NTPsec

b-ntpsec-168-hour-stats

Report generated: Wed May 22 10:46:03 2019 UTC
Start Time: Wed May 15 10:40:02 2019 UTC
End Time: Wed May 22 10:40:02 2019 UTC
Report published: Wed May 22 04:01:34 2019 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%95%StdDev  MeanUnits nessosis
Local Clock Time Offset-53.586-0.002-0.0010.0000.001 0.002101.4590.0020.0040.3120.000ms 196.48.39e+04
Local Clock Frequency Offset-35.858-6.590-6.401-6.191-6.108 -6.098-5.7870.2930.4920.317-6.224ppm -88671.912e+05

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%95%StdDev  MeanUnits nessosis
Local RMS Time Jitter0.0000.0000.0000.0010.001 0.00249.1790.0010.0020.3910.007ms 81.16 7808

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%95%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter0.0002.1952.6164.2598.894 12.7714,834.6186.27810.57641.5645.549ppb 78.97 7326

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%95%StdDev  MeanUnits nessosis
Local Clock Offset-53.586-0.002-0.0010.0000.001 0.002101.4590.0020.0040.3120.000ms 196.48.39e+04

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%95%StdDev  MeanUnits nessosis
Local Clock Frequency Offset-35.858-6.590-6.401-6.191-6.108 -6.098-5.7870.2930.4920.317-6.224ppm -88671.912e+05
Temp ZONE030.02044.54645.62248.31249.388 49.38850.4643.7664.8421.37647.930°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%95%StdDev  MeanUnits nessosis
nSats6.0006.0007.0009.00012.000 12.00012.0005.0006.0001.4019.473nSat 208.7 1303
TDOP0.4900.5500.6000.8401.420 1.9102.7800.8201.3600.2800.897 19.53 83.7

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. TDOP ranges from 1 to greater than 20. 1 denotes the highest possible confidence level. 2 to 5 is good. Greater than 20 means there will be significant inaccuracy and error.



Peer Offsets

peer offsets plot

The offset of all refclocks, peers 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.



Peer Offset 149.20.64.28

peer offset 149.20.64.28 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset 149.20.64.28-24.645-3.871-2.278-1.785-1.406 -1.16615.2410.8722.7052.116-1.840ms-16.07 158.4

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset 162.213.2.253

peer offset 162.213.2.253 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset 162.213.2.253-2.906-1.998-1.775-1.340-0.958 255.195274.0650.816257.19431.7522.581ms 4.396 40.55

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset 169.229.128.134

peer offset 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset 169.229.128.134-2.733-2.344-2.168-1.719-1.383 231.356259.8300.785233.70026.0080.950ms 5.817 62.74

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset 169.229.128.142

peer offset 169.229.128.142 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset 169.229.128.142-2.468-2.238-2.093-1.652-1.298 253.877264.7740.795256.11526.4441.090ms 5.784 61.88

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset 192.168.1.41

peer offset 192.168.1.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset 192.168.1.41-0.936-0.102-0.0560.0020.192 0.285259.4220.2480.38718.4981.371ms 10.14 144

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset 76.14.161.109

peer offset 76.14.161.109 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset 76.14.161.109-29.658-11.167-6.859-5.281-4.173 247.901308.1842.686259.06726.515-2.715ms 5.109 62.86

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset SHM(0)

peer offset SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset SHM(0)-0.488-0.429-0.414-0.368-0.324 -0.3107,716.2350.0910.11920.836-0.312s 366.21.357e+05

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Offset SHM(1)

peer offset SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Offset SHM(1)-0.001-0.000-0.0000.0000.000 0.000206,006.4940.0000.000577.1902.364s 282.78.708e+04

The offset of a peer or 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 remote. 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 peer 80µs; 90% ranges for WAN servers 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.



Peer Jitters

peer jitters plot

The RMS Jitter of all refclocks, peers 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.



Peer Jitter 149.20.64.28

peer jitter 149.20.64.28 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter 149.20.64.280.0000.0000.0000.5419.659 20.13039.8869.65920.1304.5122.827ms 2.532 21.91

The RMS Jitter of a remote peer or 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.



Peer Jitter 162.213.2.253

peer jitter 162.213.2.253 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter 162.213.2.2530.0000.0000.1880.53710.142 13.26796.8139.95413.2677.3282.964ms 7.232 89.52

The RMS Jitter of a remote peer or 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.



Peer Jitter 169.229.128.134

peer jitter 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter 169.229.128.1340.0000.0000.2280.6369.442 17.07499.8929.21417.0744.6752.920ms 5.971 108.5

The RMS Jitter of a remote peer or 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.



Peer Jitter 169.229.128.142

peer jitter 169.229.128.142 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter 169.229.128.1420.0000.0000.2160.5969.379 15.61296.8119.16315.6125.9963.097ms 6.593 90.37

The RMS Jitter of a remote peer or 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.



Peer Jitter 192.168.1.41

peer jitter 192.168.1.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter 192.168.1.410.0000.0230.0460.1458.642 8.96368.2728.5968.9403.7751.454ms 6.257 98

The RMS Jitter of a remote peer or 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.



Peer Jitter 76.14.161.109

peer jitter 76.14.161.109 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter 76.14.161.1090.0000.0000.8644.42834.816 78.055114.83433.95278.05513.4639.632ms 2.674 17.62

The RMS Jitter of a remote peer or 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.



Peer Jitter SHM(0)

peer jitter SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter SHM(0)0.0004.2715.80411.47923.981 32.3264,142.52518.17728.05514.08612.825ms 1734.067e+04

The RMS Jitter of a remote peer or 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.



Peer Jitter SHM(1)

peer jitter SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%95%StdDev  MeanUnits nessosis
Peer Jitter SHM(1)0.0000.0000.0000.0010.002 0.003878.2690.0010.0033.8200.027ms 1633.018e+04

The RMS Jitter of a remote peer or 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%95%StdDev  MeanUnits nessosis
Local Clock Frequency Offset-35.858-6.590-6.401-6.191-6.108 -6.098-5.7870.2930.4920.317-6.224ppm -88671.912e+05
Local Clock Time Offset-53.586-0.002-0.0010.0000.001 0.002101.4590.0020.0040.3120.000ms 196.48.39e+04
Local RMS Frequency Jitter0.0002.1952.6164.2598.894 12.7714,834.6186.27810.57641.5645.549ppb 78.97 7326
Local RMS Time Jitter0.0000.0000.0000.0010.001 0.00249.1790.0010.0020.3910.007ms 81.16 7808
Peer Jitter 149.20.64.280.0000.0000.0000.5419.659 20.13039.8869.65920.1304.5122.827ms 2.532 21.91
Peer Jitter 162.213.2.2530.0000.0000.1880.53710.142 13.26796.8139.95413.2677.3282.964ms 7.232 89.52
Peer Jitter 169.229.128.1340.0000.0000.2280.6369.442 17.07499.8929.21417.0744.6752.920ms 5.971 108.5
Peer Jitter 169.229.128.1420.0000.0000.2160.5969.379 15.61296.8119.16315.6125.9963.097ms 6.593 90.37
Peer Jitter 192.168.1.410.0000.0230.0460.1458.642 8.96368.2728.5968.9403.7751.454ms 6.257 98
Peer Jitter 76.14.161.1090.0000.0000.8644.42834.816 78.055114.83433.95278.05513.4639.632ms 2.674 17.62
Peer Jitter SHM(0)0.0004.2715.80411.47923.981 32.3264,142.52518.17728.05514.08612.825ms 1734.067e+04
Peer Jitter SHM(1)0.0000.0000.0000.0010.002 0.003878.2690.0010.0033.8200.027ms 1633.018e+04
Peer Offset 149.20.64.28-24.645-3.871-2.278-1.785-1.406 -1.16615.2410.8722.7052.116-1.840ms-16.07 158.4
Peer Offset 162.213.2.253-2.906-1.998-1.775-1.340-0.958 255.195274.0650.816257.19431.7522.581ms 4.396 40.55
Peer Offset 169.229.128.134-2.733-2.344-2.168-1.719-1.383 231.356259.8300.785233.70026.0080.950ms 5.817 62.74
Peer Offset 169.229.128.142-2.468-2.238-2.093-1.652-1.298 253.877264.7740.795256.11526.4441.090ms 5.784 61.88
Peer Offset 192.168.1.41-0.936-0.102-0.0560.0020.192 0.285259.4220.2480.38718.4981.371ms 10.14 144
Peer Offset 76.14.161.109-29.658-11.167-6.859-5.281-4.173 247.901308.1842.686259.06726.515-2.715ms 5.109 62.86
Peer Offset SHM(0)-0.488-0.429-0.414-0.368-0.324 -0.3107,716.2350.0910.11920.836-0.312s 366.21.357e+05
Peer Offset SHM(1)-0.001-0.000-0.0000.0000.000 0.000206,006.4940.0000.000577.1902.364s 282.78.708e+04
TDOP0.4900.5500.6000.8401.420 1.9102.7800.8201.3600.2800.897 19.53 83.7
Temp ZONE030.02044.54645.62248.31249.388 49.38850.4643.7664.8421.37647.930°C
nSats6.0006.0007.0009.00012.000 12.00012.0005.0006.0001.4019.473nSat 208.7 1303
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 Peer 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 remote clock 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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