StarLink as source for NTP
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@Gertjan Starlink dishes do have gps receivers in them, and they do serve GPS time to the network.
The issue is the NTP client in pfsense doesn’t work properly to read that time. Chronyd does work but it’s an unsupported add-on at this point. I’m getting my network time from my Starlink dish gps receiver right now and it’s very accurate as expected.
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@Gertjan The StarLink receiver being a stratum 1 NTP time server is in the first post of the thread.
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The Starlink dish itself a Stratum 1 time source. But it's operating in "the new world of GPS time" and pfSense is yet to catch up. I'm sure they will. The gent from NTP posted the issue if you read enough of this thread.
Here is the output when using the local dish through the Galleon utility.
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@Ramosel said in StarLink as source for NTP:
operating in "the new world of GPS time"
I believe the ntpd issue has to do with nuances of newer versions of the NTP protocol rather than GPS.
FWIW, the Galleon test app looks to be pretty broken. A precision of 2.26156424291633E+74 is clearly wrong.
If you are running chrony, you can ask it directly what the advertised precision of a source is. Try
chronyc ntpdata 192.168.100.1and look forPrecision. I would expect to see something in the range of -14 (61us) to -24 (61ns). -
@dennypage mine is
Precision : -25 (0.000000030 seconds)
Well shoot clearly my clocks are going to be way out ;)
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Not that amazing here; from my Starlink I get, via chronyc ntpdata using the command page on pfSense:
Precision : -9 (0.001953125 seconds)Interesting. I wonder why it's so different that what you expect or what Johnpoz reported.
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@johnpoz said in StarLink as source for NTP:
Precision : -25 (0.000000030 seconds)
Interesting -- what is the source?
Some people (companies) use -25 and justify it because the GNSS chip they are using says <= 30ns. However, the precision statement should be about the entire system rather than just the GNSS. To really be -25, you really need to have <= 20ns on the GNSS chip itself, and a very deterministic microcode implementation or high resolution hardware timestamping on each step of the process.
I have a few real -24s and -25s, and one -26. I'd really like to have a -27, but am not sure I'll get there. I have a reference timing chip that is reliable <= 5ns, but don't have the hardware to put with it. Sad, sad, sad.
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@Mission-Ghost said in StarLink as source for NTP:
@dennypage
Not that amazing here; from my Starlink I get, via chronyc ntpdata using the command page on pfSense:Precision : -9 (0.001953125 seconds)Interesting. I wonder why it's so different that what you expect or what Johnpoz reported.
To me that indicates unexpected honesty on the part of StarLink. Based on the number I'm guessing that they are using their carrier signal to communicate time rather than some form of embedded GNSS.
And to be honest, I expect 2ms is sufficient for 99% of home users.
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@dennypage said in StarLink as source for NTP:
And to be honest, I expect 2ms is sufficient for 99% of home users.
LOL.. most home user oven clocks are >5 minutes off..
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If they included ntp in the oven you wouldn't have these issues. Accuracy baked in.
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@dennypage the Starlink device knows where it is using GPS as the default locating technology, but there is a configuration item to use its own positioning system instead. I've always used the default GPS. It's NTP server reports it as stratum 1. Here's the rest of my pfSense's chronyc ntpdata from Starlink's (Gen 3 dish):
Remote address : 192.168.100.1 (C0A86401) Remote port : 123 Local address : 100.[redacted] Leap status : Normal Version : 4 Mode : Server Stratum : 1 Poll interval : 0 (1 seconds) Precision : -9 (0.001953125 seconds) Root delay : 0.000000 seconds Root dispersion : 0.000000 seconds Reference ID : 00000000 () Reference time : Sat Oct 03 22:35:19 2026 Offset : -0.000059627 seconds Peer delay : 0.001953174 seconds Peer dispersion : 0.001953174 seconds Response time : 0.000061035 seconds Jitter asymmetry: -0.50 NTP tests : 111 111 1111 Interleaved : No Authenticated : No TX timestamping : Daemon RX timestamping : Kernel Total TX : 1735 Total RX : 1735 Total valid RX : 1735 Total good RX : 1546 Total kernel TX : 0 Total kernel RX : 1735 Total HW TX : 0 Total HW RX : 0Starlink used to furnish access to the GPS location data, but they shut that feature down for reasons.
I'm not a time wonk like johnpoz or Jeff Geerling, but accurate time is fascinating and the Starlink GPS clock is good enough for my network.
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@dennypage said in StarLink as source for NTP:
Interesting -- what is the source?
oh my bad that was my ntp server reporting on one of the ntp servers I use as alternate source to pps
When I look on one of my clients I get what my ntp server 192.168.3.32 reports
Remote address : 192.168.3.32 (C0A80320) Remote port : 123 Local address : 192.168.3.10 (C0A8030A) Leap status : Normal Version : 4 Mode : Server Stratum : 1 Poll interval : 8 (256 seconds) Precision : -24 (0.000000060 seconds) Root delay : 0.000015 seconds Root dispersion : 0.000015 seconds Reference ID : 50505300 (PPS) Reference time : Sat Oct 03 22:56:58 2026 Offset : +0.000042164 seconds Peer delay : 0.000732688 seconds Peer dispersion : 0.000000112 seconds Response time : 0.000168404 seconds Jitter asymmetry: +0.00 NTP tests : 111 111 1111 Interleaved : No Authenticated : No TX timestamping : Kernel RX timestamping : Kernel Total TX : 2121 Total RX : 2121 Total valid RX : 2121 Total good RX : 2121 root@pihole:/home/pi# -
@dennypage said in StarLink as source for NTP:
I believe the ntpd issue has to do with nuances of newer versions of the NTP protocol rather than GPS.
FWIW, the Galleon test app looks to be pretty broken. A precision of 2.26156424291633E+74 is clearly wrong.
Absolutely. Galleon is just an easy utility to check GPS function... it's old and there is probably an update I just haven't gone looking for. It was posted for function and NOT usability.
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@stephenw10 said in StarLink as source for NTP:
If they included ntp in the oven you wouldn't have these issues
A dream of mine...
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@Mission-Ghost said in StarLink as source for NTP:
Starlink device knows where it is using GPS as the default locating technology, but there is a configuration item to use its own positioning system instead
Gross positioning for pointing a dish (very narrow band, narrow target area) is easy. Accurate timing isn't. Different kind of antenna to begin with... It's rather difficult in many situations.
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@dennypage said in StarLink as source for NTP:
Gross positioning for pointing a dish (very narrow band, narrow target area) is easy. Accurate timing isn't. Different kind of antenna to begin with... It's rather difficult in many situations.
But IIUC, Starlink is a low-orbit-satellite-constellation system too. They're going to be using an omnidirectional-or-close-to-it antenna, which should be plenty serviceable for GPS. If they were using geosynchronous satellites I'd agree with you, not gonna be the right antenna configuration.
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@tgl said in StarLink as source for NTP:
They're going to be using an omnidirectional-or-close-to-it antenna
Correct... it's phased array.
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@tgl said in StarLink as source for NTP:
Starlink is a low-orbit-satellite-constellation system too. They're going to be using an omnidirectional-or-close-to-it antenna, which should be plenty serviceable for GPS. If they were using geosynchronous satellites I'd agree with you, not gonna be the right antenna configuration.
FWIW, StarLink is a LEO constellation at around 500km, however the GNSS systems are MEO constellations. The lowest GNSS constellation (GLONAS) is around 19,000km, and the highest (Galileo) is around 23,000km. In addition to the MEO satellites, a few of them, BeiDou (China), QZSS (Japan) and NavIC (India) also have GEO components at 35,000km.
A bit of quick research suggests that the StarLink units do indeed have a low end GPS receiver, but that GPS is only used for initial satellite acquisition. After that, they use their own position and timing capabilities. There is a lot of research speculation that if SpaceX would just "tighten up" their implementation, StarLink could be used as an alternative to existing GNSS systems.
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