NTPsec

ntp1.wiktel.com

Report generated: Sun Oct 1 21:53:02 2023 UTC
Start Time: Sat Sep 30 21:53:01 2023 UTC
End Time: Sun Oct 1 21:53:01 2023 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 -8.942 -4.856 -3.623 -0.130 3.662 5.493 9.913 7.285 10.349 2.287 -0.007 µs -3.873 9.391
Local Clock Frequency Offset 17.367 17.384 17.402 17.491 17.550 17.576 17.586 0.147 0.192 0.040 17.487 ppm 8.033e+07 3.466e+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 0.379 0.564 0.668 1.060 1.737 2.252 3.782 1.069 1.688 0.347 1.113 µs 18.77 72.35

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 0.283 0.401 0.478 0.902 1.946 2.595 3.600 1.468 2.194 0.463 1.017 ppb 6.712 23.02

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 -8.942 -4.856 -3.623 -0.130 3.662 5.493 9.913 7.285 10.349 2.287 -0.007 µs -3.873 9.391

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 128.101.101.101

peer offset 128.101.101.101 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 128.101.101.101 -83.541 -69.757 -33.764 43.428 86.877 115.852 119.071 120.641 185.609 35.283 38.831 µs -0.492 3.692

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 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 -295.486 -251.898 52.507 240.865 559.277 680.388 819.931 506.770 932.286 151.798 264.516 µs 2.625 9.14

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) -279.809 -278.114 -248.058 -128.488 19.278 32.600 47.823 267.336 310.714 84.005 -122.879 µs -22.13 73.11

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 -6.085 -4.402 -2.997 -0.273 1.796 3.166 8.506 4.793 7.568 1.556 -0.365 ms -5.402 17.38

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 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) -209.137 -195.980 -171.806 -20.974 260.400 387.858 403.998 432.206 583.838 123.130 -7.469 µs -3.252 7.787

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) -243.198 -203.894 -111.118 -4.560 140.544 338.386 348.807 251.662 542.280 84.802 5.704 µs -2.41 8.482

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) 425.567 430.962 454.379 488.639 525.448 538.697 549.164 71.069 107.735 20.990 487.947 µs 1.108e+04 2.479e+05

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) -13.043 -13.040 -13.006 -12.961 -12.919 -12.896 -12.886 0.087 0.144 0.026 -12.962 ms -1.268e+08 6.369e+10

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) -8.943 -4.857 -3.624 -0.131 3.663 5.494 9.914 7.287 10.351 2.288 -0.007 µs -3.874 9.39

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 128.101.101.101

peer jitter 128.101.101.101 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 128.101.101.101 6.746 7.515 9.985 21.845 44.174 63.375 72.490 34.189 55.860 11.133 24.009 µs 6.225 20.38

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 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 0.247 0.322 0.371 0.596 0.847 1.015 1.239 0.476 0.693 0.152 0.601 ms 35.31 138.4

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) 7.234 7.915 10.573 22.118 41.037 54.489 61.321 30.464 46.574 9.621 23.644 µs 8.5 27.62

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 1.751 2.237 3.644 9.465 17.541 21.755 26.013 13.897 19.518 4.239 9.781 ms 6.857 20.56

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) 3.681 8.319 10.324 20.096 44.277 57.339 61.371 33.953 49.020 10.712 22.691 µs 5.925 18.71

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) 0.006 0.010 0.012 0.026 0.094 1.851 4.662 0.082 1.842 0.356 0.077 ms 6.505 78.65

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) 0.009 0.014 0.018 0.033 0.202 8.751 14.379 0.183 8.737 1.167 0.194 ms 6.2 70.26

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) 0.027 0.029 0.041 0.100 0.561 4.696 4.712 0.520 4.667 0.617 0.227 ms 3.791 27.81

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) 0.184 0.366 0.510 1.105 2.339 3.243 7.117 1.829 2.877 0.610 1.222 µs 5.995 26.55

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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 17.367 17.384 17.402 17.491 17.550 17.576 17.586 0.147 0.192 0.040 17.487 ppm 8.033e+07 3.466e+10
Local Clock Time Offset -8.942 -4.856 -3.623 -0.130 3.662 5.493 9.913 7.285 10.349 2.287 -0.007 µs -3.873 9.391
Local RMS Frequency Jitter 0.283 0.401 0.478 0.902 1.946 2.595 3.600 1.468 2.194 0.463 1.017 ppb 6.712 23.02
Local RMS Time Jitter 0.379 0.564 0.668 1.060 1.737 2.252 3.782 1.069 1.688 0.347 1.113 µs 18.77 72.35
Server Jitter 128.101.101.101 6.746 7.515 9.985 21.845 44.174 63.375 72.490 34.189 55.860 11.133 24.009 µs 6.225 20.38
Server Jitter 128.138.141.177 0.247 0.322 0.371 0.596 0.847 1.015 1.239 0.476 0.693 0.152 0.601 ms 35.31 138.4
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 7.234 7.915 10.573 22.118 41.037 54.489 61.321 30.464 46.574 9.621 23.644 µs 8.5 27.62
Server Jitter 209.87.233.53 1.751 2.237 3.644 9.465 17.541 21.755 26.013 13.897 19.518 4.239 9.781 ms 6.857 20.56
Server Jitter 2602:fd53:11e:123::2 (time2.mbix.ca) 3.681 8.319 10.324 20.096 44.277 57.339 61.371 33.953 49.020 10.712 22.691 µs 5.925 18.71
Server Jitter 2606:4700:f1::1 (time.cloudflare.com) 0.006 0.010 0.012 0.026 0.094 1.851 4.662 0.082 1.842 0.356 0.077 ms 6.505 78.65
Server Jitter 2607:f128:1:3::dd1 (dns1.steadfast.net) 0.009 0.014 0.018 0.033 0.202 8.751 14.379 0.183 8.737 1.167 0.194 ms 6.2 70.26
Server Jitter 2607:f388::123:1 (ntp1.doit.wisc.edu) 0.027 0.029 0.041 0.100 0.561 4.696 4.712 0.520 4.667 0.617 0.227 ms 3.791 27.81
Server Jitter PPS(0) 0.184 0.366 0.510 1.105 2.339 3.243 7.117 1.829 2.877 0.610 1.222 µs 5.995 26.55
Server Offset 128.101.101.101 -83.541 -69.757 -33.764 43.428 86.877 115.852 119.071 120.641 185.609 35.283 38.831 µs -0.492 3.692
Server Offset 128.138.141.177 -295.486 -251.898 52.507 240.865 559.277 680.388 819.931 506.770 932.286 151.798 264.516 µs 2.625 9.14
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -279.809 -278.114 -248.058 -128.488 19.278 32.600 47.823 267.336 310.714 84.005 -122.879 µs -22.13 73.11
Server Offset 209.87.233.53 -6.085 -4.402 -2.997 -0.273 1.796 3.166 8.506 4.793 7.568 1.556 -0.365 ms -5.402 17.38
Server Offset 2602:fd53:11e:123::2 (time2.mbix.ca) -209.137 -195.980 -171.806 -20.974 260.400 387.858 403.998 432.206 583.838 123.130 -7.469 µs -3.252 7.787
Server Offset 2606:4700:f1::1 (time.cloudflare.com) -243.198 -203.894 -111.118 -4.560 140.544 338.386 348.807 251.662 542.280 84.802 5.704 µs -2.41 8.482
Server Offset 2607:f128:1:3::dd1 (dns1.steadfast.net) 425.567 430.962 454.379 488.639 525.448 538.697 549.164 71.069 107.735 20.990 487.947 µs 1.108e+04 2.479e+05
Server Offset 2607:f388::123:1 (ntp1.doit.wisc.edu) -13.043 -13.040 -13.006 -12.961 -12.919 -12.896 -12.886 0.087 0.144 0.026 -12.962 ms -1.268e+08 6.369e+10
Server Offset PPS(0) -8.943 -4.857 -3.624 -0.131 3.663 5.494 9.914 7.287 10.351 2.288 -0.007 µs -3.874 9.39
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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