NTPsec

Backup/Meinberg

Report generated: Thu Nov 21 07:33:00 2024 UTC
Start Time: Wed Nov 20 07:33:00 2024 UTC
End Time: Thu Nov 21 07:33:00 2024 UTC
Report Period: 1.0 days
Warning: plots clipped

Daily stats   Weekly stats  

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 -145.751 -135.232 -53.084 -7.459 99.621 147.663 159.539 152.705 282.895 49.391 -1.676 µs -3.484 9.391
Local Clock Frequency Offset 1.138 1.141 1.155 1.575 2.177 2.200 2.204 1.022 1.059 0.308 1.559 ppm 79.96 383

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 0.391 0.483 0.576 1.208 3.988 9.491 10.896 3.412 9.008 1.468 1.603 µs 3.947 20.32

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 0.104 0.149 0.262 1.402 6.928 8.698 9.110 6.666 8.549 2.150 2.120 ppb 1.42 4.159

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 -145.751 -135.232 -53.084 -7.459 99.621 147.663 159.539 152.705 282.895 49.391 -1.676 µs -3.484 9.391

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 1.138 1.141 1.155 1.575 2.177 2.200 2.204 1.022 1.059 0.308 1.559 ppm 79.96 383
Temp /dev/sda 41.000 41.000 41.000 43.000 44.000 44.000 44.000 3.000 3.000 0.834 42.552 °C
Temp /dev/sdb 52.000 52.000 52.000 53.000 54.000 54.000 54.000 2.000 2.000 0.790 53.112 °C
Temp /dev/sdc 53.000 53.000 53.000 54.000 54.000 56.000 58.000 1.000 3.000 0.600 53.538 °C
Temp /dev/sdd 58.000 58.000 58.000 60.000 61.000 61.000 61.000 3.000 3.000 0.763 59.633 °C
Temp /dev/sde 41.000 41.000 41.000 43.000 44.000 44.000 44.000 3.000 3.000 0.902 42.325 °C
Temp /dev/sdf 52.000 52.000 52.000 54.000 54.000 55.000 55.000 2.000 3.000 0.901 53.395 °C
Temp LM0 26.750 26.750 26.750 28.250 37.250 37.500 37.500 10.500 10.750 3.299 29.268 °C
Temp LM1 38.000 38.000 38.000 40.000 43.000 44.000 44.000 5.000 6.000 1.611 40.033 °C
Temp LM10 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM11 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM12 41.000 41.000 41.000 43.000 44.000 44.000 44.000 3.000 3.000 0.829 42.552 °C
Temp LM13 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM14 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM15 27.750 28.000 28.000 29.500 34.500 34.750 35.000 6.500 6.750 1.991 29.960 °C
Temp LM16 52.000 52.000 52.000 54.000 55.000 55.000 55.000 3.000 3.000 0.897 53.434 °C
Temp LM17 59.000 59.000 59.000 61.000 63.500 63.500 64.500 4.500 4.500 1.338 60.776 °C
Temp LM18 58.000 58.000 59.000 60.000 61.000 61.000 61.000 2.000 3.000 0.646 59.738 °C
Temp LM19 52.000 52.000 52.000 53.000 54.000 54.000 54.000 2.000 2.000 0.810 53.238 °C
Temp LM2 41.000 41.000 41.000 42.000 44.000 44.000 44.000 3.000 3.000 0.897 42.301 °C
Temp LM20 25.000 25.000 26.000 28.000 60.000 63.000 65.000 34.000 38.000 11.286 32.304 °C
Temp LM21 25.000 25.000 26.000 28.000 59.000 63.000 65.000 33.000 38.000 9.789 31.427 °C
Temp LM22 21.000 22.000 23.000 25.000 54.000 60.000 62.000 31.000 38.000 10.339 28.913 °C
Temp LM23 24.000 24.000 25.000 27.000 57.000 60.000 62.000 32.000 36.000 10.402 30.888 °C
Temp LM24 24.000 24.000 25.000 27.000 55.000 57.000 59.000 30.000 33.000 9.564 30.276 °C
Temp LM3 31.000 31.000 31.000 32.000 37.000 37.000 37.000 6.000 6.000 1.942 32.633 °C
Temp LM4 29.000 29.500 29.500 31.000 33.000 34.000 34.000 3.500 4.500 1.156 31.087 °C
Temp LM5 24.000 24.000 24.000 24.000 24.000 24.000 24.000 0.000 0.000 0.000 24.000 °C
Temp LM6 25.500 25.500 26.000 27.500 60.500 63.500 64.000 34.500 38.000 11.584 31.944 °C
Temp LM7 59.000 59.000 59.000 61.000 63.000 63.000 63.000 4.000 4.000 1.327 60.615 °C
Temp LM8 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM9 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp ZONE0 25.000 25.000 26.000 28.000 61.000 63.000 65.000 35.000 38.000 11.604 32.210 °C
Temp ZONE1 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp ZONE2 59.000 59.000 59.000 61.000 63.500 63.500 65.000 4.500 4.500 1.361 60.787 °C
Temp ZONE3 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °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 2001:470:e815::8 (spidey.rellim.com)

peer offset 2001:470:e815::8 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:e815::8 (spidey.rellim.com) -923.045 -837.994 -600.660 47.663 439.690 519.822 539.184 1,040.350 1,357.816 295.275 38.118 µs -4.153 11.93

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 204.17.205.1

peer offset 204.17.205.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.1 -3.318 -3.143 -1.718 0.014 1.433 1.596 1.634 3.150 4.739 0.866 -0.040 ms -5.281 17.54

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 204.17.205.24

peer offset 204.17.205.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.24 -125.267 -106.777 -48.877 36.198 130.137 155.248 203.452 179.014 262.025 52.827 36.629 µs -0.9745 4.111

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 204.17.205.27

peer offset 204.17.205.27 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 204.17.205.27 -14,097.717 -430.710 -61.522 36.122 112.748 396.321 12,550.804 174.270 827.031 1,089.162 -6.538 µs -5.891 122.6

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) -145.752 -135.233 -53.085 -7.460 99.622 147.664 159.540 152.707 282.897 49.391 -1.677 µs -3.484 9.391

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 2001:470:e815::8 (spidey.rellim.com)

peer jitter 2001:470:e815::8 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 1.383 3.516 5.298 12.580 35.504 57.100 85.549 30.206 53.584 10.416 15.214 µs 4.009 18.38

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 204.17.205.1

peer jitter 204.17.205.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.1 3.009 5.151 7.585 18.295 105.943 145.341 165.771 98.358 140.190 29.960 29.198 µs 2.454 8.992

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 204.17.205.24

peer jitter 204.17.205.24 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.24 2.337 4.256 6.556 23.090 57.775 77.335 133.700 51.219 73.079 15.863 26.058 µs 3.642 13.53

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 204.17.205.27

peer jitter 204.17.205.27 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 204.17.205.27 0.001 0.003 0.005 0.015 0.070 3.580 59.031 0.065 3.577 3.312 0.270 ms 13 228.8

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 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) 0.192 0.429 0.739 3.212 15.304 48.363 60.243 14.565 47.934 7.165 5.226 µs 3.704 24.17

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 1.138 1.141 1.155 1.575 2.177 2.200 2.204 1.022 1.059 0.308 1.559 ppm 79.96 383
Local Clock Time Offset -145.751 -135.232 -53.084 -7.459 99.621 147.663 159.539 152.705 282.895 49.391 -1.676 µs -3.484 9.391
Local RMS Frequency Jitter 0.104 0.149 0.262 1.402 6.928 8.698 9.110 6.666 8.549 2.150 2.120 ppb 1.42 4.159
Local RMS Time Jitter 0.391 0.483 0.576 1.208 3.988 9.491 10.896 3.412 9.008 1.468 1.603 µs 3.947 20.32
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 1.383 3.516 5.298 12.580 35.504 57.100 85.549 30.206 53.584 10.416 15.214 µs 4.009 18.38
Server Jitter 204.17.205.1 3.009 5.151 7.585 18.295 105.943 145.341 165.771 98.358 140.190 29.960 29.198 µs 2.454 8.992
Server Jitter 204.17.205.24 2.337 4.256 6.556 23.090 57.775 77.335 133.700 51.219 73.079 15.863 26.058 µs 3.642 13.53
Server Jitter 204.17.205.27 0.001 0.003 0.005 0.015 0.070 3.580 59.031 0.065 3.577 3.312 0.270 ms 13 228.8
Server Jitter SHM(0) 0.192 0.429 0.739 3.212 15.304 48.363 60.243 14.565 47.934 7.165 5.226 µs 3.704 24.17
Server Offset 2001:470:e815::8 (spidey.rellim.com) -923.045 -837.994 -600.660 47.663 439.690 519.822 539.184 1,040.350 1,357.816 295.275 38.118 µs -4.153 11.93
Server Offset 204.17.205.1 -3.318 -3.143 -1.718 0.014 1.433 1.596 1.634 3.150 4.739 0.866 -0.040 ms -5.281 17.54
Server Offset 204.17.205.24 -125.267 -106.777 -48.877 36.198 130.137 155.248 203.452 179.014 262.025 52.827 36.629 µs -0.9745 4.111
Server Offset 204.17.205.27 -14,097.717 -430.710 -61.522 36.122 112.748 396.321 12,550.804 174.270 827.031 1,089.162 -6.538 µs -5.891 122.6
Server Offset SHM(0) -145.752 -135.233 -53.085 -7.460 99.622 147.664 159.540 152.707 282.897 49.391 -1.677 µs -3.484 9.391
Temp /dev/sda 41.000 41.000 41.000 43.000 44.000 44.000 44.000 3.000 3.000 0.834 42.552 °C
Temp /dev/sdb 52.000 52.000 52.000 53.000 54.000 54.000 54.000 2.000 2.000 0.790 53.112 °C
Temp /dev/sdc 53.000 53.000 53.000 54.000 54.000 56.000 58.000 1.000 3.000 0.600 53.538 °C
Temp /dev/sdd 58.000 58.000 58.000 60.000 61.000 61.000 61.000 3.000 3.000 0.763 59.633 °C
Temp /dev/sde 41.000 41.000 41.000 43.000 44.000 44.000 44.000 3.000 3.000 0.902 42.325 °C
Temp /dev/sdf 52.000 52.000 52.000 54.000 54.000 55.000 55.000 2.000 3.000 0.901 53.395 °C
Temp LM0 26.750 26.750 26.750 28.250 37.250 37.500 37.500 10.500 10.750 3.299 29.268 °C
Temp LM1 38.000 38.000 38.000 40.000 43.000 44.000 44.000 5.000 6.000 1.611 40.033 °C
Temp LM10 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM11 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM12 41.000 41.000 41.000 43.000 44.000 44.000 44.000 3.000 3.000 0.829 42.552 °C
Temp LM13 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp LM14 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Temp LM15 27.750 28.000 28.000 29.500 34.500 34.750 35.000 6.500 6.750 1.991 29.960 °C
Temp LM16 52.000 52.000 52.000 54.000 55.000 55.000 55.000 3.000 3.000 0.897 53.434 °C
Temp LM17 59.000 59.000 59.000 61.000 63.500 63.500 64.500 4.500 4.500 1.338 60.776 °C
Temp LM18 58.000 58.000 59.000 60.000 61.000 61.000 61.000 2.000 3.000 0.646 59.738 °C
Temp LM19 52.000 52.000 52.000 53.000 54.000 54.000 54.000 2.000 2.000 0.810 53.238 °C
Temp LM2 41.000 41.000 41.000 42.000 44.000 44.000 44.000 3.000 3.000 0.897 42.301 °C
Temp LM20 25.000 25.000 26.000 28.000 60.000 63.000 65.000 34.000 38.000 11.286 32.304 °C
Temp LM21 25.000 25.000 26.000 28.000 59.000 63.000 65.000 33.000 38.000 9.789 31.427 °C
Temp LM22 21.000 22.000 23.000 25.000 54.000 60.000 62.000 31.000 38.000 10.339 28.913 °C
Temp LM23 24.000 24.000 25.000 27.000 57.000 60.000 62.000 32.000 36.000 10.402 30.888 °C
Temp LM24 24.000 24.000 25.000 27.000 55.000 57.000 59.000 30.000 33.000 9.564 30.276 °C
Temp LM3 31.000 31.000 31.000 32.000 37.000 37.000 37.000 6.000 6.000 1.942 32.633 °C
Temp LM4 29.000 29.500 29.500 31.000 33.000 34.000 34.000 3.500 4.500 1.156 31.087 °C
Temp LM5 24.000 24.000 24.000 24.000 24.000 24.000 24.000 0.000 0.000 0.000 24.000 °C
Temp LM6 25.500 25.500 26.000 27.500 60.500 63.500 64.000 34.500 38.000 11.584 31.944 °C
Temp LM7 59.000 59.000 59.000 61.000 63.000 63.000 63.000 4.000 4.000 1.327 60.615 °C
Temp LM8 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp LM9 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 °C
Temp ZONE0 25.000 25.000 26.000 28.000 61.000 63.000 65.000 35.000 38.000 11.604 32.210 °C
Temp ZONE1 27.800 27.800 27.800 27.800 27.800 27.800 27.800 0.000 0.000 0.000 27.800 °C
Temp ZONE2 59.000 59.000 59.000 61.000 63.500 63.500 65.000 4.500 4.500 1.361 60.787 °C
Temp ZONE3 29.800 29.800 29.800 29.800 29.800 29.800 29.800 0.000 0.000 0.000 29.800 °C
Summary as CSV file


This server:

CPU: Quad core Intel Xeon E3-1241 v3
Kernel: config.gz
Motherboard: Supermicro X10SAE
OS: Gentoo stable
GPS; Meinberg GPS180PEX
GPS/PPS server: gpsd
NTP server: NTPsec
ntp.conf: current
ntp.log: current

Notes:

Notes:
03:20Z 20 Dec 2018 Change poll from 8s to 4s.  4s seems best.
01:30Z 20 Dec 2018 Change poll from 2s to 8s.
23:00Z 20 Dec 2018 Change poll from 4s to 2s.
22:00Z 20 Dec 2018 Change poll from 64s to 4s.
21:40  19 Dec 2018 -- just started

Poll:
64s   SHM(0) offset StdDev 34.5 us, jitter 5.3 us
8s    8s better jitter than 4s, but worse offset than 4s
4s    SHM(0) offset mean 0 ns StdDev 481 ns, jitter 449 ns StdDev 250 ns
      better than 2s, almost unstable
2s    




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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