NTPsec

time.achjoj.info

Report generated: Mon Mar 16 11:33:02 2026 UTC
Start Time: Sun Mar 15 09:09:02 2026 UTC
End Time: Mon Mar 16 11:33:02 2026 UTC
Report Period: 1.1 days

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 -1.198 -1.166 -0.551 -0.097 0.604 0.987 1.188 1.155 2.153 0.388 -0.063 ms -4.745 12.01
Local Clock Frequency Offset 18.657 18.658 18.658 18.674 18.691 18.692 18.692 0.033 0.034 0.0091 18.675 ppm 8.645e+09 1.774e+13

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 256.644 259.326 282.650 380.266 730.672 887.201 891.963 448.022 627.875 138.049 428.223 µs 16.94 61.95

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 0.646 0.671 0.724 0.973 1.564 1.860 1.988 0.840 1.189 0.255 1.028 ppb 37.94 157.1

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 -1.198 -1.166 -0.551 -0.097 0.604 0.987 1.188 1.155 2.153 0.388 -0.063 ms -4.745 12.01

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 18.657 18.658 18.658 18.674 18.691 18.692 18.692 0.033 0.034 0.0091 18.675 ppm 8.645e+09 1.774e+13
Temp /dev/sda 27.000 27.000 27.000 27.000 28.000 28.000 28.000 1.000 1.000 0.333 27.127 °C
Temp /dev/sdb 31.000 31.000 31.000 31.000 32.000 32.000 32.000 1.000 1.000 0.372 31.166 °C
Temp LM0 9.000 10.000 10.000 12.000 14.000 15.000 17.000 4.000 5.000 1.216 12.322 °C
Temp LM1 9.000 9.000 9.000 11.000 13.000 14.000 15.000 4.000 5.000 1.222 11.328 °C
Temp LM2 46.000 46.000 46.000 47.000 48.000 49.000 50.000 2.000 3.000 0.686 47.099 °C
Temp LM3 16.500 16.500 17.500 19.000 19.500 20.500 21.000 2.000 4.000 0.783 18.494 °C
Temp LM4 16.000 16.500 17.500 19.000 19.500 20.500 20.500 2.000 4.000 0.861 18.475 °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 150.254.190.51

peer offset 150.254.190.51 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 150.254.190.51 -2.346 -2.346 0.593 1.229 2.439 5.367 5.367 1.846 7.713 0.943 1.358 ms 2.229 13.44

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 153.19.250.123

peer offset 153.19.250.123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 153.19.250.123 -1.192 -1.192 -0.677 -0.045 0.708 1.667 1.667 1.385 2.859 0.474 -0.019 ms -3.569 9.52

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 193.110.137.171

peer offset 193.110.137.171 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 193.110.137.171 -7.434 -7.434 -3.511 -2.778 -1.671 -1.446 -1.446 1.840 5.988 0.776 -2.765 ms -112.1 644.9

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 194.146.251.100

peer offset 194.146.251.100 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 194.146.251.100 -0.921 -0.921 -0.681 0.020 0.969 1.659 1.659 1.650 2.579 0.488 0.065 ms -2.67 6.776

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 194.146.251.101

peer offset 194.146.251.101 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 194.146.251.101 -0.854 -0.854 -0.609 -0.072 0.754 1.097 1.097 1.364 1.951 0.409 -0.001 ms -3.449 7.831

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 194.29.130.252

peer offset 194.29.130.252 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 194.29.130.252 -1.570 -1.570 -0.837 0.090 1.052 1.529 1.529 1.889 3.099 0.523 0.106 ms -3.017 9.008

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 195.187.245.55

peer offset 195.187.245.55 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 195.187.245.55 -1.537 -1.537 -1.068 -0.475 0.543 5.195 5.195 1.610 6.732 0.851 -0.287 ms -2.076 18.92

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 213.135.57.60

peer offset 213.135.57.60 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 213.135.57.60 -0.918 -0.918 -0.760 -0.193 0.731 2.936 2.936 1.490 3.854 0.586 -0.049 ms -2.179 10.79

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) -4.860 -0.036 3.991 10.531 18.583 20.714 23.596 14.592 20.751 4.731 11.376 ms 6.892 17.65

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 150.254.190.51

peer jitter 150.254.190.51 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 150.254.190.51 0.138 0.138 0.257 1.198 4.171 12.158 12.158 3.913 12.021 1.785 1.615 ms 3.448 19.39

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 153.19.250.123

peer jitter 153.19.250.123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 153.19.250.123 0.236 0.236 0.288 0.751 3.587 4.602 4.602 3.299 4.366 0.947 1.137 ms 2.525 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 193.110.137.171

peer jitter 193.110.137.171 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 193.110.137.171 0.194 0.194 0.279 1.314 2.026 4.958 4.958 1.746 4.764 0.749 1.218 ms 4.103 18.78

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 194.146.251.100

peer jitter 194.146.251.100 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 194.146.251.100 0.215 0.215 0.291 1.177 2.736 2.997 2.997 2.445 2.782 0.709 1.334 ms 3.864 9.499

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 194.146.251.101

peer jitter 194.146.251.101 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 194.146.251.101 0.237 0.237 0.349 0.929 2.779 3.084 3.084 2.430 2.848 0.719 1.109 ms 2.872 7.626

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 194.29.130.252

peer jitter 194.29.130.252 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 194.29.130.252 0.313 0.313 0.318 0.980 2.862 3.158 3.158 2.544 2.845 0.779 1.228 ms 2.811 6.876

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 195.187.245.55

peer jitter 195.187.245.55 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 195.187.245.55 0.208 0.208 0.282 0.866 3.557 6.772 6.772 3.275 6.563 1.351 1.555 ms 1.762 5.57

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 213.135.57.60

peer jitter 213.135.57.60 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 213.135.57.60 0.262 0.262 0.331 0.810 2.408 2.704 2.704 2.077 2.442 0.673 1.098 ms 2.899 6.749

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) 0.212 0.605 0.842 2.116 5.027 6.827 11.055 4.186 6.222 1.340 2.413 ms 4.211 13.63

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 18.657 18.658 18.658 18.674 18.691 18.692 18.692 0.033 0.034 0.0091 18.675 ppm 8.645e+09 1.774e+13
Local Clock Time Offset -1.198 -1.166 -0.551 -0.097 0.604 0.987 1.188 1.155 2.153 0.388 -0.063 ms -4.745 12.01
Local RMS Frequency Jitter 0.646 0.671 0.724 0.973 1.564 1.860 1.988 0.840 1.189 0.255 1.028 ppb 37.94 157.1
Local RMS Time Jitter 256.644 259.326 282.650 380.266 730.672 887.201 891.963 448.022 627.875 138.049 428.223 µs 16.94 61.95
Server Jitter 150.254.190.51 0.138 0.138 0.257 1.198 4.171 12.158 12.158 3.913 12.021 1.785 1.615 ms 3.448 19.39
Server Jitter 153.19.250.123 0.236 0.236 0.288 0.751 3.587 4.602 4.602 3.299 4.366 0.947 1.137 ms 2.525 8
Server Jitter 193.110.137.171 0.194 0.194 0.279 1.314 2.026 4.958 4.958 1.746 4.764 0.749 1.218 ms 4.103 18.78
Server Jitter 194.146.251.100 0.215 0.215 0.291 1.177 2.736 2.997 2.997 2.445 2.782 0.709 1.334 ms 3.864 9.499
Server Jitter 194.146.251.101 0.237 0.237 0.349 0.929 2.779 3.084 3.084 2.430 2.848 0.719 1.109 ms 2.872 7.626
Server Jitter 194.29.130.252 0.313 0.313 0.318 0.980 2.862 3.158 3.158 2.544 2.845 0.779 1.228 ms 2.811 6.876
Server Jitter 195.187.245.55 0.208 0.208 0.282 0.866 3.557 6.772 6.772 3.275 6.563 1.351 1.555 ms 1.762 5.57
Server Jitter 213.135.57.60 0.262 0.262 0.331 0.810 2.408 2.704 2.704 2.077 2.442 0.673 1.098 ms 2.899 6.749
Server Jitter SHM(0) 0.212 0.605 0.842 2.116 5.027 6.827 11.055 4.186 6.222 1.340 2.413 ms 4.211 13.63
Server Offset 150.254.190.51 -2.346 -2.346 0.593 1.229 2.439 5.367 5.367 1.846 7.713 0.943 1.358 ms 2.229 13.44
Server Offset 153.19.250.123 -1.192 -1.192 -0.677 -0.045 0.708 1.667 1.667 1.385 2.859 0.474 -0.019 ms -3.569 9.52
Server Offset 193.110.137.171 -7.434 -7.434 -3.511 -2.778 -1.671 -1.446 -1.446 1.840 5.988 0.776 -2.765 ms -112.1 644.9
Server Offset 194.146.251.100 -0.921 -0.921 -0.681 0.020 0.969 1.659 1.659 1.650 2.579 0.488 0.065 ms -2.67 6.776
Server Offset 194.146.251.101 -0.854 -0.854 -0.609 -0.072 0.754 1.097 1.097 1.364 1.951 0.409 -0.001 ms -3.449 7.831
Server Offset 194.29.130.252 -1.570 -1.570 -0.837 0.090 1.052 1.529 1.529 1.889 3.099 0.523 0.106 ms -3.017 9.008
Server Offset 195.187.245.55 -1.537 -1.537 -1.068 -0.475 0.543 5.195 5.195 1.610 6.732 0.851 -0.287 ms -2.076 18.92
Server Offset 213.135.57.60 -0.918 -0.918 -0.760 -0.193 0.731 2.936 2.936 1.490 3.854 0.586 -0.049 ms -2.179 10.79
Server Offset SHM(0) -4.860 -0.036 3.991 10.531 18.583 20.714 23.596 14.592 20.751 4.731 11.376 ms 6.892 17.65
Temp /dev/sda 27.000 27.000 27.000 27.000 28.000 28.000 28.000 1.000 1.000 0.333 27.127 °C
Temp /dev/sdb 31.000 31.000 31.000 31.000 32.000 32.000 32.000 1.000 1.000 0.372 31.166 °C
Temp LM0 9.000 10.000 10.000 12.000 14.000 15.000 17.000 4.000 5.000 1.216 12.322 °C
Temp LM1 9.000 9.000 9.000 11.000 13.000 14.000 15.000 4.000 5.000 1.222 11.328 °C
Temp LM2 46.000 46.000 46.000 47.000 48.000 49.000 50.000 2.000 3.000 0.686 47.099 °C
Temp LM3 16.500 16.500 17.500 19.000 19.500 20.500 21.000 2.000 4.000 0.783 18.494 °C
Temp LM4 16.000 16.500 17.500 19.000 19.500 20.500 20.500 2.000 4.000 0.861 18.475 °C
Summary as CSV file

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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