Philips PM 6670 Operating Manual page 18

20
Pulse width measurements
1 .Make the preliminary settings.
2.Select PULSE WIDTH A.
3.Connect the signal to input A.
4.Push the trigger level control (DC mode) and set
the trigger level to 50% of the signal amplitude.
5.Select SLOPE, i.e. released for positive pulse
width and pushed for negative pulse width.
6.Pulse width measurements can also be performed
in the time interval mode, but require more control
settings. However, pulse width below Ips should
be made in the time interval average A-B mode.
Note;
• RPM will give
9.9.9.9.9.9.9.9.
• CHECK cannot be
overflow condition, i.e.
used for checking phase
delay, as the internal clock frequency is higher
than 1.6MHz.
Checking of COUNT A gated by B or start/stop
by B is not possible.
PULSE WIDTH will display 0, TIME INTERVAL
Single 100ns and TIME INTERVAL Average 50ns.
FREQ C (PM 6672) will display 256, i.e. the
prescaling factor.
Check mode
1 .Make the preliminary settings.
2.Press CHECK. The internal 10MHz time-base signal
is now connected to the logic circuits and all
input controls are disconnected.
CHECK enables a self-test of most measuring
functions. The resolution is given by the set measuring
time (not applicable for pulse width and time interval
single mode).
Overflow condition
An attempt to divide by zero (in ratio A/B mode)
or effective measuring times longer than 99s will
result in an overflow condition.
The display will show: 9.9.9.9.9.9.9.9.