NTPsec

NTP4: SecureSync, Rubidium, NTP (Classic)
One Month - September 23, 2025 14:00 UTC

Report generated: Tue Sep 23 14:04:19 2025 UTC
Start Time: Sun Aug 24 14:04:13 2025 UTC
End Time: Tue Sep 23 14:04:13 2025 UTC
Report Period: 30.0 days

Return to It's About Time

Section Time Frame NTP Server
Local Clock Time/Frequency Offsets One Hour NTP0: x86 SBC, Undisciplined, NTPSec
Local RMS Time Jitter Three Hour NTP1: RPi4B, Uputronics M8, NTPSec
Local RMS Frequency Jitter Six Hour NTP2: CM4, Bollar ZED-F9T, NTPSec
Local Clock Time Offset Histogram Twelve Hour NTP3: CM5, TimeHat LEA-M8T, NTPSec
Local Temperatures One Day NTP4: SecureSync, Rubidium, NTP (Classic)
Local Frequency/Temp Two Day NTP5: RPi3B+, Uputronics MAX-M8Q, NTPSec
Local GPS Three Day NTP6: CM4, TimeBeat OTC Mini, PTP
Server Offsets Seven Day NTP7: LeoNTP, Standalone GNSS, Firmware
Server Jitters Fourteen Day (Updated Daily)
Summary One Month (Updated Daily)
NTPQ Stats
GNSS Performance

NTP4 is a Safran SecureSync 1200 appliance with a Rubidium oscillator and u-blox timing GNSS receiver. It is used as a highly stable atomic reference clock for the network.

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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 -14.000 -1.000 -1.000 0.000 0.998 1.000 63.998 1.998 2.000 0.591 0.001 µs 24.38 2128
Local Clock Frequency Offset 25.805 26.007 26.039 26.088 26.178 26.236 26.251 0.139 0.229 0.041 26.091 ppm 1.114 6.772

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 0.954 0.954 0.956 0.970 1.095 1.201 34.774 0.139 0.247 0.494 1.006 µs 33.35 1391

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 0.002 0.040 0.074 0.189 0.365 0.663 11.050 0.291 0.623 0.200 0.208 ppb 20.05 662.1

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 -14.000 -1.000 -1.000 0.000 0.998 1.000 63.998 1.998 2.000 0.591 0.001 µs 24.38 2128

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 25.805 26.007 26.039 26.088 26.178 26.236 26.251 0.139 0.229 0.041 26.091 ppm 1.114 6.772
Temp BOARD 46.000 46.620 48.750 58.750 59.750 59.880 62.750 11.000 13.260 3.085 57.687 °C
Temp CPU 46.000 47.120 49.120 59.120 59.880 60.250 63.880 10.760 13.130 3.098 58.075 °C
Temp OSC 36.690 37.260 38.680 47.780 48.270 48.480 51.650 9.590 11.220 2.723 46.841 °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 15.000 18.000 19.000 22.000 25.000 26.000 29.000 6.000 8.000 1.873 22.094 nSat 0.05383 2.775
TDOP 0.180 0.180 0.190 0.190 0.200 0.200 0.220 0.010 0.020 0.005 0.194 0.2458 2.483

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 10.0.0.243

peer offset 10.0.0.243 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 10.0.0.243 -41.327 -2.241 17.899 46.730 56.373 58.718 65.774 38.474 60.959 13.775 41.439 µs -1.177 4.481

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 10.0.0.245

peer offset 10.0.0.245 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 10.0.0.245 -61.757 15.446 42.273 77.929 94.791 100.346 262.326 52.518 84.900 17.710 73.767 µs -1.326 6.062

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 10.0.50.55

peer offset 10.0.50.55 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 10.0.50.55 -631.542 15.659 24.941 40.057 51.164 58.029 592.978 26.223 42.370 10.821 39.557 µs -6.398 1220

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.



Refclock Offset 127.127.45.0

peer offset 127.127.45.0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Refclock Offset 127.127.45.0 -14.001 -1.001 -1.000 0.000 0.999 1.000 63.999 1.999 2.001 0.591 0.000 µs 24.36 2126

The offset of a local refclock in seconds. This is useful to see how the measured offset is behaving.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local serial GPS 200 ms; local PPS 20µs.

Clock Offset is field 5 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 10.0.0.243

peer jitter 10.0.0.243 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 10.0.0.243 0.954 3.000 4.721 14.344 41.737 52.434 584.449 37.016 49.434 16.614 18.197 µs 13.5 379

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 10.0.0.245

peer jitter 10.0.0.245 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 10.0.0.245 0.954 5.035 6.964 15.404 45.453 66.036 892.837 38.489 61.001 16.125 19.957 µs 16.79 763.8

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 10.0.50.55

peer jitter 10.0.50.55 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 10.0.50.55 0.954 5.898 8.647 19.602 277.428 995.666 3,811.883 268.781 989.768 179.184 63.832 µs 6.592 62.4

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.



Refclock RMS Jitter 127.127.45.0

peer jitter 127.127.45.0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Refclock RMS Jitter 127.127.45.0 0.954 0.954 0.954 0.954 1.133 1.309 64.143 0.179 0.355 0.504 0.982 µs 58.8 4604

The RMS Jitter of a local refclock. 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 25.805 26.007 26.039 26.088 26.178 26.236 26.251 0.139 0.229 0.041 26.091 ppm 1.114 6.772
Local Clock Time Offset -14.000 -1.000 -1.000 0.000 0.998 1.000 63.998 1.998 2.000 0.591 0.001 µs 24.38 2128
Local RMS Frequency Jitter 0.002 0.040 0.074 0.189 0.365 0.663 11.050 0.291 0.623 0.200 0.208 ppb 20.05 662.1
Local RMS Time Jitter 0.954 0.954 0.956 0.970 1.095 1.201 34.774 0.139 0.247 0.494 1.006 µs 33.35 1391
Refclock Offset 127.127.45.0 -14.001 -1.001 -1.000 0.000 0.999 1.000 63.999 1.999 2.001 0.591 0.000 µs 24.36 2126
Refclock RMS Jitter 127.127.45.0 0.954 0.954 0.954 0.954 1.133 1.309 64.143 0.179 0.355 0.504 0.982 µs 58.8 4604
Server Jitter 10.0.0.243 0.954 3.000 4.721 14.344 41.737 52.434 584.449 37.016 49.434 16.614 18.197 µs 13.5 379
Server Jitter 10.0.0.245 0.954 5.035 6.964 15.404 45.453 66.036 892.837 38.489 61.001 16.125 19.957 µs 16.79 763.8
Server Jitter 10.0.50.55 0.954 5.898 8.647 19.602 277.428 995.666 3,811.883 268.781 989.768 179.184 63.832 µs 6.592 62.4
Server Offset 10.0.0.243 -41.327 -2.241 17.899 46.730 56.373 58.718 65.774 38.474 60.959 13.775 41.439 µs -1.177 4.481
Server Offset 10.0.0.245 -61.757 15.446 42.273 77.929 94.791 100.346 262.326 52.518 84.900 17.710 73.767 µs -1.326 6.062
Server Offset 10.0.50.55 -631.542 15.659 24.941 40.057 51.164 58.029 592.978 26.223 42.370 10.821 39.557 µs -6.398 1220
TDOP 0.180 0.180 0.190 0.190 0.200 0.200 0.220 0.010 0.020 0.005 0.194 0.2458 2.483
Temp BOARD 46.000 46.620 48.750 58.750 59.750 59.880 62.750 11.000 13.260 3.085 57.687 °C
Temp CPU 46.000 47.120 49.120 59.120 59.880 60.250 63.880 10.760 13.130 3.098 58.075 °C
Temp OSC 36.690 37.260 38.680 47.780 48.270 48.480 51.650 9.590 11.220 2.723 46.841 °C
nSats 15.000 18.000 19.000 22.000 25.000 26.000 29.000 6.000 8.000 1.873 22.094 nSat 0.05383 2.775
Summary as CSV file

Our production NTP servers share the same mast-mounted Tallysman Accutenna® TW3972 Triple Band GNSS Antenna + L-band Correction Services antenna using a Tallysman TW164 1-to-4 Port Smart Power GNSS Signal Splitter. No external NTP servers are contacted and all servers, with the exception of NTP6, the LeoNTP 1200, poll each other. Internal NTP clients poll NTP4 or NTP6.

The LeoNTP 1200 is a black-box appliance that doesn't support timing reporting. Its status can be checked by viwing the Server Jitter & Offset from any of the other servers. It can be found at NTP7 or 10.0.50.55. The LeoNTP link above will take you to the Server Jitter between the LeoNTP and the currently selected server.

NTPQ Stats

NTPQ Statistics are not not available for this NTP server.'

GNSS Performance

GNSS Performance is not available for this NTP server.'

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.
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 FIsher-Pearson moment of skewness. There are other different ways to calculate Skewness Wikipedia describes Skewness best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
Kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses standard Kurtosis. There are other different ways to calculate 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".
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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