Sidelobe Detection in Slewing Monopulse Antennas
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Solution Overview
Problem
Radars face challenges in accurately estimating target angles during antenna slew due to low signal-to-noise ratio (SNR) and varying angles-off-boresight, which can lead to incorrect target detection and tracking, especially when targets are in antenna sidelobes.
Innovation Solution
A system and method utilizing non-coherent integration to estimate target angles and rates, involving a controller that processes monopulse signals from a slewing monopulse antenna, compares observed vectors with test vectors generated over a range of angles, and determines the target's location within the main lobe or sidelobe, allowing for accurate angle and rate estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coherent integration is used during antenna slew to maintain sensitivity, then detection capability is improved, but the system cannot correctly estimate angles since each pulse arrives from a different angle
Solution Approach 1:
The patent applies preliminary action by compensating for the known antenna slew motion before performing angle estimation. The system uses pre-calculated slew compensation values based on the antenna's motion profile to adjust the received signals, thereby eliminating the angle offset introduced by slewing and enabling accurate angle estimation even during motion.
Solution Approach 2:
The patent changes the integration parameter from coherent to non-coherent integration when antenna slew is detected. This parameter change allows the system to maintain detection capability while accommodating the varying angle-off-boresight conditions during slewing, as non-coherent integration does not require phase consistency across pulses.
Data Source
AI summary
The present system and method allow for accurate estimation of angle and angle rate for a target using a slewing antenna. These issues are accounted for by using a special form of non-coherent integration. An extension of the non-coherent integration may be used to estimate the target's angle rates. This technique can also be expanded to determine whether a target is in the main lobe or in a side lobe in one or two directions.