parameter estimation is central in passive surveillance systems, providing inputs for many information processing modules in order to detect, localize, indentify and intercept hostile targets. The proposed method for detecting radar signals and estimating their intra-pulse parameters in time-varying noisy environments consists of several stages: magnitude-squared envelopes calculation, adaptive noise floor estimation, detection statistics calculation, rising edge detection, time of arrival estimation, falling edge detection, time of departure estimation, pulse width estimation, amplitude estimation and center frequency and bandwidth estimation. Estimated intra-pulse parameters are wrapped into pulse descriptor words (PDWs) for information processing tasks, where each PDW consists of time of arrival, time of departure, pulse width, pulse amplitude, center frequency, signal bandwidth, noise floor level and additional useful information. The method is sequential, implemented in hardware platforms for real-time surveillance applications. The proposed method yielded much better performance than classical threshold-based edge (TED) detection methods.

Claims9

Dependent claims

A method for detecting radar signals and estimating their intra-pulse parameters in time-varying noisy environments, the said method comprising the steps of:

performing pre-processing tasks on input wideband IQ samples;
estimating a noise floor level hxn from magnitude-squared envelopes;
calculating detection statistics for rising and falling edge decision;
detecting a rising edge of radar pulses (i.e., a presence of radar pulses);
estimating a time of arrival (TOA) of radar pulses;
detecting a falling edge of radar pulses;
estimating a time of departure (TOD) of radar pulses;
calculating a pulse width (PW) of radar pulses;
estimating an amplitude (AMP) of radar pulses;
estimating a center frequency (FC) and bandwidth (BW) of radar pulses;
wrapping intra-pulse parameters into pulse descriptor words (PDWs),
wherein the said step of estimating the noise floor level from the magnitude-squared envelopes comprises the follow sub-steps:
estimating a local average value Xn of the magnitude-squared envelopes Xn using an FMA filter of length L;
estimating the noise floor level hxn as the minimum between a current local average value Xn and a previous noise floor level hxn−1;
updating the noise floor level hxn periodically by multiplying itself with an offset coefficient Kα>1 for each time period Tα.

12 more elements

A method for detecting radar signals and estimating their intra-pulse parameters in time-varying noisy environments, the said method comprising the steps of:

performing pre-processing tasks on input wideband IQ samples;
estimating a noise floor level hxn from magnitude-squared envelopes;
calculating detection statistics for rising and falling edge decision;
detecting a rising edge of radar pulses (i.e., a presence of radar pulses);
estimating a time of arrival (TOA) of radar pulses;
detecting a falling edge of radar pulses;
estimating a time of departure (TOD) of radar pulses;
calculating a pulse width (PW) of radar pulses;
estimating an amplitude (AMP) of radar pulses;
estimating a center frequency (FC) and bandwidth (BW) of radar pulses;
wrapping intra-pulse parameters into pulse descriptor words (PDWs),
wherein the said step of calculating detection statistics for rising and falling edge decision comprises the following sub-steps:
estimating an expectation μn of a distribution of random noises;
estimating a standard deviation σn of the distribution of random noises;
estimating a tentative pulse amplitude μx for the magnitude-squared envelopes;
calculating a log-likelihood ratio (LLR) sn between a distribution of tentative intra-pulse samples and a distribution of random noises;
calculating a detection statistic gn for rising edge decision from the said LLR sn;
calculating a detection statistic dn for falling edge decision from the said LLR sn.

15 more elements

Dependencies are inferred from the claim text.

Real-time detection and parameter estimation of radar signals in time varying noisy environments

Life of this patent

Real-time detection and parameter estimation of radar signals in time varying noisy environments

Life of this patent

Abstract

Claims9