NTPsec

scratchy

Report generated: Tue Mar 11 01:15:04 2025 UTC
Start Time: Mon Mar 10 01:15:04 2025 UTC
End Time: Tue Mar 11 01:15:04 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 -739.275 -739.275 -643.091 102.828 517.387 798.506 798.506 1,160.478 1,537.781 364.522 17.665 µs -3.849 9.315
Local Clock Frequency Offset 20.991 20.991 21.034 21.428 21.623 21.628 21.628 0.590 0.638 0.221 21.353 ppm 8.695e+05 8.301e+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 148.675 148.675 154.827 191.736 240.539 260.837 260.837 85.712 112.162 25.730 194.915 µs 304.5 2143

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 19.168 19.168 20.485 33.775 54.878 58.609 58.609 34.393 39.441 10.282 34.924 ppb 21.46 74.8

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 -739.275 -739.275 -643.091 102.828 517.387 798.506 798.506 1,160.478 1,537.781 364.522 17.665 µs -3.849 9.315

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 -0.646 -0.646 -0.566 -0.066 0.563 1.043 1.043 1.129 1.689 0.369 -0.013 ms -3.854 8.491

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 -978.565 -978.565 -940.725 -434.997 -5.632 434.350 434.350 935.093 1,412.915 315.205 -419.577 µs -19.52 63.17

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 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 -0.342 -0.342 -0.177 0.367 1.126 1.233 1.233 1.303 1.575 0.380 0.359 ms 0.1124 2.24

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) -888.827 -888.827 -872.426 -259.431 358.362 781.741 781.741 1,230.788 1,670.568 391.561 -224.218 µs -8.476 22.29

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) -0.451 -0.451 -0.398 0.204 0.920 1.277 1.277 1.318 1.728 0.425 0.237 ms -1.141 2.894

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) -862.712 -862.712 -644.003 -47.237 521.423 670.047 670.047 1,165.426 1,532.759 364.800 -32.094 µs -4.686 11.46

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 0.029 0.029 0.055 0.140 0.935 3.794 3.794 0.880 3.764 0.738 0.317 ms 2.395 12.33

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 18.995 18.995 25.218 101.278 291.212 358.838 358.838 265.994 339.843 77.132 121.369 µs 3.05 8.375

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 53.740 53.740 72.942 183.564 623.247 691.121 691.121 550.305 637.381 151.985 221.354 µs 2.996 8.783

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) 19.668 19.668 32.006 83.847 302.221 623.168 623.168 270.215 603.500 90.346 104.882 µs 3.603 18.19

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) 0.045 0.045 0.063 0.163 0.932 1.423 1.423 0.869 1.379 0.305 0.300 ms 1.5 4.477

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) 27.865 27.865 55.885 236.304 568.183 792.974 792.974 512.298 765.109 162.730 276.452 µs 3.485 10.26

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 20.991 20.991 21.034 21.428 21.623 21.628 21.628 0.590 0.638 0.221 21.353 ppm 8.695e+05 8.301e+07
Local Clock Time Offset -739.275 -739.275 -643.091 102.828 517.387 798.506 798.506 1,160.478 1,537.781 364.522 17.665 µs -3.849 9.315
Local RMS Frequency Jitter 19.168 19.168 20.485 33.775 54.878 58.609 58.609 34.393 39.441 10.282 34.924 ppb 21.46 74.8
Local RMS Time Jitter 148.675 148.675 154.827 191.736 240.539 260.837 260.837 85.712 112.162 25.730 194.915 µs 304.5 2143
Server Jitter 130.207.244.240 0.029 0.029 0.055 0.140 0.935 3.794 3.794 0.880 3.764 0.738 0.317 ms 2.395 12.33
Server Jitter 18.26.4.105 18.995 18.995 25.218 101.278 291.212 358.838 358.838 265.994 339.843 77.132 121.369 µs 3.05 8.375
Server Jitter 192.5.41.41 53.740 53.740 72.942 183.564 623.247 691.121 691.121 550.305 637.381 151.985 221.354 µs 2.996 8.783
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 19.668 19.668 32.006 83.847 302.221 623.168 623.168 270.215 603.500 90.346 104.882 µs 3.603 18.19
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.045 0.045 0.063 0.163 0.932 1.423 1.423 0.869 1.379 0.305 0.300 ms 1.5 4.477
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 27.865 27.865 55.885 236.304 568.183 792.974 792.974 512.298 765.109 162.730 276.452 µs 3.485 10.26
Server Offset 130.207.244.240 -0.646 -0.646 -0.566 -0.066 0.563 1.043 1.043 1.129 1.689 0.369 -0.013 ms -3.854 8.491
Server Offset 18.26.4.105 -978.565 -978.565 -940.725 -434.997 -5.632 434.350 434.350 935.093 1,412.915 315.205 -419.577 µs -19.52 63.17
Server Offset 192.5.41.41 -0.342 -0.342 -0.177 0.367 1.126 1.233 1.233 1.303 1.575 0.380 0.359 ms 0.1124 2.24
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -888.827 -888.827 -872.426 -259.431 358.362 781.741 781.741 1,230.788 1,670.568 391.561 -224.218 µs -8.476 22.29
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) -0.451 -0.451 -0.398 0.204 0.920 1.277 1.277 1.318 1.728 0.425 0.237 ms -1.141 2.894
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -862.712 -862.712 -644.003 -47.237 521.423 670.047 670.047 1,165.426 1,532.759 364.800 -32.094 µs -4.686 11.46
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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