LINEAR FREQUENCY MODULATOR FOR A FREQUENCY MODULATED MAINTAINED WAVE RADIO-ALTIMETER

摘要

P THE INVENTION CONCERNS A LINEAR FREQUENCY MODULATOR FOR A MICROWAVE OSCILLATOR TUNED BY MEANS OF A VARACTOR AND USED IN A FREQUENCY MODULATED MAINTAINED WAVE RADIO-ALTIMETER. THE TRIANGULAR WAVE PRODUCED BY A GENERATOR 19, 22, 23 IS CONVERTED BY A NON-LINEAR FUNCTION GENERATOR 28 INTO THE NON-LINEAR WAVE REQUIRED TO POLARIZE VARACTOR 24 IN A WAY THAT ENSURES A MODULATION OF THE LINEAR FREQUENCY OF THE OSCILLATOR . VARIATIONS IN THE PERIOD OF A SAMPLING SIGNAL PRODUCED BY A DELAY LINE 29 ARE MEASURED BY A PERIOD-METER 32 AT TIMES CORRESPONDING TO THE LOW FREQUENCY AND HIGH FREQUENCY OUTPUT SIGNAL AND SIGNALS RESULTANT ERRORS ARE USED TO CONTROL THE FUNCTION GENERATOR TO MODIFY, IN CLOSED LOOP, THE VARACTOR POLARIZATION SIGNAL IN THE PARTS OF THIS SIGNAL THAT MATCH THE LOW AND HIGH FREQUENCY PARTS OF THE OSCILLATOR OUTPUT SIGNAL . /P