PULSED DOPPLER RADIO ALTIMETER SYSTEM Russian patent published in 2013 - IPC G01S13/60 

FIELD: radio engineering, communication.

SUBSTANCE: packet of probing radio pulses is radiated towards an underlying surface, wherein the number of the radiated pulses and repetition period thereof are selected in a programmed manner so as to provide a maximum number of radiated pulses over an a priori delay time set by an exchange controller, and simultaneously eliminate uncertainty of the measured altitude and prevent the radiated signal falling into a zone of uncertainty, wherein the reflected signal is sought; the packet of radio pulses reflected from the underlying surface is received; video pulses are converted to a sequence of digital binary signals with sampling frequency; said sequence is stored synchronously with the beginning of the packet of the radiated radio pulses and at the end of radiation, the memory cell address corresponding to the a priori delay of the reflected signal relative the beginning of the radiation packet is determined; narrow-band Doppler filtering of the digital binary signals read successively from the memory cell is performed in the memory address search range; the overall filtration result is accumulated for all digital binary signals of the received packet for each value of the estimated delay; a signal is present if a predetermined accumulation threshold is exceeded; the delay of the reflected signal relative the beginning of the packet of radiated radio pulses is determined; information on the measured altitude is sent to the output of the radio altimeter system through the exchange controller.

EFFECT: high stealthiness of radiation and maximum measured altitude without increasing radiated power.