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Title:
User's Manual (MUT)
N1145 Quad Scaler and Preset Counter/Timer
4. Operating modes
4.1. Gated up-counting
When in NORMAL MODE, the counters (sections 1 to 4) do not require a GATE input.
However, when in GATE (or GATE+CLEAR) mode, a NIM/TTL signal must be supplied
at the GATE input of each counter used. NOTE: when using NIM input signals, this signal
has to be terminated with a 50 Ω impedance at the other GATE bridged input, on
sections 1 or 3.
A single GATE signal can be sent in parallel, to two channels via cables; if t h e last
section is either 2 or 4 then this also provides the correct 50 Ω cable termination. For
example, sections 1 and 2 can share a GATE by feeding the external GATE signal to the
GATE input of section 1 and then connecting a cable between the other GATE output of
section 1 to the GATE input of section 2, which has a 50 Ω impedance. It is also possible
to connect three sections (for instance #1 with #3, and then #3 with #2 or #4) via cables,
in order to send them a single external GATE input.
The OUT signal of section 5 can be used as the GATE input to the counters. The double
OUT connector permits parallel GATE feeding of all four sections, as described above.
4.2. 16- or 24- Digit Up-Counting
It is possible to increase the up-counting range to 16 or 24 digits by using the CARRY
outputs of sections 2 and 4.
For instance, 16-digit up-counting is obtained by connecting the CARRY output of
section 2 to the input of section 1. When the counter of section 2 has fully cycled
(transition 99,999,999 to zero) the CARRY output supplies a NIM input pulse to section 1,
and so on. Thus section 1 will show the most significant digits, and section 2 the least
significant digits of the counting operation.
Similarly, for 24-digit up-counting, the CARRY output of section 2 may be connected to
the input of section 4; the CARRY output of section 4 may then be fed to the input of
section 1 or 3.
4.3. Frequency measurements
This is a way of making relative frequency measurements.
By using section 5 in TIMER MODE, it is possible to make a frequency measurement.
For that purpose:
•
select the clock rate:
NPO:
00115/01:N1145.MUTx/00
ƒ=1/τ
Filename:
N1145_REV0.doc
Revision date:
Re vision:
05/11/2003
0
Number of pages:
14
Page:
12
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