
The Raspberry Pi as a Stratum-1 NTP Server - virtualsue
https://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html
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stephen-mw
I just built one of these. It's fun to have a little computer that can
synchronize highly accurate time without an internet connection by listening
to things in outer space!

I built an auto-install script that anyone here is welcome to use or
reference[1]. If you know what you're doing, just change the GPIO pin to your
PPS input and fire away.

Unlike the author I used Chrony instead of NTP. It's lighter-weight and much
easier to configure with a PPS/GPS reference clock.

The GPS chip I used was an ATGM336H, which can be had for less than $8 on
ebay. I'm able to lock consistently 11 satellites from my desk[2]

Keep in mind the Pi has no hw RTC. If you're doing this for fun spend a few
more bucks and buy an rtc chip from ebay so you don't drift considerably
between being powered off.

1\. [https://github.com/stephen-
mw/raspberrypi/blob/master/roles/...](https://github.com/stephen-
mw/raspberrypi/blob/master/roles/stratum_1_timeserver/install)

2\.
[https://www.ebay.com/sch/i.html?_from=R40&_nkw=ATGM336H&_sac...](https://www.ebay.com/sch/i.html?_from=R40&_nkw=ATGM336H&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15)

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glenneroo
I had one of these running with a 10 meter cable to the window so the receiver
could get enough satellites. After 24/7 for about a year it just died and I
haven't had time to figure out what's wrong. Lights blink but it's not
reachable via ping, ssh or scp. HDMI output shows nothing. I had to move on to
other projects, so I gave up and assumed I either got hacked or I hit the
cheap-SD-card problem of corruption that seems to plague other users running
their Pi continuously for longer periods.

I've started buying SanDisk's "High Endurance" microSD cards hoping it will
mitigate any such issues in the future, but I haven't had time to get the NTP
set up again... I really should have cloned the image.

I think the hardest part was finding a case with space for the GPS hat[0] with
an open end for the coax connector. The hat sits a bit crooked because of
something bulbous on top (condensator?).

[0]:
[https://store.uputronics.com/index.php?route=product/product...](https://store.uputronics.com/index.php?route=product/product&product_id=81&search=GPS+Expansion+Board+)

~~~
steve19
I wonder how much the rpi foundation would need to sell a pi if it included
32gb of storage. I would gladly pay not to feel like I'm playing roulette with
my microsd.

~~~
copperx
They just need to make booting from a USB drive easy. Plug in a $20 SSD and
stop worrying about reliability.

~~~
bigiain
They're working on it: [https://www.raspberrypi.org/blog/pi-3-booting-part-i-
usb-mas...](https://www.raspberrypi.org/blog/pi-3-booting-part-i-usb-mass-
storage-boot/)

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jwildeboer
Maybe add [2012] to the title, dear mods?

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Jaruzel
Off topic: I love this couples website. If you click through to the homepage
they've got lots of stuff to browse.

Yes, it maybe old-style, but it's these sort of sites that the internet was
originally built on. It's a real shame that they are becoming a dying breed.

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cremp
> Configuring Wi-Fi

That alone will negate _any_ benefit of running a stratum 1. You lose the
precision and accuracy over wifi. Jitter on intranet with the pi as a
timesource would be magnitudes greater than the GPS link.

~~~
johnklos
Not exactly. Sometimes it's more helpful to have a local time source that you
know is accurate but has a little jitter than to have a remote time source
with intermittent Internet.

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epynonymous
this is pretty cool. i was looking at your case, could you tell me the exact
model case you were using? i couldn't find the exact model on modmypi.

also, here's a writeup i did on my experiences creating something with an rpi
3 model b+:

[https://github.com/stephenhu/written/blob/master/raspberrypi...](https://github.com/stephenhu/written/blob/master/raspberrypi.md)

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skykooler
What is the use case for microsecond-accurate timekeeping?

~~~
cremp
I've done it; and my primary argument to family and friends is time attack
vectors.

The real reason though, is because I can, and I like saying my computers are
more accurate and precise than their phones.

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homero
I built a nixie tube clock like that with a gps receiver, it works amazingly

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tramtrist
They still haven't separated the USB/Ethernet Bus :/

~~~
makomk
This is also possible with the Orange Pi/NanoPi boards which have actual
Ethernet that doesn't go over USB, though I don't think there's such a good
writeup of how to do that.

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berbec
This would be a perfect case for a NanoPi Neo. [1] It's designed to be ultra-
tiny and run headless. It's also $13. I find FriendlyElec's board better
designed and supported than Orange by a bit and miles above the Banana folks.

1:
[https://www.friendlyarm.com/index.php?route=product/product&...](https://www.friendlyarm.com/index.php?route=product/product&path=69&product_id=132)

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gsich
Are there performance differences regarding Pi 1/2/3?

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abraham_lincoln
Yes, very much so.

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gsich
Do you have some numbers?

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mwambua
The biggest factor is that each generation of the Pi has gotten a better
processor (700Mhz single-core in the original Pi to a 1.4Ghz quad-core in the
3B+). There are also a number of detailed benchmarks out there if you bother
to Google it.

~~~
gsich
Especially in the context of a stratum 1?

