Operating Manual Vol 1 - ES Documentation

Digital Standard PHSSMIQ2.11.1 Sync and Trigger SignalsThe data generator generates a data sequence with modulation data, control signals for envelopecontrol, and synchronization signals.When TRIGGER MODE AUTO is selected, the PHS signal generation automatically starts.This start can also be activated by an external trigger signal (TRIGGER MODE ARMED_AUTO) whichallows a synchronous sequence for BER measurements to be carried out on receivers.Trigger signals for synchronized sequences can be used for measuring the bit error rate of receivers. Atrigger signal can be fed via the TRIGIN input at connector PAR DATA. The active slope of a triggersignal applied there executes a trigger event.PHS signal generation at a frame limit is started after a trigger event. Data from data lists are insertedinto the selected slots starting from the first bit. PRBS generators start with the set initialization status.Signal generation either starts immediately after the active slope of the trigger signal or after a settablenumber of symbols (EXT TRIGGER DELAY). Retriggering (RETRIG) can be inhibited for a settablenumber of symbols (EXT RETRIGGER INHIBIT).A trigger event can be executed manually or via the IEC/IEEE bus using EXECUTE TRIGGER.When a trigger event is executed, a trigger signal is output at the TRIGOUT 3 output of SMIQ.SMIQ also generates the following sync signals:• a frame clock at TRIGOUT 1 output,• a frame or multiframe clock at TRIGOUT 2 output with settable position in the frame,• the symbol clock and the bit clock.A clock synthesizer on the modulation coder generates the symbol clock and the bit clock in SMIQ. Allthe clock signals are synchronized to the 10-MHz reference of SMIQ. The symbol clock is available atconnector SYMBOL CLOCK and the bit clock at connector BIT CLOCK. If required, the clocksynthesizer in SMIQ can be synchronized to an external symbol or bit clock.The clock signal is selected in the menu via CLOCK-CLOCK SOURCE EXT.To allow for a trouble-free synchronization of the clock synthesizer first apply the external clock and setthe correct symbol rate at SMIQ. Then switch CLOCK SOURCE from INT to EXT.Notes: - The set symbol rate should not differ by more than 1% from the symbol rate of theexternal signal.1125.5555.03 2.116E-9