NTPsec

A-ntpsec-7-day-stats

Report generated: Mon Oct 19 15:02:49 2020 UTC
Start Time: Mon Oct 12 15:02:37 2020 UTC
End Time: Mon Oct 19 15:02:37 2020 UTC
Report published: Mon Oct 19 08:03:28 2020 PDT
Report Period: 7.0 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 -3.167 -1.693 -1.121 0.021 1.061 1.491 3.107 2.182 3.184 0.675 0.002 µs -4.17 10.94
Local Clock Frequency Offset -625.656 -606.415 -543.854 -340.714 -215.546 -201.187 -197.327 328.308 405.228 106.790 -357.993 ppb -95.94 482.2

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 189.000 283.000 333.000 497.000 761.000 889.000 1,238.000 428.000 606.000 131.349 515.160 ns 34.45 136.3

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 47.000 66.000 79.000 136.000 272.000 435.000 853.000 193.000 369.000 70.363 152.712 10e-12 7.439 33.28

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 -3.167 -1.693 -1.121 0.021 1.061 1.491 3.107 2.182 3.184 0.675 0.002 µs -4.17 10.94

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 -625.656 -606.415 -543.854 -340.714 -215.546 -201.187 -197.327 328.308 405.228 106.790 -357.993 ppb -95.94 482.2
Temp ZONE0 56.920 56.920 57.996 60.686 62.838 63.376 63.914 4.842 6.456 1.542 60.422 °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 7.000 7.000 10.000 12.000 12.000 12.000 5.000 5.000 1.291 9.646 nSat 290.1 2003
TDOP 0.520 0.540 0.610 0.820 1.400 1.660 2.480 0.790 1.120 0.243 0.874 26.6 104.2

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 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 -403.871 0.693 1.342 1.973 12.520 15.070 82.337 11.178 14.378 16.550 3.709 ms -24.5 611.6

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 -97.115 3.957 39.223 126.761 175.441 192.036 254.712 136.218 188.079 41.924 119.720 µs 11.22 30.52

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 -1.509 1.783 2.082 2.453 2.961 3.244 4.996 0.879 1.461 0.307 2.478 ms 375.3 2810

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 -1.271 1.788 2.058 2.448 3.003 3.421 4.276 0.945 1.634 0.322 2.475 ms 320.2 2290

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 73.158.5.1

peer offset 73.158.5.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 73.158.5.1 -3.543 -1.694 -1.011 0.249 1.169 1.905 7.256 2.180 3.599 0.719 0.189 ms -2.446 13.39

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) -75.521 -57.964 -55.417 -48.764 -43.266 -41.527 -37.918 12.152 16.436 3.755 -48.929 ms -2804 3.995e+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) -3.168 -1.694 -1.122 0.022 1.062 1.492 3.108 2.184 3.186 0.676 0.002 µs -4.17 10.93

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 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 0.000 0.230 0.394 2.039 9.718 15.109 354.562 9.323 14.879 13.553 3.988 ms 19.38 471.4

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 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 0.009 0.025 0.041 0.140 8.669 8.981 69.214 8.628 8.955 2.895 1.265 ms 3.497 75.93

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 0.157 0.252 0.396 1.983 9.261 12.983 33.459 8.865 12.731 3.327 3.246 ms 2.317 14.05

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 0.061 0.234 0.363 1.859 9.494 12.863 60.317 9.131 12.628 3.685 3.173 ms 4.354 58.18

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 73.158.5.1

peer jitter 73.158.5.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 73.158.5.1 0.400 0.707 0.984 2.297 10.717 15.277 112.819 9.733 14.571 6.105 3.993 ms 9.412 143.5

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) 0.068 0.313 0.465 1.216 3.303 6.077 18.772 2.838 5.764 1.094 1.523 ms 3.828 20.11

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) 0.048 0.179 0.242 0.473 0.941 1.209 1.848 0.699 1.030 0.218 0.515 µs 7.825 25.97

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 -625.656 -606.415 -543.854 -340.714 -215.546 -201.187 -197.327 328.308 405.228 106.790 -357.993 ppb -95.94 482.2
Local Clock Time Offset -3.167 -1.693 -1.121 0.021 1.061 1.491 3.107 2.182 3.184 0.675 0.002 µs -4.17 10.94
Local RMS Frequency Jitter 47.000 66.000 79.000 136.000 272.000 435.000 853.000 193.000 369.000 70.363 152.712 10e-12 7.439 33.28
Local RMS Time Jitter 189.000 283.000 333.000 497.000 761.000 889.000 1,238.000 428.000 606.000 131.349 515.160 ns 34.45 136.3
Server Jitter 137.190.2.4 0.000 0.230 0.394 2.039 9.718 15.109 354.562 9.323 14.879 13.553 3.988 ms 19.38 471.4
Server Jitter 192.168.1.12 0.009 0.025 0.041 0.140 8.669 8.981 69.214 8.628 8.955 2.895 1.265 ms 3.497 75.93
Server Jitter 216.218.192.202 0.157 0.252 0.396 1.983 9.261 12.983 33.459 8.865 12.731 3.327 3.246 ms 2.317 14.05
Server Jitter 216.218.254.202 0.061 0.234 0.363 1.859 9.494 12.863 60.317 9.131 12.628 3.685 3.173 ms 4.354 58.18
Server Jitter 73.158.5.1 0.400 0.707 0.984 2.297 10.717 15.277 112.819 9.733 14.571 6.105 3.993 ms 9.412 143.5
Server Jitter SHM(0) 0.068 0.313 0.465 1.216 3.303 6.077 18.772 2.838 5.764 1.094 1.523 ms 3.828 20.11
Server Jitter SHM(1) 0.048 0.179 0.242 0.473 0.941 1.209 1.848 0.699 1.030 0.218 0.515 µs 7.825 25.97
Server Offset 137.190.2.4 -403.871 0.693 1.342 1.973 12.520 15.070 82.337 11.178 14.378 16.550 3.709 ms -24.5 611.6
Server Offset 192.168.1.12 -97.115 3.957 39.223 126.761 175.441 192.036 254.712 136.218 188.079 41.924 119.720 µs 11.22 30.52
Server Offset 216.218.192.202 -1.509 1.783 2.082 2.453 2.961 3.244 4.996 0.879 1.461 0.307 2.478 ms 375.3 2810
Server Offset 216.218.254.202 -1.271 1.788 2.058 2.448 3.003 3.421 4.276 0.945 1.634 0.322 2.475 ms 320.2 2290
Server Offset 73.158.5.1 -3.543 -1.694 -1.011 0.249 1.169 1.905 7.256 2.180 3.599 0.719 0.189 ms -2.446 13.39
Server Offset SHM(0) -75.521 -57.964 -55.417 -48.764 -43.266 -41.527 -37.918 12.152 16.436 3.755 -48.929 ms -2804 3.995e+04
Server Offset SHM(1) -3.168 -1.694 -1.122 0.022 1.062 1.492 3.108 2.184 3.186 0.676 0.002 µs -4.17 10.93
TDOP 0.520 0.540 0.610 0.820 1.400 1.660 2.480 0.790 1.120 0.243 0.874 26.6 104.2
Temp ZONE0 56.920 56.920 57.996 60.686 62.838 63.376 63.914 4.842 6.456 1.542 60.422 °C
nSats 6.000 7.000 7.000 10.000 12.000 12.000 12.000 5.000 5.000 1.291 9.646 nSat 290.1 2003
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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