6 ms·

In the spirit of a 1990s time server is I also got Timelord + Tardis working (time service over AppleTalk, tested on a Mac SE/30, courtesy of netatalk) and test

In the spirit of a 1990s time server is I also got Timelord + Tardis working (time service over AppleTalk, tested on a Mac SE/30, courtesy of netatalk) and tested multiple NTPv1, NTPv3, and NTPv4 clients through this (and soon an Xserve G5). It's less about getting the 1995 hardware working, and more about rebuilding the actual time server to serve the original purpose, for the next 5-10 years at least. I'm planning on using this chassis to build up an NTP Stratum 1 server for the global NTP pool, hopefully later this year. I thought it would be a lot more fun than letting the box go to e-waste. And leaving the guts completely untouched means I can do a full restoration someday, if I want. The two main things I'd need to do: 1. Modify the RF chain so I can use normal GPS antennas that don't down-convert the frequency. 2. Modify the DC bias voltage so it doesn't fry GPS antennas. After that, I could work on patching firmware, but I'd probably just use the original guts as a frequency reference and leave time to other hardware. I could even run the Pi and the old hardware simultaneously. The old hardware providing IRIG-B, 10 MHz, and 1 PPS references that are a little more accurate (it has a TCXO, haven't measured its timing accuracy yet). And the Pi could provide PTP and NTP, using a more modern GPS chip which even supports dual band and survey-in for more accuracy.

anitil 10d ago
I thought it was a fun video (the first I've watched of yours, though I read the blog). And I'd honestly forgotten about the Telstra outage even though it was news here
ssl-3 9d ago
Or option C? I'm spitballing a bit, but it looks like an absolutely-correct antenna for your clock might be a Symmetricom 140-615. There's a couple (literally two) on the ebay right now that look minty-fresh; they're not the cheapest things, but they're cheap compared to many other things in the low-volume RF world. :) If that's the right antenna (just because I think it is doesn't mean that you should agree), then that would certainly simplify the RF side of the project. No hardware mods required at all. It takes 12v and does internal downconversion to the right frequencies. After that, you only have the daunting task of patching firmware -- if it turns out (from testing) that it patching is even required. (IIRC, you speculated in the video that it might already be patched and I don't disagree with that outlook at all.) Both legs of this thing represent interesting projects. I find that time is strangely rewarding to get exactly-right even when that doesn't really matter for the application at-hand. It's a good kind of weird. (I really need to fire up my own little GPS-sourced Pi Zero NTP server some day soon. Chasing temperature-based clock deviations on that was actually kind of fun.)

anitil 10d ago

I thought it was a fun video (the first I've watched of yours, though I read the blog). And I'd honestly forgotten about the Telstra outage even though it was news here

ssl-3 9d ago

Or option C? I'm spitballing a bit, but it looks like an absolutely-correct antenna for your clock might be a Symmetricom 140-615. There's a couple (literally two) on the ebay right now that look minty-fresh; they're not the cheapest things, but they're cheap compared to many other things in the low-volume RF world. :) If that's the right antenna (just because I think it is doesn't mean that you should agree), then that would certainly simplify the RF side of the project. No hardware mods required at all. It takes 12v and does internal downconversion to the right frequencies. After that, you only have the daunting task of patching firmware -- if it turns out (from testing) that it patching is even required. (IIRC, you speculated in the video that it might already be patched and I don't disagree with that outlook at all.) Both legs of this thing represent interesting projects. I find that time is strangely rewarding to get exactly-right even when that doesn't really matter for the application at-hand. It's a good kind of weird. (I really need to fire up my own little GPS-sourced Pi Zero NTP server some day soon. Chasing temperature-based clock deviations on that was actually kind of fun.)