NTPsec

Backup/Meinberg

Report generated: Sun Jul 6 15:43:04 2025 UTC
Start Time: Sun Jun 29 15:43:04 2025 UTC
End Time: Sun Jul 6 15:43:04 2025 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 -1.864 -0.048 -0.017 -0.002 0.026 0.102 11.449 0.043 0.150 0.193 0.005 ms 48.03 2667
Local Clock Frequency Offset 3.453 5.582 5.617 6.092 6.619 6.764 11.176 1.001 1.182 0.441 6.158 ppm 5.87 65.9

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 0.344 0.472 0.557 0.828 2.631 8.676 4,162.027 2.074 8.204 165.088 11.082 µs 19.85 423.8

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 0.094 0.138 0.552 1.784 6.877 861.146 1.646 6.783 32.971 2.794 ppb 19.19 400

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 -1.864 -0.048 -0.017 -0.002 0.026 0.102 11.449 0.043 0.150 0.193 0.005 ms 48.03 2667

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 3.453 5.582 5.617 6.092 6.619 6.764 11.176 1.001 1.182 0.441 6.158 ppm 5.87 65.9
Temp /dev/sda 44.000 44.000 45.000 47.000 49.000 50.000 56.000 4.000 6.000 1.351 46.999 °C
Temp /dev/sdb 54.000 55.000 56.000 58.000 63.000 67.000 68.000 7.000 12.000 2.428 58.091 °C
Temp /dev/sdc 56.000 56.000 56.000 58.000 61.000 61.000 67.000 5.000 5.000 1.383 58.525 °C
Temp /dev/sdd 60.000 61.000 62.000 64.000 71.000 76.000 76.000 9.000 15.000 2.808 65.115 °C
Temp /dev/sde 45.000 45.000 46.000 46.000 47.000 47.000 47.000 1.000 2.000 0.439 46.125 °C
Temp /dev/sdf 54.000 55.000 56.000 58.000 64.000 68.000 69.000 8.000 13.000 2.588 58.822 °C
Temp LM0 28.750 28.750 29.000 31.250 34.000 37.500 45.250 5.000 8.750 1.957 31.562 °C
Temp LM1 40.500 41.500 42.000 44.000 46.500 46.500 47.000 4.500 5.000 1.201 44.334 °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 45.000 47.000 49.000 50.000 52.000 4.000 50.000 5.280 46.437 °C
Temp LM12 27.800 27.800 27.800 27.800 27.800 45.000 56.000 0.000 17.200 2.118 28.030 °C
Temp LM13 27.800 27.800 29.800 29.800 29.800 29.800 29.800 0.000 2.000 0.218 29.776 °C
Temp LM14 29.800 29.800 30.250 32.500 35.500 37.250 39.750 5.250 7.450 1.682 32.776 °C
Temp LM15 30.250 30.750 56.000 58.000 64.000 69.000 69.000 8.000 38.250 4.024 58.674 °C
Temp LM16 54.000 56.000 61.500 63.500 66.000 69.500 71.500 4.500 13.500 1.849 63.754 °C
Temp LM17 61.000 62.000 63.000 65.000 72.000 76.000 77.000 9.000 14.000 2.765 65.345 °C
Temp LM18 55.000 55.000 56.000 58.000 63.000 68.000 68.000 7.000 13.000 2.481 58.322 °C
Temp LM19 27.000 27.000 28.000 30.000 35.000 57.000 79.000 7.000 30.000 5.026 31.358 °C
Temp LM2 33.000 33.000 33.000 36.000 38.000 46.000 47.000 5.000 13.000 1.759 35.774 °C
Temp LM20 26.000 27.000 28.000 30.000 34.000 42.000 79.000 6.000 15.000 4.008 30.552 °C
Temp LM21 24.000 25.000 25.000 28.000 31.000 41.000 74.000 6.000 16.000 4.026 28.423 °C
Temp LM22 25.000 26.000 27.000 30.000 34.000 48.000 73.000 7.000 22.000 3.992 30.433 °C
Temp LM23 25.000 26.000 27.000 29.000 33.000 41.000 70.000 6.000 15.000 3.636 29.848 °C
Temp LM24 26.000 26.000 26.000 27.000 29.000 29.000 29.000 3.000 3.000 0.789 27.292 °C
Temp LM3 31.500 31.500 32.000 34.500 37.000 37.500 37.500 5.000 6.000 1.584 34.477 °C
Temp LM4 24.000 24.000 24.000 24.000 24.000 32.000 32.500 0.000 8.000 0.880 24.097 °C
Temp LM5 24.000 24.000 30.500 30.500 30.500 30.500 30.500 0.000 6.500 0.708 30.422 °C
Temp LM6 27.000 28.000 61.000 63.000 66.000 70.000 71.000 5.000 42.000 4.242 63.140 °C
Temp LM7 0.000 0.000 0.000 0.000 0.000 62.000 66.000 0.000 62.000 6.802 0.750 °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 26.000 27.000 28.000 30.000 34.000 48.000 79.000 6.000 21.000 4.283 30.730 °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 61.000 61.000 61.500 63.500 66.000 69.500 71.500 4.500 8.500 1.615 63.842 °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) -1.983 -0.585 -0.177 0.031 0.182 0.433 11.195 0.359 1.018 0.358 0.028 ms 23.64 708

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 -1,024.611 -759.816 -481.208 17.973 518.025 821.286 908.692 999.233 1,581.102 287.238 1.377 µs 0.04978 3.978

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 -2.040 -0.049 -0.015 0.049 0.089 0.151 11.613 0.104 0.201 0.368 0.058 ms 28.62 882.6

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 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 -1.550 -0.070 -0.004 0.046 0.096 0.189 11.990 0.101 0.259 0.350 0.058 ms 30.24 980.8

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 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) -83.074 -45.529 -17.306 -2.394 25.062 86.617 142.677 42.368 132.146 18.795 0.363 µs 2.266 18.75

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 0.003 0.005 0.012 0.058 0.084 10.277 0.053 0.081 0.270 0.029 ms 33.1 1140

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 2.317 3.837 5.318 12.010 29.255 45.465 124.380 23.937 41.628 9.039 14.276 µs 3.343 26.37

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 0.024 0.093 0.148 10.736 0.087 0.144 0.317 0.044 ms 28.71 857.1

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 0.003 0.005 0.012 0.050 0.148 10.637 0.045 0.145 0.264 0.027 ms 34.14 1242

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) 0.155 0.376 0.580 1.954 6.998 26.774 59.962 6.418 26.398 4.502 2.976 µs 6.567 57.12

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 3.453 5.582 5.617 6.092 6.619 6.764 11.176 1.001 1.182 0.441 6.158 ppm 5.87 65.9
Local Clock Time Offset -1.864 -0.048 -0.017 -0.002 0.026 0.102 11.449 0.043 0.150 0.193 0.005 ms 48.03 2667
Local RMS Frequency Jitter 0.000 0.094 0.138 0.552 1.784 6.877 861.146 1.646 6.783 32.971 2.794 ppb 19.19 400
Local RMS Time Jitter 0.344 0.472 0.557 0.828 2.631 8.676 4,162.027 2.074 8.204 165.088 11.082 µs 19.85 423.8
Server Jitter 2001:470:e815::8 (spidey.rellim.com) 0.000 0.003 0.005 0.012 0.058 0.084 10.277 0.053 0.081 0.270 0.029 ms 33.1 1140
Server Jitter 204.17.205.1 2.317 3.837 5.318 12.010 29.255 45.465 124.380 23.937 41.628 9.039 14.276 µs 3.343 26.37
Server Jitter 204.17.205.24 0.000 0.004 0.006 0.024 0.093 0.148 10.736 0.087 0.144 0.317 0.044 ms 28.71 857.1
Server Jitter 204.17.205.27 0.000 0.003 0.005 0.012 0.050 0.148 10.637 0.045 0.145 0.264 0.027 ms 34.14 1242
Server Jitter SHM(0) 0.155 0.376 0.580 1.954 6.998 26.774 59.962 6.418 26.398 4.502 2.976 µs 6.567 57.12
Server Offset 2001:470:e815::8 (spidey.rellim.com) -1.983 -0.585 -0.177 0.031 0.182 0.433 11.195 0.359 1.018 0.358 0.028 ms 23.64 708
Server Offset 204.17.205.1 -1,024.611 -759.816 -481.208 17.973 518.025 821.286 908.692 999.233 1,581.102 287.238 1.377 µs 0.04978 3.978
Server Offset 204.17.205.24 -2.040 -0.049 -0.015 0.049 0.089 0.151 11.613 0.104 0.201 0.368 0.058 ms 28.62 882.6
Server Offset 204.17.205.27 -1.550 -0.070 -0.004 0.046 0.096 0.189 11.990 0.101 0.259 0.350 0.058 ms 30.24 980.8
Server Offset SHM(0) -83.074 -45.529 -17.306 -2.394 25.062 86.617 142.677 42.368 132.146 18.795 0.363 µs 2.266 18.75
Temp /dev/sda 44.000 44.000 45.000 47.000 49.000 50.000 56.000 4.000 6.000 1.351 46.999 °C
Temp /dev/sdb 54.000 55.000 56.000 58.000 63.000 67.000 68.000 7.000 12.000 2.428 58.091 °C
Temp /dev/sdc 56.000 56.000 56.000 58.000 61.000 61.000 67.000 5.000 5.000 1.383 58.525 °C
Temp /dev/sdd 60.000 61.000 62.000 64.000 71.000 76.000 76.000 9.000 15.000 2.808 65.115 °C
Temp /dev/sde 45.000 45.000 46.000 46.000 47.000 47.000 47.000 1.000 2.000 0.439 46.125 °C
Temp /dev/sdf 54.000 55.000 56.000 58.000 64.000 68.000 69.000 8.000 13.000 2.588 58.822 °C
Temp LM0 28.750 28.750 29.000 31.250 34.000 37.500 45.250 5.000 8.750 1.957 31.562 °C
Temp LM1 40.500 41.500 42.000 44.000 46.500 46.500 47.000 4.500 5.000 1.201 44.334 °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 45.000 47.000 49.000 50.000 52.000 4.000 50.000 5.280 46.437 °C
Temp LM12 27.800 27.800 27.800 27.800 27.800 45.000 56.000 0.000 17.200 2.118 28.030 °C
Temp LM13 27.800 27.800 29.800 29.800 29.800 29.800 29.800 0.000 2.000 0.218 29.776 °C
Temp LM14 29.800 29.800 30.250 32.500 35.500 37.250 39.750 5.250 7.450 1.682 32.776 °C
Temp LM15 30.250 30.750 56.000 58.000 64.000 69.000 69.000 8.000 38.250 4.024 58.674 °C
Temp LM16 54.000 56.000 61.500 63.500 66.000 69.500 71.500 4.500 13.500 1.849 63.754 °C
Temp LM17 61.000 62.000 63.000 65.000 72.000 76.000 77.000 9.000 14.000 2.765 65.345 °C
Temp LM18 55.000 55.000 56.000 58.000 63.000 68.000 68.000 7.000 13.000 2.481 58.322 °C
Temp LM19 27.000 27.000 28.000 30.000 35.000 57.000 79.000 7.000 30.000 5.026 31.358 °C
Temp LM2 33.000 33.000 33.000 36.000 38.000 46.000 47.000 5.000 13.000 1.759 35.774 °C
Temp LM20 26.000 27.000 28.000 30.000 34.000 42.000 79.000 6.000 15.000 4.008 30.552 °C
Temp LM21 24.000 25.000 25.000 28.000 31.000 41.000 74.000 6.000 16.000 4.026 28.423 °C
Temp LM22 25.000 26.000 27.000 30.000 34.000 48.000 73.000 7.000 22.000 3.992 30.433 °C
Temp LM23 25.000 26.000 27.000 29.000 33.000 41.000 70.000 6.000 15.000 3.636 29.848 °C
Temp LM24 26.000 26.000 26.000 27.000 29.000 29.000 29.000 3.000 3.000 0.789 27.292 °C
Temp LM3 31.500 31.500 32.000 34.500 37.000 37.500 37.500 5.000 6.000 1.584 34.477 °C
Temp LM4 24.000 24.000 24.000 24.000 24.000 32.000 32.500 0.000 8.000 0.880 24.097 °C
Temp LM5 24.000 24.000 30.500 30.500 30.500 30.500 30.500 0.000 6.500 0.708 30.422 °C
Temp LM6 27.000 28.000 61.000 63.000 66.000 70.000 71.000 5.000 42.000 4.242 63.140 °C
Temp LM7 0.000 0.000 0.000 0.000 0.000 62.000 66.000 0.000 62.000 6.802 0.750 °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 26.000 27.000 28.000 30.000 34.000 48.000 79.000 6.000 21.000 4.283 30.730 °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 61.000 61.000 61.500 63.500 66.000 69.500 71.500 4.500 8.500 1.615 63.842 °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.
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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