Devices, systems, and methods for radar-based artificial reality tracking

1. A radar system comprising:

a radar mechanism comprising at least one transmitter and at least one receiver;

a signal generator that generates a frequency-modulated radar signal; and

at least one frequency multiplier that, after multiplying a frequency of the frequency-modulated radar signal by a certain factor, synchronously passes the frequency-modulated radar signal to at least:

the transmitter to be transmitted to at least one transponder located on a wearable device; and

a processing device communicatively coupled to the receiver, wherein:

the frequency-modulated radar signal as received by the transmitter is in phase with the frequency-modulated radar signal as received by the processing device; and

the processing device:

detects a signal returned to the receiver from the transponder in response to the frequency-modulated radar signal; and

calculates a distance between the transponder and the receiver based at least in part on an analysis of the signal returned from the transponder and the frequency-modulated radar signal received from the frequency multiplier.

2. The radar system of claim 1 , further comprising an additional wearable device that secures at least:

the transmitter;

the receiver;

the signal generator; and

the frequency multiplier.

3. The radar system of claim 2 , wherein the receiver comprises a plurality of receivers that are secured to the additional wearable device such that each of the plurality of receivers are separated by at least a certain distance.

4. The radar system of claim 3 , wherein the processing device comprises a plurality of processing devices that are each communicatively coupled to one of the plurality of receivers.

5. The radar system of claim 4 , wherein the frequency multiplier comprises a plurality of frequency multipliers that each synchronously pass the frequency-modulated radar signal to one of the plurality of processing devices.

6. The radar system of claim 4 , wherein:

the plurality of receivers each receive the signal returned from the transponder in response to the frequency-modulated radar signal; and

each of the plurality of processing devices calculates a distance between the transponder and the receiver communicatively coupled to the processing device.

7. The radar system of claim 1 , wherein the frequency multiplier comprises at least:

a first frequency multiplier positioned between the signal generator and the processing device; and

a second frequency multiplier positioned between the signal generator and the transmitter.

8. The radar system of claim 1 , wherein the processing device calculates the distance between the transponder and the receiver based at least in part on calculating a beat frequency that:

corresponds to a difference between an instantaneous frequency of the frequency-modulated radar signal received at the processing device and an instantaneous frequency of the signal returned from the transponder; and

is proportional to the distance between the transponder and the receiver.

9. The radar system of claim 1 , wherein the frequency-modulated radar signal traverses a greater distance between the signal generator and the frequency multiplier than between the frequency multiplier and the transmitter.

10. The radar system of claim 1 , further comprising a power amplifier that:

is positioned between the frequency multiplier and the transmitter;

receives the frequency-modulated radar signal from the frequency multiplier; and

after amplifying a power level of the frequency-modulated radar signal by a certain amount, passes the frequency-modulated radar signal to the transmitter.

11. The radar system of claim 1 , further comprising a delay mechanism that:

is positioned between the signal generator and the frequency multiplier;

receives the frequency-modulated radar signal from the signal generator; and

after a certain period of delay, passes the frequency-modulated radar signal to the transmitter.

12. The radar system of claim 1 , wherein the processing device further determines, based at least in part on the distance between the transponder and the receiver, a current three-dimensional location of at least a portion of a user wearing the wearable device.

13. The radar system of claim 12 , wherein:

the processing device further passes the current three-dimensional location of the portion of the user to an artificial reality system that provides virtual content to the user; and

the artificial reality system modifies at least one virtual component of the artificial reality system to account for the current three-dimensional location of the portion of the user.

14. An artificial reality system comprising:

a radar mechanism comprising at least one transmitter and at least one receiver;

a signal generator that generates a frequency-modulated radar signal; and

at least one frequency multiplier that, after multiplying a frequency of the frequency-modulated radar signal by a certain factor, synchronously passes the frequency-modulated radar signal to at least:

the transmitter to be transmitted to at least one transponder located on a wearable device; and

a processing device communicatively coupled to the receiver, wherein:

the frequency-modulated radar signal as received by the transmitter is in phase with the frequency-modulated radar signal as received by the processing device; and

the processing device:

detects a signal returned to the receiver from the transponder in response to the frequency-modulated radar signal; and

calculates a distance between the transponder and the receiver based at least in part on an analysis of the signal returned from the transponder and the frequency-modulated radar signal received from the frequency multiplier.

15. The artificial reality system of claim 14 , further comprising an additional wearable device that secures at least:

the transmitter;

the receiver;

the signal generator; and

the frequency multiplier.

16. The artificial reality system of claim 15 , wherein the receiver comprises a plurality of receivers that are secured to the additional wearable device such that each of the plurality of receivers are separated by at least a certain distance.

17. The artificial reality system of claim 16 , wherein the processing device comprises a plurality of processing devices that are each communicatively coupled to one of the plurality of receivers.

18. The artificial reality system of claim 17 , wherein the frequency multiplier comprises a plurality of frequency multipliers that each synchronously pass the frequency-modulated radar signal to one of the plurality of processing devices.

19. A method comprising:

generating a frequency-modulated radar signal;

passing the frequency-modulated radar signal to at least one frequency multiplier that, after multiplying a frequency of the frequency-modulated radar signal by a certain factor, synchronously passes the frequency-modulated radar signal to at least:

a transmitter to be transmitted to at least one transponder located on a wearable device; and

a processing device communicatively coupled to a receiver, wherein the frequency-modulated radar signal as received by the transmitter is in phase with the frequency-modulated radar signal as received by the processing device;

detecting a signal returned to the receiver from the transponder in response to the frequency-modulated radar signal; and

calculating a distance between the transponder and the receiver based at least in part on an analysis of the signal returned from the transponder and the frequency-modulated radar signal received from the frequency multiplier.