NTPsec

Pi4/Uputronics

Report generated: Sun Aug 14 09:03:04 2022 UTC
Start Time: Sat Aug 13 09:03:02 2022 UTC
End Time: Sun Aug 14 09:03:02 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 -10.203 -8.461 -5.907 -0.895 8.264 12.206 32.341 14.171 20.667 4.539 0.042 µs -3.12 8.178
Local Clock Frequency Offset -2.408 -2.396 -2.305 -1.051 -0.166 -0.144 -0.139 2.139 2.252 0.737 -1.126 ppm -23.95 82.97

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 0.102 0.138 0.158 0.248 1.221 1.842 5.602 1.063 1.704 0.395 0.376 µs 4.586 37.76

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 0.052 0.101 0.187 0.830 2.097 2.981 5.162 1.910 2.880 0.596 0.934 ppb 3.448 13.16

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 -10.203 -8.461 -5.907 -0.895 8.264 12.206 32.341 14.171 20.667 4.539 0.042 µs -3.12 8.178

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 -2.396 -2.305 -1.051 -0.166 -0.144 -0.139 2.139 2.252 0.737 -1.126 ppm -23.95 82.97
Temp ZONE0 48.312 49.388 49.388 54.230 57.996 58.534 58.534 8.608 9.146 2.938 54.077 °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 10.000 12.000 13.000 15.000 18.000 19.000 20.000 5.000 7.000 1.770 15.497 nSat 489.7 3981
TDOP 0.440 0.500 0.540 0.700 0.960 1.110 1.770 0.420 0.610 0.134 0.713 94.3 481.3

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) -71.077 -28.214 -22.797 4.460 65.525 78.181 86.231 88.322 106.395 30.937 13.011 µs -1.466 3.129

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) -333.710 -304.316 -265.062 -21.678 201.600 279.949 321.119 466.662 584.265 136.765 -17.670 µs -4.87 11.95

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 -500.302 -440.180 -374.621 7.536 218.870 255.305 287.980 593.491 695.485 182.025 -26.305 µs -5.435 14.25

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 -133.688 -59.128 -40.138 9.471 73.923 94.960 138.545 114.061 154.088 35.340 12.315 µs -2.091 5.814

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 -110.112 -87.413 -65.892 -13.005 59.001 86.879 134.640 124.893 174.292 40.930 -8.236 µs -4.992 11.7

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 -96.978 -79.599 -61.555 -10.645 64.339 77.332 137.197 125.894 156.931 39.207 -3.614 µs -4.264 9.661

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) 21.868 47.626 129.184 501.169 883.417 979.721 1,156.812 754.233 932.095 210.607 515.575 µs 7.535 20.93

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 SHM(0)

peer offset SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(0) -47.545 -29.870 -26.071 -20.337 -16.614 -13.036 -11.245 9.457 16.834 3.038 -20.579 ms -494.1 4054

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) -10.204 -8.462 -5.908 -0.896 8.265 12.207 32.342 14.173 20.669 4.540 0.042 µs -3.12 8.178

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) 2.264 3.709 6.266 21.301 73.317 90.951 100.517 67.051 87.242 23.965 31.035 µs 1.679 3.768

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) 5.207 9.668 13.503 32.312 84.717 114.565 126.804 71.214 104.897 22.320 37.896 µs 3.771 11.63

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 204.17.205.1

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 5.079 6.759 11.063 32.511 81.963 407.895 2,293.915 70.900 401.136 166.416 51.001 µs 10.1 133.4

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

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

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 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 1.611 5.829 7.327 23.231 79.054 98.601 172.261 71.727 92.772 24.027 31.377 µs 2.434 8.533

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 5.165 7.383 10.739 31.321 84.032 111.578 143.955 73.293 104.195 23.050 37.817 µs 3.372 10.22

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 204.17.205.30

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 4.670 6.159 10.456 33.080 82.782 101.361 2,022.197 72.326 95.202 85.125 42.170 µs 19.84 457.8

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) 0.151 0.201 0.299 0.550 1.094 1.355 1.824 0.795 1.154 0.246 0.608 ms 8.771 29.95

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.



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) 0.163 0.333 0.473 1.140 4.111 7.819 21.737 3.638 7.485 1.482 1.540 ms 4.678 37.35

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) 0.049 0.098 0.142 0.507 2.744 5.868 27.105 2.602 5.770 1.267 0.850 µs 6.629 100.6

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 -2.396 -2.305 -1.051 -0.166 -0.144 -0.139 2.139 2.252 0.737 -1.126 ppm -23.95 82.97
Local Clock Time Offset -10.203 -8.461 -5.907 -0.895 8.264 12.206 32.341 14.171 20.667 4.539 0.042 µs -3.12 8.178
Local RMS Frequency Jitter 0.052 0.101 0.187 0.830 2.097 2.981 5.162 1.910 2.880 0.596 0.934 ppb 3.448 13.16
Local RMS Time Jitter 0.102 0.138 0.158 0.248 1.221 1.842 5.602 1.063 1.704 0.395 0.376 µs 4.586 37.76
Server Jitter 2001:470:e815::23 (pi3.rellim.com) 2.264 3.709 6.266 21.301 73.317 90.951 100.517 67.051 87.242 23.965 31.035 µs 1.679 3.768
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 5.207 9.668 13.503 32.312 84.717 114.565 126.804 71.214 104.897 22.320 37.896 µs 3.771 11.63
Server Jitter 204.17.205.1 5.079 6.759 11.063 32.511 81.963 407.895 2,293.915 70.900 401.136 166.416 51.001 µs 10.1 133.4
Server Jitter 204.17.205.17 1.611 5.829 7.327 23.231 79.054 98.601 172.261 71.727 92.772 24.027 31.377 µs 2.434 8.533
Server Jitter 204.17.205.27 5.165 7.383 10.739 31.321 84.032 111.578 143.955 73.293 104.195 23.050 37.817 µs 3.372 10.22
Server Jitter 204.17.205.30 4.670 6.159 10.456 33.080 82.782 101.361 2,022.197 72.326 95.202 85.125 42.170 µs 19.84 457.8
Server Jitter 2606:4700:f1::123 (time.cloudflare.com) 0.151 0.201 0.299 0.550 1.094 1.355 1.824 0.795 1.154 0.246 0.608 ms 8.771 29.95
Server Jitter SHM(0) 0.163 0.333 0.473 1.140 4.111 7.819 21.737 3.638 7.485 1.482 1.540 ms 4.678 37.35
Server Jitter SHM(1) 0.049 0.098 0.142 0.507 2.744 5.868 27.105 2.602 5.770 1.267 0.850 µs 6.629 100.6
Server Offset 2001:470:e815::23 (pi3.rellim.com) -71.077 -28.214 -22.797 4.460 65.525 78.181 86.231 88.322 106.395 30.937 13.011 µs -1.466 3.129
Server Offset 2001:470:e815::8 (spidey.rellim.com) -333.710 -304.316 -265.062 -21.678 201.600 279.949 321.119 466.662 584.265 136.765 -17.670 µs -4.87 11.95
Server Offset 204.17.205.1 -500.302 -440.180 -374.621 7.536 218.870 255.305 287.980 593.491 695.485 182.025 -26.305 µs -5.435 14.25
Server Offset 204.17.205.17 -133.688 -59.128 -40.138 9.471 73.923 94.960 138.545 114.061 154.088 35.340 12.315 µs -2.091 5.814
Server Offset 204.17.205.27 -110.112 -87.413 -65.892 -13.005 59.001 86.879 134.640 124.893 174.292 40.930 -8.236 µs -4.992 11.7
Server Offset 204.17.205.30 -96.978 -79.599 -61.555 -10.645 64.339 77.332 137.197 125.894 156.931 39.207 -3.614 µs -4.264 9.661
Server Offset 2606:4700:f1::123 (time.cloudflare.com) 21.868 47.626 129.184 501.169 883.417 979.721 1,156.812 754.233 932.095 210.607 515.575 µs 7.535 20.93
Server Offset SHM(0) -47.545 -29.870 -26.071 -20.337 -16.614 -13.036 -11.245 9.457 16.834 3.038 -20.579 ms -494.1 4054
Server Offset SHM(1) -10.204 -8.462 -5.908 -0.896 8.265 12.207 32.342 14.173 20.669 4.540 0.042 µs -3.12 8.178
TDOP 0.440 0.500 0.540 0.700 0.960 1.110 1.770 0.420 0.610 0.134 0.713 94.3 481.3
Temp ZONE0 48.312 49.388 49.388 54.230 57.996 58.534 58.534 8.608 9.146 2.938 54.077 °C
nSats 10.000 12.000 13.000 15.000 18.000 19.000 20.000 5.000 7.000 1.770 15.497 nSat 489.7 3981
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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