NTPsec

Pi4/Uputronics

Report generated: Mon Sep 26 21:03:05 2022 UTC
Start Time: Sun Sep 25 21:03:02 2022 UTC
End Time: Mon Sep 26 21:03:02 2022 UTC
Report Period: 1.0 days
Warning: plots clipped

Daily stats   Weekly stats   24 Hour Scatter Plots: ( 1   2   )

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 -7.618 -4.443 -3.572 -0.948 5.264 8.783 29.875 8.836 13.226 3.154 0.070 µs -2.451 9.728
Local Clock Frequency Offset -1.727 -1.704 -1.664 -0.815 -0.299 -0.280 -0.277 1.365 1.423 0.466 -0.894 ppm -33.92 128.6

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 0.112 0.135 0.155 0.233 1.194 1.748 5.396 1.039 1.613 0.385 0.359 µs 4.509 36.83

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 0.063 0.085 0.191 0.603 1.314 2.001 4.779 1.123 1.916 0.398 0.660 ppb 5.147 32.01

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 -7.618 -4.443 -3.572 -0.948 5.264 8.783 29.875 8.836 13.226 3.154 0.070 µs -2.451 9.728

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 -1.727 -1.704 -1.664 -0.815 -0.299 -0.280 -0.277 1.365 1.423 0.466 -0.894 ppm -33.92 128.6
Temp ZONE0 51.540 51.540 51.540 55.306 57.458 57.458 57.996 5.918 5.918 1.879 54.869 °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.



Local GPS

local gps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
nSats 9.000 12.000 13.000 16.000 19.000 20.000 20.000 6.000 8.000 1.756 15.897 nSat 546.7 4602
TDOP 0.410 0.470 0.530 0.670 0.960 1.120 1.780 0.430 0.650 0.136 0.697 83.3 414.2

Local GPS. The Time Dilution of Precision (TDOP) is plotted in blue. The number of visible satellites (nSat) is plotted in red.

TDOP is field 3, and nSats is field 4, from the gpsd log file. The gpsd log file is created by the ntploggps program.

TDOP is a dimensionless error factor. Smaller numbers are better. TDOP ranges from 1 (ideal), 2 to 5 (good), to greater than 20 (poor). Some GNSS receivers report TDOP less than one which is theoretically impossible.



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::23 (pi3.rellim.com)

peer offset 2001:470:e815::23 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:e815::23 (pi3.rellim.com) -44.263 -28.581 -21.261 6.524 63.962 72.219 73.483 85.223 100.800 28.518 12.920 µs -1.316 2.902

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: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) -538.594 -510.901 -447.257 16.750 270.777 324.417 390.051 718.034 835.318 215.572 -20.718 µs -5.18 13.71

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 -378.180 -336.146 -286.452 5.569 202.434 282.799 304.644 488.886 618.945 149.386 -12.953 µs -4.874 12.29

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 204.17.205.17

peer offset 204.17.205.17 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.17 -92.111 -50.034 -31.726 19.211 77.986 106.206 144.872 109.712 156.240 34.665 21.471 µs -0.9673 3.587

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 -138.600 -93.558 -72.480 -13.339 58.632 75.828 110.801 131.112 169.386 40.132 -10.928 µs -5.722 14.24

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 204.17.205.30

peer offset 204.17.205.30 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.30 -92.943 -74.428 -60.776 -11.854 69.608 88.955 102.374 130.384 163.383 39.801 -4.939 µs -4.267 9.424

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) 0.105 0.166 0.329 0.669 1.195 1.551 1.803 0.867 1.385 0.269 0.710 ms 10.22 33.67

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) -47.720 -30.633 -26.950 -20.918 -17.939 -17.072 -14.837 9.010 13.562 2.865 -21.481 ms -640.8 5707

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(1)

peer offset SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(1) -7.619 -4.444 -3.573 -0.949 5.265 8.784 29.876 8.838 13.228 3.155 0.070 µs -2.452 9.725

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::23 (pi3.rellim.com)

peer jitter 2001:470:e815::23 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:e815::23 (pi3.rellim.com) 4.930 5.744 7.421 18.794 70.997 268.999 272.860 63.576 263.255 36.204 32.324 µs 3.876 24.84

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: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) 5.642 8.278 13.084 32.576 83.695 114.251 132.264 70.611 105.973 22.166 38.120 µs 3.87 12.19

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 2.370 6.433 10.930 31.150 83.700 103.325 1,649.419 72.770 96.892 114.287 44.843 µs 11.28 155.7

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 204.17.205.17

peer jitter 204.17.205.17 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.17 4.683 5.235 8.297 26.990 78.661 130.148 277.063 70.364 124.913 26.766 34.624 µs 3.254 18.89

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 0.004 0.005 0.009 0.030 0.082 1.443 2.279 0.072 1.438 0.197 0.056 ms 6.929 70.51

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 204.17.205.30

peer jitter 204.17.205.30 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.30 5.456 8.149 12.027 32.863 83.563 102.689 115.419 71.536 94.540 22.282 37.898 µs 3.489 9.652

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) 0.179 0.189 0.296 0.613 1.416 2.363 3.271 1.121 2.174 0.411 0.705 ms 4.979 22.02

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 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) 0.101 0.327 0.467 1.213 3.672 7.298 23.456 3.205 6.971 1.364 1.563 ms 5.646 59.4

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 SHM(1)

peer jitter SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(1) 0.034 0.088 0.133 0.403 2.609 5.957 26.162 2.476 5.869 1.217 0.727 µs 6.762 105

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 -1.727 -1.704 -1.664 -0.815 -0.299 -0.280 -0.277 1.365 1.423 0.466 -0.894 ppm -33.92 128.6
Local Clock Time Offset -7.618 -4.443 -3.572 -0.948 5.264 8.783 29.875 8.836 13.226 3.154 0.070 µs -2.451 9.728
Local RMS Frequency Jitter 0.063 0.085 0.191 0.603 1.314 2.001 4.779 1.123 1.916 0.398 0.660 ppb 5.147 32.01
Local RMS Time Jitter 0.112 0.135 0.155 0.233 1.194 1.748 5.396 1.039 1.613 0.385 0.359 µs 4.509 36.83
Server Jitter 2001:470:e815::23 (pi3.rellim.com) 4.930 5.744 7.421 18.794 70.997 268.999 272.860 63.576 263.255 36.204 32.324 µs 3.876 24.84
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 5.642 8.278 13.084 32.576 83.695 114.251 132.264 70.611 105.973 22.166 38.120 µs 3.87 12.19
Server Jitter 204.17.205.1 2.370 6.433 10.930 31.150 83.700 103.325 1,649.419 72.770 96.892 114.287 44.843 µs 11.28 155.7
Server Jitter 204.17.205.17 4.683 5.235 8.297 26.990 78.661 130.148 277.063 70.364 124.913 26.766 34.624 µs 3.254 18.89
Server Jitter 204.17.205.27 0.004 0.005 0.009 0.030 0.082 1.443 2.279 0.072 1.438 0.197 0.056 ms 6.929 70.51
Server Jitter 204.17.205.30 5.456 8.149 12.027 32.863 83.563 102.689 115.419 71.536 94.540 22.282 37.898 µs 3.489 9.652
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 0.179 0.189 0.296 0.613 1.416 2.363 3.271 1.121 2.174 0.411 0.705 ms 4.979 22.02
Server Jitter SHM(0) 0.101 0.327 0.467 1.213 3.672 7.298 23.456 3.205 6.971 1.364 1.563 ms 5.646 59.4
Server Jitter SHM(1) 0.034 0.088 0.133 0.403 2.609 5.957 26.162 2.476 5.869 1.217 0.727 µs 6.762 105
Server Offset 2001:470:e815::23 (pi3.rellim.com) -44.263 -28.581 -21.261 6.524 63.962 72.219 73.483 85.223 100.800 28.518 12.920 µs -1.316 2.902
Server Offset 2001:470:e815::8 (spidey.rellim.com) -538.594 -510.901 -447.257 16.750 270.777 324.417 390.051 718.034 835.318 215.572 -20.718 µs -5.18 13.71
Server Offset 204.17.205.1 -378.180 -336.146 -286.452 5.569 202.434 282.799 304.644 488.886 618.945 149.386 -12.953 µs -4.874 12.29
Server Offset 204.17.205.17 -92.111 -50.034 -31.726 19.211 77.986 106.206 144.872 109.712 156.240 34.665 21.471 µs -0.9673 3.587
Server Offset 204.17.205.27 -138.600 -93.558 -72.480 -13.339 58.632 75.828 110.801 131.112 169.386 40.132 -10.928 µs -5.722 14.24
Server Offset 204.17.205.30 -92.943 -74.428 -60.776 -11.854 69.608 88.955 102.374 130.384 163.383 39.801 -4.939 µs -4.267 9.424
Server Offset 2606:4700:f1::123 (time.cloudflare.com) 0.105 0.166 0.329 0.669 1.195 1.551 1.803 0.867 1.385 0.269 0.710 ms 10.22 33.67
Server Offset SHM(0) -47.720 -30.633 -26.950 -20.918 -17.939 -17.072 -14.837 9.010 13.562 2.865 -21.481 ms -640.8 5707
Server Offset SHM(1) -7.619 -4.444 -3.573 -0.949 5.265 8.784 29.876 8.838 13.228 3.155 0.070 µs -2.452 9.725
TDOP 0.410 0.470 0.530 0.670 0.960 1.120 1.780 0.430 0.650 0.136 0.697 83.3 414.2
Temp ZONE0 51.540 51.540 51.540 55.306 57.458 57.458 57.996 5.918 5.918 1.879 54.869 °C
nSats 9.000 12.000 13.000 16.000 19.000 20.000 20.000 6.000 8.000 1.756 15.897 nSat 546.7 4602
Summary as CSV file


This server:

Motherboard: Raspberry Pi 3
OS: Gentoo stable
GPS; Adafruit GPS HAT
GPS/PPS server: gpsd
NTP server: NTPsec
../ntp.conf

Notes:

22:00 29 Nov 2017 SD card crash, start over

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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