Harmonic Radar with Adaptively Phase-Coherent Auxiliary Transmitters

In harmonic radar (HR), the radio frequency transmitter illuminates a nonlinear target (the tag), causing the return signal to consist of harmonics at multiples of the transmitted carrier frequency. Of them, the second harmonic is usually the strongest and the one to which the receiver is tuned. Thi...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on signal processing 2022-01, Vol.70, p.1-1
Main Authors: Lavrenko, Anastasia, Cavers, James K., Woodward, Graeme
Format: Article
Language:English
Subjects:
Adaptive algorithms
adaptive phase coherence
auxiliary transmitters
Carrier frequencies
Clutter
Distance measurement
Downlink
Harmonic analysis
Harmonic radar
harmonic RFID
harmonic tags
Harmonics
Intermodulation
nonlinear radar
Oscillators
Phase coherence
Power system harmonics
Radar
range extension
Signal to noise ratio
Transmitters
Transmitting antennas
Uplink
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In harmonic radar (HR), the radio frequency transmitter illuminates a nonlinear target (the tag), causing the return signal to consist of harmonics at multiples of the transmitted carrier frequency. Of them, the second harmonic is usually the strongest and the one to which the receiver is tuned. This frequency difference distinguishes the tag reflection from environmental clutter, which remains at the uplink (transmitter to tag) frequency. However, the passive nature of HR tags severely limits the reflected power, and therefore the operational range of a HR system. We propose to increase the range and/or signal to noise ratio (SNR) by novel restructuring at the physical and signal levels. For this, we accompany the original transmitter with auxiliary transmitters able to send simple tones that are synchronized to arrive at the tag in phase, and we design the receiver to detect an intermodulation component. The resulting range and SNR are much greater than those of the original, conventional HR system, even if the original system were to transmit with power equal to the aggregate power of the proposed system. Achieving mutually coherent, i.e., in phase, arrival of the tones at the tag is the focus of the present paper. We provide a system framework that models the tag and the uplink and downlink (tag to receiver), then present the adaptive phase coherence algorithm and analyze the probabilistic growth of the output signal power. We also account for the effects of frequency shifts due to transmitter mobility and the frequency offset errors in the transmitter local oscillators.
ISSN:1053-587X
1941-0476
DOI:10.1109/TSP.2022.3164183