Improved precision of virtual height measurements with coherent radio pulse sounding based on the maximum likelihood method

The paper describes a new technique that improves precision of the virtual height measurements by a coherent pulse sounding of the ionosphere. Proposed technique is based on the method of maximum likelihood that matches expected and observed spectral domain signatures of the signal intermixed with the noise. Computer simulations show that our technique allows measurements of the echo virtual height with ∼100 m precision even at a much coarser step of the height sampling in the sounder. In experiment, we expect an average 300 m precision of the virtual height measurements for single echoes received during periods of little spread due to ionospheric irregularities.