Compensation of the Doppler Effect in RedShift Measurement Experiments

The Doppler effect is a physical phenomenon characterized by a frequency shift (or corresponding wavelength) of electromagnetic radiation resulting from relative motion between the emitting source and the detecting observer. The nonrelativistic Doppler effect constitutes a critical challenge for precision measurements of the RedShift effect in the RadioAstron mission. In these experiments the first-order Doppler effect exceeded the target signal by five orders of magnitude, while the relativistic effect remained one order of magnitude smaller. Conventional compensation techniques based on spacecraft navigation data proved inappropriate due to inherent limitations in velocity determination. We present an original compensation method employing alternating ‘‘oneway’’ and ‘‘twoway’’ signal transmission modes that effectively suppresses Doppler shift without requiring velocity data. When combined with relativistic Doppler effect compensation, this approach successfully extracted the RedShift signal from dominant Doppler effects. The developed method demonstrates significant improvement in detecting weak RedShift effects against strong Doppler background and shows potential for application in future high-precision space astronomy missions.