Radar unit, integrated circuit and methods for detecting and mitigating mutual interference
A radar unit ( 400 ) for detecting an existence of interference is described that includes: a millimetre wave (mmW) transceiver (Tx/Rx) circuit configured support a normal data acquisition mode of operation that comprises transmitting a radar signal waveform and receiving an echo signal thereof; a mixed analog and baseband circuit operably coupled to the mmW Tx/Rx circuit; and a signal processor circuit ( 452 ) operably coupled to the mixed analog and baseband circuit. An interference detection unit ( 448 ) is operably coupled to the mmW Tx/Rx circuit. The radar unit is configured to operate a time-discontinuous mode of operation that includes a first time portion used as an interference monitoring period and a second time portion used by the radar unit in the normal data acquisition mode of operation, whereby the mixed analog and baseband circuit, signal processor circuit ( 452 ) and interference detection unit ( 448 ) are configured to detect interference signals during the monitoring period.
1. A radar unit for detecting an existence of interference, wherein the radar unit comprises:
a millimetre wave transceiver circuit configured to support a normal data acquisition mode of operation that comprises transmitting a radar signal waveform and receiving an echo signal thereof;
a mixed analog and baseband circuit operably coupled to the millimetre wave transceiver circuit; and
a signal processor circuit operably coupled to the mixed analog and baseband circuit;
the radar unit characterized by:
an interference detection unit operably coupled to the millimetre wave transceiver circuit; and
wherein the radar unit is configured to operate a time-discontinuous mode of operation that includes a first time portion used as an interference monitoring period and a second time portion used by the radar unit in the normal data acquisition mode of operation, whereby the mixed analog and baseband circuit, signal processor circuit and interference detection unit are configured to detect interference signals during the monitoring period;
wherein the interference detection unit is configured to identify a direction and level of interference of at least one detected interference signal during the monitoring period and output an interference detected signal; and wherein the signal processor circuit is configured to analyse the interference detected signal and quantify a response to the detection;
wherein the radar unit further comprises an architecture reconfiguration control unit coupled to the signal processor circuit and the mixed analog and baseband circuit that comprises at least an amplifier, a filter and an analog-to-digital convertor, wherein the architecture reconfiguration control unit is configured in response to the interference detected signal to adjust at least one of: a gain and/or filter bandwidth of the mixed analog and baseband circuit to avoid saturation of the analog-to-digital convertor.
2. The radar unit of claim 1 wherein the interference detection unit is configured to detect an existence of interference before the radar unit commences the normal radar target acquisition mode of operation.
3. The radar unit of claim 2 wherein the radar unit only powers on receiver circuits to scan at least a portion of supported radar frequency sub-bands during the first time portion.
4. The radar unit of claim 2 further comprising a waveform generator coupled to the signal processor circuit and configured to generate a frequency chirp sequence waveform during the second time portion of a chirp interval, wherein the time-discontinuous mode of operation is performed in each of a plurality of chirp intervals with a start frequency and an end frequency of the chirps in one chirp sequence being the same, and wherein at least one of the following exists:
where a start frequency and an end frequency of the chirps is different between each chirp sequence; or
where a start frequency and an end frequency of the chirps is the same across a plurality of chirp sequences.
5. The radar unit of claim 2 further comprising a waveform generator coupled to the signal processor circuit and configured to generate a frequency chirp sequence waveform during the second time portion of a chirp interval, wherein the time-discontinuous mode of operation is performed in each of a plurality of chirp intervals with a start frequency and an end frequency of the chirps in one chirp sequence being the same, and wherein at least one of the following exists:
where a start frequency and an end frequency of the chirps is different between each chirp sequence; or
where a start frequency and an end frequency of the chirps is the same across a plurality of chirp sequences.
6. The radar unit of claim 2 wherein the signal processor circuit re-configures at least one receiver path of multiple receiver paths in the mixed analog and baseband circuit and the millimetre wave transceiver circuit as at least one mutual interference detector receiver.
7. The radar unit of claim 1 wherein the radar unit only powers on receiver circuits to scan at least a portion of supported radar frequency sub-bands during the first time portion.
8. The radar unit of claim 1 further comprising a waveform generator coupled to the signal processor circuit and configured to generate a frequency chirp sequence waveform during the second time portion of a chirp interval, wherein the time-discontinuous mode of operation is performed in each of a plurality of chirp intervals with a start frequency and an end frequency of the chirps in one chirp sequence being the same, and wherein at least one of the following exists:
where a start frequency and an end frequency of the chirps is different between each chirp sequence; or
where a start frequency and an end frequency of the chirps is the same across a plurality of chirp sequences.
9. The radar unit of claim 8 wherein the waveform generator is configured to generate a set of fixed frequencies that correspond to a center frequency of each sub-band to be monitored in the first time portion.
10. The radar unit of claim 1 wherein the millimetre wave transceiver circuit comprises a transmitter phase array and in response to the indication of the arrival direction of the detected interference signal, the signal processor circuit is configured to adjust at least one parameter of the transmitter phase array to reduce the level of interference.
11. The radar unit of claim 10 wherein the signal processor circuit is configured to steer an antenna beam of the transmitter phase array to reduce the level of interference.
12. The radar unit of claim 10 wherein the signal processor circuit is configured to steer an antenna beam to perform at least one of:
spatial filtering to reduce the level of interference;
create one or more beam nulls focused towards the direction of the detected interference signal to reduce the level of interference.
13. The radar unit of claim 1 wherein the architecture reconfiguration control unit is coupled to a waveform generator and configured in response to a detected interference signal to adjust at least one of: a chirp bandwidth, a chirp duration, a starting chirp frequency, an ending chirp frequency.
14. The radar unit of claim 1 wherein the signal processor circuit re-configures at least one receiver path of multiple receiver paths in the mixed analog and baseband circuit and the millimetre wave transceiver circuit as at least one mutual interference detector receiver.
15. The radar unit of claim 1 further comprising an auxiliary detection path incorporating at least one auxiliary receiver coupled to the interference detection unit and comprising one or more programmable bandpass filter(s), one or more programmable gain amplifiers, PGAs, and an analog to digital converter, and configured to detect the interference signal.
16. The radar unit of claim 15 wherein the auxiliary detection path includes a number of wideband receivers configured to cover the complete radar operational bandwidth to detect both frequency and direction of interference signals.