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Out of complete curiosity, and knowing nothing about these technologies:

How does these system avoid interference with other cars? Say if ten exact same car, with the exact same model of LIDAR are on the same street / crossing. Can I expect some noise being received by the sensor?



Yep. Every sensor will receive the output from the other emitters. This problem is actually pretty similar to the problem of sharing the wireless signal spectrum - how do all the cell phones in one area work at the same time? There's a few standard approaches to solving these problems:

- Frequency Division: each detector uses a different frequency/wavelength. This approach is very simple to implement, but the usable range of wavelengths for LIDAR is fairly narrow. So we'd run out of choices pretty quickly.

- Time Division: each detector is allocated a different operating time slot, so that only one is active at a time. For cell phones, this is relatively easy to implement because they all connect to a central system that can coordinate the timing. But for cars, this would be more difficult since there's no central system that links the detectors on different cars together (although they could still communicate with each other through other means).

- Code Division: each detector's output is pulsed in a unique pattern so that the reflected signals will return that same pattern, then the processor can reject any patterns that it didn't send out. This approach is much more complex, but doesn't suffer from many of the drawbacks of the other solutions.

Code division is by far the most widely used approach here, but frequency and time division also play a small role as well since different manufacturers/detectors use different wavelengths and not all detectors are being operated at exactly the same time (the time needed to send and receive a single signal is extremely short).


thanks!




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