HP 8153A - Page 61

The Auto Key
2
lAutol enables or disables automatic ranging for the result. Automatic ranging
ensures that the result has a displayed value between 9% and 100% of full
scale. While you have automatic ranging enabled, the operation-indicator shows
AUTO in the middle of the display. The default state is for automatic ranging to
be enabled.
The Up Key
This key selects the next higher range. If automatic ranging was in operation,
this key disables it.
Eccample If the instrument is currently in the range 2.000 to 19.999/«W,
pressing (u0 takes it to the 20.00 to 199.99/iiW range.
The Down Key
This key selects the next lower range. If automatic ranging was in operation,
this key disables it.
Example If the instrument is currently in the -20dBm range, pressing
(Down) takes it to the -30dBm range.
The Analog Output
The analog output is the BNC connector on the front of the sensor module. It
outputs a voltage directly proportional to the strength of the optical signal at
the optical input, in the current range.
The analog signal is always in the range 0 to 2V, 2V corresponding to a full
power input signal in the current range, OV corresponding to no input signal.
If the range changes, for example, during autoranging, the level to which 2V
corresponds changes. Therefore it is recommended, if you want to use the
analog output, disable autoranging and select the best range for the application
with or (Down ) .
Possible applications for the analog output, would be to close the feedback loop
controling the current supplied to a laser; or to monitor optical power on an
oscilliscope (the analog signal reacts instantaneously to the input signal, whereas
the power shown on the display is subject to averaging).
Local Control - Measure Mode 2-13