BNC 745 - Manual (Page 13)

Model 745 Digital Delay Generator. November 2013
6- O
PERATING
I
NFORMATION
Operating Principles
The principle of the programmable delay generator is described in the figure 4 below:
Figure - 4. Principle
Trigger source can be provided by the TRIG IN input, by an internal trigger, by a software command
trigger. Repetitive, single shot trigger and burst modes are available with internal and external
sources. An asynchronous single shot and burst mode are also available.
Repetitive triggers
When the external trigger source is selected a rising edge on “TRIG IN” starts a delay sequence. The
sequence is depicted on Figure - 6. It has to be noticed that a Prescaler value can be used to divide
the Trig Ext input signal frequency.
To get this feature, the user has to select ‘EXT’ as trigger source on the device via the front panel or
via remote control (web page, Ethernet link).
If the internal trigger source is selected, the user can specify the needed trigger source via the front
panel or via remote control (web page, Ethernet link). 2 frequency generators derived from input
clock can be used as repetitive triggers: IN1 and IN2 corresponding to programmable Frequency 1
and 2. The use of internal trigger is depicted on Figure - 8. Frequency generation restarts when a
push on the ESC button is detected while Frequency/Period menu is displayed.
Note: The internal period P1 et P2 can only be increment by step of 5ns.
Single Shot triggers
3 single shot modes are available: one synchronous to the external source (SSE), one to an internal
source (SS1 synchronous to Frequency 1, SS2 synchronous to Frequency 2) and the last, an
asynchronous one (LSS).
Each single shot mode is triggered by a software command. Software trigger command is available
either via remote control or via front panel (by pressing ESC button when items #6 to 13 are
displayed or by using item #20).
Single shots synchronous to external source is depicted on Figure - 6. The same principle can be
applied to any of the internal sources.
© Berkeley Nucleonics Corp. 12 Model 745 User Manual