NTPsec

C-ntpsec-6-hour-stats

Report generated: Mon Nov 30 04:01:27 2020 UTC
Start Time: Sun Nov 29 22:01:27 2020 UTC
End Time: Mon Nov 30 04:01:27 2020 UTC
Report published: Sun Nov 29 20:01:32 2020 PST
Report Period: 0.2 days

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 -1,490.000 -591.000 -345.000 177.000 758.000 991.000 1,203.000 1,103.000 1,582.000 340.845 192.125 ns -1.429 4.548
Local Clock Frequency Offset -5.323 -5.322 -5.314 -5.268 -5.255 -5.252 -5.251 0.059 0.070 0.0181 -5.273 ppm -2.49e+07 7.27e+09

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 104.000 113.000 128.000 194.000 305.000 429.000 599.000 177.000 316.000 59.142 202.013 ns 23.38 99.91

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 25.000 29.000 38.000 83.000 197.000 320.000 393.000 159.000 291.000 54.653 95.960 10e-12 4.737 18.53

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 -1,490.000 -591.000 -345.000 177.000 758.000 991.000 1,203.000 1,103.000 1,582.000 340.845 192.125 ns -1.429 4.548

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Local Temperatures

local temps plot

Local temperatures. These will be site-specific depending upon what temperature sensors you collect data from. Temperature changes affect the local clock crystal frequency and stability. The math of how temperature changes frequency is complex, and also depends on crystal aging. So there is no easy way to correct for it in software. This is the single most important component of frequency drift.

The Local Temperatures are from field 3 from the tempstats log file.



Local Frequency/Temp

local freq temps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -5.323 -5.322 -5.314 -5.268 -5.255 -5.252 -5.251 0.059 0.070 0.0181 -5.273 ppm -2.49e+07 7.27e+09
Temp ZONE0 56.920 56.920 57.458 57.996 58.534 58.534 59.072 1.076 1.614 0.265 58.020 °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 7.000 8.000 8.000 9.000 11.000 12.000 12.000 3.000 4.000 1.042 9.167 nSat 498.1 4090
TDOP 0.500 0.510 0.560 0.810 1.190 1.380 1.690 0.630 0.870 0.203 0.858 44.19 183.2

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 104.131.155.175

peer offset 104.131.155.175 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 104.131.155.175 0.945 0.945 0.945 1.909 3.324 3.324 3.324 2.379 2.379 0.605 2.000 ms 19.58 66.18

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 162.159.200.1

peer offset 162.159.200.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 162.159.200.1 -5.212 -5.212 -5.069 -4.665 -2.115 -0.033 -0.033 2.955 5.179 0.903 -4.475 ms -225.8 1404

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 173.11.101.155

peer offset 173.11.101.155 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 173.11.101.155 -1.108 -1.108 -0.762 0.253 1.312 3.551 3.551 2.073 4.659 0.661 0.224 ms -0.2672 8.942

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 178.62.68.79

peer offset 178.62.68.79 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 178.62.68.79 2.636 2.636 3.079 5.928 7.798 9.852 9.852 4.719 7.216 1.274 5.748 ms 53.66 227.8

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 192.168.1.10

peer offset 192.168.1.10 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.168.1.10 -65.707 -42.019 -25.053 20.413 63.191 93.040 97.801 88.244 135.059 28.570 18.397 µs -1.033 3.651

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 204.123.2.5

peer offset 204.123.2.5 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.123.2.5 1.949 1.949 2.024 2.366 3.454 7.752 7.752 1.430 5.803 0.925 2.587 ms 16 91.45

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 2405:fc00:0:1::123

peer offset 2405:fc00:0:1::123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2405:fc00:0:1::123 4.231 4.231 4.392 4.884 7.448 8.133 8.133 3.056 3.902 0.757 5.055 ms 202.9 1304

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) -69.247 -68.316 -64.383 -55.860 -48.030 -46.122 -44.814 16.352 22.194 4.930 -55.802 ms -1907 2.396e+04

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

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

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

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



Server Offset SHM(1)

peer offset SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(1) -1,491.000 -592.000 -346.000 178.000 759.000 992.000 1,204.000 1,105.000 1,584.000 341.489 192.527 ns -1.431 4.545

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 104.131.155.175

peer jitter 104.131.155.175 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 104.131.155.175 0.621 0.621 0.621 3.259 18.740 18.740 18.740 18.119 18.119 6.184 6.323 ms 1.13 2.774

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 162.159.200.1

peer jitter 162.159.200.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 162.159.200.1 0.141 0.141 0.289 6.088 14.155 20.567 20.567 13.867 20.426 5.030 5.877 ms 1.034 2.876

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 173.11.101.155

peer jitter 173.11.101.155 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 173.11.101.155 0.892 0.892 1.140 2.434 13.813 101.980 101.980 12.672 101.088 12.036 6.561 ms 5.272 42.45

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 178.62.68.79

peer jitter 178.62.68.79 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 178.62.68.79 0.226 0.226 0.494 2.264 18.299 19.544 19.544 17.806 19.318 6.064 5.837 ms 0.8583 2.434

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 192.168.1.10

peer jitter 192.168.1.10 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.168.1.10 0.018 0.026 0.052 0.157 8.666 8.713 8.731 8.614 8.687 2.372 1.080 ms 0.6793 4.105

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 204.123.2.5

peer jitter 204.123.2.5 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.123.2.5 0.229 0.229 0.340 2.284 17.138 17.387 17.387 16.797 17.157 5.067 5.476 ms 0.9709 2.618

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 2405:fc00:0:1::123

peer jitter 2405:fc00:0:1::123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2405:fc00:0:1::123 0.351 0.351 0.571 9.304 26.349 29.959 29.959 25.779 29.609 8.099 10.194 ms 1.362 3.447

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) 0.074 0.200 0.302 0.949 3.233 6.060 9.266 2.930 5.860 1.051 1.232 ms 3.279 15.27

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) 49.000 78.000 108.000 227.000 533.000 771.000 1,422.000 425.000 693.000 143.773 264.633 ns 4.962 20.09

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 -5.323 -5.322 -5.314 -5.268 -5.255 -5.252 -5.251 0.059 0.070 0.0181 -5.273 ppm -2.49e+07 7.27e+09
Local Clock Time Offset -1,490.000 -591.000 -345.000 177.000 758.000 991.000 1,203.000 1,103.000 1,582.000 340.845 192.125 ns -1.429 4.548
Local RMS Frequency Jitter 25.000 29.000 38.000 83.000 197.000 320.000 393.000 159.000 291.000 54.653 95.960 10e-12 4.737 18.53
Local RMS Time Jitter 104.000 113.000 128.000 194.000 305.000 429.000 599.000 177.000 316.000 59.142 202.013 ns 23.38 99.91
Server Jitter 104.131.155.175 0.621 0.621 0.621 3.259 18.740 18.740 18.740 18.119 18.119 6.184 6.323 ms 1.13 2.774
Server Jitter 162.159.200.1 0.141 0.141 0.289 6.088 14.155 20.567 20.567 13.867 20.426 5.030 5.877 ms 1.034 2.876
Server Jitter 173.11.101.155 0.892 0.892 1.140 2.434 13.813 101.980 101.980 12.672 101.088 12.036 6.561 ms 5.272 42.45
Server Jitter 178.62.68.79 0.226 0.226 0.494 2.264 18.299 19.544 19.544 17.806 19.318 6.064 5.837 ms 0.8583 2.434
Server Jitter 192.168.1.10 0.018 0.026 0.052 0.157 8.666 8.713 8.731 8.614 8.687 2.372 1.080 ms 0.6793 4.105
Server Jitter 204.123.2.5 0.229 0.229 0.340 2.284 17.138 17.387 17.387 16.797 17.157 5.067 5.476 ms 0.9709 2.618
Server Jitter 2405:fc00:0:1::123 0.351 0.351 0.571 9.304 26.349 29.959 29.959 25.779 29.609 8.099 10.194 ms 1.362 3.447
Server Jitter SHM(0) 0.074 0.200 0.302 0.949 3.233 6.060 9.266 2.930 5.860 1.051 1.232 ms 3.279 15.27
Server Jitter SHM(1) 49.000 78.000 108.000 227.000 533.000 771.000 1,422.000 425.000 693.000 143.773 264.633 ns 4.962 20.09
Server Offset 104.131.155.175 0.945 0.945 0.945 1.909 3.324 3.324 3.324 2.379 2.379 0.605 2.000 ms 19.58 66.18
Server Offset 162.159.200.1 -5.212 -5.212 -5.069 -4.665 -2.115 -0.033 -0.033 2.955 5.179 0.903 -4.475 ms -225.8 1404
Server Offset 173.11.101.155 -1.108 -1.108 -0.762 0.253 1.312 3.551 3.551 2.073 4.659 0.661 0.224 ms -0.2672 8.942
Server Offset 178.62.68.79 2.636 2.636 3.079 5.928 7.798 9.852 9.852 4.719 7.216 1.274 5.748 ms 53.66 227.8
Server Offset 192.168.1.10 -65.707 -42.019 -25.053 20.413 63.191 93.040 97.801 88.244 135.059 28.570 18.397 µs -1.033 3.651
Server Offset 204.123.2.5 1.949 1.949 2.024 2.366 3.454 7.752 7.752 1.430 5.803 0.925 2.587 ms 16 91.45
Server Offset 2405:fc00:0:1::123 4.231 4.231 4.392 4.884 7.448 8.133 8.133 3.056 3.902 0.757 5.055 ms 202.9 1304
Server Offset SHM(0) -69.247 -68.316 -64.383 -55.860 -48.030 -46.122 -44.814 16.352 22.194 4.930 -55.802 ms -1907 2.396e+04
Server Offset SHM(1) -1,491.000 -592.000 -346.000 178.000 759.000 992.000 1,204.000 1,105.000 1,584.000 341.489 192.527 ns -1.431 4.545
TDOP 0.500 0.510 0.560 0.810 1.190 1.380 1.690 0.630 0.870 0.203 0.858 44.19 183.2
Temp ZONE0 56.920 56.920 57.458 57.996 58.534 58.534 59.072 1.076 1.614 0.265 58.020 °C
nSats 7.000 8.000 8.000 9.000 11.000 12.000 12.000 3.000 4.000 1.042 9.167 nSat 498.1 4090
Summary as CSV file


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.



This page autogenerated by ntpviz, part of the NTPsec project
html 5    Valid CSS!