Doppler radar apparatus and power saving method thereof
A Doppler radar apparatus, including a transmitter, a receiver, and a processor, is provided. The transmitter transmits a radio frequency signal to a field. The receiver is coupled to the transmitter and receives a reflected signal corresponding to the radio frequency signal from the field. The processor is coupled to the receiver and is configured to detect a target in the field according to the reflected signal. In response to the target not being detected in the field, the processor switches to a power saving mode according to workload reduction information, and workload of the radio frequency signal in the power saving mode decreases based on the workload reduction information.
1. A Doppler radar apparatus, comprising:
a transmitter, transmitting a radio frequency signal to a field, wherein the radio frequency signal includes a plurality of frames;
a receiver, coupled to the transmitter and receiving a reflected signal corresponding to the radio frequency signal from the field; and
a processor, coupled to the receiver and configured to:
detect a target in the field according to the reflected signal;
switch from a normal working mode to a power saving mode according to workload reduction information in response to the target not being detected in the field, the workload reduction information includes a total number of frames corresponding to the radio frequency signal and a number of detection signals emitted in each of the frames, wherein
workload of the radio frequency signal in the power saving mode decreases based on the workload reduction information,
adjust the frequency of the radio frequency signal according to workload reduction information during the power saving mode; and
instruct the transmitter to stop transmitting the radio frequency signal within the waiting time after switching from the normal working mode to the power saving mode.
2. The Doppler radar apparatus according to claim 1 , wherein:
the radio frequency signal comprises the plurality of frames,
a first frame of the frames comprises a plurality of first detection signals, a second frame of the frames comprises a plurality of second detection signals, and
a number of the second detection signals is less than a number of the first detection signals after switching to the power saving mode.
3. The Doppler radar apparatus according to claim 1 , wherein the radio frequency signal comprises the plurality of frames, and a third frame of the frames comprises a plurality of third detection signals, wherein the processor is further configured to:
capture a fourth detection signal from the third detection signals, and detect the target in the field according to the fourth detection signal.
4. The Doppler radar apparatus according to claim 1 , wherein the radio frequency signal comprises the plurality of frames, wherein the processor is further configured to:
adjust a number of the frames according to the workload reduction information.
5. The Doppler radar apparatus according to claim 1 , wherein the radio frequency signal comprises the plurality of frames, wherein the processor is further configured to:
switch from the power saving mode to the normal working mode in response to the target being detected in the field, and restore the workload of the frames in the normal working mode.
6. The Doppler radar apparatus according to claim 1 , wherein the transmitter comprises:
a signal generator, generating a chirp signal according to a sweep cycle, wherein a frequency of the chirp signal changes with time within the sweep cycle, wherein the radio frequency signal comprises the plurality of frames, and at least one of the frames comprises the chirp signal.
7. The Doppler radar apparatus according to claim 6 , wherein the receiver comprises:
a frequency modulated continuous wave demodulation circuit, coupled to the signal generator and demodulating the reflected signal according to the chirp signal to obtain an intermediate frequency signal; and
an analog-to-digital converter, coupled to the frequency modulated continuous wave demodulation circuit and converting the intermediate frequency signal into digital data.
8. The Doppler radar apparatus according to claim 7 , wherein the detection of the target in the field according to the reflected signal comprises:
performing range fast Fourier transform (FFT) on the digital data to obtain at least one distance frequency; and
judging that the target is detected in the field in response to an amplitude value of the at least one distance frequency being greater than a first threshold value.
9. The Doppler radar apparatus according to claim 7 , wherein the detection of the target in the field according to the reflected signal comprises:
performing range FFT and Doppler FFT on the digital data to obtain at least one Doppler frequency; and
judging that the target is detected in the field in response to an amplitude value of the at least one Doppler frequency being greater than a second threshold value.
10. The Doppler radar apparatus according to claim 6 , wherein the transmitter further comprises:
a frequency modulated continuous wave emission circuit, coupled to the signal generator and amplifying the chirp signal to generate the radio frequency signal; and
an emission antenna, coupled to the frequency modulated continuous wave emission circuit and emitting the radio frequency signal.
11. A power saving method, applicable to a Doppler radar apparatus, the power saving method comprising:
detecting a target in the field according to a reflected signal;
switching from a normal working mode to a power saving mode according to workload reduction information in response to the target not being detected in the field, the workload reduction information includes a total number of frames corresponding to the radio frequency signal and a number of detection signals emitted in each of the frames, wherein
workload of the radio frequency signal in the power saving mode decreases based on the workload reduction information,
adjust the frequency of the radio frequency signal according to workload reduction information during the power saving mode; and
instructing the transmitter to stop transmitting the radio frequency signal within the waiting time after switching from the normal working mode to the power saving mode.
12. The power saving method according to claim 11 , further comprising:
transmitting the radio frequency signal to a field, wherein the radio frequency signal includes a plurality of frames; and
receiving the reflected signal corresponding to the radio frequency signal from the field.
13. The power saving method according to claim 12 , wherein the radio frequency signal comprises the plurality of frames,
a first frame of the frames comprises a plurality of first detection signals, a second frame of the frames comprises a plurality of second detection signals, and
a number of the second detection signals is less than or equal to a number of the first detection signals after switching to the power saving mode.
14. The power saving method according to claim 12 , wherein the radio frequency signal comprises the plurality of frames, and a third frame of the frames comprises a plurality of third detection signals, the power saving method further comprising:
capturing a fourth detection signal from the third detection signals, and detecting the target in the field according to the fourth detection signal.
15. The power saving method according to claim 12 , wherein the radio frequency signal comprises the plurality of frames, the power saving method further comprising:
adjusting a number of the frames according to the workload reduction information.
16. The power saving method according to claim 12 , wherein the radio frequency signal comprises the plurality of frames, the power saving method further comprising:
switching from the power saving mode to the normal working mode in response to the target being detected in the field, and restoring the workload of the frames in the normal working mode.
17. The power saving method according to claim 12 , further comprising:
generating a chirp signal according to a sweep cycle, wherein a frequency of the chirp signal changes with time within the sweep cycle, wherein the radio frequency signal comprises the plurality of frames, and at least one of the frames comprises the chirp signal;
demodulating the reflected signal according to the chirp signal to obtain an intermediate frequency signal; and
converting the intermediate frequency signal into digital data.
18. The power saving method according to claim 17 , wherein the step of detecting the target in the field according to the reflected signal comprises:
performing range FFT on the digital data to obtain at least one distance frequency; and
judging that the target is detected in the field in response to an amplitude value of the at least one distance frequency being greater than a first threshold value.
19. The power saving method according to claim 17 , wherein the step of detecting the target in the field according to the reflected signal comprises:
performing range FFT and Doppler FFT on the digital data to obtain at least one Doppler frequency; and
judging that the target is detected in the field in response to an amplitude value of the at least one Doppler frequency being greater than a second threshold value.