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by Joel_Mckay 801 days ago
If you are running Bind or SSL/x.509 certs, than an RTC is pretty much a requirement on the raspberry pi. Network time leaps over NTP even when working (first big leap was allowed etc.) can still bork a lot of services.

Local stratum 1 GPS time (even with PPS pin) servers based on Pi's can suffer similar issues when they lose satellite lock (weather etc.)

Have a great day =)
1 comments
hcfman 801 days ago
Having said that, I've never personally seen my stratum #1 Pi loose sync due to weather and I run about 4 of em here. I also use a cheap 7 euro ublox 7m. So long as you position it or an antennae with a reasonable view of the sky that shouldn't happen I reckon.

Why all the complex solutions when it's so easy and cheap now to install a stratum #1 time server, even a Pi 3 will suffice. It works on a Pi Zero, but then you only have a wifi link.

The sbts-au project make's it incredibly easy to setup. git lone and then install. One command, it's that simple.

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teruakohatu 801 days ago
Any advice for a cheap USB GPS for a stratum #1 time server?

EDIT: Any any advice on how essential PPS is?

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Joel_Mckay 801 days ago
The PPS can be good (pi kernel support is stable), but one needs to be careful as some modules PPS signal has a great deal of instability.

Some U-Blox modules support the additional ground based navigation signal and cellular beacons. This is recommended in addition to the 3 satellite networks classes, but note some modules will not work with some antennas (get the unified hardware with built in antenna/lna if unsure about RF notes).

Best regards, =)

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hcfman 801 days ago
If you have good sky visibility, then I don't need an antenna. Though this often tends to mean putting a Pi outside. I'm also using just the first Antenna I find actually.
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hcfman 801 days ago
I have good results with cheap ublox 6m's and 7m's from aliexpress. For some reason the 8m's I got were poor in sensitivity.

Adafruit ones also work great, but are a lot mor expensive, I do have several though.

PPS is criticial to proper timing. However... I was using the time synched systems for sound localization. But as they only cost around 7 euros on aliexpress, why not.

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