Aim-TTI TGA1240 Series, Инструкция по эксплуатации

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Synchronising Two Generators
Two generators can be synchronised together following the procedure outlined below. It is
possible to link more than two generators in this way but results are not guaranteed.
Synchronising Principles
Frequency locking is achieved by using the clock output from the ‘master’ generator to drive the
clock inputs of a slave. The additional connection of an initialising SYNC signal permits the slave
to be synchronised such that the phase relationship between master and slave outputs is that
specified on the slave generator’s Inter
−
channel set
−
up screen.
Synchronisation is only possible between generators when the ratio of the master and slave
frequencies is rational, e.g. 3kHz can be synchronised with 2kHz but not with 7kHz. Special
considerations arise with waveforms generated by Clock Synthesis mode (squarewave, arbitrary,
pulse, pulse
−
train and sequence) because of the relatively poor precision with which the
frequency is actually derived in the hardware. With these waveforms, frequencies with an
apparently rational relationship (e.g. 3:1) may be individually synthesised such that the ratio is not
close enough to e.g. 3:1 to maintain phase lock over a period of time; the only relationships
guaranteed to be realised precisely are 2
n
:1 because the division stages in Clock Synthesis
mode are binary. A further complication arises with arb waveforms because waveform frequency
depends on both waveform size and clock frequency (waveform frequency = clock frequency
÷
waveform size). The important relationship with arbs is the ratio of clock frequencies and
the above considerations on precision apply to them. The most practical use of synchronisation
will be to provide outputs at the same frequency, or maybe harmonics, but with phase
differences.
Connections for Synchronisation
The clock connection arrangement is for the rear panel REF CLOCK IN/OUT of the master
(which will be set to
phase lock master
) to be connected directly to the REF CLOCK
IN/OUT socket of the slave (which will be set to
phase lock slave
).
Similarly the synchronising connection is from any SYNC OUT of the master, which all default to
phase lock
, to the TRIG IN input of the slave.
Generator Set-ups
Each generator can have its main parameters set to any value, with the exception that the ratio of
frequencies between master and slave must be rational and each generator can be set to any
waveform, but see Synchronising Principles section above. Best results will be achieved if the
constraints forced on inter
−
channel synchronisation are adopted for inter
−
generator
synchronisation.
The master has its CLOCK IN/OUT set to
phase lock master
on the
REF. CLOCK I/O
SETUP
menu called by the
ref. clock i/o
soft
−
key on the UTILITY screen, see System
Operations section.
REF CLOCK I/O SETUP
◊
input
◊
output
phase lock slave
Repeated presses of the
phase lock
soft
−
key toggle between
master
and
slave
.
The slave is set to
slave.
Setting the slave generator to
phase lock slave
forces the
slave’s mode to continuous and defaults all the SYNC OUT outputs to phase lock. Only one of
the SYNC OUTs is needed for inter
−
generator synchronisation; the others may be reset to other
functions if required. The phase relationship between the slave and the master is set on the
Inter
−
channel set
−
up screen of the slave, accessed by pressing the INTERCHannel key.