SDR-Based ILS Signal Demodulation and Simulation

Instrument Landing System (ILS), as a key navigation equipment in the approach and landing phase of civil aircraft, its signal demodulation accuracy is directly related to the accuracy of runway alignment deviation parameter (DDM) measurement. Traditional demodulation methods have greater limitations in low signal-to-noise ratios and complex electromagnetic environments, making it difficult to meet the increasingly stringent flight safety requirements. In recent years, the development of software radio (SDR) technology and high-speed ADC has promoted the development of digital demodulation technology for ILS signals. In this paper, a digital demodulation scheme for ILS signals based on the principle of software radio is proposed, which effectively extracts and recovers the key modulation components of ILS signals by utilizing high-speed ADC sampling, digital downconversion, downsampling, and orthogonal demodulation and low-pass filtering, and the experimental results of MATLAB simulation show that, under the condition of noise interference, the proposed method can still realize high-precision signal demodulation, and it shows good robustness and good performance. It shows good robustness and anti-interference ability, and provides theoretical support for ILS digital processing.