NTPsec

Pi4/Uputronics

Report generated: Sat Aug 13 15:13:13 2022 UTC
Start Time: Sat Aug 6 15:13:01 2022 UTC
End Time: Sat Aug 13 15:13:01 2022 UTC
Report Period: 7.0 days

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 -19.169 -10.191 -6.017 -0.425 6.402 11.108 35.355 12.419 21.299 4.077 -0.071 µs -3.534 11.42
Local Clock Frequency Offset -2.408 -2.165 -1.848 -0.397 0.328 0.517 0.541 2.176 2.682 0.695 -0.557 ppm -11.87 36.87

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 0.138 0.162 0.252 1.123 1.747 5.506 0.961 1.609 0.366 0.369 µs 4.86 40.5

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 0.050 0.105 0.171 0.671 1.945 2.833 5.847 1.774 2.728 0.587 0.804 ppb 3.205 13.92

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 -19.169 -10.191 -6.017 -0.425 6.402 11.108 35.355 12.419 21.299 4.077 -0.071 µs -3.534 11.42

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 -2.408 -2.165 -1.848 -0.397 0.328 0.517 0.541 2.176 2.682 0.695 -0.557 ppm -11.87 36.87
Temp ZONE0 48.312 49.926 51.540 56.920 60.686 61.762 65.528 9.146 11.836 3.013 56.473 °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 16.000 19.000 20.000 20.000 7.000 9.000 1.846 15.540 nSat 430.6 3361
TDOP 0.440 0.490 0.530 0.680 0.950 1.120 2.120 0.420 0.630 0.134 0.701 89.95 457.1

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) -99.467 -39.162 -22.993 4.568 65.992 76.254 86.568 88.985 115.416 30.396 11.941 µs -1.635 3.62

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) -636.962 -453.012 -329.535 10.605 207.160 274.229 408.155 536.695 727.241 164.317 -13.829 µs -5.167 14.27

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 204.17.205.1

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 -599.290 -458.826 -342.867 -29.836 222.229 430.575 541.060 565.096 889.401 175.725 -41.168 µs -5.579 14.63

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 -138.848 -58.583 -39.120 12.648 74.996 95.292 154.913 114.116 153.875 35.047 14.813 µs -1.79 4.79

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 -191.589 -88.220 -68.700 -16.499 65.274 87.226 156.765 133.974 175.446 41.699 -9.988 µs -5.247 12.72

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 -200.922 -102.644 -69.848 -16.271 62.302 81.205 137.197 132.150 183.849 42.520 -10.812 µs -5.571 13.93

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) -1.664 -0.772 -0.343 0.542 1.170 1.545 2.181 1.513 2.317 0.421 0.516 ms 0.04199 4.967

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) -54.090 -30.575 -26.236 -20.475 -16.474 -14.753 -10.193 9.762 15.823 3.160 -20.743 ms -457.2 3677

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) -19.170 -10.192 -6.018 -0.425 6.403 11.109 35.356 12.421 21.301 4.077 -0.071 µs -3.535 11.42

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) 1.463 4.854 6.503 19.656 75.490 90.452 278.262 68.987 85.598 25.208 30.452 µs 2.354 12.3

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 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) 2.207 8.068 12.105 31.286 87.479 120.430 2,334.943 75.374 112.362 116.405 45.575 µs 13.81 245

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 3.006 6.770 10.229 30.096 82.664 149.298 2,440.331 72.435 142.528 122.745 45.485 µs 11.75 186.3

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 2.293 5.029 7.345 24.587 75.629 98.507 737.030 68.284 93.478 36.351 33.335 µs 9.972 174

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 2.745 6.737 10.172 33.015 90.292 127.175 2,341.695 80.120 120.438 112.491 47.928 µs 12.26 203

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 1.805 6.971 10.781 32.680 85.118 118.801 1,590.562 74.337 111.830 74.773 43.485 µs 12.21 199

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) 0.138 0.211 0.294 0.599 1.192 2.128 13.857 0.898 1.917 0.537 0.672 ms 16 373.2

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) 0.077 0.317 0.471 1.198 3.918 8.376 27.418 3.446 8.059 1.610 1.605 ms 5.673 55.54

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) 0.031 0.100 0.149 0.509 2.588 5.606 25.670 2.439 5.506 1.174 0.834 µs 6.413 94.02

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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -2.408 -2.165 -1.848 -0.397 0.328 0.517 0.541 2.176 2.682 0.695 -0.557 ppm -11.87 36.87
Local Clock Time Offset -19.169 -10.191 -6.017 -0.425 6.402 11.108 35.355 12.419 21.299 4.077 -0.071 µs -3.534 11.42
Local RMS Frequency Jitter 0.050 0.105 0.171 0.671 1.945 2.833 5.847 1.774 2.728 0.587 0.804 ppb 3.205 13.92
Local RMS Time Jitter 0.101 0.138 0.162 0.252 1.123 1.747 5.506 0.961 1.609 0.366 0.369 µs 4.86 40.5
Server Jitter 2001:470:e815::23 (pi3.rellim.com) 1.463 4.854 6.503 19.656 75.490 90.452 278.262 68.987 85.598 25.208 30.452 µs 2.354 12.3
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 2.207 8.068 12.105 31.286 87.479 120.430 2,334.943 75.374 112.362 116.405 45.575 µs 13.81 245
Server Jitter 204.17.205.1 3.006 6.770 10.229 30.096 82.664 149.298 2,440.331 72.435 142.528 122.745 45.485 µs 11.75 186.3
Server Jitter 204.17.205.17 2.293 5.029 7.345 24.587 75.629 98.507 737.030 68.284 93.478 36.351 33.335 µs 9.972 174
Server Jitter 204.17.205.27 2.745 6.737 10.172 33.015 90.292 127.175 2,341.695 80.120 120.438 112.491 47.928 µs 12.26 203
Server Jitter 204.17.205.30 1.805 6.971 10.781 32.680 85.118 118.801 1,590.562 74.337 111.830 74.773 43.485 µs 12.21 199
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 0.138 0.211 0.294 0.599 1.192 2.128 13.857 0.898 1.917 0.537 0.672 ms 16 373.2
Server Jitter SHM(0) 0.077 0.317 0.471 1.198 3.918 8.376 27.418 3.446 8.059 1.610 1.605 ms 5.673 55.54
Server Jitter SHM(1) 0.031 0.100 0.149 0.509 2.588 5.606 25.670 2.439 5.506 1.174 0.834 µs 6.413 94.02
Server Offset 2001:470:e815::23 (pi3.rellim.com) -99.467 -39.162 -22.993 4.568 65.992 76.254 86.568 88.985 115.416 30.396 11.941 µs -1.635 3.62
Server Offset 2001:470:e815::8 (spidey.rellim.com) -636.962 -453.012 -329.535 10.605 207.160 274.229 408.155 536.695 727.241 164.317 -13.829 µs -5.167 14.27
Server Offset 204.17.205.1 -599.290 -458.826 -342.867 -29.836 222.229 430.575 541.060 565.096 889.401 175.725 -41.168 µs -5.579 14.63
Server Offset 204.17.205.17 -138.848 -58.583 -39.120 12.648 74.996 95.292 154.913 114.116 153.875 35.047 14.813 µs -1.79 4.79
Server Offset 204.17.205.27 -191.589 -88.220 -68.700 -16.499 65.274 87.226 156.765 133.974 175.446 41.699 -9.988 µs -5.247 12.72
Server Offset 204.17.205.30 -200.922 -102.644 -69.848 -16.271 62.302 81.205 137.197 132.150 183.849 42.520 -10.812 µs -5.571 13.93
Server Offset 2606:4700:f1::123 (time.cloudflare.com) -1.664 -0.772 -0.343 0.542 1.170 1.545 2.181 1.513 2.317 0.421 0.516 ms 0.04199 4.967
Server Offset SHM(0) -54.090 -30.575 -26.236 -20.475 -16.474 -14.753 -10.193 9.762 15.823 3.160 -20.743 ms -457.2 3677
Server Offset SHM(1) -19.170 -10.192 -6.018 -0.425 6.403 11.109 35.356 12.421 21.301 4.077 -0.071 µs -3.535 11.42
TDOP 0.440 0.490 0.530 0.680 0.950 1.120 2.120 0.420 0.630 0.134 0.701 89.95 457.1
Temp ZONE0 48.312 49.926 51.540 56.920 60.686 61.762 65.528 9.146 11.836 3.013 56.473 °C
nSats 8.000 11.000 12.000 16.000 19.000 20.000 20.000 7.000 9.000 1.846 15.540 nSat 430.6 3361
Summary as CSV file


This server:

Motherboard: Raspberry Pi 2
OS: Gentoo stable
GPS; Uputronics 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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