32
Triggered Burst and Gate
General
Triggered Burst and Gated modes are selected from the
MODE
screen, called by the MODE key,
as alternatives to the default continuous mode.
MODE:
♦
continuous
◊
gated setup…
◊
◊
triggered setup…
◊
In Triggered Burst mode a defined number of cycles are generated following each trigger event.
This mode is edge triggered.
In gated mode the generator runs whenever the gating signal is true. This mode is level sensitive.
Triggered Burst mode can be controlled by either the Internal Trigger Generator, an external
trigger input, the (internal) Trigger Out signal from an adjacent channel on a multi
−
channel
instrument, by the front panel MAN TRIG key or by remote control. Gated mode can be
controlled by the Internal Trigger Generator or on external trigger input.
In both modes the start phase, i.e. the starting point on the waveform cycle, can be specified.
Internal Trigger Generator
The period of the Internal Trigger Generator is set with the
period
soft
−
key on the
TRIGGER IN
setup screen called by the TRIG IN key.
TRIGGER IN: force
◊
◊
source: internal
◊
slope: positive
♦
period: 2·00ms
The Internal Trigger Generator divides down a crystal oscillator to produce a 1:1 square wave
with a period from 0·01ms (100kHz) to 200s (·005Hz). Generator period entries that cannot be
exactly set are accepted and rounded up to the nearest available value, e.g. ·109ms is rounded
to ·11ms.
When Triggered Burst or Gated modes are selected the SYNC OUT source automatically
defaults to
trigger
which is the output of the internal trigger generator when internal triggering
or gating is specified.
In Triggered Burst mode the selected edge of each cycle of the trigger generator is used to
initiate a burst; the interval between bursts is therefore 0·01ms to 200s as set by the generator
period.
In Gated mode the output of the main generator is gated on whilst the Internal Trigger Generator
output is true; the duration of the gate is therefore ·005ms to 100s in step with trigger generator
periods of ·01ms to 200s.
External Trigger Input
External trigger or gate signals are applied to the front panel TRIG IN socket which has a TTL
level (1·5V) threshold. In Triggered Burst mode the input is edge sensitive; the selected edge of
each external trigger initiates the specified burst. In Gated mode the input is level sensitive; the
output of the main generator is on whilst the gate signal is true.
The minimum pulse width that can be used with TRIG IN in Triggered Burst and Gated mode is
50ns and the maximum repetition rate is 1MHz. The maximum signal level that can be applied
without damage is ±10V.
When Triggered Burst or Gated modes are selected the SYNC OUT source automatically
defaults to
trigger
which is always a positive
−
edged version of the external trigger or gate
signal when external triggering or gating is specified.
