NTPsec

B-ntpsec-6-hour-stats

Report generated: Sun Jul 3 08:02:37 2022 UTC
Start Time: Sun Jul 3 02:02:36 2022 UTC
End Time: Sun Jul 3 08:02:36 2022 UTC
Report published: Sun Jul 03 01:02:41 2022 PDT
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 -3.896 -2.857 -2.137 -0.429 0.450 0.754 1.043 2.587 3.611 0.762 -0.560 µs -11.38 37.89
Local Clock Frequency Offset -5.312 -5.311 -5.305 -5.264 -5.074 -5.072 -5.071 0.231 0.239 0.076 -5.233 ppm -3.45e+05 2.421e+07

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 240.000 279.000 336.000 513.000 727.000 896.000 1,466.000 391.000 617.000 126.411 522.754 ns 41.59 181.9

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 0.066 0.076 0.087 0.141 0.663 1.053 1.538 0.576 0.977 0.213 0.227 ppb 2.975 13.16

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 -3.896 -2.857 -2.137 -0.429 0.450 0.754 1.043 2.587 3.611 0.762 -0.560 µs -11.38 37.89

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 -5.312 -5.311 -5.305 -5.264 -5.074 -5.072 -5.071 0.231 0.239 0.076 -5.233 ppm -3.45e+05 2.421e+07
Temp ZONE0 46.160 46.160 46.160 47.236 49.388 49.926 49.926 3.228 3.766 0.870 47.573 °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.



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 169.229.128.134

peer offset 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 169.229.128.134 2.126 2.126 2.264 2.685 2.982 3.166 3.166 0.718 1.040 0.223 2.659 ms 1326 1.48e+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 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 -1.787 -1.787 -0.941 0.130 1.035 1.346 1.346 1.976 3.133 0.601 0.057 ms -4.037 11.65

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 11.218 24.105 85.484 192.483 496.577 645.521 704.815 411.093 621.416 123.424 216.735 µs 4.282 14.17

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 2.228 2.228 2.262 2.691 3.092 3.680 3.680 0.830 1.451 0.298 2.673 ms 531.7 4469

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) -406.548 -391.052 -383.059 -357.841 -325.040 -316.059 -292.663 58.019 74.993 17.695 -356.284 ms -9503 2.022e+05

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) -3.897 -2.858 -2.138 -0.430 0.450 0.755 1.044 2.588 3.613 0.763 -0.560 µs -11.38 37.88

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 169.229.128.134

peer jitter 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 169.229.128.134 0.205 0.205 0.374 1.302 8.483 19.047 19.047 8.109 18.842 3.109 2.132 ms 3.361 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 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 0.485 0.485 0.992 1.945 4.066 16.684 16.684 3.074 16.199 1.898 2.306 ms 6.507 49.43

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 0.000 0.065 0.158 0.525 4.081 12.545 13.559 3.923 12.480 1.883 1.035 ms 3.158 19.55

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 0.739 0.739 0.844 1.329 1.855 2.053 2.053 1.011 1.315 0.308 1.339 ms 47.86 199

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) 2.052 3.980 5.334 10.259 21.035 29.658 46.235 15.701 25.679 5.156 11.380 ms 6.927 25.14

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) 0.101 0.195 0.264 0.513 1.030 1.409 2.731 0.766 1.214 0.252 0.566 µs 7.247 28.18

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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -5.312 -5.311 -5.305 -5.264 -5.074 -5.072 -5.071 0.231 0.239 0.076 -5.233 ppm -3.45e+05 2.421e+07
Local Clock Time Offset -3.896 -2.857 -2.137 -0.429 0.450 0.754 1.043 2.587 3.611 0.762 -0.560 µs -11.38 37.89
Local RMS Frequency Jitter 0.066 0.076 0.087 0.141 0.663 1.053 1.538 0.576 0.977 0.213 0.227 ppb 2.975 13.16
Local RMS Time Jitter 240.000 279.000 336.000 513.000 727.000 896.000 1,466.000 391.000 617.000 126.411 522.754 ns 41.59 181.9
Server Jitter 169.229.128.134 0.205 0.205 0.374 1.302 8.483 19.047 19.047 8.109 18.842 3.109 2.132 ms 3.361 18
Server Jitter 173.11.101.155 0.485 0.485 0.992 1.945 4.066 16.684 16.684 3.074 16.199 1.898 2.306 ms 6.507 49.43
Server Jitter 192.168.1.10 0.000 0.065 0.158 0.525 4.081 12.545 13.559 3.923 12.480 1.883 1.035 ms 3.158 19.55
Server Jitter 216.218.254.202 0.739 0.739 0.844 1.329 1.855 2.053 2.053 1.011 1.315 0.308 1.339 ms 47.86 199
Server Jitter SHM(0) 2.052 3.980 5.334 10.259 21.035 29.658 46.235 15.701 25.679 5.156 11.380 ms 6.927 25.14
Server Jitter SHM(1) 0.101 0.195 0.264 0.513 1.030 1.409 2.731 0.766 1.214 0.252 0.566 µs 7.247 28.18
Server Offset 169.229.128.134 2.126 2.126 2.264 2.685 2.982 3.166 3.166 0.718 1.040 0.223 2.659 ms 1326 1.48e+04
Server Offset 173.11.101.155 -1.787 -1.787 -0.941 0.130 1.035 1.346 1.346 1.976 3.133 0.601 0.057 ms -4.037 11.65
Server Offset 192.168.1.10 11.218 24.105 85.484 192.483 496.577 645.521 704.815 411.093 621.416 123.424 216.735 µs 4.282 14.17
Server Offset 216.218.254.202 2.228 2.228 2.262 2.691 3.092 3.680 3.680 0.830 1.451 0.298 2.673 ms 531.7 4469
Server Offset SHM(0) -406.548 -391.052 -383.059 -357.841 -325.040 -316.059 -292.663 58.019 74.993 17.695 -356.284 ms -9503 2.022e+05
Server Offset SHM(1) -3.897 -2.858 -2.138 -0.430 0.450 0.755 1.044 2.588 3.613 0.763 -0.560 µs -11.38 37.88
Temp ZONE0 46.160 46.160 46.160 47.236 49.388 49.926 49.926 3.228 3.766 0.870 47.573 °C
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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