NTPsec

A-ntpsec-6-hour-stats

Report generated: Fri Jan 28 11:02:37 2022 UTC
Start Time: Fri Jan 28 05:02:37 2022 UTC
End Time: Fri Jan 28 11:02:37 2022 UTC
Report published: Fri Jan 28 03:02:43 2022 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 -1,386.000 -996.000 -569.000 57.000 635.000 988.000 1,421.000 1,204.000 1,984.000 373.990 49.662 ns -3.485 9.842
Local Clock Frequency Offset -82.245 -82.031 -81.390 -71.793 -65.872 -64.880 -64.667 15.518 17.151 5.896 -73.033 ppb -2439 3.319e+04

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 197.000 245.000 300.000 447.000 736.000 893.000 955.000 436.000 648.000 131.015 470.514 ns 26.22 100.5

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 41.000 46.000 57.000 86.000 136.000 161.000 194.000 79.000 115.000 24.187 89.594 10e-12 28.76 110.7

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 -1,386.000 -996.000 -569.000 57.000 635.000 988.000 1,421.000 1,204.000 1,984.000 373.990 49.662 ns -3.485 9.842

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 -82.245 -82.031 -81.390 -71.793 -65.872 -64.880 -64.667 15.518 17.151 5.896 -73.033 ppb -2439 3.319e+04
Temp ZONE0 55.306 55.306 55.844 56.920 57.458 57.996 57.996 1.614 2.690 0.585 56.607 °C

The frequency offsets and temperatures. Showing frequency offset (red, in parts per million, scale on right) and the temperatures.

These are field 4 (frequency) from the loopstats log file, and field 3 from the tempstats log file.



Local GPS

local gps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
nSats 8.000 8.000 8.000 10.000 12.000 12.000 12.000 4.000 4.000 1.120 9.961 nSat 515.7 4258
TDOP 0.510 0.510 0.610 0.820 1.420 1.460 1.470 0.810 0.950 0.237 0.862 27.06 102.8

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 137.190.2.4

peer offset 137.190.2.4 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 137.190.2.4 0.610 0.610 1.096 1.409 1.943 2.226 2.226 0.848 1.616 0.264 1.431 ms 100.2 511.2

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 192.168.1.12

peer offset 192.168.1.12 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.168.1.12 -18.024 -15.083 33.940 131.664 173.712 209.214 230.768 139.772 224.297 39.587 126.645 µs 15.99 46.82

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 216.218.192.202

peer offset 216.218.192.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 216.218.192.202 2.275 2.275 2.479 2.724 2.992 3.175 3.175 0.513 0.900 0.170 2.728 ms 3485 5.329e+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 216.218.254.202

peer offset 216.218.254.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 216.218.254.202 2.504 2.504 2.538 2.729 2.989 3.413 3.413 0.451 0.910 0.148 2.747 ms 5499 9.777e+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 24.5.152.24

peer offset 24.5.152.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 24.5.152.24 -1.310 -1.310 -0.517 0.340 2.029 3.204 3.204 2.546 4.513 0.761 0.405 ms -0.4338 5.156

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) -71.131 -60.977 -57.009 -49.879 -44.096 -42.148 -41.067 12.913 18.829 3.980 -50.262 ms -2573 3.564e+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) -1,387.000 -997.000 -570.000 58.000 636.000 989.000 1,422.000 1,206.000 1,986.000 374.749 49.797 ns -3.485 9.829

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 137.190.2.4

peer jitter 137.190.2.4 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 137.190.2.4 0.107 0.107 0.395 2.086 24.219 30.481 30.481 23.824 30.375 6.364 4.219 ms 1.891 7.772

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 192.168.1.12

peer jitter 192.168.1.12 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.168.1.12 0.015 0.019 0.035 0.119 1.234 2.456 4.826 1.199 2.437 0.509 0.271 ms 4.235 36.38

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 216.218.192.202

peer jitter 216.218.192.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 216.218.192.202 0.229 0.229 0.338 2.938 10.228 22.697 22.697 9.890 22.468 3.957 3.629 ms 3.168 15.1

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 216.218.254.202

peer jitter 216.218.254.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 216.218.254.202 0.230 0.230 0.296 1.175 6.352 6.482 6.482 6.057 6.252 1.482 1.639 ms 2.267 7.551

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 24.5.152.24

peer jitter 24.5.152.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 24.5.152.24 0.780 0.780 1.004 1.995 16.560 65.206 65.206 15.556 64.427 10.695 4.643 ms 3.151 18.77

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) 0.101 0.321 0.481 1.232 3.435 6.088 16.069 2.953 5.767 1.123 1.556 ms 3.856 20.76

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) 0.088 0.150 0.212 0.430 0.875 1.189 1.631 0.663 1.039 0.211 0.469 µs 6.934 24.32

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 -82.245 -82.031 -81.390 -71.793 -65.872 -64.880 -64.667 15.518 17.151 5.896 -73.033 ppb -2439 3.319e+04
Local Clock Time Offset -1,386.000 -996.000 -569.000 57.000 635.000 988.000 1,421.000 1,204.000 1,984.000 373.990 49.662 ns -3.485 9.842
Local RMS Frequency Jitter 41.000 46.000 57.000 86.000 136.000 161.000 194.000 79.000 115.000 24.187 89.594 10e-12 28.76 110.7
Local RMS Time Jitter 197.000 245.000 300.000 447.000 736.000 893.000 955.000 436.000 648.000 131.015 470.514 ns 26.22 100.5
Server Jitter 137.190.2.4 0.107 0.107 0.395 2.086 24.219 30.481 30.481 23.824 30.375 6.364 4.219 ms 1.891 7.772
Server Jitter 192.168.1.12 0.015 0.019 0.035 0.119 1.234 2.456 4.826 1.199 2.437 0.509 0.271 ms 4.235 36.38
Server Jitter 216.218.192.202 0.229 0.229 0.338 2.938 10.228 22.697 22.697 9.890 22.468 3.957 3.629 ms 3.168 15.1
Server Jitter 216.218.254.202 0.230 0.230 0.296 1.175 6.352 6.482 6.482 6.057 6.252 1.482 1.639 ms 2.267 7.551
Server Jitter 24.5.152.24 0.780 0.780 1.004 1.995 16.560 65.206 65.206 15.556 64.427 10.695 4.643 ms 3.151 18.77
Server Jitter SHM(0) 0.101 0.321 0.481 1.232 3.435 6.088 16.069 2.953 5.767 1.123 1.556 ms 3.856 20.76
Server Jitter SHM(1) 0.088 0.150 0.212 0.430 0.875 1.189 1.631 0.663 1.039 0.211 0.469 µs 6.934 24.32
Server Offset 137.190.2.4 0.610 0.610 1.096 1.409 1.943 2.226 2.226 0.848 1.616 0.264 1.431 ms 100.2 511.2
Server Offset 192.168.1.12 -18.024 -15.083 33.940 131.664 173.712 209.214 230.768 139.772 224.297 39.587 126.645 µs 15.99 46.82
Server Offset 216.218.192.202 2.275 2.275 2.479 2.724 2.992 3.175 3.175 0.513 0.900 0.170 2.728 ms 3485 5.329e+04
Server Offset 216.218.254.202 2.504 2.504 2.538 2.729 2.989 3.413 3.413 0.451 0.910 0.148 2.747 ms 5499 9.777e+04
Server Offset 24.5.152.24 -1.310 -1.310 -0.517 0.340 2.029 3.204 3.204 2.546 4.513 0.761 0.405 ms -0.4338 5.156
Server Offset SHM(0) -71.131 -60.977 -57.009 -49.879 -44.096 -42.148 -41.067 12.913 18.829 3.980 -50.262 ms -2573 3.564e+04
Server Offset SHM(1) -1,387.000 -997.000 -570.000 58.000 636.000 989.000 1,422.000 1,206.000 1,986.000 374.749 49.797 ns -3.485 9.829
TDOP 0.510 0.510 0.610 0.820 1.420 1.460 1.470 0.810 0.950 0.237 0.862 27.06 102.8
Temp ZONE0 55.306 55.306 55.844 56.920 57.458 57.996 57.996 1.614 2.690 0.585 56.607 °C
nSats 8.000 8.000 8.000 10.000 12.000 12.000 12.000 4.000 4.000 1.120 9.961 nSat 515.7 4258
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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