NTPsec

Pi3/Uputronics

Report generated: Wed Mar 20 15:43:14 2019 UTC
Start Time: Wed Mar 13 15:43:02 2019 UTC
End Time: Wed Mar 20 15:43:02 2019 UTC
Report Period: 7.0 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 -19.578 -8.086 -2.475 -0.331 3.152 12.256 28.420 5.627 20.342 2.877 -0.001 µs -0.6215 26.09
Local Clock Frequency Offset -5.899 -5.864 -5.779 -4.764 -4.237 -4.013 -3.512 1.542 1.851 0.485 -4.866 ppm -1380 1.561e+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 0.100 0.166 0.203 0.346 0.881 1.560 3.594 0.678 1.394 0.253 0.420 µs 5.266 26.44

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 0.054 0.105 0.141 0.436 2.410 6.434 12.834 2.269 6.329 1.188 0.760 ppb 4.238 32.62

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 -19.578 -8.086 -2.475 -0.331 3.152 12.256 28.420 5.627 20.342 2.877 -0.001 µs -0.6215 26.09

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 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) -79.724 -50.640 -35.128 -2.613 33.650 63.396 113.131 68.778 114.036 21.474 -2.051 µs -4.072 10.97

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 -1.326 -1.020 -0.508 0.267 0.490 0.679 1.043 0.997 1.700 0.312 0.176 ms -3.101 11.47

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 204.17.205.16

peer offset 204.17.205.16 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.16 -914.375 -849.566 -827.081 -627.712 -287.751 -245.466 -181.586 539.330 604.100 179.090 -598.026 µs -94.35 462.9

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 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 -89.345 -25.164 -14.840 5.896 60.438 72.216 110.749 75.278 97.380 23.950 12.279 µs -0.8834 3.959

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 204.17.205.24

peer offset 204.17.205.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.24 -173.632 -67.548 -45.005 9.403 46.351 76.801 123.152 91.356 144.349 24.594 7.722 µs -2.987 11.27

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 -405.267 -154.114 -64.465 -0.533 46.924 123.230 284.435 111.389 277.344 43.584 -4.333 µs -5.611 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 204.17.205.30

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 -67.400 -46.888 -34.661 -5.525 46.781 79.597 105.200 81.442 126.485 22.689 -4.166 µs -3.6 10.08

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) -133.643 -119.388 -113.625 -24.581 5.425 6.767 10.697 119.050 126.155 54.761 -53.324 ms -13.61 39.6

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(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) -19.579 -8.087 -2.476 -0.332 3.153 12.257 28.421 5.629 20.344 2.878 -0.001 µs -0.6231 26.08

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::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) 1.217 3.413 4.906 12.497 35.648 58.251 948.363 30.742 54.838 18.059 15.774 µs 31.31 1574

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 5.035 11.687 17.252 58.309 167.374 236.537 510.874 150.122 224.850 48.844 70.572 µs 3.197 12.63

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 204.17.205.16

peer jitter 204.17.205.16 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.16 99.692 120.263 159.424 250.151 389.491 440.559 508.122 230.067 320.296 73.900 259.752 µs 23.86 84.61

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 1.637 3.549 5.041 12.859 58.431 71.982 157.950 53.390 68.433 17.376 20.136 µs 2.177 7.252

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 204.17.205.24

peer jitter 204.17.205.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.24 1.297 3.207 4.405 11.137 61.739 80.476 248.661 57.334 77.269 18.129 18.294 µs 2.396 12.22

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 1.670 3.224 4.750 12.912 39.065 67.723 128.573 34.315 64.499 12.874 16.590 µs 3.71 19.96

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 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 2.114 6.543 9.161 18.590 48.485 73.899 323.633 39.324 67.356 13.746 22.379 µs 6.214 72.07

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) 0.090 0.309 0.478 3.431 105.672 110.747 122.495 105.194 110.438 40.616 33.827 ms 0.1739 1.478

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) 0.030 0.109 0.152 0.343 1.292 4.560 11.546 1.140 4.451 0.788 0.527 µs 5.74 52.95

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 -5.899 -5.864 -5.779 -4.764 -4.237 -4.013 -3.512 1.542 1.851 0.485 -4.866 ppm -1380 1.561e+04
Local Clock Time Offset -19.578 -8.086 -2.475 -0.331 3.152 12.256 28.420 5.627 20.342 2.877 -0.001 µs -0.6215 26.09
Local RMS Frequency Jitter 0.054 0.105 0.141 0.436 2.410 6.434 12.834 2.269 6.329 1.188 0.760 ppb 4.238 32.62
Local RMS Time Jitter 0.100 0.166 0.203 0.346 0.881 1.560 3.594 0.678 1.394 0.253 0.420 µs 5.266 26.44
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 1.217 3.413 4.906 12.497 35.648 58.251 948.363 30.742 54.838 18.059 15.774 µs 31.31 1574
Server Jitter 204.17.205.1 5.035 11.687 17.252 58.309 167.374 236.537 510.874 150.122 224.850 48.844 70.572 µs 3.197 12.63
Server Jitter 204.17.205.16 99.692 120.263 159.424 250.151 389.491 440.559 508.122 230.067 320.296 73.900 259.752 µs 23.86 84.61
Server Jitter 204.17.205.17 1.637 3.549 5.041 12.859 58.431 71.982 157.950 53.390 68.433 17.376 20.136 µs 2.177 7.252
Server Jitter 204.17.205.24 1.297 3.207 4.405 11.137 61.739 80.476 248.661 57.334 77.269 18.129 18.294 µs 2.396 12.22
Server Jitter 204.17.205.27 1.670 3.224 4.750 12.912 39.065 67.723 128.573 34.315 64.499 12.874 16.590 µs 3.71 19.96
Server Jitter 204.17.205.30 2.114 6.543 9.161 18.590 48.485 73.899 323.633 39.324 67.356 13.746 22.379 µs 6.214 72.07
Server Jitter SHM(0) 0.090 0.309 0.478 3.431 105.672 110.747 122.495 105.194 110.438 40.616 33.827 ms 0.1739 1.478
Server Jitter SHM(1) 0.030 0.109 0.152 0.343 1.292 4.560 11.546 1.140 4.451 0.788 0.527 µs 5.74 52.95
Server Offset 2001:470:e815::8 (spidey.rellim.com) -79.724 -50.640 -35.128 -2.613 33.650 63.396 113.131 68.778 114.036 21.474 -2.051 µs -4.072 10.97
Server Offset 204.17.205.1 -1.326 -1.020 -0.508 0.267 0.490 0.679 1.043 0.997 1.700 0.312 0.176 ms -3.101 11.47
Server Offset 204.17.205.16 -914.375 -849.566 -827.081 -627.712 -287.751 -245.466 -181.586 539.330 604.100 179.090 -598.026 µs -94.35 462.9
Server Offset 204.17.205.17 -89.345 -25.164 -14.840 5.896 60.438 72.216 110.749 75.278 97.380 23.950 12.279 µs -0.8834 3.959
Server Offset 204.17.205.24 -173.632 -67.548 -45.005 9.403 46.351 76.801 123.152 91.356 144.349 24.594 7.722 µs -2.987 11.27
Server Offset 204.17.205.27 -405.267 -154.114 -64.465 -0.533 46.924 123.230 284.435 111.389 277.344 43.584 -4.333 µs -5.611 29
Server Offset 204.17.205.30 -67.400 -46.888 -34.661 -5.525 46.781 79.597 105.200 81.442 126.485 22.689 -4.166 µs -3.6 10.08
Server Offset SHM(0) -133.643 -119.388 -113.625 -24.581 5.425 6.767 10.697 119.050 126.155 54.761 -53.324 ms -13.61 39.6
Server Offset SHM(1) -19.579 -8.087 -2.476 -0.332 3.153 12.257 28.421 5.629 20.344 2.878 -0.001 µs -0.6231 26.08
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

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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