INDOCAL versus NRC via Common-View UTC(NIST)


Grid 1 Day Averages 1 Hour Averages 10 Minute Averages Next Date Last Date Flip    

Server 1INDOCALIP Address66.98.69.224 LocationDominican RepublicDate2021-09-13 (MJD 59470)
Server 2NRCIP Address132.246.11.227 LocationOttawa, CanadaPeriod1 day

Method Hours Time Offset (ms) Range (ms) Frequency Offset Confidence (r)
AVG 24.00 -9.9931 6.904 -6.80 x 10-8 -0.63
MIN 24.00 -7.5539 1.773 -3.76 x 10-8 -0.54




Allan Deviation (ADEV)
Averaging Period ()
(hours, minutes)		 Samples ADEV
(AVG Method)		 ADEV
(MIN Method)
0 h, 10 min 67 2.08 x 10-6 1.02 x 10-6
0 h, 20 min 65 8.85 x 10-7 5.39 x 10-7
0 h, 40 min 61 5.70 x 10-7 2.71 x 10-7
1 h, 20 min 53 2.58 x 10-7 1.39 x 10-7
2 h, 40 min 37 1.27 x 10-7 5.68 x 10-8


Time Deviation (TDEV)
Averaging Period ()
(hours, minutes)		 Samples TDEV
(AVG Method), ms		 TDEV
(MIN Method), ms
0 h, 10 min 67 0.7191 0.3527
0 h, 20 min 64 0.4460 0.2674
0 h, 40 min 58 0.5107 0.1777
1 h, 20 min 46 0.3862 0.2126
2 h, 40 min 22 0.2404 0.0888


Legend
AVG MethodThe AVG method involves comparing each NTP server to UTC(NIST) every 10 seconds, and then averaging these measurements for 10 minutes (60 readings). UTC(NIST) is available with 0.0001 ms resolution. The common-view comparison is made by subtracting the two 10 minute averages to get the time difference between two servers.
MIN MethodThe MIN method involves comparing each NTP server to UTC(NIST) every 10 seconds for a 10 minute interval (60 measurements). However, only one of the 60 measurements is saved, the one with the shortest round trip delay. This method saves only 1.67% of the measurements, and is based on the assumption that NTP measurements with the shortest round trip delays provide the best estimate of the true time difference. UTC(NIST) is available with 0.0001 ms resolution. The common-view comparison is made by subtracting the measurements with the minimum round trip delay to get the time difference between two servers.
HoursThe duration of the comparision in hours.
Time OffsetThe average time offset obtained during the entire comparison, expressed in milliseconds.
RangeThe difference between the maximum and minimum time offset values, expressed in milliseconds.
Frequency OffsetThe average frequency offset betweeen the two NTP servers. This estimate is obtained by fitting a least squares line to all of the recorded data and then applying the equation: delta-t/T, where delta-t is estimated from the slope of the least squares line.
Confidence Level (r)The confidence level of the estimated frequency offset. The confidence level is the correlation coefficient (r) of the least squares line fitted to the data.
Time DeviationThe time deviation (TDEV) of the collected data at various intervals, expressed in milliseconds. TDEV is a metric used to estimate time stability.
Allan DeviationThe Allan deviation (ADEV) of the collected data at various intervals, expressed as a dimensionless value. ADEV is a metric used to estimate frequency stability.