DGP000814AAA
2-01
5-26
GSS6100 operating details
GSS6100 and SimCHAN user manual©
Spirent Communications Plc 2005 - 2007
5.6 Synchronisation
The GSS6100 signal generator incorporates input and output signal ports
which can be used in various ways to synchronise time between the
GSS6100 signal generator and the remainder of the system. This section
describes how to use the 1PPS IN and/or TRIG IN inputs to achieve
synchronisation.
The GSS6100 signal generator maintains time internally by means of a time
counter, clocked by an internal 10MHz clock. Operations always start on a
one-second rollover of this timer.
The timer may be synchronised to an external system before starting an
operation by applying a rising edge to the 1PPS IN rear panel input
5
. Then
operations may be started either by appropriate timing of the software run
command (
Trigger Mode: Disabled
); or by selecting
Delayed Trigger
Mode
and applying a rising edge to the TRIG IN input. Both cause the
operation to start on the next one-second rollover of the timer.
Alternatively, you can select
Immediate Trigger Mode
, which forces the
timer to a point just before the one second rollover and freezes it until a
rising edge is detected on the TRIG IN input, the operation starts running
after a short delay.
Note
: the use of TRIG IN (
Immediate Trigger Mode
) together with 1PPS IN
is inappropriate, as both would be attempting to control the timer. However,
TRIG IN (
Delayed Trigger Mode
) can be used with 1PPS IN.
If coarse synchronisation to your system is sufficient, the methods described
above may be used with no additional considerations. However certain fixed
delays, and uncertainties of the order of 100ns will exist.
To get precise synchronisation you must supply the GSS6100 with an
external 10MHz frequency reference and observe certain timing
requirements between the 1PPS IN and/or TRIG IN signals and the EXT
REF IN signal. The following sections detail these requirements.
5
Note this is a 50
Ω
input and the pulse width of incoming signals should be
≥
120nsecs.
