NTPsec

Backup/Meinberg

Report generated: Tue Oct 22 18:33:01 2024 UTC
Start Time: Mon Oct 21 18:33:00 2024 UTC
End Time: Tue Oct 22 18:33:00 2024 UTC
Report Period: 1.0 days
Warning: plots clipped

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 -99.978 -82.667 -49.039 -2.028 41.684 76.555 132.777 90.723 159.222 28.493 -1.199 µs -4.103 12.02
Local Clock Frequency Offset 1.538 1.594 1.634 1.923 2.189 2.208 2.226 0.554 0.614 0.175 1.928 ppm 1033 1.065e+04

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 9.995 11.235 14.617 30.864 51.696 58.663 61.390 37.079 47.428 11.038 32.201 µs 13.11 40.6

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 5.258 5.893 8.204 14.689 27.389 39.500 45.069 19.185 33.607 6.532 16.211 ppb 8.908 30.29

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 -99.978 -82.667 -49.039 -2.028 41.684 76.555 132.777 90.723 159.222 28.493 -1.199 µs -4.103 12.02

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 1.538 1.594 1.634 1.923 2.189 2.208 2.226 0.554 0.614 0.175 1.928 ppm 1033 1.065e+04
Temp /dev/sda 43.000 43.000 43.000 45.000 46.000 46.000 46.000 3.000 3.000 0.957 44.636 °C
Temp /dev/sdb 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.106 56.752 °C
Temp /dev/sdc 54.000 54.000 54.000 56.000 58.000 58.000 58.000 4.000 4.000 1.569 55.643 °C
Temp /dev/sdd 60.000 60.000 61.000 63.000 71.000 71.000 71.000 10.000 11.000 3.737 64.091 °C
Temp /dev/sde 43.000 43.000 43.000 44.000 48.000 48.000 48.000 5.000 5.000 1.736 44.668 °C
Temp /dev/sdf 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.070 57.091 °C
Temp LM0 27.500 27.500 27.750 29.250 31.250 33.500 36.250 3.500 6.000 1.252 29.492 °C
Temp LM1 40.000 40.000 40.500 41.500 42.000 42.500 44.000 1.500 2.500 0.545 41.260 °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 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM12 43.000 43.000 43.000 45.000 46.000 46.000 46.000 3.000 3.000 0.954 44.636 °C
Temp LM13 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM14 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM15 28.500 28.750 28.750 30.250 32.000 32.250 33.750 3.250 3.500 1.030 30.466 °C
Temp LM16 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.066 57.164 °C
Temp LM17 60.000 60.000 60.500 62.500 66.000 66.000 66.000 5.500 6.000 1.865 62.795 °C
Temp LM18 61.000 61.000 61.000 63.000 71.000 71.000 71.000 10.000 10.000 3.709 64.266 °C
Temp LM19 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.103 56.811 °C
Temp LM2 43.000 43.000 43.000 44.000 48.000 48.000 48.000 5.000 5.000 1.751 44.650 °C
Temp LM20 26.000 26.000 27.000 29.000 31.000 37.000 57.000 4.000 11.000 2.332 28.864 °C
Temp LM21 25.000 25.000 26.000 28.000 31.000 36.000 52.000 5.000 11.000 2.185 28.479 °C
Temp LM22 24.000 24.000 25.000 27.000 29.000 35.000 49.000 4.000 11.000 2.145 26.871 °C
Temp LM23 25.000 25.000 25.000 27.000 31.000 36.000 57.000 6.000 11.000 2.473 27.874 °C
Temp LM24 25.000 25.000 26.000 28.000 31.000 35.000 53.000 5.000 10.000 2.245 28.252 °C
Temp LM3 32.000 32.000 32.000 33.000 34.000 35.000 36.000 2.000 3.000 0.679 33.189 °C
Temp LM4 30.000 30.000 30.000 32.000 32.500 33.000 33.500 2.500 3.000 0.709 31.635 °C
Temp LM5 24.000 24.000 24.000 24.000 24.000 24.000 24.000 0.000 0.000 0.000 24.000 °C
Temp LM6 26.000 26.000 26.500 28.000 30.500 36.000 57.000 4.000 10.000 2.306 28.425 °C
Temp LM7 60.000 60.000 60.000 62.000 66.000 66.000 66.000 6.000 6.000 1.922 62.552 °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 26.000 26.000 28.000 31.000 36.000 57.000 5.000 10.000 2.373 28.654 °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 60.000 60.000 60.500 62.500 66.000 66.000 66.500 5.500 6.000 1.872 62.790 °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) -391.091 -323.061 -106.256 47.524 127.701 174.673 237.805 233.957 497.734 88.385 27.000 µs -4.107 15.52

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 -961.331 -869.209 -269.202 133.836 389.046 554.119 581.781 658.248 1,423.328 262.988 81.527 µs -3.587 11.66

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 -138.543 -109.198 -64.581 -4.636 48.650 129.460 165.803 113.231 238.658 36.813 -5.068 µs -4.481 13.89

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 -271.944 -77.668 -38.505 8.034 60.305 99.826 251.936 98.810 177.494 39.058 8.926 µs -3.29 24.38

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) 0.787 2.587 4.608 13.166 36.234 59.651 84.978 31.626 57.064 11.084 15.857 µs 3.627 15.93

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 3.332 5.246 7.276 16.022 45.760 69.136 108.473 38.484 63.890 12.730 19.727 µs 4.151 18.33

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 2.780 4.019 6.828 20.767 59.538 101.081 3,390.758 52.710 97.062 196.029 36.730 µs 13.94 238.8

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 1.631 2.659 4.478 13.808 43.854 99.154 126.125 39.376 96.495 15.408 18.044 µs 3.489 17.64

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 1.538 1.594 1.634 1.923 2.189 2.208 2.226 0.554 0.614 0.175 1.928 ppm 1033 1.065e+04
Local Clock Time Offset -99.978 -82.667 -49.039 -2.028 41.684 76.555 132.777 90.723 159.222 28.493 -1.199 µs -4.103 12.02
Local RMS Frequency Jitter 5.258 5.893 8.204 14.689 27.389 39.500 45.069 19.185 33.607 6.532 16.211 ppb 8.908 30.29
Local RMS Time Jitter 9.995 11.235 14.617 30.864 51.696 58.663 61.390 37.079 47.428 11.038 32.201 µs 13.11 40.6
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 0.787 2.587 4.608 13.166 36.234 59.651 84.978 31.626 57.064 11.084 15.857 µs 3.627 15.93
Server Jitter 204.17.205.1 3.332 5.246 7.276 16.022 45.760 69.136 108.473 38.484 63.890 12.730 19.727 µs 4.151 18.33
Server Jitter 204.17.205.24 2.780 4.019 6.828 20.767 59.538 101.081 3,390.758 52.710 97.062 196.029 36.730 µs 13.94 238.8
Server Jitter 204.17.205.27 1.631 2.659 4.478 13.808 43.854 99.154 126.125 39.376 96.495 15.408 18.044 µs 3.489 17.64
Server Offset 2001:470:e815::8 (spidey.rellim.com) -391.091 -323.061 -106.256 47.524 127.701 174.673 237.805 233.957 497.734 88.385 27.000 µs -4.107 15.52
Server Offset 204.17.205.1 -961.331 -869.209 -269.202 133.836 389.046 554.119 581.781 658.248 1,423.328 262.988 81.527 µs -3.587 11.66
Server Offset 204.17.205.24 -138.543 -109.198 -64.581 -4.636 48.650 129.460 165.803 113.231 238.658 36.813 -5.068 µs -4.481 13.89
Server Offset 204.17.205.27 -271.944 -77.668 -38.505 8.034 60.305 99.826 251.936 98.810 177.494 39.058 8.926 µs -3.29 24.38
Temp /dev/sda 43.000 43.000 43.000 45.000 46.000 46.000 46.000 3.000 3.000 0.957 44.636 °C
Temp /dev/sdb 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.106 56.752 °C
Temp /dev/sdc 54.000 54.000 54.000 56.000 58.000 58.000 58.000 4.000 4.000 1.569 55.643 °C
Temp /dev/sdd 60.000 60.000 61.000 63.000 71.000 71.000 71.000 10.000 11.000 3.737 64.091 °C
Temp /dev/sde 43.000 43.000 43.000 44.000 48.000 48.000 48.000 5.000 5.000 1.736 44.668 °C
Temp /dev/sdf 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.070 57.091 °C
Temp LM0 27.500 27.500 27.750 29.250 31.250 33.500 36.250 3.500 6.000 1.252 29.492 °C
Temp LM1 40.000 40.000 40.500 41.500 42.000 42.500 44.000 1.500 2.500 0.545 41.260 °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 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM12 43.000 43.000 43.000 45.000 46.000 46.000 46.000 3.000 3.000 0.954 44.636 °C
Temp LM13 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM14 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM15 28.500 28.750 28.750 30.250 32.000 32.250 33.750 3.250 3.500 1.030 30.466 °C
Temp LM16 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.066 57.164 °C
Temp LM17 60.000 60.000 60.500 62.500 66.000 66.000 66.000 5.500 6.000 1.865 62.795 °C
Temp LM18 61.000 61.000 61.000 63.000 71.000 71.000 71.000 10.000 10.000 3.709 64.266 °C
Temp LM19 54.000 54.000 54.000 56.000 63.000 63.000 63.000 9.000 9.000 3.103 56.811 °C
Temp LM2 43.000 43.000 43.000 44.000 48.000 48.000 48.000 5.000 5.000 1.751 44.650 °C
Temp LM20 26.000 26.000 27.000 29.000 31.000 37.000 57.000 4.000 11.000 2.332 28.864 °C
Temp LM21 25.000 25.000 26.000 28.000 31.000 36.000 52.000 5.000 11.000 2.185 28.479 °C
Temp LM22 24.000 24.000 25.000 27.000 29.000 35.000 49.000 4.000 11.000 2.145 26.871 °C
Temp LM23 25.000 25.000 25.000 27.000 31.000 36.000 57.000 6.000 11.000 2.473 27.874 °C
Temp LM24 25.000 25.000 26.000 28.000 31.000 35.000 53.000 5.000 10.000 2.245 28.252 °C
Temp LM3 32.000 32.000 32.000 33.000 34.000 35.000 36.000 2.000 3.000 0.679 33.189 °C
Temp LM4 30.000 30.000 30.000 32.000 32.500 33.000 33.500 2.500 3.000 0.709 31.635 °C
Temp LM5 24.000 24.000 24.000 24.000 24.000 24.000 24.000 0.000 0.000 0.000 24.000 °C
Temp LM6 26.000 26.000 26.500 28.000 30.500 36.000 57.000 4.000 10.000 2.306 28.425 °C
Temp LM7 60.000 60.000 60.000 62.000 66.000 66.000 66.000 6.000 6.000 1.922 62.552 °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 26.000 26.000 28.000 31.000 36.000 57.000 5.000 10.000 2.373 28.654 °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 60.000 60.000 60.500 62.500 66.000 66.000 66.500 5.500 6.000 1.872 62.790 °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.
kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of 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".
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 Pearson's moment coefficient of skewness. Wikipedia describes it best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
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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