NTPsec

time.achjoj.info

Report generated: Thu Oct 15 22:33:02 2026 UTC
Start Time: Wed Oct 14 20:09:02 2026 UTC
End Time: Thu Oct 15 22:33:02 2026 UTC
Report Period: 1.1 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 -1.078 -0.987 -0.802 0.042 1.287 1.574 1.582 2.089 2.561 0.612 0.166 ms -2.285 5.007
Local Clock Frequency Offset 18.706 18.706 18.720 19.025 19.066 19.071 19.080 0.346 0.364 0.111 18.955 ppm 4.884e+06 8.287e+08

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 121.558 125.426 142.714 246.976 388.905 502.224 525.348 246.191 376.798 78.102 259.022 µs 19.94 69.37

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 1.849 1.850 2.106 9.763 33.689 46.330 49.083 31.583 44.480 10.586 12.960 ppb 1.76 4.759

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 -1.078 -0.987 -0.802 0.042 1.287 1.574 1.582 2.089 2.561 0.612 0.166 ms -2.285 5.007

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 18.706 18.706 18.720 19.025 19.066 19.071 19.080 0.346 0.364 0.111 18.955 ppm 4.884e+06 8.287e+08
Temp /dev/sdb 29.000 29.000 29.000 30.000 30.000 30.000 30.000 1.000 1.000 0.347 29.860 °C
Temp LM0 10.000 10.000 11.000 13.000 15.000 16.000 17.000 4.000 6.000 1.343 12.752 °C
Temp LM1 9.000 9.000 10.000 12.000 15.000 15.000 16.000 5.000 6.000 1.378 12.048 °C
Temp LM2 47.000 47.000 47.000 49.000 50.000 51.000 51.000 3.000 4.000 0.864 48.678 °C
Temp LM3 16.500 17.500 17.500 19.000 20.500 20.500 21.000 3.000 3.000 0.803 18.846 °C
Temp LM4 16.500 17.500 17.500 19.000 20.500 21.000 21.000 3.000 3.500 0.834 18.869 °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 4.000 4.000 5.000 7.000 9.000 10.000 12.000 4.000 6.000 1.283 7.226 nSat 113.5 596.5
TDOP 0.580 0.680 0.770 1.220 2.560 3.760 10.850 1.790 3.080 0.871 1.389 8.374 78.57

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 150.254.190.51

peer offset 150.254.190.51 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 150.254.190.51 -2.687 -2.687 0.366 1.428 2.580 3.181 3.181 2.214 5.868 0.820 1.413 ms 0.6807 9.267

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 153.19.250.123

peer offset 153.19.250.123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 153.19.250.123 -1.453 -1.453 -0.953 -0.034 1.208 2.181 2.181 2.162 3.634 0.674 0.016 ms -3.378 8.303

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 193.110.137.171

peer offset 193.110.137.171 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 193.110.137.171 -1.924 -1.924 -0.832 0.039 1.367 2.186 2.186 2.198 4.111 0.657 0.162 ms -2.384 6.923

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 194.146.251.100

peer offset 194.146.251.100 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 194.146.251.100 -1.389 -1.389 -0.900 0.047 1.389 2.227 2.227 2.289 3.617 0.721 0.170 ms -2.246 5.363

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 194.146.251.101

peer offset 194.146.251.101 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 194.146.251.101 -1.305 -1.305 -0.837 0.045 1.321 2.826 2.826 2.158 4.131 0.702 0.142 ms -2.123 6.044

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 194.29.130.252

peer offset 194.29.130.252 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 194.29.130.252 -0.840 -0.840 -0.550 0.300 1.280 1.589 1.589 1.829 2.429 0.522 0.353 ms -0.8239 3.173

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 195.187.245.55

peer offset 195.187.245.55 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 195.187.245.55 -1.216 -1.216 -1.036 0.015 1.079 1.380 1.380 2.115 2.596 0.580 0.035 ms -3.49 8.386

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 213.135.57.60

peer offset 213.135.57.60 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 213.135.57.60 -1.270 -1.270 -0.645 0.238 1.891 2.589 2.589 2.535 3.858 0.726 0.376 ms -0.713 4.137

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 150.254.190.51

peer jitter 150.254.190.51 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 150.254.190.51 0.259 0.259 0.383 0.991 5.831 11.422 11.422 5.448 11.163 2.320 1.854 ms 2.06 8.2

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 153.19.250.123

peer jitter 153.19.250.123 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 153.19.250.123 0.263 0.263 0.319 0.898 2.725 4.156 4.156 2.406 3.893 0.810 1.138 ms 2.749 8.643

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 193.110.137.171

peer jitter 193.110.137.171 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 193.110.137.171 0.292 0.292 0.433 0.815 2.196 3.328 3.328 1.763 3.035 0.592 1.019 ms 4.292 14.65

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 194.146.251.100

peer jitter 194.146.251.100 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 194.146.251.100 0.240 0.240 0.405 1.240 2.222 3.936 3.936 1.817 3.696 0.596 1.285 ms 6.064 21.15

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 194.146.251.101

peer jitter 194.146.251.101 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 194.146.251.101 0.384 0.384 0.457 1.269 2.538 3.507 3.507 2.082 3.123 0.635 1.355 ms 5.663 16.48

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 194.29.130.252

peer jitter 194.29.130.252 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 194.29.130.252 0.263 0.263 0.401 1.085 2.374 2.495 2.495 1.973 2.232 0.620 1.199 ms 4.21 10.45

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 195.187.245.55

peer jitter 195.187.245.55 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 195.187.245.55 0.161 0.161 0.261 0.828 1.615 1.949 1.949 1.354 1.787 0.437 0.870 ms 4.12 9.491

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 213.135.57.60

peer jitter 213.135.57.60 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 213.135.57.60 0.279 0.279 0.366 0.902 1.996 2.382 2.382 1.629 2.103 0.543 1.021 ms 3.995 10.07

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

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

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 18.706 18.706 18.720 19.025 19.066 19.071 19.080 0.346 0.364 0.111 18.955 ppm 4.884e+06 8.287e+08
Local Clock Time Offset -1.078 -0.987 -0.802 0.042 1.287 1.574 1.582 2.089 2.561 0.612 0.166 ms -2.285 5.007
Local RMS Frequency Jitter 1.849 1.850 2.106 9.763 33.689 46.330 49.083 31.583 44.480 10.586 12.960 ppb 1.76 4.759
Local RMS Time Jitter 121.558 125.426 142.714 246.976 388.905 502.224 525.348 246.191 376.798 78.102 259.022 µs 19.94 69.37
Server Jitter 150.254.190.51 0.259 0.259 0.383 0.991 5.831 11.422 11.422 5.448 11.163 2.320 1.854 ms 2.06 8.2
Server Jitter 153.19.250.123 0.263 0.263 0.319 0.898 2.725 4.156 4.156 2.406 3.893 0.810 1.138 ms 2.749 8.643
Server Jitter 193.110.137.171 0.292 0.292 0.433 0.815 2.196 3.328 3.328 1.763 3.035 0.592 1.019 ms 4.292 14.65
Server Jitter 194.146.251.100 0.240 0.240 0.405 1.240 2.222 3.936 3.936 1.817 3.696 0.596 1.285 ms 6.064 21.15
Server Jitter 194.146.251.101 0.384 0.384 0.457 1.269 2.538 3.507 3.507 2.082 3.123 0.635 1.355 ms 5.663 16.48
Server Jitter 194.29.130.252 0.263 0.263 0.401 1.085 2.374 2.495 2.495 1.973 2.232 0.620 1.199 ms 4.21 10.45
Server Jitter 195.187.245.55 0.161 0.161 0.261 0.828 1.615 1.949 1.949 1.354 1.787 0.437 0.870 ms 4.12 9.491
Server Jitter 213.135.57.60 0.279 0.279 0.366 0.902 1.996 2.382 2.382 1.629 2.103 0.543 1.021 ms 3.995 10.07
Server Offset 150.254.190.51 -2.687 -2.687 0.366 1.428 2.580 3.181 3.181 2.214 5.868 0.820 1.413 ms 0.6807 9.267
Server Offset 153.19.250.123 -1.453 -1.453 -0.953 -0.034 1.208 2.181 2.181 2.162 3.634 0.674 0.016 ms -3.378 8.303
Server Offset 193.110.137.171 -1.924 -1.924 -0.832 0.039 1.367 2.186 2.186 2.198 4.111 0.657 0.162 ms -2.384 6.923
Server Offset 194.146.251.100 -1.389 -1.389 -0.900 0.047 1.389 2.227 2.227 2.289 3.617 0.721 0.170 ms -2.246 5.363
Server Offset 194.146.251.101 -1.305 -1.305 -0.837 0.045 1.321 2.826 2.826 2.158 4.131 0.702 0.142 ms -2.123 6.044
Server Offset 194.29.130.252 -0.840 -0.840 -0.550 0.300 1.280 1.589 1.589 1.829 2.429 0.522 0.353 ms -0.8239 3.173
Server Offset 195.187.245.55 -1.216 -1.216 -1.036 0.015 1.079 1.380 1.380 2.115 2.596 0.580 0.035 ms -3.49 8.386
Server Offset 213.135.57.60 -1.270 -1.270 -0.645 0.238 1.891 2.589 2.589 2.535 3.858 0.726 0.376 ms -0.713 4.137
TDOP 0.580 0.680 0.770 1.220 2.560 3.760 10.850 1.790 3.080 0.871 1.389 8.374 78.57
Temp /dev/sdb 29.000 29.000 29.000 30.000 30.000 30.000 30.000 1.000 1.000 0.347 29.860 °C
Temp LM0 10.000 10.000 11.000 13.000 15.000 16.000 17.000 4.000 6.000 1.343 12.752 °C
Temp LM1 9.000 9.000 10.000 12.000 15.000 15.000 16.000 5.000 6.000 1.378 12.048 °C
Temp LM2 47.000 47.000 47.000 49.000 50.000 51.000 51.000 3.000 4.000 0.864 48.678 °C
Temp LM3 16.500 17.500 17.500 19.000 20.500 20.500 21.000 3.000 3.000 0.803 18.846 °C
Temp LM4 16.500 17.500 17.500 19.000 20.500 21.000 21.000 3.000 3.500 0.834 18.869 °C
nSats 4.000 4.000 5.000 7.000 9.000 10.000 12.000 4.000 6.000 1.283 7.226 nSat 113.5 596.5
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.



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