NTPsec

ntp1.wiktel.com

Report generated: Fri Mar 7 02:53:01 2025 UTC
Start Time: Thu Mar 6 02:53:01 2025 UTC
End Time: Fri Mar 7 02:53:01 2025 UTC
Report Period: 1.0 days

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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 -5.920 -1.732 -1.177 0.007 1.149 1.644 2.750 2.326 3.376 0.725 -0.004 µs -4.322 12.95
Local Clock Frequency Offset 17.879 17.883 17.890 17.971 17.991 17.999 18.002 0.101 0.116 0.033 17.958 ppm 1.676e+08 9.242e+10

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 0.337 0.432 0.503 0.720 1.070 1.581 3.004 0.567 1.149 0.212 0.751 µs 26.83 128.5

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 157.000 195.000 222.000 322.000 520.000 695.000 1,045.000 298.000 500.000 97.609 340.550 10e-12 24.51 99.47

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 -5.920 -1.732 -1.177 0.007 1.149 1.644 2.750 2.326 3.376 0.725 -0.004 µs -4.322 12.95

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats 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 128.138.141.177

peer offset 128.138.141.177 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 128.138.141.177 -0.164 -0.122 -0.092 0.035 2.174 2.474 2.598 2.266 2.596 0.676 0.292 ms 0.4989 3.728

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 2001:470:0:2c8::2 (clock.nyc.he.net)

peer offset 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -147.865 -134.819 -93.134 -36.857 24.767 49.711 61.691 117.901 184.530 36.678 -36.565 µs -13.95 42.75

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 209.87.233.53

peer offset 209.87.233.53 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 209.87.233.53 -5.720 -3.249 -1.261 1.266 3.004 4.298 4.597 4.265 7.547 1.336 1.128 ms -1.358 6.741

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 2602:fd53:11e:123::2 (time2.mbix.ca)

peer offset 2602:fd53:11e:123::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2602:fd53:11e:123::2 (time2.mbix.ca) -102.432 -81.414 -71.917 -36.653 -15.493 -10.650 -4.598 56.424 70.764 16.504 -39.293 µs -49.48 212.2

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 2606:4700:f1::1 (time.cloudflare.com)

peer offset 2606:4700:f1::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -372.034 -370.561 -348.231 -312.133 -250.104 -230.674 -195.445 98.127 139.887 32.320 -309.128 µs -1210 1.31e+04

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 2606:4700:f1::123 (time.cloudflare.com)

peer offset 2606:4700:f1::123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2606:4700:f1::123 (time.cloudflare.com) -330.577 -326.516 -318.959 -268.503 -177.965 -167.538 -155.390 140.994 158.978 44.726 -260.049 µs -336.4 2424

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 2607:f128:1:3::dd1 (dns1.steadfast.net)

peer offset 2607:f128:1:3::dd1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2607:f128:1:3::dd1 (dns1.steadfast.net) -88.769 -81.929 -58.554 -14.745 28.158 53.456 66.707 86.712 135.385 26.068 -15.198 µs -8.623 23.91

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 2607:f388::123:1 (ntp1.doit.wisc.edu)

peer offset 2607:f388::123:1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2607:f388::123:1 (ntp1.doit.wisc.edu) -418.230 -404.930 -390.986 -357.338 -312.077 -299.471 -278.469 78.909 105.459 22.820 -355.823 µs -4618 7.743e+04

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 PPS(0)

peer offset PPS(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset PPS(0) -5.921 -1.733 -1.178 0.008 1.150 1.645 2.751 2.328 3.378 0.725 -0.004 µs -4.321 12.94

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 128.138.141.177

peer jitter 128.138.141.177 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 128.138.141.177 0.259 0.303 0.390 0.613 0.860 1.760 2.008 0.470 1.457 0.237 0.639 ms 12.94 61.96

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 2001:470:0:2c8::2 (clock.nyc.he.net)

peer jitter 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 5.591 8.732 11.677 22.079 47.629 77.378 913.950 35.952 68.646 74.585 30.516 µs 9.496 110.8

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 209.87.233.53

peer jitter 209.87.233.53 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 209.87.233.53 1.299 1.657 2.741 8.123 24.894 81.976 82.047 22.153 80.318 10.507 10.399 ms 4.603 29.02

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 2602:fd53:11e:123::2 (time2.mbix.ca)

peer jitter 2602:fd53:11e:123::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2602:fd53:11e:123::2 (time2.mbix.ca) 4.607 8.029 10.439 21.303 40.192 46.641 52.568 29.753 38.612 9.174 22.361 µs 8.003 23.98

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 2606:4700:f1::1 (time.cloudflare.com)

peer jitter 2606:4700:f1::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 4.752 4.922 10.011 21.039 48.955 69.906 71.895 38.944 64.984 12.358 24.096 µs 5.153 17.39

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 2606:4700:f1::123 (time.cloudflare.com)

peer jitter 2606:4700:f1::123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 8.331 8.757 10.017 21.402 60.185 229.877 230.973 50.168 221.120 34.331 28.469 µs 4.493 25.23

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 2607:f128:1:3::dd1 (dns1.steadfast.net)

peer jitter 2607:f128:1:3::dd1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2607:f128:1:3::dd1 (dns1.steadfast.net) 11.402 14.289 18.994 34.441 61.764 399.405 625.672 42.770 385.116 47.553 40.891 µs 9.015 96.7

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 2607:f388::123:1 (ntp1.doit.wisc.edu)

peer jitter 2607:f388::123:1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2607:f388::123:1 (ntp1.doit.wisc.edu) 8.257 9.614 12.213 24.067 43.063 67.229 69.530 30.850 57.615 10.521 25.404 µs 8.209 27.5

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 PPS(0)

peer jitter PPS(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter PPS(0) 0.149 0.277 0.371 0.701 1.436 2.029 6.048 1.065 1.752 0.369 0.778 µs 7.346 41.15

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 17.879 17.883 17.890 17.971 17.991 17.999 18.002 0.101 0.116 0.033 17.958 ppm 1.676e+08 9.242e+10
Local Clock Time Offset -5.920 -1.732 -1.177 0.007 1.149 1.644 2.750 2.326 3.376 0.725 -0.004 µs -4.322 12.95
Local RMS Frequency Jitter 157.000 195.000 222.000 322.000 520.000 695.000 1,045.000 298.000 500.000 97.609 340.550 10e-12 24.51 99.47
Local RMS Time Jitter 0.337 0.432 0.503 0.720 1.070 1.581 3.004 0.567 1.149 0.212 0.751 µs 26.83 128.5
Server Jitter 128.138.141.177 0.259 0.303 0.390 0.613 0.860 1.760 2.008 0.470 1.457 0.237 0.639 ms 12.94 61.96
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 5.591 8.732 11.677 22.079 47.629 77.378 913.950 35.952 68.646 74.585 30.516 µs 9.496 110.8
Server Jitter 209.87.233.53 1.299 1.657 2.741 8.123 24.894 81.976 82.047 22.153 80.318 10.507 10.399 ms 4.603 29.02
Server Jitter 2602:fd53:11e:123::2 (time2.mbix.ca) 4.607 8.029 10.439 21.303 40.192 46.641 52.568 29.753 38.612 9.174 22.361 µs 8.003 23.98
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 4.752 4.922 10.011 21.039 48.955 69.906 71.895 38.944 64.984 12.358 24.096 µs 5.153 17.39
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 8.331 8.757 10.017 21.402 60.185 229.877 230.973 50.168 221.120 34.331 28.469 µs 4.493 25.23
Server Jitter 2607:f128:1:3::dd1 (dns1.steadfast.net) 11.402 14.289 18.994 34.441 61.764 399.405 625.672 42.770 385.116 47.553 40.891 µs 9.015 96.7
Server Jitter 2607:f388::123:1 (ntp1.doit.wisc.edu) 8.257 9.614 12.213 24.067 43.063 67.229 69.530 30.850 57.615 10.521 25.404 µs 8.209 27.5
Server Jitter PPS(0) 0.149 0.277 0.371 0.701 1.436 2.029 6.048 1.065 1.752 0.369 0.778 µs 7.346 41.15
Server Offset 128.138.141.177 -0.164 -0.122 -0.092 0.035 2.174 2.474 2.598 2.266 2.596 0.676 0.292 ms 0.4989 3.728
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -147.865 -134.819 -93.134 -36.857 24.767 49.711 61.691 117.901 184.530 36.678 -36.565 µs -13.95 42.75
Server Offset 209.87.233.53 -5.720 -3.249 -1.261 1.266 3.004 4.298 4.597 4.265 7.547 1.336 1.128 ms -1.358 6.741
Server Offset 2602:fd53:11e:123::2 (time2.mbix.ca) -102.432 -81.414 -71.917 -36.653 -15.493 -10.650 -4.598 56.424 70.764 16.504 -39.293 µs -49.48 212.2
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -372.034 -370.561 -348.231 -312.133 -250.104 -230.674 -195.445 98.127 139.887 32.320 -309.128 µs -1210 1.31e+04
Server Offset 2606:4700:f1::123 (time.cloudflare.com) -330.577 -326.516 -318.959 -268.503 -177.965 -167.538 -155.390 140.994 158.978 44.726 -260.049 µs -336.4 2424
Server Offset 2607:f128:1:3::dd1 (dns1.steadfast.net) -88.769 -81.929 -58.554 -14.745 28.158 53.456 66.707 86.712 135.385 26.068 -15.198 µs -8.623 23.91
Server Offset 2607:f388::123:1 (ntp1.doit.wisc.edu) -418.230 -404.930 -390.986 -357.338 -312.077 -299.471 -278.469 78.909 105.459 22.820 -355.823 µs -4618 7.743e+04
Server Offset PPS(0) -5.921 -1.733 -1.178 0.008 1.150 1.645 2.751 2.328 3.378 0.725 -0.004 µs -4.321 12.94
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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