Spw-10x spacewire router – Atmel SpaceWire Router SpW-10X User Manual
Page 135
Ref.: UoD_SpW-10X_
UserManual
Issue: 3.4
SpW-10X
SpaceWire Router
User Manual
Date: 11
th
July 2008
Preliminary
135
10.6.5 Time-code Jitter
The variation in time to propagate a time-code through a routing switch.
Time-code jitter occurs in the synchronisation handshaking circuits and the transmitter where the
maximum delay time the time-code has to wait to be transmitted is one data character. The jitter is
measured as
(
) (
)
TXPERIOD
SYSPERIOD
TCJIT
T
T
T
Ч
+
Ч
=
5
2
10.6.6 200M bits/s Input and Output Bit Rate Example
The following table defines the latency and jitter measurements when the transmit bit rate and receive
bit rate are 200M bits/s.
Table 10-6 SpaceWire Router Latency and Jitter Measurements (Bit rate = 200Mbits/s
Description Symbol
Value
Units
Switching Latency
T
SWITCH
133.3
ns,
max
Router Latency – SpaceWire to SpaceWire port
T
SSDATA
546.6
ns,
max
Router Latency – SpaceWire to External port
T
SEDATA
316.6
ns,
max
Router Latency – External to SpaceWire port
T
ESDATA
363.3
ns,
max
Router Latency – External to External port
T
EEDATA
166.6
ns,
max
Time-code Latency – SpaceWire to SpaceWire port
T
SSTC
409.3
ns,
max
Time-code Latency – SpaceWire to External port
T
SETC
316.6
ns,
max
Time-code Latency – External to SpaceWire port
T
ESTC
359.9
ns,
max
Time-code Jitter
T
TCJIT
116.6
ns,
max
[1] Note all figures are worst case