METHOD OF REDUCING LOWER BOUNDARY OF LOW ALTITUDE MEASUREMENT TO ZERO AND DESIGN OF COHERENT IMPULSE DOPPLER RADIOALTIMETRE TO THIS END Russian patent published in 2011 - IPC G01S13/06 

FIELD: physics.

SUBSTANCE: proposed impulse Doppler radio altimetre uses simple probing signal with period and duration adjusted by range gate delay. In reception of reflected signal on rage gate delay, program provides linear operating mode of receiver. Before coherent accumulation of signal (Doppler filtration), probing signal leakage signals and low-frequency correlated noises are rejected by digitising quadrature signal components. Digitised signal is correlated with range and crab gate. Correlation results are subtracted on range and crab gate from correlation results on range gate delay. Note here that crab gate advance relative to range gate equal the duration of probing signal.

EFFECT: minimum measured altitude reduction to zero altitude in impulse Doppler radio altimetre.

4 cl, 4 dwg