Low power mode of operation for mm-wave radar

1. A method comprising:

transmitting, by a radar system in a first mode, a first transmission that includes a first frame and a second frame temporally separated by a first sleep time interval;

receiving, by the radar system in the first mode, a first reflected signal based on the first transmission;

detecting an object based on the first reflected signal;

in response to the detecting of the object, transitioning the radar system to a second mode;

transmitting, by the radar system in the second mode, a second transmission that includes a third frame and a fourth frame temporally separated by a second sleep time interval;

receiving, by the radar system in the second mode, a second reflected signal based on the second transmission; and

determining an attribute of the object based on the second reflected signal, wherein the first mode is different from the second mode in at least one of: a duration of the first frame and the second frame compared to a duration of the third frame and the fourth frame or the first sleep time interval compared to the second sleep time interval.

2. The method of claim 1 , wherein the attribute includes at least one of: a range of the object, a velocity of the object, or an angle of the object.

3. The method of claim 1 , wherein the first sleep time interval is longer than the second sleep time interval.

4. The method of claim 1 , wherein the duration of the first frame and the second frame is shorter than the duration of the third frame and the fourth frame.

5. The method of claim 1 further comprising determining the attribute of the object from the first reflected signal prior to the determining of the attribute of the object from the second reflected signal.

6. The method of claim 1 , wherein the attribute of the object includes a range of the object and the method further comprises changing at least one of the first sleep time interval or the second sleep time interval based on the range of the object.

7. The method of claim 1 further comprising, in response to determining that the object is no longer within a threshold range, transitioning the radar system from the second mode to the first mode.

8. The method of claim 1 , wherein:

the detecting of the object includes amplifying the first reflected signal using a set of amplifiers according to a first gain setting; and

the determining of the attribute of the object includes amplifying the second reflected signal using the set of amplifiers according to a second gain setting that is different from the first gain setting.

9. The method of claim 8 , wherein the first and second gain settings are such that:

the set of amplifiers operating according to the first gain setting has a first noise figure; and

the set of amplifiers operating according to the second gain setting has a second noise figure that is greater than the first noise figure.

10. The method of claim 8 , wherein the first and second gain settings are such that:

the set of amplifiers operating according to the first gain setting has a first linearity; and

the set of amplifiers operating according to the second gain setting has a second linearity that is greater than the first linearity.

11. A device comprising:

a processor;

a transmitter circuit coupled to the processor; and

a receiver circuit coupled to the processor, wherein the processor is configured to:

operate in a first mode to:

control the transmitter circuit to transmit a first set of frames such that frames of the first set of frames are separated by a first sleep time interval;

receive, via the receiver circuit, a first reflected signal based on the first set of frames;

detect an object based on the first reflected signal; and

in response to the detection of the object, transition from the first mode to a second mode; and

operate in the second mode to:

control the transmitter circuit to transmit a second set of frames such that frames of the first set of frames are separated by a second sleep time interval;

receive, via the receiver circuit, a second reflected signal based on the second set of frames; and

determine an attribute of the object based on the second reflected signal, wherein the first mode is different from the second mode in at least one of: a frame duration of first set of frames compared to a frame duration of the second set of frames or the first sleep time interval compared to the second sleep time interval.

12. The device of claim 11 , wherein the attribute includes at least one of: a range of the object, a velocity of the object, or an angle of the object.

13. The device of claim 11 , wherein the first sleep time interval is longer than the second sleep time interval.

14. The device of claim 11 , wherein the frame duration of the first set of frames is shorter than the frame duration of the second set of frames.

15. The device of claim 11 , wherein the attribute of the object includes a range of the object and the processor is configured to change at least one of the first sleep time interval or the second sleep time interval based on the range of the object.

16. A device comprising:

a processor;

a transmitter circuit coupled to the processor; and

a receiver circuit coupled to the processor that includes a set of amplifiers, wherein the processor is configured to:

control the transmitter circuit to transmit a first set of frames;

receive, via the receiver circuit, a first reflected signal based on the first set of frames by amplifying the first reflected signal using the set of amplifiers according to a first gain setting;

detect an object based on the first reflected signal;

control the transmitter circuit to transmit a second set of frames;

receive, via the receiver circuit, a second reflected signal based on the second set of frames by amplifying the second reflected signal using the set of amplifiers according to a second gain setting that is different from the first gain setting; and

determine an attribute of the object based on the second reflected signal.

17. The device of claim 16 , wherein the processor is operable to cause the set of amplifiers to amplify the second reflected signal according to the second gain setting based on the detection of the object based on the first reflected signal.

18. The device of claim 16 , wherein the first and second gain settings are such that:

the set of amplifiers operating according to the first gain setting has a first noise figure; and

the set of amplifiers operating according to the second gain setting has a second noise figure that is greater than the first noise figure.

19. The device of claim 16 , wherein the first and second gain settings are such that:

the set of amplifiers operating according to the first gain setting has a first linearity; and

the set of amplifiers operating according to the second gain setting has a second linearity that is greater than the first linearity.

20. The device of claim 16 , wherein the attribute includes at least one of: a range of the object, a velocity of the object, or an angle of the object.