User Manual

14.2 External I/O
394
An external signal can be input to set the sampling frequency.
External sampling is possible only when the Memory Function or FFT function is
enabled.
When the Roll Mode is enabled, supported pulse widths are those shown above
for the Model 8958, regardless of input modules.
• When the 8937, 8947, and 8957 are used, the anti-aliasing filter (AAF) is not
available, even if it is set to [On] in the Channel Settings screen
1 Connect the EXT.SMPL terminal and the sampling signal output destination with
a BNC cable.
14.2.3 External Sampling (EXT.SMPL)
Sampling Input Signals
Voltage range
HIGH level: 3.0 to 5.0 V, LOW level: 0 to 0.8 V
Pulse width HIGH, LOW level: 50 ns or greater
Response frequency 10 MHz or lower
Maximum input voltage -2 to 7 V
Sampling signal input
Sample the data of the instr
u-
ment.
EXT.SMPL
HIGH
3.0 to 5.0 V
EXT SMPL
LOW
0 to 0.8 V
49.9 Ω
150 pF
5 V
GND
t
t
L
t
H
t
H
> 50 ns
t
L
> 50 ns
t
> 100 ns
10 kΩ
5 V
• Normal operation is not possible when the pulse width is below that shown in
the following table.
Supported external sampling pulse widths
Setting
(EXT.SMPL)
Pulse width
When 8958 is used When other input module is used
t
H
t
L
t t
H
t
L
t
↑
> 5 μs> 5 μs> 10 μs > 50 ns > 50 ns > 100 ns
↓
> 5 μs> 5 μs> 10 μs > 50 ns > 50 ns > 100 ns
↑&↓
> 10
μs> 10 μs> 20 μs > 100 ns > 100 ns > 200 ns
Signal Input Procedure