RADIO PHYSICS AND RADIO ASTRONOMY

Subject and Purpose. The work aims to develop and study an interference-immune radio communication system for transmitting and receiving digital information and video images using a Software-Defined Radio (SDR).

Methods and Methodology. The processes of generation, reception, and decoding of broadband pseudorandom signals formed by the Direct Sequence Spread Spectrum (DSSS) technology are mathematically modeled. Basic software solutions are experimentally developed for data receiving, transforming, processing, and displaying. The functional capabilities of the hardware and software tools are evaluated and analyzed for their subsequent integration into the system. Results. An algorithm has been developed for generating and decoding from a sub-noise spread spectrum correlation communication system using DSSS technology. The processes of data formation and transmission by noise-like signals based on the Gold codes have been modeled. An algorithm for noise-like signal identification has been developed, based on the mathematical determination of the autocorrelation function which evaluates the relationship (degree of similarity) between the signal and its time-shifted copy. To maintain the phase coherence between the expected (received from air) and reference (key) signals at any time, a cyclically operating multi-channel correlator was developed. We estimated the maximum radio data rates over the radio channels when transmitting low-frequency telemetry signals, control signals, and video signals.

Conclusions. The research and development of digital communication channels using signal coding through the Direct Sequence Spread Spectrum (DSSS) method along with Gold codes have demonstrated the potential to create compact devices for establishing interference-immune and low-noise multi-channel communication which is particularly suitable for data transmission in modern environments.

Keywords: communication system, interference-immune communication, DSSS technology, Gold codes, multi-channel correlator, SDR receiver, digital stream

Manuscript submitted  25.07.2024

Radio phys. radio astron. 2025, 30(1): 011-022

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