Comment by ck2
11 hours ago
BTW with self-driving cars, what happens when there are hundreds of Lidar signals at one intersection?
There's no way a sensor can tell if a signal was from its own origin?
Guessing any signal should be treated as untrusted until verified somehow
but I suspect coders won't be doing that unless it's easy
> There's no way a sensor can tell if a signal was from its own origin?
https://ui.adsabs.harvard.edu/abs/1978ntc.....2...18F/abstra...
https://apps.dtic.mil/sti/tr/pdf/ADA218226.pdf
> An increasingly popular modulation scheme is Binary Pseudo Random Phase Coding (BPRPC), whereby the phase of the transmitted signal is switched between 0 and 180 under the control of a binary pseudo random sequence
this applies straightforwardly to lidar
basically: optical CDMA or DSSS
spoofing replay may still be a concern
Typically you use a pulse train and filter your train from the noise
If one lidar hits another, it will result in at most one bad reading (perhaps a bad column?). This can likely be filtered, or a bad scan (360deg) can be altogether rejected and the data predicted using models based on past sensor readings.
Worked adjacent to the AV space 5~ years ago. This wasn’t my area but I remember learning that this was a robustly solved problem long ago.
I guess phase and timing sensitivity help a lot, because it's unlikely that another emitter will perfectly match your emission/detection duty cycle. It's also hard to get hundreds of cars at one intersection, because cars are very big.
The key terms in your literature/patent search should probably be "Crosstalk" and "multi-LIDaR".