GE L90 Instruction Manual page 507

9 THEORY OF OPERATION
Time stamp values are snapshots of the local 256 bit sample counter taken at the time of the transmission or receipt of the
first message in a time stamp sequence. This could be done either in software or hardware, provided the jitter is limited to
less than plus or minus 130 s. A fixed bias in the time stamp is acceptable, provided it is the same for all terminals.
Relay 1
Send T1
i-3
Store T1
i-3
Capture T1
Send T1
Store T2
i-2
Send T1
i-1
Capture T2 T1
i-1,
( T1 T2 T2
i -3, i-2, i -1,
δ θ
Calculate 1, 1.
Slow down
Figure 9–2: ROUND TRIP DELAY AND CLOCK OFFSET COMPUTATION FROM TIME STAMPS
GE Multilin
COMMUNICATION PATH
8.3 ms
i-2 T1
i-2
i-2
8.3 ms
T1
i-1
8.3 ms
T1
i
i
T1 )
i
t 1
L90 Line Current Differential System
Relay 2
Clocks mismatch
Send T2
i-3
Store T2
i-3
Capture T2
i-2
T2
i-2
8.3 ms
Send T2
i-2
Store T1
i-2
8.3 ms
T2
i-1 Send T2
i-1
Capture T1 T2
i-1, i
( T2 T1 T1 T2 )
T2
i-3, i -2, i-1, i
i
δ θ
Calculate 2, 2.
Speed up
831729A2.CDR
t 2
9.1 OVERVIEW
9
9-9