USE OF FREQUENCY OFFSETS IN GENERATION OF LIDAR DATA
A LIDAR system includes a light source that outputs an outgoing LIDAR signal that includes multiple different channels. The LIDAR system also generate multiple composite light signals that each carries a signal couple and are each associated with a different one of the channels. A signal couple includes a reference signal and an associated comparative signal. The comparative signals each include light from the outgoing LIDAR signal that has been reflected by one or more objects located outside of the LIDAR system. The reference signals also include light from the outgoing LIDAR signal but also exclude light that has been reflected by any object located outside of the LIDAR system. There is a frequency differential between a frequency of the reference signal and a frequency of the associated comparative signal. The frequency differential includes a contribution from a frequency offset that is induced by electronics. The electronics induce the frequency offset such that the frequency offset is different for each signal couple.
1 . A system, comprising:
a LIDAR system that includes a light source configured to output an outgoing LIDAR signal,
the LIDAR system being configured to generate multiple composite light signals that each carries at least a signal couple, a signal couple including a reference signal and an associated comparative signal, each signal couple being associated with a different channel,
the comparative signals each including light from the outgoing LIDAR signal that has been reflected by one or more objects located outside of the LIDAR system and the reference signals each including light from the outgoing LIDAR signal but excluding light that has been reflected by any object located outside of the LIDAR system; and
electronics configured to induce a frequency offset for at least a portion of the signal couples,
the frequency offset for a signal couple being a differential between a frequency of the comparative signal and a frequency of the reference signal included in the signal couple, and
the frequency offset being different for each signal couple.
2 . The system of claim 1 , wherein the channels are a linear function of wavelength and can be sequentially numbered with a channel index such that the frequency differential is a linear function of the channel index,
the channel index including channel indices that are integers and are increased by a value of 1 for different channels.
3 . The system of claim 1 , wherein light included in the reference signal and in the associated comparative signal was generated by the same laser.
4 . The system of claim 1 , wherein each signal pair has a non-zero frequency differential.
5 . The system of claim 1 , wherein the frequency offset introduced by the electronics is a portion of a total frequency differential between the comparative signal and the reference signal included in each signal pair.
6 . The system of claim 5 , wherein a portion of the total frequency differential is induced by a distance between the LIDAR system and the one or more objects located outside of the LIDAR system.
7 . The system of claim 1 , wherein the LIDAR system outputs multiple LIDAR output signals that each carries one of the channels,
the comparative signals each including light from a different one of the LIDAR output signals.
8 . The system of claim 7 , wherein the LIDAR output signals have a frequency versus time pattern that is repeated over sequential cycles.
9 . The system of claim 8 , wherein each cycle includes multiple data periods and the frequency versus time pattern is the same for corresponding data periods in different cycles.
10 . The system of claim 9 , wherein one or more of the data periods includes an output period and a feedback period, a rate of a frequency change in the LIDAR output signals being the same during the output period and the feedback period of the same data period.
11 . The system of claim 10 , wherein an offset period is present between the output period and the feedback period in each data period that is included in the one or more data periods, the frequency of the LIDAR output signal changing by the frequency offset during the offset period.
12 . The system of claim 11 , wherein for at least a portion of the LIDAR output signals, each cycle includes multiple data periods and each data period includes an offset period between the output period and the feedback period.
13 . The system of claim 11 , wherein the electronics are configured to generate LIDAR data from signal pairs that occur during the feedback periods but not during the output periods.