An experimental demonstration of a posteriori digital calibration of MIMO radar system

Abstract

MIMO radar is a promising concept as demonstrated by many studies, especially for possible improvements in term of target detection and localization. Moreover, the transmission of orthogonal waveforms opens the door to more flexibility for system control and calibration, by making possible to transfer radar functions to the digital domain. Nevertheless, MIMO radar considerations have rarely been performed with real signals. At ONERA, a collocated MIMO-capable radar testbed has been specially designed and installed to perform experiments in realworld conditions. In this paper, we explain first how MIMO radar can bring more flexibility and performance for system control and calibration. In a second part, we introduce the MIMO radar testbed and the experiments we did with it, in a context of transmitter phase miscalibration. Then, we describe our method for the a posteriori calibration of transmission antenna phases. This method digitally aligns the phases of the transmitters directly in the received signal, in the case the transmitters are originally not fully calibrated, by choice or incidentally. Eventually, we present the results of this method applied to the experimental data.

Experimental study on multi-channel waveform agile beamforming and testbed calibration

“…Tx/Rx Channels Frequency Bandwidth BEEMER [5] 4/4 3.5 GHz 40 MHz HYCAM [6], [7] 12/16 S-Band 500 MHz MATE [8] 8/1 28.5 GHz 1 GHz RIAS [9] 25/48 VHF 250 kHz MMRS [10] 2/4 9.55 GHz 150 MHz MISO RADAR [11] 4/1 Comparing to the conventional radars exploiting multiple degrees of freedom on receive; MIMO radars allow to exploit similar benefits on transmit using multiple independent transmissions [12], [13], [14], [5], [15] and [16]. However, a few multi-channel radar testbeds are developed in [5], [6], [8], [9], [10], [11] to support simultaneous independent signal transmissions and are listed in Table II.…”