Re:Open Source Time-of-Flight DIY Lidar
by regularfry on Thursday March 12, 2020 @08:52AM
(#22556248)
Yeah, I'm just not clear on how to go from that theory to practice in this case. Like, could you do it with this specific photoamplifier, or would you need something very different? Are we immediately into FPGA territory to get enough processing speed, or is there something you can do with the delay lines to have the same effect?
You basically do AM of the laser, and then otherwise normal baseband radar processing. You don't need much bandwidth, but more bandwidth needs less SNR, as you can do superresolution if you have sufficient SNR.
There is no need for an FPGA, but you will rather quickly throw FFT correlation processing at it.
This would not use any delay lines. You'd just need to lock the sampling of your ADC to the signal generation, because 2ns jitter are 30cm/1ft jitter in distance.
Peak power vs. SNR favours pseudorandom sequences with a peaky autocorrelation function. In practice, an LFSR is typical, but if you use e.g. AES-CTR, you can get quite a lot of resilience against (intentional) jamming and be potentially undetectable as long as the sensor doesn't move directly into the beam.