NTPsec

Pi4/Uputronics

Report generated: Sat Dec 3 05:03:04 2022 UTC
Start Time: Fri Dec 2 05:03:02 2022 UTC
End Time: Sat Dec 3 05:03:02 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 -9.578 -8.170 -6.504 -0.322 7.887 11.476 38.016 14.391 19.646 4.838 -0.051 µs -3.299 9.367
Local Clock Frequency Offset -3.460 -3.439 -3.312 -2.179 -2.029 -1.941 -1.918 1.283 1.499 0.449 -2.452 ppm -290.6 2024

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 0.101 0.122 0.144 0.231 1.296 1.953 6.184 1.152 1.831 0.419 0.361 µs 4.48 38.25

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 0.073 0.120 0.219 0.982 1.974 2.413 6.270 1.755 2.293 0.581 1.029 ppb 4.592 23.63

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 -9.578 -8.170 -6.504 -0.322 7.887 11.476 38.016 14.391 19.646 4.838 -0.051 µs -3.299 9.367

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 -3.460 -3.439 -3.312 -2.179 -2.029 -1.941 -1.918 1.283 1.499 0.449 -2.452 ppm -290.6 2024
Temp ZONE0 45.084 45.084 46.160 49.926 50.464 51.540 51.540 4.304 6.456 1.586 49.041 °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 8.000 11.000 12.000 15.000 18.000 19.000 20.000 6.000 8.000 1.854 15.275 nSat 400.6 3054
TDOP 0.420 0.480 0.520 0.660 0.930 1.050 1.730 0.410 0.570 0.130 0.679 90.06 455

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) -87.433 -73.679 -22.606 8.092 69.124 75.378 88.102 91.730 149.057 32.430 13.501 µs -1.778 4.388

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) -1.133 -1.095 -0.909 0.123 0.875 1.016 1.084 1.784 2.111 0.499 0.027 ms -4.02 10.01

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 -2.177 -1.965 -0.708 0.103 0.649 0.839 0.948 1.357 2.804 0.493 0.042 ms -5.149 19.34

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 -99.645 -61.453 -44.341 12.763 93.103 118.652 157.504 137.444 180.105 41.330 16.334 µs -1.609 4.31

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 -361.806 -154.201 -75.873 9.399 106.072 150.724 318.160 181.945 304.925 63.190 10.203 µs -3.706 15.21

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 -244.723 -197.176 -127.556 -5.900 96.433 158.115 227.216 223.989 355.291 65.329 -11.348 µs -5.29 15.23

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) 0.786 0.871 1.060 1.501 1.855 1.944 2.152 0.795 1.073 0.253 1.480 ms 128 689.5

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) -46.103 -28.120 -25.028 -18.603 -12.941 -10.946 -9.253 12.087 17.173 3.787 -18.755 ms -229.3 1484

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) -9.579 -8.171 -6.505 -0.323 7.888 11.477 38.017 14.393 19.648 4.839 -0.051 µs -3.299 9.366

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) 4.457 5.680 6.761 19.284 73.758 85.829 92.130 66.997 80.149 23.334 30.236 µs 1.782 3.986

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) 4.517 8.448 12.673 33.032 93.061 130.309 2,204.238 80.388 121.861 96.796 45.925 µs 17.82 391

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 5.117 7.219 11.176 33.014 119.678 455.072 665.725 108.502 447.853 68.004 49.386 µs 5.264 42.5

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

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

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 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 3.525 5.168 7.482 24.531 73.060 86.555 476.759 65.578 81.387 27.445 31.528 µs 7.661 116.9

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 5.359 9.350 16.275 48.089 110.667 689.759 2,186.575 94.392 680.409 156.255 67.354 µs 8.803 107.8

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 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 4.511 6.180 8.538 23.932 74.721 92.425 107.184 66.183 86.245 20.668 30.686 µs 2.859 8.041

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) 0.182 0.217 0.270 0.582 1.287 4.429 15.422 1.017 4.212 1.002 0.739 ms 10.18 141.8

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 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) 0.078 0.269 0.400 1.041 3.612 7.161 22.019 3.212 6.892 1.323 1.412 ms 4.423 34.89

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 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) 0.047 0.092 0.138 0.496 2.921 6.877 28.266 2.783 6.785 1.342 0.864 µs 6.097 89.39

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

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

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -3.460 -3.439 -3.312 -2.179 -2.029 -1.941 -1.918 1.283 1.499 0.449 -2.452 ppm -290.6 2024
Local Clock Time Offset -9.578 -8.170 -6.504 -0.322 7.887 11.476 38.016 14.391 19.646 4.838 -0.051 µs -3.299 9.367
Local RMS Frequency Jitter 0.073 0.120 0.219 0.982 1.974 2.413 6.270 1.755 2.293 0.581 1.029 ppb 4.592 23.63
Local RMS Time Jitter 0.101 0.122 0.144 0.231 1.296 1.953 6.184 1.152 1.831 0.419 0.361 µs 4.48 38.25
Server Jitter 2001:470:e815::23 (pi3.rellim.com) 4.457 5.680 6.761 19.284 73.758 85.829 92.130 66.997 80.149 23.334 30.236 µs 1.782 3.986
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 4.517 8.448 12.673 33.032 93.061 130.309 2,204.238 80.388 121.861 96.796 45.925 µs 17.82 391
Server Jitter 204.17.205.1 5.117 7.219 11.176 33.014 119.678 455.072 665.725 108.502 447.853 68.004 49.386 µs 5.264 42.5
Server Jitter 204.17.205.17 3.525 5.168 7.482 24.531 73.060 86.555 476.759 65.578 81.387 27.445 31.528 µs 7.661 116.9
Server Jitter 204.17.205.27 5.359 9.350 16.275 48.089 110.667 689.759 2,186.575 94.392 680.409 156.255 67.354 µs 8.803 107.8
Server Jitter 204.17.205.30 4.511 6.180 8.538 23.932 74.721 92.425 107.184 66.183 86.245 20.668 30.686 µs 2.859 8.041
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 0.182 0.217 0.270 0.582 1.287 4.429 15.422 1.017 4.212 1.002 0.739 ms 10.18 141.8
Server Jitter SHM(0) 0.078 0.269 0.400 1.041 3.612 7.161 22.019 3.212 6.892 1.323 1.412 ms 4.423 34.89
Server Jitter SHM(1) 0.047 0.092 0.138 0.496 2.921 6.877 28.266 2.783 6.785 1.342 0.864 µs 6.097 89.39
Server Offset 2001:470:e815::23 (pi3.rellim.com) -87.433 -73.679 -22.606 8.092 69.124 75.378 88.102 91.730 149.057 32.430 13.501 µs -1.778 4.388
Server Offset 2001:470:e815::8 (spidey.rellim.com) -1.133 -1.095 -0.909 0.123 0.875 1.016 1.084 1.784 2.111 0.499 0.027 ms -4.02 10.01
Server Offset 204.17.205.1 -2.177 -1.965 -0.708 0.103 0.649 0.839 0.948 1.357 2.804 0.493 0.042 ms -5.149 19.34
Server Offset 204.17.205.17 -99.645 -61.453 -44.341 12.763 93.103 118.652 157.504 137.444 180.105 41.330 16.334 µs -1.609 4.31
Server Offset 204.17.205.27 -361.806 -154.201 -75.873 9.399 106.072 150.724 318.160 181.945 304.925 63.190 10.203 µs -3.706 15.21
Server Offset 204.17.205.30 -244.723 -197.176 -127.556 -5.900 96.433 158.115 227.216 223.989 355.291 65.329 -11.348 µs -5.29 15.23
Server Offset 2606:4700:f1::123 (time.cloudflare.com) 0.786 0.871 1.060 1.501 1.855 1.944 2.152 0.795 1.073 0.253 1.480 ms 128 689.5
Server Offset SHM(0) -46.103 -28.120 -25.028 -18.603 -12.941 -10.946 -9.253 12.087 17.173 3.787 -18.755 ms -229.3 1484
Server Offset SHM(1) -9.579 -8.171 -6.505 -0.323 7.888 11.477 38.017 14.393 19.648 4.839 -0.051 µs -3.299 9.366
TDOP 0.420 0.480 0.520 0.660 0.930 1.050 1.730 0.410 0.570 0.130 0.679 90.06 455
Temp ZONE0 45.084 45.084 46.160 49.926 50.464 51.540 51.540 4.304 6.456 1.586 49.041 °C
nSats 8.000 11.000 12.000 15.000 18.000 19.000 20.000 6.000 8.000 1.854 15.275 nSat 400.6 3054
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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