NTPsec

sam.ljay.org.uk

Report generated: Tue Jul 1 04:00:01 2025 UTC
Start Time: Sun Jun 29 19:00:01 2025 UTC
End Time: Tue Jul 1 04:00:01 2025 UTC
Report Period: 1.4 days

Top   Daily Stats   Weekly Stats  

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 -91.065 -69.950 -35.709 1.045 28.158 39.878 74.585 63.867 109.828 19.946 -0.841 µs -5.176 17.2
Local Clock Frequency Offset 13.469 13.472 13.481 13.684 13.824 13.857 13.869 0.343 0.385 0.099 13.666 ppm 2.572e+06 3.524e+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 0.283 0.336 0.576 10.599 18.001 20.947 29.090 17.425 20.611 5.130 10.212 µs 3.776 8.965

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 0.039 0.052 0.223 0.790 2.486 3.951 4.382 2.263 3.899 0.706 0.994 ppb 3.612 14.36

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 -91.065 -69.950 -35.709 1.045 28.158 39.878 74.585 63.867 109.828 19.946 -0.841 µs -5.176 17.2

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 13.469 13.472 13.481 13.684 13.824 13.857 13.869 0.343 0.385 0.099 13.666 ppm 2.572e+06 3.524e+08
Temp LM0 43.000 43.000 43.000 44.000 46.000 46.000 46.000 3.000 3.000 0.799 44.360 °C
Temp LM1 23.000 23.000 24.000 25.000 28.000 30.000 32.000 4.000 7.000 1.390 25.484 °C
Temp LM2 36.000 36.000 37.000 38.000 39.000 40.000 40.000 2.000 4.000 0.757 37.763 °C
Temp LM3 37.000 37.000 37.000 38.000 39.000 40.000 40.000 2.000 3.000 0.662 38.010 °C
Temp LM4 36.000 36.000 36.000 37.000 38.000 39.000 39.000 2.000 3.000 0.719 36.809 °C
Temp LM5 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM6 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM7 34.000 34.000 35.000 37.000 38.000 40.000 42.000 3.000 6.000 1.150 36.602 °C
Temp LM8 34.000 34.000 35.000 37.000 38.000 40.000 42.000 3.000 6.000 1.168 36.615 °C
Temp LM9 31.000 32.000 32.000 34.000 35.000 37.000 38.000 3.000 5.000 0.958 33.741 °C
Temp ZONE0 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp ZONE1 33.000 34.000 35.000 36.000 39.000 40.000 42.000 4.000 6.000 1.234 36.587 °C
Temp ZONE2 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °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 6.000 6.000 7.000 9.000 10.000 11.000 11.000 3.000 5.000 0.941 8.705 nSat 586.9 5050
TDOP 0.540 0.590 0.640 0.940 1.500 1.680 2.650 0.860 1.090 0.276 0.980 25.67 103.1

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.



Refclock Offset 127.127.28.0 SHM(0)

peer offset 127.127.28.0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Refclock Offset 127.127.28.0 SHM(0) -704.267 -690.004 -675.588 -637.458 -595.413 -582.220 -559.476 80.176 107.784 24.504 -636.204 ms -1.968e+04 5.329e+05

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

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local serial GPS 200 ms; local PPS 20µs.

Clock Offset is field 5 in the peerstats log file.



Refclock Offset 127.127.28.1 SHM(1)

peer offset 127.127.28.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Refclock Offset 127.127.28.1 SHM(1) -91.066 -69.951 -35.710 1.046 28.159 39.879 74.586 63.869 109.830 19.947 -0.841 µs -5.176 17.2

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

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local serial GPS 200 ms; local PPS 20µs.

Clock Offset is field 5 in the peerstats log file.



Server Offset 139.143.5.31

peer offset 139.143.5.31 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 139.143.5.31 -79.629 -41.831 178.168 364.639 435.996 506.055 562.449 257.828 547.886 91.479 347.125 µs 27.84 91.74

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 193.67.79.202

peer offset 193.67.79.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 193.67.79.202 -412.191 -311.996 -201.359 87.858 169.136 220.221 309.709 370.495 532.217 102.201 67.377 µs -3.109 11.37

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 2001:8b0:0:23::205 (ntp2.aa.net.uk)

peer offset 2001:8b0:0:23::205 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:8b0:0:23::205 (ntp2.aa.net.uk) -261.138 -68.713 105.536 374.525 488.745 567.336 626.037 383.209 636.049 114.104 357.082 µs 14.22 40.59

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 81.187.26.174

peer offset 81.187.26.174 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 81.187.26.174 -707.024 -518.418 -278.506 -99.985 336.935 441.598 519.945 615.441 960.016 156.992 -81.624 µs -6.835 19.38

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.



Refclock RMS Jitter 127.127.28.0 SHM(0)

peer jitter 127.127.28.0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Refclock RMS Jitter 127.127.28.0 SHM(0) 0.647 2.401 4.150 11.867 25.253 32.692 60.116 21.102 30.291 6.476 12.961 ms 5.158 17.19

The RMS Jitter of a local refclock. 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.



Refclock RMS Jitter 127.127.28.1 SHM(1)

peer jitter 127.127.28.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Refclock RMS Jitter 127.127.28.1 SHM(1) 0.143 0.341 0.693 10.629 28.922 38.581 54.296 28.229 38.240 9.006 11.857 µs 2.01 6.252

The RMS Jitter of a local refclock. 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 139.143.5.31

peer jitter 139.143.5.31 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 139.143.5.31 0.012 0.019 0.024 0.059 0.372 1.610 3.714 0.348 1.591 0.279 0.116 ms 5.851 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 193.67.79.202

peer jitter 193.67.79.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 193.67.79.202 0.016 0.021 0.025 0.059 0.322 1.445 2.267 0.297 1.424 0.205 0.105 ms 5.687 50.45

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 2001:8b0:0:23::205 (ntp2.aa.net.uk)

peer jitter 2001:8b0:0:23::205 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:8b0:0:23::205 (ntp2.aa.net.uk) 0.014 0.018 0.022 0.062 0.427 2.324 21.666 0.405 2.306 1.765 0.266 ms 8.6 107

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 81.187.26.174

peer jitter 81.187.26.174 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 81.187.26.174 0.016 0.018 0.023 0.059 0.351 1.404 1.652 0.328 1.386 0.182 0.101 ms 5.125 42.22

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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 13.469 13.472 13.481 13.684 13.824 13.857 13.869 0.343 0.385 0.099 13.666 ppm 2.572e+06 3.524e+08
Local Clock Time Offset -91.065 -69.950 -35.709 1.045 28.158 39.878 74.585 63.867 109.828 19.946 -0.841 µs -5.176 17.2
Local RMS Frequency Jitter 0.039 0.052 0.223 0.790 2.486 3.951 4.382 2.263 3.899 0.706 0.994 ppb 3.612 14.36
Local RMS Time Jitter 0.283 0.336 0.576 10.599 18.001 20.947 29.090 17.425 20.611 5.130 10.212 µs 3.776 8.965
Refclock Offset 127.127.28.0 SHM(0) -704.267 -690.004 -675.588 -637.458 -595.413 -582.220 -559.476 80.176 107.784 24.504 -636.204 ms -1.968e+04 5.329e+05
Refclock Offset 127.127.28.1 SHM(1) -91.066 -69.951 -35.710 1.046 28.159 39.879 74.586 63.869 109.830 19.947 -0.841 µs -5.176 17.2
Refclock RMS Jitter 127.127.28.0 SHM(0) 0.647 2.401 4.150 11.867 25.253 32.692 60.116 21.102 30.291 6.476 12.961 ms 5.158 17.19
Refclock RMS Jitter 127.127.28.1 SHM(1) 0.143 0.341 0.693 10.629 28.922 38.581 54.296 28.229 38.240 9.006 11.857 µs 2.01 6.252
Server Jitter 139.143.5.31 0.012 0.019 0.024 0.059 0.372 1.610 3.714 0.348 1.591 0.279 0.116 ms 5.851 63
Server Jitter 193.67.79.202 0.016 0.021 0.025 0.059 0.322 1.445 2.267 0.297 1.424 0.205 0.105 ms 5.687 50.45
Server Jitter 2001:8b0:0:23::205 (ntp2.aa.net.uk) 0.014 0.018 0.022 0.062 0.427 2.324 21.666 0.405 2.306 1.765 0.266 ms 8.6 107
Server Jitter 81.187.26.174 0.016 0.018 0.023 0.059 0.351 1.404 1.652 0.328 1.386 0.182 0.101 ms 5.125 42.22
Server Offset 139.143.5.31 -79.629 -41.831 178.168 364.639 435.996 506.055 562.449 257.828 547.886 91.479 347.125 µs 27.84 91.74
Server Offset 193.67.79.202 -412.191 -311.996 -201.359 87.858 169.136 220.221 309.709 370.495 532.217 102.201 67.377 µs -3.109 11.37
Server Offset 2001:8b0:0:23::205 (ntp2.aa.net.uk) -261.138 -68.713 105.536 374.525 488.745 567.336 626.037 383.209 636.049 114.104 357.082 µs 14.22 40.59
Server Offset 81.187.26.174 -707.024 -518.418 -278.506 -99.985 336.935 441.598 519.945 615.441 960.016 156.992 -81.624 µs -6.835 19.38
TDOP 0.540 0.590 0.640 0.940 1.500 1.680 2.650 0.860 1.090 0.276 0.980 25.67 103.1
Temp LM0 43.000 43.000 43.000 44.000 46.000 46.000 46.000 3.000 3.000 0.799 44.360 °C
Temp LM1 23.000 23.000 24.000 25.000 28.000 30.000 32.000 4.000 7.000 1.390 25.484 °C
Temp LM2 36.000 36.000 37.000 38.000 39.000 40.000 40.000 2.000 4.000 0.757 37.763 °C
Temp LM3 37.000 37.000 37.000 38.000 39.000 40.000 40.000 2.000 3.000 0.662 38.010 °C
Temp LM4 36.000 36.000 36.000 37.000 38.000 39.000 39.000 2.000 3.000 0.719 36.809 °C
Temp LM5 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM6 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM7 34.000 34.000 35.000 37.000 38.000 40.000 42.000 3.000 6.000 1.150 36.602 °C
Temp LM8 34.000 34.000 35.000 37.000 38.000 40.000 42.000 3.000 6.000 1.168 36.615 °C
Temp LM9 31.000 32.000 32.000 34.000 35.000 37.000 38.000 3.000 5.000 0.958 33.741 °C
Temp ZONE0 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp ZONE1 33.000 34.000 35.000 36.000 39.000 40.000 42.000 4.000 6.000 1.234 36.587 °C
Temp ZONE2 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
nSats 6.000 6.000 7.000 9.000 10.000 11.000 11.000 3.000 5.000 0.941 8.705 nSat 586.9 5050
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!