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Synchronization
Synchronizing Two Generators13
13-5
3. Pulse and pulse train waveforms will lock to other pulse and pulse-trains (and to each
other) but should be built with equal periods.
4. Arb waveforms should be the same length (althou
gh this requirement is not forced
and violations do not create error messages).
Synchronizing Two Generators
This section covers the use of two generators to produce two or more synchronous
signals. It is possible to link more than two generators in this way but the results are not
guaranteed.
Synchronizing 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 initializing SYNC
signal permits the slave to be synchronized such that the phase relat
ionship between
master and slave outputs is that specified on the slave generator’s inter-channel set-up
screen.
Synchronization is only possible between generators when the ratio of the m
aster and
slave frequencies is rational, e.g. 3 kHz can be synchronized with 2 kHz but not with 7
kHz.
Special considerations arise with waveforms generated b
y clock synthesis mode (square
wave, 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
synthesized 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 realized 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 b
oth waveform size and clock frequency (waveform frequency = clock frequency
divided by 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 synchronization will be to provide outputs at the same frequency, or maybe
harmonics, but with phase differences.
Connections for Synchronization
The clock connection arrangement is for the rear panel REF CLOCK IN/OUT of the
mast
er, which will be set to phase lock master, to be connected directly to the
REF CL
OCK IN/OUT socket of the slave, which will be set to phase lock slave.
Similarly the synchronizing connection is from any SYNC OUT of the master (which all
default to phase lock) to the TRIG IN socket of the slave.
Generator Set-ups
Each generator can have its main parameters set to any values, with the exception that the
ratio of frequencies between master and
slave must obey the rules above; and each
generator can be set to any waveform (but see the section on Synchronizing Principles
above). Best results will be achieved if the constraints forced on inter-channel
synchronization are adopted for inter-generator synchronization.
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
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