Fluke 281 User Manual page 104

281, 282, 284
Users Manual
UTILITY screen. Refer to chapter 14, System Operations from the Utility Menu for
additional information.
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 synchronization; 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 INTER CHannel key.
The phase of the slave generator is set by adjusting the phase of the master channel on the
slave generator's inter-channel set-up screen exactly as described above for phase setting
between the channels of a multi-channel instrument. The same section also covers the set-
up for the phase(s) of the slave channel(s) on the slave generator.
When a single-channel generator (which has no inter-channel set-up key or screen) is the
slave, its phase is set using the TRIGGER/GATE SETUP screen. The Trigger Phase
section of the Triggered Burst and Gate chapter covers this process.
The convention adopted for the phase relationship between generators is the same as that
used between channels, i.e. a positive phase setting advances the slave generator with
respect to the master and a negative setting delays the slave generator. The status of the
slave generator on the inter-channel set-up screen must be set to on (this is automatic
on a single channel instrument).
Hardware delays become increasingly significant as frequency increases causing
additional phase delay between the master and slaves. However, these delays can be
largely nulled-out by backing off the phase settings of the slaves.
Typically these hardware delays are as follows:
DDS waveforms:
Clock Synthesized waveforms:
Clearly a multi-channel generator gives much closer inter-channel phase-locking and is
the recommended method for up to 4 channels.
13-6
REF CLOCK I/O SETUP
input
output
phase lock slave
mode: indep
phase: +000.0º
(actual: +000.0º
status: off
<± 25 ns <1° to 100 kHz
<300 ns <1° to 10 kHz.
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