method for calibration of a fmcw radarhu00f6henmessers and radarhu00f6henmesser for implementation of the procedure

摘要

The FMCW radio altimeter has a linear oscillator (3) providing a spread spectrum signal. The signal passes to a transmitter antenna. The receive antenna signal passes to a mixer (4) and is mixed with part of the linear oscillator signal. A processor (2) processes the mixer output. An auxiliary sawtooth waveform is injected (1) into the receive circuit. The waveform shape is digitally programmable. The auxiliary waveform allows a height measure to be obtained by a beat frequency between the two waveforms and compared with a standard formula to check that the actual altimeter height is correct.