IXIA AFD2, Manual, Page: 8 / 10

Ixia IRIG-B Auxiliary Function Device (AFD2)
Calculating Latency Accuracy for AFD2 (IRIG-B)
15-8 Ixia Platform Reference Manual Manual, Release 6.30
15
different means. Table 15-2 on page 15-8 describes the full set of options
available and their approximate relative accuracies.
Calculating Latency
Accuracy for AFD2
(IRIG-B)
Use the following calculation for latency accuracy for AFD2 ( IRIG-B ) setups.
Latency A to B = Lab
Latency B to A = Lba
Transmit path A to B = T1
Transmit path B to A = T2
Time at A = Ta
Time at B = Tb
Time Absolute = T
Time Error at any site = Terr
Lab=Ta+T1-Tb
Lba=Tb+T2-Ta
Delta L = Lab – Lba
Delta L = Ta+T1-Tb – ( Tb+T2-Ta )
Delta L = T1-T2+2( Ta-Tb )
Delta L = 2(Ta – Tb)
If Ta = T+/-Terr and Tb = T+/-Terr
Then
Delta L= 2(T+/-Terr – T+/-Terr)
Delta L= 2( |Terr|+|Terr|)
Delta L = 4Terr
Table 15-2. Summary of Timing Options
Available on
Devices
Timing Option Time of Day
Accuracy
Frequency
Source
Frequency Accuracy
All Chassis IRIG-B/GPS 150 nanoseconds
from GMT Ixia AFD2 Stratum 1
Ixia 100, 400T,
1600T Synchronous N/A Internal PC clock 1 microsecond/second
Ixia 250 CDMA 100 microseconds
from GMT CDMA Stratum 2
Ixia 100 CDMA in-built 100 microseconds
from GMT CDMA Stratum 2
Ixia 100 GPS in-built 150 nanoseconds
from GMT GPS Stratum 1