record digital signal

[eddiec]

Hi All,

This is a newbie-q...

If I want to record an analog signal I can sample it, convert digital to analog and store the result in memory for playback. What happens if I want to record a digital signal where I do not know the frquency of the signal? It seems that I could do the same thing.. sample the signal quickly enough to get the right state change points (1 - 0 or 0 -1) accurately, then store the results in memory (like analog recording, just missing the d-a conversion.)

This way I don't need to know anything about the nature of the frequency, encryption etc etc, I can just record and playback. Is this the right approach for a microcontroller based digital signal recording system?

Thanks,

ec

 

[frankqt]

It is not that simple..
- You need to have an idea about the clock of the system, 1 and than 0 may well mean 111 and 000. Knowing the clock is also not enough you need to be able to recover the clock from the data stream since your internal clock and recorded clock may not be perfectly synced. You may need a PLL for this.

If you need to interpret the data, you need to know the encoding scheme as most of these signals are encoded, additional bits are padded for various purposes including clock recovery.