NTPsec

Backup/Meinberg

Report generated: Sat Jul 5 15:43:00 2025 UTC
Start Time: Sat Jun 28 15:43:00 2025 UTC
End Time: Sat Jul 5 15:43:00 2025 UTC
Report Period: 7.0 days

Daily stats   Weekly stats  

Local Clock Time/Frequency Offsets

local offset plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Time Offset -83.073 -53.141 -18.371 -3.423 25.015 107.677 165.087 43.386 160.818 20.832 -0.101 µs 2.698 20.56
Local Clock Frequency Offset 5.589 5.598 5.639 6.097 6.612 6.752 6.768 0.974 1.154 0.298 6.129 ppm 0.1469 2.161

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 0.344 0.467 0.549 0.813 2.509 6.938 12.232 1.960 6.471 1.040 1.069 µs 5.561 40.52

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 0.045 0.097 0.143 0.577 1.848 6.128 9.369 1.705 6.031 0.985 0.804 ppb 4.608 29.69

The RMS Frequency Jitter (aka wander) of the local clock's frequency. In other words, how fast the local clock changes frequency.

Lower is better. An ideal clock would be a horizontal line at 0ppm.

RMS Frequency Jitter is field 6 in the loopstats log file.



Local Clock Time Offset Histogram

local offset histogram plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Offset -83.073 -53.141 -18.371 -3.423 25.015 107.677 165.087 43.386 160.818 20.832 -0.101 µs 2.698 20.56

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Local Temperatures

local temps plot

Local temperatures. These will be site-specific depending upon what temperature sensors you collect data from. Temperature changes affect the local clock crystal frequency and stability. The math of how temperature changes frequency is complex, and also depends on crystal aging. So there is no easy way to correct for it in software. This is the single most important component of frequency drift.

The Local Temperatures are from field 3 from the tempstats log file.



Local Frequency/Temp

local freq temps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 5.589 5.598 5.639 6.097 6.612 6.752 6.768 0.974 1.154 0.298 6.129 ppm 0.1469 2.161
Temp /dev/sda 44.000 44.000 45.000 47.000 49.000 50.000 52.000 4.000 6.000 1.347 46.926 °C
Temp /dev/sdb 55.000 55.000 56.000 58.000 63.000 67.000 68.000 7.000 12.000 2.460 58.004 °C
Temp /dev/sdc 56.000 56.000 56.000 58.000 61.000 61.000 67.000 5.000 5.000 1.506 58.396 °C
Temp /dev/sdd 61.000 61.000 62.000 64.000 71.000 76.000 76.000 9.000 15.000 2.826 65.063 °C
Temp /dev/sdf 55.000 55.000 56.000 58.000 64.000 68.000 69.000 8.000 13.000 2.621 58.772 °C
Temp LM0 28.750 28.750 29.000 31.250 34.750 41.500 47.250 5.750 12.750 2.150 31.582 °C
Temp LM1 41.500 42.000 42.500 44.000 46.500 46.500 47.000 4.000 4.500 1.215 44.323 °C
Temp LM10 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM11 44.000 44.000 45.000 47.000 49.000 50.000 52.000 4.000 6.000 1.347 46.926 °C
Temp LM12 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM13 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM14 30.000 30.000 30.250 32.500 35.500 38.000 41.750 5.250 8.000 1.767 32.781 °C
Temp LM15 55.000 55.000 56.000 58.000 64.000 69.000 69.000 8.000 14.000 2.631 58.939 °C
Temp LM16 61.000 61.000 61.500 63.500 66.000 69.500 71.500 4.500 8.500 1.648 63.810 °C
Temp LM17 61.000 62.000 63.000 65.000 72.000 76.000 77.000 9.000 14.000 2.795 65.282 °C
Temp LM18 55.000 55.000 56.000 58.000 63.000 68.000 68.000 7.000 13.000 2.495 58.164 °C
Temp LM19 27.000 28.000 28.000 30.000 34.000 67.000 80.000 6.000 39.000 4.937 31.174 °C
Temp LM2 33.000 33.000 33.000 36.000 38.000 38.000 41.000 5.000 5.000 1.386 35.640 °C
Temp LM20 26.000 27.000 28.000 30.000 34.000 65.000 80.000 6.000 38.000 4.762 30.699 °C
Temp LM21 24.000 25.000 25.000 28.000 31.000 61.000 76.000 6.000 36.000 4.588 28.494 °C
Temp LM22 25.000 26.000 27.000 30.000 34.000 60.000 73.000 7.000 34.000 4.464 30.531 °C
Temp LM23 26.000 27.000 27.000 29.000 33.000 59.000 72.000 6.000 32.000 4.160 30.014 °C
Temp LM3 31.500 31.500 32.000 34.500 37.000 37.500 37.500 5.000 6.000 1.642 34.432 °C
Temp LM4 24.000 24.000 24.000 24.000 24.000 24.000 24.000 0.000 0.000 0.000 24.000 °C
Temp LM5 30.500 30.500 30.500 30.500 30.500 30.500 30.500 0.000 0.000 0.000 30.500 °C
Temp LM6 61.000 61.000 61.000 63.000 66.000 69.000 71.000 5.000 8.000 1.704 63.522 °C
Temp LM7 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM8 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM9 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp ZONE0 26.000 27.000 28.000 30.000 34.000 67.000 81.000 6.000 40.000 5.006 30.873 °C
Temp ZONE1 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp ZONE2 61.000 61.500 61.500 63.500 66.000 69.500 71.500 4.500 8.000 1.645 63.812 °C
Temp ZONE3 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C

The frequency offsets and temperatures. Showing frequency offset (red, in parts per million, scale on right) and the temperatures.

These are field 4 (frequency) from the loopstats log file, and field 3 from the tempstats log file.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 2001:470:e815::8 (spidey.rellim.com)

peer offset 2001:470:e815::8 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:e815::8 (spidey.rellim.com) -628.529 -410.700 -160.463 30.480 180.966 481.323 611.053 341.429 892.023 134.889 24.429 µs 0.001095 7.236

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 204.17.205.1

peer offset 204.17.205.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.1 -2.187 -0.946 -0.496 0.022 0.565 1.144 1.509 1.061 2.090 0.361 0.011 ms -0.5004 9.715

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 204.17.205.24

peer offset 204.17.205.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.24 -107.163 -46.087 -14.880 48.260 88.343 151.802 247.142 103.223 197.889 34.045 45.045 µs 0.3142 7.028

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 204.17.205.27

peer offset 204.17.205.27 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.27 -238.745 -56.557 -1.659 46.606 94.314 148.900 469.461 95.973 205.457 36.514 46.201 µs 0.8087 19.71

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset SHM(0)

peer offset SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(0) -83.074 -53.142 -18.372 -3.424 25.016 107.678 165.088 43.388 160.820 20.833 -0.101 µs 2.697 20.56

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Jitters

peer jitters plot

The RMS Jitter of all refclocks and servers. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2001:470:e815::8 (spidey.rellim.com)

peer jitter 2001:470:e815::8 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 0.810 2.921 4.752 12.924 58.799 83.973 145.768 54.047 81.052 17.971 20.078 µs 1.924 7.173

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 204.17.205.1

peer jitter 204.17.205.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.1 1.831 3.783 5.265 12.226 32.104 70.366 182.247 26.839 66.583 12.670 15.197 µs 5.166 44.45

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 204.17.205.24

peer jitter 204.17.205.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.24 1.355 4.088 6.192 23.862 87.602 131.465 226.158 81.410 127.377 25.784 30.490 µs 2.571 11.86

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 204.17.205.27

peer jitter 204.17.205.27 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.27 0.968 3.210 4.879 11.646 43.764 97.599 167.034 38.885 94.389 16.672 16.684 µs 3.859 23.27

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter SHM(0)

peer jitter SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(0) 0.158 0.373 0.566 1.887 6.688 25.656 67.163 6.122 25.283 4.637 2.889 µs 7.305 70.95

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 5.589 5.598 5.639 6.097 6.612 6.752 6.768 0.974 1.154 0.298 6.129 ppm 0.1469 2.161
Local Clock Time Offset -83.073 -53.141 -18.371 -3.423 25.015 107.677 165.087 43.386 160.818 20.832 -0.101 µs 2.698 20.56
Local RMS Frequency Jitter 0.045 0.097 0.143 0.577 1.848 6.128 9.369 1.705 6.031 0.985 0.804 ppb 4.608 29.69
Local RMS Time Jitter 0.344 0.467 0.549 0.813 2.509 6.938 12.232 1.960 6.471 1.040 1.069 µs 5.561 40.52
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 0.810 2.921 4.752 12.924 58.799 83.973 145.768 54.047 81.052 17.971 20.078 µs 1.924 7.173
Server Jitter 204.17.205.1 1.831 3.783 5.265 12.226 32.104 70.366 182.247 26.839 66.583 12.670 15.197 µs 5.166 44.45
Server Jitter 204.17.205.24 1.355 4.088 6.192 23.862 87.602 131.465 226.158 81.410 127.377 25.784 30.490 µs 2.571 11.86
Server Jitter 204.17.205.27 0.968 3.210 4.879 11.646 43.764 97.599 167.034 38.885 94.389 16.672 16.684 µs 3.859 23.27
Server Jitter SHM(0) 0.158 0.373 0.566 1.887 6.688 25.656 67.163 6.122 25.283 4.637 2.889 µs 7.305 70.95
Server Offset 2001:470:e815::8 (spidey.rellim.com) -628.529 -410.700 -160.463 30.480 180.966 481.323 611.053 341.429 892.023 134.889 24.429 µs 0.001095 7.236
Server Offset 204.17.205.1 -2.187 -0.946 -0.496 0.022 0.565 1.144 1.509 1.061 2.090 0.361 0.011 ms -0.5004 9.715
Server Offset 204.17.205.24 -107.163 -46.087 -14.880 48.260 88.343 151.802 247.142 103.223 197.889 34.045 45.045 µs 0.3142 7.028
Server Offset 204.17.205.27 -238.745 -56.557 -1.659 46.606 94.314 148.900 469.461 95.973 205.457 36.514 46.201 µs 0.8087 19.71
Server Offset SHM(0) -83.074 -53.142 -18.372 -3.424 25.016 107.678 165.088 43.388 160.820 20.833 -0.101 µs 2.697 20.56
Temp /dev/sda 44.000 44.000 45.000 47.000 49.000 50.000 52.000 4.000 6.000 1.347 46.926 °C
Temp /dev/sdb 55.000 55.000 56.000 58.000 63.000 67.000 68.000 7.000 12.000 2.460 58.004 °C
Temp /dev/sdc 56.000 56.000 56.000 58.000 61.000 61.000 67.000 5.000 5.000 1.506 58.396 °C
Temp /dev/sdd 61.000 61.000 62.000 64.000 71.000 76.000 76.000 9.000 15.000 2.826 65.063 °C
Temp /dev/sdf 55.000 55.000 56.000 58.000 64.000 68.000 69.000 8.000 13.000 2.621 58.772 °C
Temp LM0 28.750 28.750 29.000 31.250 34.750 41.500 47.250 5.750 12.750 2.150 31.582 °C
Temp LM1 41.500 42.000 42.500 44.000 46.500 46.500 47.000 4.000 4.500 1.215 44.323 °C
Temp LM10 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM11 44.000 44.000 45.000 47.000 49.000 50.000 52.000 4.000 6.000 1.347 46.926 °C
Temp LM12 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM13 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM14 30.000 30.000 30.250 32.500 35.500 38.000 41.750 5.250 8.000 1.767 32.781 °C
Temp LM15 55.000 55.000 56.000 58.000 64.000 69.000 69.000 8.000 14.000 2.631 58.939 °C
Temp LM16 61.000 61.000 61.500 63.500 66.000 69.500 71.500 4.500 8.500 1.648 63.810 °C
Temp LM17 61.000 62.000 63.000 65.000 72.000 76.000 77.000 9.000 14.000 2.795 65.282 °C
Temp LM18 55.000 55.000 56.000 58.000 63.000 68.000 68.000 7.000 13.000 2.495 58.164 °C
Temp LM19 27.000 28.000 28.000 30.000 34.000 67.000 80.000 6.000 39.000 4.937 31.174 °C
Temp LM2 33.000 33.000 33.000 36.000 38.000 38.000 41.000 5.000 5.000 1.386 35.640 °C
Temp LM20 26.000 27.000 28.000 30.000 34.000 65.000 80.000 6.000 38.000 4.762 30.699 °C
Temp LM21 24.000 25.000 25.000 28.000 31.000 61.000 76.000 6.000 36.000 4.588 28.494 °C
Temp LM22 25.000 26.000 27.000 30.000 34.000 60.000 73.000 7.000 34.000 4.464 30.531 °C
Temp LM23 26.000 27.000 27.000 29.000 33.000 59.000 72.000 6.000 32.000 4.160 30.014 °C
Temp LM3 31.500 31.500 32.000 34.500 37.000 37.500 37.500 5.000 6.000 1.642 34.432 °C
Temp LM4 24.000 24.000 24.000 24.000 24.000 24.000 24.000 0.000 0.000 0.000 24.000 °C
Temp LM5 30.500 30.500 30.500 30.500 30.500 30.500 30.500 0.000 0.000 0.000 30.500 °C
Temp LM6 61.000 61.000 61.000 63.000 66.000 69.000 71.000 5.000 8.000 1.704 63.522 °C
Temp LM7 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM8 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM9 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp ZONE0 26.000 27.000 28.000 30.000 34.000 67.000 81.000 6.000 40.000 5.006 30.873 °C
Temp ZONE1 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp ZONE2 61.000 61.500 61.500 63.500 66.000 69.500 71.500 4.500 8.000 1.645 63.812 °C
Temp ZONE3 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Summary as CSV file


This server:

CPU: Quad core Intel Xeon E3-1241 v3
Kernel: config.gz
Motherboard: Supermicro X10SAE
OS: Gentoo stable
GPS; Meinberg GPS180PEX
GPS/PPS server: gpsd
NTP server: NTPsec
ntp.conf: current
ntp.log: current

Notes:

Notes:
03:20Z 20 Dec 2018 Change poll from 8s to 4s.  4s seems best.
01:30Z 20 Dec 2018 Change poll from 2s to 8s.
23:00Z 20 Dec 2018 Change poll from 4s to 2s.
22:00Z 20 Dec 2018 Change poll from 64s to 4s.
21:40  19 Dec 2018 -- just started

Poll:
64s   SHM(0) offset StdDev 34.5 us, jitter 5.3 us
8s    8s better jitter than 4s, but worse offset than 4s
4s    SHM(0) offset mean 0 ns StdDev 481 ns, jitter 449 ns StdDev 250 ns
      better than 2s, almost unstable
2s    




Glossary:

frequency offset:
The difference between the ntpd calculated frequency and the local system clock frequency (usually in parts per million, ppm)
jitter, dispersion:
The short term change in a value. NTP measures Local Time Jitter, Refclock Jitter, and Server Jitter in seconds. Local Frequency Jitter is in ppm or ppb.
ms, millisecond:
One thousandth of a second = 0.001 seconds, 1e-3 seconds
mu, mean:
The arithmetic mean: the sum of all the values divided by the number of values. The formula for mu is: "mu = (∑xi) / N". Where xi denotes the data points and N is the number of data points.
ns, nanosecond:
One billionth of a second, also one thousandth of a microsecond, 0.000000001 seconds and 1e-9 seconds.
percentile:
The value below which a given percentage of values fall.
ppb, parts per billion:
Ratio between two values. These following are all the same: 1 ppb, one in one billion, 1/1,000,000,000, 0.000,000,001, 1e-9 and 0.000,000,1%
ppm, parts per million:
Ratio between two values. These following are all the same: 1 ppm, one in one million, 1/1,000,000, 0.000,001, and 0.000,1%
‰, parts per thousand:
Ratio between two values. These following are all the same: 1 ‰. one in one thousand, 1/1,000, 0.001, and 0.1%
refclock:
Reference clock, a local GPS module or other local source of time.
remote clock:
Any clock reached over the network, LAN or WAN. Also called a peer or server.
time offset:
The difference between the ntpd calculated time and the local system clock's time. Also called phase offset.
σ, sigma:
Sigma denotes the standard deviation (SD) and is centered on the arithmetic mean of the data set. The SD is simply the square root of the variance of the data set. Two sigma is simply twice the standard deviation. Three sigma is three times sigma. Smaller is better.
The formula for sigma is: "σ = √[ ∑(xi-mu)^2 / N ]". Where xi denotes the data points and N is the number of data points.
Skewness, Skew:
The skewness of a random variable X is the third standardized moment and is a dimension-less ratio. ntpviz uses the FIsher-Pearson moment of skewness. There are other different ways to calculate Skewness Wikipedia describes Skewness best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
Kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses standard Kurtosis. There are other different ways to calculate Kurtosis.
A normal distribution has a Kurtosis of three. NIST describes a kurtosis over three as "heavy tailed" and one under three as "light tailed".
upstream clock:
Any server or reference clock used as a source of time.
µs, us, microsecond:
One millionth of a second, also one thousandth of a millisecond, 0.000,001 seconds, and 1e-6 seconds.



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