NTPsec

Pi3/Uputronics

Report generated: Fri Oct 7 12:03:03 2022 UTC
Start Time: Thu Oct 6 12:03:01 2022 UTC
End Time: Fri Oct 7 12:03:01 2022 UTC
Report Period: 1.0 days

Daily stats   Weekly stats   24 Hour scatter plots ( 1  2  3)  

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 -5.735 -2.753 -1.884 -0.100 1.675 3.841 20.521 3.559 6.594 1.262 -0.066 µs -1.151 36.31
Local Clock Frequency Offset -5.266 -5.219 -5.127 -4.441 -3.962 -3.934 -3.919 1.165 1.285 0.433 -4.516 ppm -1529 1.787e+04

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 86.000 131.000 152.000 223.000 458.000 917.000 4,143.000 306.000 786.000 176.004 256.763 ns 10.16 140.5

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 0.064 0.083 0.110 0.334 1.152 1.721 7.302 1.042 1.638 0.421 0.451 ppb 5.95 72.62

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 -5.735 -2.753 -1.884 -0.100 1.675 3.841 20.521 3.559 6.594 1.262 -0.066 µs -1.151 36.31

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 -5.266 -5.219 -5.127 -4.441 -3.962 -3.934 -3.919 1.165 1.285 0.433 -4.516 ppm -1529 1.787e+04
Temp ZONE0 44.008 44.546 45.084 47.774 49.926 50.464 50.464 4.842 5.918 1.878 47.397 °C

The frequency offsets and temperatures. Showing frequency offset (red, in parts per million, scale on right) and the temperatures.

These are field 4 (frequency) from the loopstats log file, and field 3 from the tempstats log file.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 2001:470:e815::24 (pi4.rellim.com)

peer offset 2001:470:e815::24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:e815::24 (pi4.rellim.com) -115.992 -75.976 -59.980 -3.113 58.199 86.493 91.430 118.179 162.469 30.812 -5.020 µs -4.742 13.03

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::27 (kong.rellim.com)

peer offset 2001:470:e815::27 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:e815::27 (kong.rellim.com) -122.208 -66.122 -34.967 22.253 68.103 94.383 112.386 103.070 160.505 32.127 20.113 µs -1.652 5.955

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) -358.889 -346.921 -306.970 50.999 223.063 260.989 282.069 530.033 607.910 190.014 -10.727 µs -4.69 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 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 -612.029 -561.071 -485.967 55.486 290.294 339.536 351.034 776.261 900.607 257.264 -5.445 µs -4.713 11.85

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 -60.881 -48.338 -27.689 11.769 62.628 80.754 126.241 90.317 129.092 27.849 13.768 µs -1.314 4.063

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 -89.915 -78.726 -47.339 -7.839 24.096 58.025 78.916 71.435 136.751 23.951 -8.747 µs -6.757 19.6

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) 0.307 0.383 0.507 0.811 1.169 1.432 1.516 0.661 1.049 0.183 0.822 ms 53.48 233.6

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) -58.378 -56.413 -54.867 -49.050 -42.440 -39.826 -37.717 12.426 16.586 3.783 -48.954 ms -2751 3.893e+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 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) -5.736 -2.754 -1.885 -0.100 1.675 3.842 20.522 3.560 6.596 1.263 -0.066 µs -1.155 36.26

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::24 (pi4.rellim.com)

peer jitter 2001:470:e815::24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:e815::24 (pi4.rellim.com) 2.739 3.859 5.789 18.557 71.316 87.248 121.661 65.527 83.389 21.147 26.614 µs 2.075 5.658

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::27 (kong.rellim.com)

peer jitter 2001:470:e815::27 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:e815::27 (kong.rellim.com) 5.058 7.265 11.867 26.666 63.140 84.273 110.286 51.273 77.008 16.253 30.165 µs 4.648 15.82

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) 5.267 6.332 9.397 24.022 52.785 73.491 132.626 43.388 67.159 14.785 26.949 µs 4.68 18.74

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 4.275 6.754 8.925 21.890 48.878 95.473 1,089.865 39.953 88.719 46.446 26.943 µs 19.26 436.3

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 3.085 3.689 4.830 13.672 56.214 72.822 83.711 51.384 69.133 15.644 19.161 µs 2.458 7.713

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 2.707 7.347 10.938 26.901 56.190 82.996 172.382 45.252 75.649 16.644 29.039 µs 5.491 32.8

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 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) 0.140 0.169 0.243 0.583 1.434 2.287 4.377 1.192 2.118 0.449 0.672 ms 5.017 30.97

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) 0.143 0.285 0.442 1.096 2.619 3.556 5.187 2.178 3.271 0.701 1.262 ms 4.244 13.84

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 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) 0.039 0.086 0.119 0.248 0.738 3.156 13.683 0.619 3.070 0.552 0.359 µs 8.532 132.8

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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -5.266 -5.219 -5.127 -4.441 -3.962 -3.934 -3.919 1.165 1.285 0.433 -4.516 ppm -1529 1.787e+04
Local Clock Time Offset -5.735 -2.753 -1.884 -0.100 1.675 3.841 20.521 3.559 6.594 1.262 -0.066 µs -1.151 36.31
Local RMS Frequency Jitter 0.064 0.083 0.110 0.334 1.152 1.721 7.302 1.042 1.638 0.421 0.451 ppb 5.95 72.62
Local RMS Time Jitter 86.000 131.000 152.000 223.000 458.000 917.000 4,143.000 306.000 786.000 176.004 256.763 ns 10.16 140.5
Server Jitter 2001:470:e815::24 (pi4.rellim.com) 2.739 3.859 5.789 18.557 71.316 87.248 121.661 65.527 83.389 21.147 26.614 µs 2.075 5.658
Server Jitter 2001:470:e815::27 (kong.rellim.com) 5.058 7.265 11.867 26.666 63.140 84.273 110.286 51.273 77.008 16.253 30.165 µs 4.648 15.82
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 5.267 6.332 9.397 24.022 52.785 73.491 132.626 43.388 67.159 14.785 26.949 µs 4.68 18.74
Server Jitter 204.17.205.1 4.275 6.754 8.925 21.890 48.878 95.473 1,089.865 39.953 88.719 46.446 26.943 µs 19.26 436.3
Server Jitter 204.17.205.17 3.085 3.689 4.830 13.672 56.214 72.822 83.711 51.384 69.133 15.644 19.161 µs 2.458 7.713
Server Jitter 204.17.205.30 2.707 7.347 10.938 26.901 56.190 82.996 172.382 45.252 75.649 16.644 29.039 µs 5.491 32.8
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 0.140 0.169 0.243 0.583 1.434 2.287 4.377 1.192 2.118 0.449 0.672 ms 5.017 30.97
Server Jitter SHM(0) 0.143 0.285 0.442 1.096 2.619 3.556 5.187 2.178 3.271 0.701 1.262 ms 4.244 13.84
Server Jitter SHM(1) 0.039 0.086 0.119 0.248 0.738 3.156 13.683 0.619 3.070 0.552 0.359 µs 8.532 132.8
Server Offset 2001:470:e815::24 (pi4.rellim.com) -115.992 -75.976 -59.980 -3.113 58.199 86.493 91.430 118.179 162.469 30.812 -5.020 µs -4.742 13.03
Server Offset 2001:470:e815::27 (kong.rellim.com) -122.208 -66.122 -34.967 22.253 68.103 94.383 112.386 103.070 160.505 32.127 20.113 µs -1.652 5.955
Server Offset 2001:470:e815::8 (spidey.rellim.com) -358.889 -346.921 -306.970 50.999 223.063 260.989 282.069 530.033 607.910 190.014 -10.727 µs -4.69 11
Server Offset 204.17.205.1 -612.029 -561.071 -485.967 55.486 290.294 339.536 351.034 776.261 900.607 257.264 -5.445 µs -4.713 11.85
Server Offset 204.17.205.17 -60.881 -48.338 -27.689 11.769 62.628 80.754 126.241 90.317 129.092 27.849 13.768 µs -1.314 4.063
Server Offset 204.17.205.30 -89.915 -78.726 -47.339 -7.839 24.096 58.025 78.916 71.435 136.751 23.951 -8.747 µs -6.757 19.6
Server Offset 2606:4700:f1::123 (time.cloudflare.com) 0.307 0.383 0.507 0.811 1.169 1.432 1.516 0.661 1.049 0.183 0.822 ms 53.48 233.6
Server Offset SHM(0) -58.378 -56.413 -54.867 -49.050 -42.440 -39.826 -37.717 12.426 16.586 3.783 -48.954 ms -2751 3.893e+04
Server Offset SHM(1) -5.736 -2.754 -1.885 -0.100 1.675 3.842 20.522 3.560 6.596 1.263 -0.066 µs -1.155 36.26
Temp ZONE0 44.008 44.546 45.084 47.774 49.926 50.464 50.464 4.842 5.918 1.878 47.397 °C
Summary as CSV file


This server:

CPU: Rasberry Pi 3
OS: Gentoo stable
Kernel: 4.4.26, Config
GPS; Uputronics GPS HAT
GPS/PPS server: gpsd
NTP server: NTPsec
ntp.conf: current
ntp.log: current

Many thanks to Uputronics for their support and donation of the GPS.

Notes:

20:00 13 Aug 2018 UTC Change poll fro 2 to 3 on PPS
                      poll 2 Local Time Clock Offet Std Dev 1.067
05:00 10 Aug 2018 UTC Change pol from 4 to 2 on PPS
                      4 clearly worse than 1
04:00  9 Aug 2018 UTC Change pol from 1 to 4 on PPS
20:00 20 Oct 2016 UTC SD corruption, rolled back to 27 Sep backup...
19:30 26 Sep 2016 UTC minpoll=mapxpoll=1 on PPS
19:30 26 Sep 2016 UTC maxpoll=minpoll=0 results:
                      Local Clock Freq Offset: 90% 1.01 ppm, Jitter 90% 0.65 us
                      Local Stability 90%: 8.24 ppt
                      PPS Offset  90% 1.55 us, Jitter 90% 0.76 us
22:30 23 Sep 2016 UTC minpoll=mapxpoll=0 on PPS
22:30 23 Sep 2016 UTC maxpoll=minpoll=8 results:
                      Local Clock Freq Offset: 90% 886 ppb, Jitter 90% 39.9 us
                      Local Stability 90%: 6.86 ppt
                      PPS Offset  90% 977 us, Jitter 90% 95.2 us
01:10 22 Sep 2016 UTC minpoll=mapxpoll=8 on PPS
01:10 22 Sep 2016 UTC maxpoll=minpoll=7 results:
                      Local Clock Freq Offset: 90% 1.15ppm, Jitter 90% 1.14 us
                      Local Stability 90%: 1.77 ppt
                      PPS Offset  90% 9.48 us, Jitter 90% 3.45 us
21:50 20 Sep 2016 UTC minpoll=mapxpoll=7 on PPS
21:50 20 Sep 2016 UTC maxpoll=minpoll=5 results:
                      Local Clock Freq Offset: 90% 1.36ppm, Jitter 90% 1.34 us
                      Local Stability 90%: 2.64 ppt
                      PPS Offset  90% 11.4us, Jitter 90% 4.43 us
20:35 19 Sep 2016 UTC minpoll=mapxpoll=5 on PPS
20:35 19 Sep 2016 UTC maxpoll=minpoll=4 results:
                      Local Clock Freq Offset: 90% 1.12ppm, Jitter 90% 1.27 us
                      Local Stability 90%: 2.26 ppt
                      PPS Offset  90% 10.3us, Jitter 90% 4.11 us
19:10 18 Sep 2016 UTC minpoll=mapxpoll=4 on PPS
19:10 18 Sep 2016 UTC maxpoll=minpoll=3 results:
                      Local Clock Freq Offset: 90% 0.5ppm, Jitter 90% 0.18 us
                      Local Stability 90%: 1.9 ppt
                      PPS Offset  90% 3.0us, Jitter 90% 0.56 us
19:25 15 Sep 2016 UTC minpoll=mapxpoll=3 on PPS
19:25 15 Sep 2016 UTC maxpoll=minpoll=2 results:
                      Local Clock Freq Offset: 90% 1.1ppm, Jitter 90% 0.08 us
                      Local Stability 90%: 2.9 ppt
                      PPS Offset  90% 2.2us, Jitter 90% 0.20 us
20:00 13 Sep 2016 UTC minpoll=mapxpoll=2 on PPS
20:00 13 Sep 2016 UTC maxpoll=minpoll=1 results:
                      Local Clock Freq Offset: 90% 1.1ppm, Jitter 90% 0.43 us
                      Local Stability 90%: 2.3 ppt
                      PPS Offset  90% 1.6us, Jitter 90% 0.34 us
18:25 12 Sep 2016 UTC minpoll=mapxpoll=1 on PPS
18:20 12 Sep 2016 UTC maxpoll=minpoll=6 results:
                      Local Clock Freq Offset: 90% 1.4ppm, Jitter 90% 3.3 us
                      Local Stability 90%: 2.2 ppt
                      PPS Offset  90% 68us, Jitter 90% 9.7 us
21:00  9 Sep 2016 UTC minpoll=mapxpoll=6 on PPS
22:15 11 Aug 2016 UTC added prefer to SHM(1)
20:30 26 Jul 2016 UTC git head for gpsd and ntpsec
                      kernel 4.4.14 tto 4.4.15, premption server to low latency
01:24 19 Jul 2016 UTC move GPS fudge 0.108 to 0.1085
19:00 15 Jul 2016 UTC move GPS fudge 0.95 to 0.108
          Use new NTPsec reflock config
18:00  1 Jul 2016 UTC, nice the graph creation
          Note, fewer smaller, spikes in Local Clock Time Offset
00:00 30 Jun 2016 UTC add no_hz=off
          Note decreased Local Clock Time offset
               increased RMS time Jitter

Poll:

      Local Clock      Local Clock  Local Clock    PPS         PPS
Poll  Freq Offset 90%  Jitter 90%   Stability 90%  Offset 90%  Jitter 90%
0          1.0 ppm        0.65µs       8.2 ppt         1.55µs    0.76µs
1          1.1 ppm        0.43µs       2.3 ppt         1.6µs     0.34µs
2          1.1 ppm        0.08µs       2.9 ppt         2.2µs     0.20µs
3          0.5 ppm        0.18µs       1.9 ppt         3.0µs     0.56µs 
4          1.12ppm        1.27µs       2.26ppt        10.3µs     4.11µs 
5          1.36ppm        1.34µs       2.64ppt        11.4µs     4.43µs 
6          1.4 ppm        3.3 µs       2.2 ppt        68. µs     9.7 µs 
7          1.15ppm        1.14µs       1.77ppt         9.4µs     3.45µs
8          0.89ppm       39.9 µs       6.86ppt       977. µs    95.2 µs

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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