Achieving n-Fold Increase in the Unambiguous Radar Range of a Uniform Pulse Train by Turning Off Every n’th Pulse (for n = 3, 4, 5…)

Abstract

This correspondence addresses the radar challenge of extending the unambiguous delay in a uniform pulse train beyond the pulse repetition interval (PRI). The proposed approach involves dividing the streaming transmitted pulses into consecutive groups, each comprising $n$ pulses. These $n$ transmitted pulses undergo overlay with a coded sequence ${\text{S}}_{n}$ (e.g., S3 = {1 1 0}). Concurrently, the corresponding $n$ reference pulses in the receiver undergo overlay with a coded sequence ${\text{R}}_{n}$ (e.g., R3 = { $1\,\,1-1$ }), requiring a sidelobe-free periodic cross-correlation between ${\text{S}}_{n}$ and ${\text{R}}_{n}$ . The initially identical transmitted pulses may be either plain or compressed, and the corresponding reference pulses can be matched or mismatched. This innovative approach extends the unambiguous range by a factor of $n$ . However, it does not address the issue of masked target returns coinciding with detection of the system’s own pulses, when the isolation of own pulses is insufficient and they saturate the receiver. Notably, the proposed approach is applicable to both coherent and non-coherent systems such as Lidar. However, our emphasis here is mainly on non-coherent systems. The presentation includes simple examples with $n$ values of 3, 4, and 5, and considers system performances in the presence of noise.