Estimation of Array Locations, Orientations, Timing Offsets and Target Locations in Bistatic Radars

This paper presents a technique that simultaneously estimates the timing offsets, the array locations and orientations, and the target locations in bistatic radar systems employing at least two antennas at the transmitter (Tx) and the receiver (Rx). The method exploits that each target provides three independent measurements, being the bistatic distance, the direction of arrival (DOA) and the direction of departure (DOD), while only requiring two parameters to be estimated, being the $x$ and $y$ coordinates. This provides one excess degree of freedom for each detected target, which allows the additional system parameters to be estimated. The technique operates on the target list level of the radar system and incorporates all unknown parameters into the target localization, which is formulated as a nonlinear least squares (NLS) estimation problem. An optimization procedure is proposed and evaluated in simulations using a short-range radar system, demonstrating sub-meter location accuracy of the targets and array locations, orientation errors of a few degrees or less, and nanosecond accurate timing estimates. The method has several advantages. For example, it does not impose any burden on the hardware or require any special signaling between the Tx and Rx arrays. Furthermore, it works with a single Tx and Rx array, and does not alter the baseband processor, allowing for a high-level implementation in a central processing unit.