NTPsec

Backup/Meinberg

Report generated: Tue Oct 22 15:43:01 2024 UTC
Start Time: Tue Oct 15 15:43:01 2024 UTC
End Time: Tue Oct 22 15:43:01 2024 UTC
Report Period: 7.0 days

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 -31.371 -0.084 -0.042 -0.002 0.032 0.087 0.183 0.074 0.171 0.657 -0.023 ms -42.02 1690
Local Clock Frequency Offset 1.337 1.394 1.578 6.412 6.747 7.005 7.041 5.169 5.611 2.260 4.903 ppm 4.454 8.477

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 0.000 0.000 0.001 0.001 0.047 0.207 11.084 0.047 0.206 0.470 0.046 ms 13.98 274.6

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 0.000 0.095 0.137 0.879 23.777 35.127 481.997 23.640 35.032 22.719 7.674 ppb 11.64 206.8

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 -31.371 -0.084 -0.042 -0.002 0.032 0.087 0.183 0.074 0.171 0.657 -0.023 ms -42.02 1690

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 1.337 1.394 1.578 6.412 6.747 7.005 7.041 5.169 5.611 2.260 4.903 ppm 4.454 8.477
Temp /dev/sda 31.000 41.000 42.000 44.000 45.000 46.000 47.000 3.000 5.000 1.080 43.671 °C
Temp /dev/sdb 31.000 51.000 53.000 54.000 61.000 62.000 63.000 8.000 11.000 2.513 54.788 °C
Temp /dev/sdc 37.000 51.000 53.000 54.000 56.000 58.000 58.000 3.000 7.000 1.389 54.077 °C
Temp /dev/sdd 32.000 56.000 59.000 61.000 70.000 71.000 71.000 11.000 15.000 3.166 61.510 °C
Temp /dev/sde 26.000 40.000 42.000 43.000 46.000 48.000 48.000 4.000 8.000 1.569 43.341 °C
Temp /dev/sdf 31.000 50.000 53.000 55.000 62.000 63.000 63.000 9.000 13.000 2.652 54.938 °C
Temp LM0 23.500 26.750 27.000 28.500 30.500 33.250 38.000 3.500 6.500 1.207 28.545 °C
Temp LM1 32.000 39.500 39.500 41.000 42.000 42.500 45.000 2.500 3.000 0.808 40.946 °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 31.000 41.000 42.000 44.000 45.000 46.000 47.000 3.000 5.000 1.080 43.672 °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 23.250 27.750 28.000 29.750 31.000 32.500 34.250 3.000 4.750 0.990 29.569 °C
Temp LM16 31.000 50.000 53.000 55.000 62.000 63.000 63.000 9.000 13.000 2.661 55.014 °C
Temp LM17 45.500 59.500 59.500 61.500 63.000 66.000 66.000 3.500 6.500 1.265 61.409 °C
Temp LM18 32.000 56.000 60.000 61.000 70.000 71.000 71.000 10.000 15.000 3.195 61.647 °C
Temp LM19 31.000 51.000 53.000 55.000 61.000 62.000 63.000 8.000 11.000 2.521 54.905 °C
Temp LM2 26.000 40.000 42.000 43.000 46.000 48.000 48.000 4.000 8.000 1.584 43.340 °C
Temp LM20 24.000 25.000 26.000 28.000 30.000 40.000 70.000 4.000 15.000 3.146 28.040 °C
Temp LM21 24.000 25.000 25.000 28.000 30.000 40.000 69.000 5.000 15.000 2.848 27.745 °C
Temp LM22 22.000 23.000 23.000 25.000 28.000 39.000 70.000 5.000 16.000 2.970 25.654 °C
Temp LM23 23.000 23.000 24.000 26.000 29.000 40.000 67.000 5.000 17.000 2.963 26.727 °C
Temp LM24 24.000 24.000 25.000 27.000 30.000 39.000 59.000 5.000 15.000 2.778 27.169 °C
Temp LM3 22.000 31.000 31.000 33.000 34.000 34.000 38.000 3.000 3.000 0.923 32.731 °C
Temp LM4 23.000 29.000 29.500 31.000 32.000 33.000 33.500 2.500 4.000 0.887 31.050 °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 24.500 25.000 25.500 27.000 30.000 43.000 69.500 4.500 18.000 3.163 27.524 °C
Temp LM7 45.000 59.000 59.000 61.000 63.000 66.000 66.000 4.000 7.000 1.272 61.180 °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 24.000 25.000 26.000 27.000 30.000 42.000 69.000 4.000 17.000 3.162 27.740 °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 45.500 59.500 59.500 61.500 63.000 66.000 66.500 3.500 6.500 1.262 61.410 °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) -32.293 -0.256 -0.090 0.018 0.149 0.254 43.649 0.239 0.509 1.159 0.012 ms -1.703 840.8

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 -11.221 -0.419 -0.312 0.039 0.339 1.122 23.414 0.650 1.541 0.630 0.041 ms 10.48 547.5

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 -119.871 -0.106 -0.054 0.018 0.075 0.106 0.259 0.129 0.212 3.219 -0.103 ms -34.5 1105

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 -6.694 -0.174 -0.032 0.025 0.073 0.200 57.385 0.105 0.374 1.285 0.050 ms 32.66 1323

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) -89.932 -78.648 -31.394 -2.528 19.401 119.485 183.006 50.795 198.133 23.789 -2.772 µs -2.476 20.19

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) 0.000 0.002 0.004 0.011 0.030 0.056 58.018 0.026 0.054 1.935 0.106 ms 20.19 531

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 0.000 0.004 0.006 0.014 0.038 0.078 22.772 0.032 0.074 0.643 0.043 ms 25.72 823.2

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 0.000 0.004 0.006 0.022 0.061 0.108 74.425 0.054 0.104 2.513 0.145 ms 19.98 507.2

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 0.000 0.002 0.004 0.012 0.041 0.101 40.998 0.037 0.099 1.384 0.081 ms 20.89 546.5

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 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) 0.000 0.324 0.543 1.923 6.630 39.826 106.548 6.087 39.502 6.730 3.188 µs 6.561 71.17

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 1.337 1.394 1.578 6.412 6.747 7.005 7.041 5.169 5.611 2.260 4.903 ppm 4.454 8.477
Local Clock Time Offset -31.371 -0.084 -0.042 -0.002 0.032 0.087 0.183 0.074 0.171 0.657 -0.023 ms -42.02 1690
Local RMS Frequency Jitter 0.000 0.095 0.137 0.879 23.777 35.127 481.997 23.640 35.032 22.719 7.674 ppb 11.64 206.8
Local RMS Time Jitter 0.000 0.000 0.001 0.001 0.047 0.207 11.084 0.047 0.206 0.470 0.046 ms 13.98 274.6
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 0.000 0.002 0.004 0.011 0.030 0.056 58.018 0.026 0.054 1.935 0.106 ms 20.19 531
Server Jitter 204.17.205.1 0.000 0.004 0.006 0.014 0.038 0.078 22.772 0.032 0.074 0.643 0.043 ms 25.72 823.2
Server Jitter 204.17.205.24 0.000 0.004 0.006 0.022 0.061 0.108 74.425 0.054 0.104 2.513 0.145 ms 19.98 507.2
Server Jitter 204.17.205.27 0.000 0.002 0.004 0.012 0.041 0.101 40.998 0.037 0.099 1.384 0.081 ms 20.89 546.5
Server Jitter SHM(0) 0.000 0.324 0.543 1.923 6.630 39.826 106.548 6.087 39.502 6.730 3.188 µs 6.561 71.17
Server Offset 2001:470:e815::8 (spidey.rellim.com) -32.293 -0.256 -0.090 0.018 0.149 0.254 43.649 0.239 0.509 1.159 0.012 ms -1.703 840.8
Server Offset 204.17.205.1 -11.221 -0.419 -0.312 0.039 0.339 1.122 23.414 0.650 1.541 0.630 0.041 ms 10.48 547.5
Server Offset 204.17.205.24 -119.871 -0.106 -0.054 0.018 0.075 0.106 0.259 0.129 0.212 3.219 -0.103 ms -34.5 1105
Server Offset 204.17.205.27 -6.694 -0.174 -0.032 0.025 0.073 0.200 57.385 0.105 0.374 1.285 0.050 ms 32.66 1323
Server Offset SHM(0) -89.932 -78.648 -31.394 -2.528 19.401 119.485 183.006 50.795 198.133 23.789 -2.772 µs -2.476 20.19
Temp /dev/sda 31.000 41.000 42.000 44.000 45.000 46.000 47.000 3.000 5.000 1.080 43.671 °C
Temp /dev/sdb 31.000 51.000 53.000 54.000 61.000 62.000 63.000 8.000 11.000 2.513 54.788 °C
Temp /dev/sdc 37.000 51.000 53.000 54.000 56.000 58.000 58.000 3.000 7.000 1.389 54.077 °C
Temp /dev/sdd 32.000 56.000 59.000 61.000 70.000 71.000 71.000 11.000 15.000 3.166 61.510 °C
Temp /dev/sde 26.000 40.000 42.000 43.000 46.000 48.000 48.000 4.000 8.000 1.569 43.341 °C
Temp /dev/sdf 31.000 50.000 53.000 55.000 62.000 63.000 63.000 9.000 13.000 2.652 54.938 °C
Temp LM0 23.500 26.750 27.000 28.500 30.500 33.250 38.000 3.500 6.500 1.207 28.545 °C
Temp LM1 32.000 39.500 39.500 41.000 42.000 42.500 45.000 2.500 3.000 0.808 40.946 °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 31.000 41.000 42.000 44.000 45.000 46.000 47.000 3.000 5.000 1.080 43.672 °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 23.250 27.750 28.000 29.750 31.000 32.500 34.250 3.000 4.750 0.990 29.569 °C
Temp LM16 31.000 50.000 53.000 55.000 62.000 63.000 63.000 9.000 13.000 2.661 55.014 °C
Temp LM17 45.500 59.500 59.500 61.500 63.000 66.000 66.000 3.500 6.500 1.265 61.409 °C
Temp LM18 32.000 56.000 60.000 61.000 70.000 71.000 71.000 10.000 15.000 3.195 61.647 °C
Temp LM19 31.000 51.000 53.000 55.000 61.000 62.000 63.000 8.000 11.000 2.521 54.905 °C
Temp LM2 26.000 40.000 42.000 43.000 46.000 48.000 48.000 4.000 8.000 1.584 43.340 °C
Temp LM20 24.000 25.000 26.000 28.000 30.000 40.000 70.000 4.000 15.000 3.146 28.040 °C
Temp LM21 24.000 25.000 25.000 28.000 30.000 40.000 69.000 5.000 15.000 2.848 27.745 °C
Temp LM22 22.000 23.000 23.000 25.000 28.000 39.000 70.000 5.000 16.000 2.970 25.654 °C
Temp LM23 23.000 23.000 24.000 26.000 29.000 40.000 67.000 5.000 17.000 2.963 26.727 °C
Temp LM24 24.000 24.000 25.000 27.000 30.000 39.000 59.000 5.000 15.000 2.778 27.169 °C
Temp LM3 22.000 31.000 31.000 33.000 34.000 34.000 38.000 3.000 3.000 0.923 32.731 °C
Temp LM4 23.000 29.000 29.500 31.000 32.000 33.000 33.500 2.500 4.000 0.887 31.050 °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 24.500 25.000 25.500 27.000 30.000 43.000 69.500 4.500 18.000 3.163 27.524 °C
Temp LM7 45.000 59.000 59.000 61.000 63.000 66.000 66.000 4.000 7.000 1.272 61.180 °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 24.000 25.000 26.000 27.000 30.000 42.000 69.000 4.000 17.000 3.162 27.740 °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 45.500 59.500 59.500 61.500 63.000 66.000 66.500 3.500 6.500 1.262 61.410 °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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