Stratum 1 PTP/NTP Server
A Raspberry Pi CM5 time server acting as a hardware-timestamped PTP (IEEE-1588) grandmaster and Stratum 1 NTP server, disciplined by a u-blox MAX-M8Q multi-GNSS receiver. Under the hood, the project utilizes jclark's Satpulse to turn raw satellite pulses into a steady clock, with ptp4l and chrony handling time distribution. This page shows live data pushed from the server, updated every ~30 seconds.
StratumDistance from the authoritative time source. Stratum 0 is a hardware clock (GPS in this case); stratum 1 means this server syncs directly from one.
1
Reference
GNSS
Leap
Normal
Successfully Synchronised to GPS
Last sync
30.0 s ago
fetched 0.0 s ago
Uptime
17d 15h 57m
Time service
Discipline status from chrony.
System offsetCurrent measured difference between this clock and its reference. Chrony continuously nudges the local clock to drive this toward zero.
+11.0 ns
rms 29.0 ns
goal ≈ 0
Root dispersionWorst-case estimated error accumulated across the chain back to the root reference clock.
5.24 µs
root delay 1.0 ns
goal < 1 ms
FrequencyHow fast or slow the local oscillator runs vs ideal, in parts-per-million. The value should be stable over time. Residual is the leftover frequency error in the selected source after chrony's compensation has been applied; once the regression converges it sits at or near zero, so a pinned-looking +0.000 ppm is the healthy state, not a stuck reading.
+3.260 ppm
residual +0.000 ppm
goal: stable
Time uncertainty1-sigma estimate of how far this clock is from true UTC: the rolling RMS of recent offset samples + drift accumulated since the last PPS update. Tracks the measured variability of the local clock relative to true UTC.
29 ns
last offset +7.0 ns
goal < 1 µs
System offset · last 24 h
Time uncertainty · last 24 h
PTP grandmaster
IEEE-1588 grandmaster on eth0, hardware-timestamped. Disciplined by SatPulse from the same GPS PPS as NTP.
Port stateptp4l port role from PORT_DATA_SET. MASTER means this box is actively serving PTP to the LAN as the grandmaster.
MASTER
ptp4l role on eth0
goal: MASTER
PHC offset (vs GNSS)NIC PHC offset from GNSS/PPS, disciplined by SatPulse.
4 ns
PHC vs GNSS/PPS
goal ≈ 0
Serving onptp4l distributes hardware-timestamped time over multicast on UDP 319/320.
UDP 319/320
hardware-timestamped · IEEE-1588
PHC offset (vs GNSS) · last 24 h
GPS & PPS
Reference clock health. PPS provides the nanosecond-level discipline; NMEA fixes provide the second-of-day.
Satellites used / visible
14 / 17
PPS pulsesPulse-per-second ticks from the GPS receiver. The hardware edge that provides nanosecond-level discipline; should arrive exactly once per second.
0.999 / s
30 in last 30 s
goal ≈ 1.000/s
GPS fixSolution quality from the GNSS receiver (via satpulsetool satellites): NO FIX / 2D / 3D. A 3D fix is required for accurate time.
3D fix
refId GNSS
goal: 3D
Satellites used / visible · last 24 h
usedvisible
Satellites by constellation · live
GPS — United States (USSF)
GLONASS — Russia (Roscosmos)
Galileo — European Union (EUSPA)
BeiDou — China (CSNO)
QZSS — Japan (JAXA / Cabinet Office)
NavIC — India (ISRO)
SBAS — regional augmentation (WAAS, EGNOS, MSAS, GAGAN)
used in fixvisible
PPS pulses · last 24 h
Signal quality
GNSS reception health: carrier-to-noise from used satellites and the four dilution-of-precision values.
Avg signal (CN0)Mean carrier-to-noise density of the satellites contributing to the current fix. Reflects antenna placement and sky view. Open-sky rooftops typically read 35-45 dB-Hz.
23.6 dB-Hz
across used satellites
goal ≥ 35 dB-Hz
Peak signal (CN0)Strongest carrier-to-noise reading among currently used satellites.
34.0 dB-Hz
strongest used sat
goal ≥ 40 dB-Hz
HDOPHorizontal Dilution of Precision: a unitless quality score for the current GPS satellite geometry. Lower means tighter fixes.
0.87
horizontal geometry
goal < 2
PDOPPosition Dilution of Precision: how the current satellite geometry amplifies the full 3D position-solution error.
1.63
position (3D) geometry
goal < 2
VDOPVertical Dilution of Precision: how satellite geometry amplifies altitude-solution error. Typically larger than HDOP because satellites are only above the horizon.
1.38
vertical geometry
goal < 2
TDOPTime Dilution of Precision: how the current satellite geometry amplifies clock-solution error.
0.89
time geometry
goal < 2
Avg signal (CN0) · last 24 h
Peak signal (CN0) · last 24 h
HDOP · last 24 h
VDOP · last 24 h
PDOP · last 24 h
TDOP · last 24 h
NTP service load
NTP-specific traffic counters from chrony (PTP is not counted here).
NTP packets servedTotal NTP queries this server has answered since boot. Grows continuously while clients are polling.
23,687
since boot
goal: steadily rising
Requests / sec
0.00/s
dropped 0
Avg requests / sec (24h)Average NTP requests per second across the last 24 hours, computed from the request-rate history series.
0.01/s
mean over last 24 h
Active client records
4
recent unique sources
Requests per second · last 24 h
Host
Raspberry Pi Compute Module 5 hardware telemetry.
CPU utilization
0.3%
load1 0.13
CPU temperature
40.3 °C
thermal zone 0
Memory used
5.2%
of 3.9 GB
Network
6.7 kbps
rx + tx in 30 s
CPU utilization · last 24 h
CPU temperature · last 24 h
Memory used · last 24 h
Network throughput · last 24 h
rxtx