search

montoyatim01 / TimTime

Open Source Timecode Lock Box
1 stars 0 forks source link

Time tracking accuracy? #1

Open mungewell opened 2 years ago

mungewell commented 2 years ago

Found the project and it looks very interesting, gave the schems/layout a quick review and only see the 19.2MHz XTAL.

What level of time accuracy are you able to keep, once the "jamming master" has been removed?

montoyatim01 commented 2 years ago

Hey, thanks for checking out the project! At this point in time this is all very much a work in progress, so I'm still tinkering with the design a bit and writing out all of the firmware. But I have several other "prototype" units I've built using the same hardware that I've been able to run some tests on. After calibration, I've been able to maintain ~+-1 frame over 24 hours. The only reference I have currently to test against are other lock boxes with similar accuracy though, so my results are relatively anecdotal. That being said, for the XTAL I'm using a 7P-19.200MBP-T which should be +- 0.28ppm according to DigiKey and the datasheet. Though again I don't necessarily have a way to easily test that, short of maybe letting it run for several days/weeks.

mungewell commented 2 years ago

Cool. Is your project for fun, or do you have plans to sell units?

I started to get interested in LTC last year, and I was using Linux box with Chrony and the LTC-Utils project to monitor a LTC feed from a Sync-IO (that I picked up cheap on E-Bay). It's pretty trival to set up a PC NTP'ed and then monitor the delta between that and LTC. Though I'm not sure what 'absolute' accuracy that gives you.

I've since got my hands on some Evertz gear, the 5300 Time Code Analyzer. Interestingly this has a phase indication of LTC vs VITC. I've still got to work out how to log it's serial port, but I believe that it will give me a good way to check my (future) project...

montoyatim01 commented 2 years ago

Mostly for fun/my own uses, but I have toyed around with the idea of selling some assembled and ready to go units. Everything will obviously be up in the repository so anyone else will be able to make the exact same thing.

Also as kind of a separate side project (and to help with this one) I've been looking into GPS-locked timecode. Something to where I can either use GPS time to generate timecode, or use GPS to correct a free-running timecode. I'd use that as my reference to determine the drift/accuracy of these lock boxes.