Contribution to the nonlinear theory of the Doppler effect for radio signals from geophysical rockets

The use of the Doppler effect of radio signals transmitted from rockets is a standard method of obtaining electron density profiles. Due to the low electron density in the D region of the ionosphere, it is necessary to decrease the frequency and increase transmitter power. At the same time, the increase in power may lead to a disturbance of the plasma parameters, thus increasing the systematic error of the method. The aim of the present paper is to assess this error. An analysis of the plasma disturbance leads to the conclusion that at frequencies between 1 and 10 MHz and transmitter powers on the order of or greater tahn 1 W, no pronounced increase in electron temperature should be expected. Nonlinear correction to the Doppler frequency shift is negligible.