NTPsec

Backup/Meinberg

Report generated: Wed Jul 2 15:43:00 2025 UTC
Start Time: Wed Jun 25 15:43:00 2025 UTC
End Time: Wed Jul 2 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 -82.105 -45.579 -16.308 -2.768 24.929 112.233 201.689 41.237 157.812 21.027 0.835 µs 3.53 27.33
Local Clock Frequency Offset 5.589 5.598 5.632 5.964 6.612 6.752 6.768 0.981 1.154 0.316 6.026 ppm 0.6882 2.396

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 0.357 0.475 0.553 0.825 2.591 8.768 14.587 2.038 8.293 1.295 1.125 µs 5.768 41.4

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 0.090 0.132 0.566 1.881 6.203 10.354 1.749 6.113 1.018 0.783 ppb 5.042 34.72

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 -82.105 -45.579 -16.308 -2.768 24.929 112.233 201.689 41.237 157.812 21.027 0.835 µs 3.53 27.33

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 5.632 5.964 6.612 6.752 6.768 0.981 1.154 0.316 6.026 ppm 0.6882 2.396
Temp /dev/sda 44.000 44.000 45.000 46.000 49.000 50.000 51.000 4.000 6.000 1.442 46.492 °C
Temp /dev/sdb 55.000 55.000 55.000 57.000 63.000 67.000 68.000 8.000 12.000 2.623 57.746 °C
Temp /dev/sdc 56.000 56.000 56.000 58.000 61.000 61.000 67.000 5.000 5.000 1.632 57.835 °C
Temp /dev/sdd 61.000 61.000 62.000 64.000 72.000 76.000 76.000 10.000 15.000 2.988 64.770 °C
Temp /dev/sdf 55.000 55.000 56.000 58.000 64.000 68.000 69.000 8.000 13.000 2.770 58.479 °C
Temp LM0 28.750 28.750 29.000 30.750 34.000 38.500 50.000 5.000 9.750 2.127 31.202 °C
Temp LM1 41.500 42.000 42.000 44.000 46.500 46.500 47.000 4.500 4.500 1.276 44.084 °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 46.000 49.000 50.000 51.000 4.000 6.000 1.442 46.491 °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 32.000 35.500 37.250 41.750 5.250 7.250 1.792 32.417 °C
Temp LM15 55.000 55.000 56.000 58.000 64.000 69.000 69.000 8.000 14.000 2.801 58.635 °C
Temp LM16 61.000 61.000 61.500 63.000 66.000 69.500 71.500 4.500 8.500 1.727 63.424 °C
Temp LM17 61.000 62.000 62.000 64.000 72.000 76.000 77.000 10.000 14.000 2.987 64.959 °C
Temp LM18 55.000 55.000 55.000 57.000 63.000 68.000 68.000 8.000 13.000 2.662 57.913 °C
Temp LM19 27.000 27.000 28.000 30.000 34.000 45.000 98.000 6.000 18.000 4.803 30.675 °C
Temp LM2 33.000 33.000 33.000 35.000 38.000 38.000 41.000 5.000 5.000 1.424 35.307 °C
Temp LM20 26.000 27.000 27.000 29.000 34.000 39.000 98.000 7.000 12.000 4.677 30.213 °C
Temp LM21 24.000 25.000 25.000 27.000 31.000 39.000 97.000 6.000 14.000 4.365 28.069 °C
Temp LM22 25.000 26.000 27.000 29.000 34.000 44.000 94.000 7.000 18.000 4.429 29.774 °C
Temp LM23 26.000 26.000 27.000 29.000 33.000 45.000 89.000 6.000 19.000 4.008 29.774 °C
Temp LM3 31.500 31.500 32.000 34.000 37.000 37.500 37.500 5.000 6.000 1.657 34.149 °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 1.768 63.136 °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 29.000 34.000 46.000 97.000 6.000 19.000 4.838 30.374 °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 63.000 66.000 69.500 71.500 4.500 8.000 1.722 63.425 °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) -736.808 -362.581 -166.567 18.308 155.307 474.063 611.053 321.874 836.644 126.003 9.543 µs -0.2413 9.916

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 -0.614 -0.369 0.015 0.407 1.144 1.509 0.776 1.758 0.317 0.008 ms -0.7363 14.76

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 -39.111 -8.875 49.590 88.119 176.803 264.740 96.994 215.914 33.862 47.364 µs 0.8528 9.473

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 -452.224 -102.218 -1.901 47.343 99.769 184.766 469.461 101.670 286.984 44.713 46.451 µs -1.52 29.91

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) -82.106 -45.580 -16.309 -2.769 24.930 112.234 201.690 41.239 157.814 21.028 0.835 µs 3.529 27.32

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 2.758 4.805 13.901 61.411 84.724 145.768 56.606 81.966 18.965 21.537 µs 1.737 6.298

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 1.719 3.604 5.023 11.546 28.389 60.722 182.247 23.366 57.118 11.694 14.043 µs 5.986 58.29

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 1.905 4.010 6.062 23.372 82.691 127.999 226.158 76.629 123.989 24.550 29.121 µs 2.763 13.67

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 3.181 4.689 11.512 50.190 117.596 252.022 45.501 114.415 20.361 17.456 µs 4.471 30.55

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) 0.170 0.385 0.578 1.946 6.705 36.224 76.131 6.127 35.839 5.815 3.115 µs 7.274 64.68

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 5.632 5.964 6.612 6.752 6.768 0.981 1.154 0.316 6.026 ppm 0.6882 2.396
Local Clock Time Offset -82.105 -45.579 -16.308 -2.768 24.929 112.233 201.689 41.237 157.812 21.027 0.835 µs 3.53 27.33
Local RMS Frequency Jitter 0.045 0.090 0.132 0.566 1.881 6.203 10.354 1.749 6.113 1.018 0.783 ppb 5.042 34.72
Local RMS Time Jitter 0.357 0.475 0.553 0.825 2.591 8.768 14.587 2.038 8.293 1.295 1.125 µs 5.768 41.4
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 0.810 2.758 4.805 13.901 61.411 84.724 145.768 56.606 81.966 18.965 21.537 µs 1.737 6.298
Server Jitter 204.17.205.1 1.719 3.604 5.023 11.546 28.389 60.722 182.247 23.366 57.118 11.694 14.043 µs 5.986 58.29
Server Jitter 204.17.205.24 1.905 4.010 6.062 23.372 82.691 127.999 226.158 76.629 123.989 24.550 29.121 µs 2.763 13.67
Server Jitter 204.17.205.27 0.968 3.181 4.689 11.512 50.190 117.596 252.022 45.501 114.415 20.361 17.456 µs 4.471 30.55
Server Jitter SHM(0) 0.170 0.385 0.578 1.946 6.705 36.224 76.131 6.127 35.839 5.815 3.115 µs 7.274 64.68
Server Offset 2001:470:e815::8 (spidey.rellim.com) -736.808 -362.581 -166.567 18.308 155.307 474.063 611.053 321.874 836.644 126.003 9.543 µs -0.2413 9.916
Server Offset 204.17.205.1 -2.187 -0.614 -0.369 0.015 0.407 1.144 1.509 0.776 1.758 0.317 0.008 ms -0.7363 14.76
Server Offset 204.17.205.24 -107.163 -39.111 -8.875 49.590 88.119 176.803 264.740 96.994 215.914 33.862 47.364 µs 0.8528 9.473
Server Offset 204.17.205.27 -452.224 -102.218 -1.901 47.343 99.769 184.766 469.461 101.670 286.984 44.713 46.451 µs -1.52 29.91
Server Offset SHM(0) -82.106 -45.580 -16.309 -2.769 24.930 112.234 201.690 41.239 157.814 21.028 0.835 µs 3.529 27.32
Temp /dev/sda 44.000 44.000 45.000 46.000 49.000 50.000 51.000 4.000 6.000 1.442 46.492 °C
Temp /dev/sdb 55.000 55.000 55.000 57.000 63.000 67.000 68.000 8.000 12.000 2.623 57.746 °C
Temp /dev/sdc 56.000 56.000 56.000 58.000 61.000 61.000 67.000 5.000 5.000 1.632 57.835 °C
Temp /dev/sdd 61.000 61.000 62.000 64.000 72.000 76.000 76.000 10.000 15.000 2.988 64.770 °C
Temp /dev/sdf 55.000 55.000 56.000 58.000 64.000 68.000 69.000 8.000 13.000 2.770 58.479 °C
Temp LM0 28.750 28.750 29.000 30.750 34.000 38.500 50.000 5.000 9.750 2.127 31.202 °C
Temp LM1 41.500 42.000 42.000 44.000 46.500 46.500 47.000 4.500 4.500 1.276 44.084 °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 46.000 49.000 50.000 51.000 4.000 6.000 1.442 46.491 °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 32.000 35.500 37.250 41.750 5.250 7.250 1.792 32.417 °C
Temp LM15 55.000 55.000 56.000 58.000 64.000 69.000 69.000 8.000 14.000 2.801 58.635 °C
Temp LM16 61.000 61.000 61.500 63.000 66.000 69.500 71.500 4.500 8.500 1.727 63.424 °C
Temp LM17 61.000 62.000 62.000 64.000 72.000 76.000 77.000 10.000 14.000 2.987 64.959 °C
Temp LM18 55.000 55.000 55.000 57.000 63.000 68.000 68.000 8.000 13.000 2.662 57.913 °C
Temp LM19 27.000 27.000 28.000 30.000 34.000 45.000 98.000 6.000 18.000 4.803 30.675 °C
Temp LM2 33.000 33.000 33.000 35.000 38.000 38.000 41.000 5.000 5.000 1.424 35.307 °C
Temp LM20 26.000 27.000 27.000 29.000 34.000 39.000 98.000 7.000 12.000 4.677 30.213 °C
Temp LM21 24.000 25.000 25.000 27.000 31.000 39.000 97.000 6.000 14.000 4.365 28.069 °C
Temp LM22 25.000 26.000 27.000 29.000 34.000 44.000 94.000 7.000 18.000 4.429 29.774 °C
Temp LM23 26.000 26.000 27.000 29.000 33.000 45.000 89.000 6.000 19.000 4.008 29.774 °C
Temp LM3 31.500 31.500 32.000 34.000 37.000 37.500 37.500 5.000 6.000 1.657 34.149 °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 1.768 63.136 °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 29.000 34.000 46.000 97.000 6.000 19.000 4.838 30.374 °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 63.000 66.000 69.500 71.500 4.500 8.000 1.722 63.425 °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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