NTPsec

scratchy

Report generated: Fri Apr 4 02:15:03 2025 UTC
Start Time: Thu Apr 3 02:15:03 2025 UTC
End Time: Fri Apr 4 02:15:03 2025 UTC
Report Period: 1.0 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 -0.367 -0.367 -0.316 0.070 0.771 1.026 1.026 1.087 1.394 0.349 0.139 ms -1.414 3.44
Local Clock Frequency Offset 20.971 20.971 20.979 21.452 21.619 21.634 21.634 0.640 0.664 0.235 21.313 ppm 7.219e+05 6.478e+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 129.572 129.572 135.086 178.610 336.183 408.689 408.689 201.097 279.117 61.133 196.550 µs 19.11 72.82

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 14.733 14.733 15.761 30.986 58.888 65.815 65.815 43.127 51.082 13.674 34.051 ppb 8.313 23.62

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 -0.367 -0.367 -0.316 0.070 0.771 1.026 1.026 1.087 1.394 0.349 0.139 ms -1.414 3.44

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats 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 130.207.244.240

peer offset 130.207.244.240 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 130.207.244.240 -0.336 -0.336 -0.139 0.157 0.961 1.123 1.123 1.100 1.459 0.361 0.257 ms -0.1083 2.107

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 18.26.4.105

peer offset 18.26.4.105 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 18.26.4.105 -748.250 -748.250 -683.194 -387.123 477.021 700.263 700.263 1,160.215 1,448.513 389.988 -208.568 µs -7.486 17.4

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 192.5.41.41

peer offset 192.5.41.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.5.41.41 -2.080 -2.080 -2.011 -1.768 -0.910 -0.816 -0.816 1.102 1.264 0.364 -1.620 ms -177 1041

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 2001:470:0:2c8::2 (clock.nyc.he.net)

peer offset 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -610.177 -610.177 -540.001 -264.402 492.987 702.432 702.432 1,032.988 1,312.609 356.838 -152.726 µs -6.323 13.99

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 2604:a880:2:d1::116:d001 (itchy.podsix.net)

peer offset 2604:a880:2:d1::116:d001 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) -1.796 -1.796 -1.680 -0.770 0.145 0.240 0.240 1.825 2.037 0.489 -0.755 ms -23.95 81.9

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 2610:20:6f15:15::26 (time-e-g.nist.gov)

peer offset 2610:20:6f15:15::26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -0.471 -0.471 -0.444 0.132 0.930 1.142 1.142 1.374 1.612 0.381 0.164 ms -1.591 3.91

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 130.207.244.240

peer jitter 130.207.244.240 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 130.207.244.240 37.193 37.193 46.456 117.671 528.912 992.574 992.574 482.456 955.381 168.286 166.734 µs 3.317 15.16

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 18.26.4.105

peer jitter 18.26.4.105 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 18.26.4.105 30.485 30.485 44.906 113.163 272.376 439.449 439.449 227.470 408.964 80.411 131.341 µs 3.734 12.53

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 192.5.41.41

peer jitter 192.5.41.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.5.41.41 35.106 35.106 52.131 125.659 414.873 483.686 483.686 362.742 448.580 97.755 148.570 µs 3.501 11.48

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 2001:470:0:2c8::2 (clock.nyc.he.net)

peer jitter 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 15.823 15.823 33.567 86.334 171.233 192.959 192.959 137.666 177.136 42.040 91.171 µs 5.645 15.41

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 2604:a880:2:d1::116:d001 (itchy.podsix.net)

peer jitter 2604:a880:2:d1::116:d001 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.048 0.048 0.055 0.118 3.878 17.325 17.325 3.823 17.277 2.188 0.667 ms 3.913 32.5

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 2610:20:6f15:15::26 (time-e-g.nist.gov)

peer jitter 2610:20:6f15:15::26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 43.467 43.467 103.982 267.942 528.443 598.250 598.250 424.461 554.783 138.744 277.096 µs 4.422 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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 20.971 20.971 20.979 21.452 21.619 21.634 21.634 0.640 0.664 0.235 21.313 ppm 7.219e+05 6.478e+07
Local Clock Time Offset -0.367 -0.367 -0.316 0.070 0.771 1.026 1.026 1.087 1.394 0.349 0.139 ms -1.414 3.44
Local RMS Frequency Jitter 14.733 14.733 15.761 30.986 58.888 65.815 65.815 43.127 51.082 13.674 34.051 ppb 8.313 23.62
Local RMS Time Jitter 129.572 129.572 135.086 178.610 336.183 408.689 408.689 201.097 279.117 61.133 196.550 µs 19.11 72.82
Server Jitter 130.207.244.240 37.193 37.193 46.456 117.671 528.912 992.574 992.574 482.456 955.381 168.286 166.734 µs 3.317 15.16
Server Jitter 18.26.4.105 30.485 30.485 44.906 113.163 272.376 439.449 439.449 227.470 408.964 80.411 131.341 µs 3.734 12.53
Server Jitter 192.5.41.41 35.106 35.106 52.131 125.659 414.873 483.686 483.686 362.742 448.580 97.755 148.570 µs 3.501 11.48
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 15.823 15.823 33.567 86.334 171.233 192.959 192.959 137.666 177.136 42.040 91.171 µs 5.645 15.41
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.048 0.048 0.055 0.118 3.878 17.325 17.325 3.823 17.277 2.188 0.667 ms 3.913 32.5
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 43.467 43.467 103.982 267.942 528.443 598.250 598.250 424.461 554.783 138.744 277.096 µs 4.422 11
Server Offset 130.207.244.240 -0.336 -0.336 -0.139 0.157 0.961 1.123 1.123 1.100 1.459 0.361 0.257 ms -0.1083 2.107
Server Offset 18.26.4.105 -748.250 -748.250 -683.194 -387.123 477.021 700.263 700.263 1,160.215 1,448.513 389.988 -208.568 µs -7.486 17.4
Server Offset 192.5.41.41 -2.080 -2.080 -2.011 -1.768 -0.910 -0.816 -0.816 1.102 1.264 0.364 -1.620 ms -177 1041
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -610.177 -610.177 -540.001 -264.402 492.987 702.432 702.432 1,032.988 1,312.609 356.838 -152.726 µs -6.323 13.99
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) -1.796 -1.796 -1.680 -0.770 0.145 0.240 0.240 1.825 2.037 0.489 -0.755 ms -23.95 81.9
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -0.471 -0.471 -0.444 0.132 0.930 1.142 1.142 1.374 1.612 0.381 0.164 ms -1.591 3.91
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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