# Search for New Complex Sequences for the Implementation of an Aviation Group Interaction System of Small-Sized Airborne Radars

## TL;DR

This paper explores new complex sequences for small airborne radar systems to improve cooperative surface mapping.

## Contribution

The paper introduces new complex M-sequences with reduced sidelobe levels for improved radar signal distinguishability.

## Key findings

- New complex M-sequences with lower sidelobe levels in autocorrelation functions were developed.
- Optimal complex values for sequences were determined using numerical methods and simulations.
- Phase-modulated signals based on new sequences show improved performance for cooperative radar systems.

## Abstract

Recently, when forming radar video frames for surface mapping, group-interacting compact onboard radar systems (CORS) are increasingly being utilized. In this context, for the cooperative functioning of the group, each compact radar should use its own unique marked signal as the probing signal. This signal must be distinguishable in the common channel and should not destructively affect the probing signals emitted by other radars within the group. This organization allows for associating the marked signals reflected from the underlying surface with specific CORS in the group. This requirement arises because each compact onboard radar in the group emits a single probing signal and then receives all reflected signals from the surface emitted by the other CORS in the group. Such an organization of the group-based system of technical vision requires the search for and study of specialized marked code structures used for phase modulation of probing signals to identify them in the shared radar channel. The study focuses on the search for new complex M-sequences with lower sidelobe levels of the normalized autocorrelation function compared to traditional M-sequences. This is achieved by replacing the traditional alphabet of positive and negative ones with an asymmetric set consisting of complex numbers. Using numerical methods and computer simulations, the optimal complex values of the sequence with the minimum sidelobe level in the autocorrelation function are determined. In addition to correlation properties, the phase-modulated signals generated based on the new marked sequences are also investigated. The results obtained open new possibilities for the construction of a group-based technical vision system, enabling cooperative surface probing among all CORS in the interacting group.