Radar transponder operation with compensation for distortion due to amplitude modulation
In radar transponder operation, a variably delayed gating signal is used to gate a received radar pulse and thereby produce a corresponding gated radar pulse for transmission back to the source of the received radar pulse. This compensates for signal distortion due to amplitude modulation on the retransmitted pulse.
1. A radar transponder method, comprising:
receiving a sequence of input radar pulses from a moving radar apparatus;
providing a gating signal;
delaying said gating signal by a delay amount that varies with time to produce a variably delayed gating signal;
in response to said delayed gating signal and one of said input radar pulses, producing a gated pulse that corresponds to said one input radar pulse; and
in response to said gated pulse, producing a corresponding output radar pulse.
2. The method of claim 1 , wherein said delay amount varies nonlinearly with time.
3. The method of claim 2 , including determining said delay amount based on a pulse repetition frequency associated with said sequence of input radar pulses.
4. The method of claim 3 , including determining said delay amount based on a transmit frequency associated with said input radar pulses.
5. The method of claim 2 , including determining said delay amount based on a transmit frequency associated with said input radar pulses.
6. The method of claim 2 , wherein said delay amount varies randomly with time.
7. The method of claim 6 , including determining said delay amount based on a pulse repetition frequency associated with said sequence of input radar pulses.
8. The method of claim 7 , including determining said delay amount based on a transmit frequency associated with said input radar pulses.
9. The method of claim 8 , including determining said delay amount based on a uniform random distribution.
10. The method of claim 7 , including determining said delay amount based on a uniform random distribution.
11. The method of claim 6 , including determining said delay amount based on a transmit frequency associated with said input radar pulses.
12. The method of claim 11 , including determining said delay amount based on a uniform random distribution.
13. The method of claim 6 , including determining said delay amount based on a uniform random distribution.
14. A radar transponder apparatus, comprising:
an input for receiving a sequence of input radar pulses from a moving radar apparatus;
a delay element for receiving a gating signal and delaying said gating signal by a delay amount that varies with time to produce a variably delayed gating signal;
a gate coupled to said input and said delay element, said gate responsive to said delayed gating signal and one of said input radar pulses for producing a gated pulse that corresponds to said one input radar pulse; and
a radar output portion coupled to said gate and responsive to said gated pulse for producing a corresponding output radar pulse.
15. A radar system, comprising:
a mobile radar apparatus configured to transmit radar pulses; and
a radar transponder apparatus, including
an input for receiving from said mobile radar apparatus a sequence of input radar pulses transmitted by said mobile radar apparatus while said mobile radar apparatus is moving, a delay element for receiving a gating signal and delaying said gating signal by a delay amount that varies with time to produce a variably delayed gating signal, a gate coupled to said input and said delay element, said gate responsive to said delayed gating signal and one of said input radar pulses for producing a gated pulse that corresponds to said one input radar pulse, and a radar output portion coupled to said gate and responsive to said gated pulse for producing a corresponding output radar pulse.