Yes, people attack particular techniques. If you have the system to play with then they can be developed. For reasonable applications where there is little benefit to be had in spoofing them I am not too worried. The bigger issues are pure cilvil liberties and design/implementation bias. There was some fuss recently when it turned out the big new development at Kings Cross had been lending out CCTV to the police for facial recognition purposes.
Back to the OP device, I suspect that signal noise would mean that a long loop back to the sameness point would not be closed. However, as a toy giving a record of the dive it might be fun.
Back to the OP device, I suspect that signal noise would mean that a long loop back to the sameness point would not be closed. However, as a toy giving a record of the dive it might be fun.