Patent RU-2106655-C1 (RU)
Title: Frequency-modulated altimeter
Inventor: ZEJGMAN JU L
IPC: G01S13/34
Filed: 1996-06-17
Granted: 1998-03-10
Abstract: FIELD: radiolocation. SUBSTANCE: there exist some types of interference which act on altimeter changing its output readings. Such types of interference diminish authenticity of output information of altimeter in range. Frequency-modulated altimeter has source of reference analog signal, unit controlling speed of retuning of transmitter frequency, sawtooth voltage generator, transmitter and transmitting antenna connected in series, former of measurement interval of modulation band, unit changing over direction of retuning of transmitter frequency which output is linked to second input of sawtooth voltage generator connected in series, receiving antenna, mixer, converted signal amplifier and digital relay element which first output is coupled to second input of unit controlling speed of retuning of transmitter connected in series, clock pulse generator and time interval-to-code converter. Second and third outputs of transmitter are correspondingly connected to second input of mixer and input of former of measurement interval of modulation band which second output is connected to first input of time interval-to-code converter. Output of clock pulse generator is connected to second input of digital relay element. Altimeter also incorporates generator of rectangular oscillations, first delay circuit, and first modulo two adder, second modulo two adder and first AND gate connected in series, first key, first storage circuit and first threshold device connected in series, second key, second storage circuit and second threshold device connected in series, second AND gate which inputs are connected to outputs of threshold devices, second delay circuit placed between second output of former of measurement interval of modulation band and third input of digital relay element which first output is connected to first inputs of keys, which second output is connected to second inputs of storage circuits, which third and fourth outputs are connected to inputs of first modulo two adder. Output of generator of rectangular oscillations is connected to third input of sawtooth voltage generator, to second input of time interval-to-code converter and to input of first delay circuit which output is connected to second input of second modulo two adder and to second inputs of keys. Output of second AND gate is connected to second input of first AND gate and to third input of unit controlling speed of retuning of transmitter frequency which fourth input is connected to output of first AND gate. In proposed altimeter output information on measured altitude is considered reliable if second AND gate forms signal LOCK-ON across its output corresponding to state "logic one". In case of action of range deviating interference on altimeter output information on measured altitude does not change up to moment of pick-off of signal LOCK-ON. Output information on measured altitude is considered unreliable if second AND gate forms signal RESET corresponding to state "logic zero" across its output. EFFECT: usage of proposed frequency-modulated altimeter makes it possible to increase reliability of output information under action of range deviating interference.