System and method for continuous wave interference cancellation

1. A method of cancelling continuous wave interference in a radar sensor system configured to transmit a transmission radar signal at a carrier frequency, comprising:

defining an integration time period, the radar sensor system being configured to integrate a detected signal during the integration time period, the detected signal including a continuous wave (CW) interferer signal;

dividing the integration time period into a first sub-period and a second sub-period, the radar sensor system transmitting the transmission radar signal during the first sub-period and the second sub-period of the integration time period;

integrating the detected signal during both the first sub-period and the second sub-period to generate respective sub-period integrated values, wherein integration in the first sub-period and second sub-period is triggered at points of symmetrical opposite polarities of a down converted interferer signal based on the CW interferer signal and having a non-integer number of cycles in each sub-period, resulting in interference residue in each of the respective sub-periods; and

adding the first sub-period integrated value and the second sub-period integrated value to cancel the interference residue of opposite polarity in the respective sub-periods, so as to generate a corrected integrated value for the integration time period.

2. The method of claim 1 , wherein the symmetrical opposite polarities comprise positive and negative zero crossings of the down converted interferer signal.

3. The method of claim 1 , further comprising down mixing the detected signal to obtain the down mixed CW interferer signal.

4. The method of claim 1 , wherein, the first sub-period and the second sub-period are of equal size.

5. The method of claim 1 , wherein the CW interferer signal has a frequency different than the carrier frequency and the down converted interferer signal has a frequency that is the difference between the carrier frequency and the CW interferer signal frequency.

6. The method of claim 1 , wherein integration during the first sub-period and the second sub-period ends after a predetermined amount of time.

7. The method of claim 1 , wherein the radar sensor system comprises an automotive radar system, and the CW interferer signal is transmitted from a second automotive radar system.

8. The method of claim 1 , further comprising adjusting the integration in the respective sub-periods to a length of time equaling an integer number of down converted interferer signal cycles.

9. The method of claim 1 , wherein the down converted interferer signal composes one of an in-phase (I) and quadrature (Q) signal of the radar sensor system.

10. The method of claim 1 , wherein a comparator and a controllable switch are used to trigger integration of the detected signal.

11. A radar sensor system with continuous wave (CW) interference cancellation, comprising:

a transmitter for emitting a transmission radar signal at a carrier frequency;

a receiver configured to detect a signal including reflections of the emitted transmission radar signal and a CW interferer signal; and

a controller and/or processor for processing signals associated with the radar sensor system, the controller and/or processor:

(i) defining an integration time period, the radar sensor system being configured to integrate a detected signal during the integration time period;

(ii) dividing the integration time period into a first sub-period and a second sub-period, the radar sensor system transmitting the transmission radar signal during the first sub-period and the second sub-period of the integration time period;

(iii) integrating the detected signal during both the first sub-period and the second sub-period to generate respective sub-period integrated values, wherein integration in the first sub-period and second sub-period is triggered at points of symmetrical opposite polarities of a down converted interferer signal based on the CW interferer signal and having a non-integer number of cycles in each sub-period, resulting in interference residue in each of the respective sub-periods; and

(iv) adding the first sub-period integrated value and the second sub-period integrated value to cancel the interference residue of opposite polarity in the respective sub-periods, so as to generate a corrected integrated value for the integration time period.

12. The system of claim 11 , wherein the symmetrical opposite polarities comprise positive and negative zero crossings of the down converted interferer signal.

13. The system of claim 11 , wherein the controller and/or processor down mix the detected signal to obtain the down mixed CW interferer signal.

14. The system of claim 11 , wherein the first sub-period and the second sub-period are of equal size.

15. The system of claim 11 , wherein the CW interferer signal has a frequency different than the carrier frequency and the down converted interferer signal has a frequency that is the difference between the carrier frequency and the CW interferer signal frequency.

16. The system of claim 11 , wherein integration during the first sub-period and the second sub-period ends after a predetermined amount of time.

17. The system of claim 11 , wherein the radar sensor system comprises an automotive radar system, and the CW interferer signal is transmitted from a second automotive radar system.

18. The system of claim 11 , wherein the controller and/or processor adjust the integration in the respective sub-periods to a length of time equaling an integer number of down converted interferer signal cycles.

19. The system of claim 11 , wherein the down converted interferer signal comprises one of an in-phase (I) and quadrature (Q) signal of the radar sensor system.

20. The system of claim 11 , further comprising a comparator and a controllable switch configured to trigger integration of the detected signal.