An Improved TDOA Method for Land-Based Long-Range HF Skywave Source Geolocation and Experimental Results

Area of Science:

• Geophysics
• Radio Science
• Signal Processing

Background:

• Accurate geolocation of High Frequency (HF) sources is hindered by real-time, unknown ionospheric conditions.
• High Frequency (HF) skywave propagation is significantly affected by non-line-of-sight (NLOS) biases due to ionospheric reflection.

Purpose of the Study:

• To develop an improved High Frequency (HF) skywave source geolocation method.
• To achieve timely and accurate geolocation of HF sources without requiring prior ionospheric information.

Main Methods:

• Utilized time-difference-of-arrival (TDOA) combined with semidefinite programming (SDP).
• Modeled High Frequency (HF) signal propagation paths with non-line-of-sight (NLOS) biases.
• Employed ray tracing and a 3D ionospheric electron density model for realistic path simulation.

Main Results:

• The proposed method demonstrated improved positioning accuracy by approximately 50% compared to existing techniques.
• Achieved an average relative positioning error of less than 2.7% in simulations and experiments.
• Generated detailed geolocation error distribution maps.

Conclusions:

• The novel method effectively geolocates High Frequency (HF) sources accurately and in real-time.
• Eliminates the need for prior ionospheric data, particularly virtual heights of reflection.
• Offers a significant advancement in High Frequency (HF) source geolocation technology.