4-10
IM 704610-01E
Explanation
Arming refers to the cue used to start the measurement. As opposed to a trigger, which
refers to the cue used to measure the pulse width or phase difference of each pulse,
arming refers to the starting point of the measurement of a set of pulse widths or phase
differences used to derive the jitter.
Auto Arming (Internal Arming)
If you turn OFF both the
and
indicators, auto arming is activated. The internal
signal of the TA220 is the arming source. Arming is the cue used to start the first
measurement (the first trigger).
External Arming
Arming is activated when an external signal (arming source) is applied to the external
arming input terminal.
• Slope
•
: Arming is activated on the rising slope of the external arming signal.
•
: Arming is activated on the falling slope of the external arming signal.
• Arming Delay
When using external arming, set the delay time of arming in the range shown below.
Setting range: 0.0 to 100.0 ms (in steps of 0.1 ms)
• External Arming Signal
Input the external arming signal to the terminal labeled “EXT ARM IN” on the rear
panel.
Item
Description
Connector type
BNC
Input Impedance
10 k
Ω
(typical value*)
Input coupling
DC
Input level
TTL level
Allowable input voltage range
–5 to 10 V (DC+ACpeak)
Minimum input pulse width
30 ns
*
The typical value is a representative or standard value. It is not strictly guaranteed.
(External arming
signal input
terminal)
External arming input circuit
IN
EXT ARM
(TTL)
+5 V
10 k
Ω
74LS14 or
equivalent
470
Ω
CAUTION
Do not apply a voltage that exceeds the allowable input voltage range to the
external arming signal input terminal. This may cause damage to the TA220.
4.6 Setting the Arming