Firstly I just want to say I have next to 0 electronics knowledge so if I say something dumb I apologize.
I am wanting to make a device which outputs a 1 pps square wave signal that is highly accurate over the course of 60 mins. I don't want the timing of the signal to be off by more than 1-2 ms each hour but less error is better, so an accuracy of ~0.1 ppm would be ideal.
The intended use is to send the PPS signal to a DAQ device which is time-agnostic, to provide it with an accurate clock while the DAQ is recording. The DAQ's reported sample rate isn't accurate, but if I have a signal that represents accurate time I can get a more accurate estimate of sample rate by comparing the number of samples with the time elapsed between two samples I know to be X time apart. The DAC can record the square wave signal input, so I wish to use the rising edge of each pulse in the recording to mark a sample as 1 second elapsed from the previous rising edge sample. The DAQ's sample rate is ~30000 Hz, and if the time I estimate each sample to have occurred is off by more than 10 ms then the collected data becomes at best a lot more difficult to analyze, and at worst unusable hence why I'd like ~0.1 ppm accuracy. Although I probably can't know the exact sample rate as it does drift slightly over time, I do know it's usually around 29998-30002 Hz on average over an hour, and that the sample rate is consistent enough over this period that having the average rate over the hour is sufficient for my analysis.
I should add that this all needs to be set up in a room that cannot receive GPS signal, so GPS modules aren't feasible. Also for what it's worth, the entire set up will just remain in a room that probably doesn't ever vary in temperature by more than 5°C.
Right now I have two main questions.
- Would using a TCXO be appropriate for this purpose? Or otherwise what should I be looking into that might be better suited? I started off looking at the Adafruit DS3231 RTC but I was told the TCXO it uses is relatively low quality and I should look into other ones.
- I would need to convert the output signal from a TCXO to a 1pps signal. Is this the kind of thing I should be looking at to accomplish this? http://www.leapsecond.com/pic/picdiv.htm
Update: I'm going to mark this as answered because at the very least I've been given a lot to think about, but definitely have got some more clarity on this problem now as well. thanks all