OPHIR vega User Manual page 64

5.4.2. To choose Manual or Automatic Ranging or dBm
Autorange - The Vega allows you to choose autorange or
manual ranging. In both cases, the reading will be
displayed in watts. In autorange mode, you do not have
to change scales. When the reading of the meter or bar
is more than 100% of full scale, the range goes to the next
higher one. When the reading falls below 9% of full
scale, the range changes to one range lower.
change occurs after a short delay. This provides overlap
(hysteresis) to keep the Vega from flipping back and forth
when reading close to the end of the scale.
Manual Range - There are certain disadvantages to
autorange since it changes scale even if you don't want it
to do so. If you want to measure the same range all the
time, it is better to use manual range. The correct range
to select is the lowest one that is larger than the largest
expected measurement. To configure the Vega to be in
manual mode when switched on, see Section 5.3.
dBm - The Vega allows the measurement to be made in
units of dBm that is a logarithmic scale. dBm units are
defined as:
10 x log (reading in mW)
At 1mW the reading will be 0 dBm, at 100mW it will be 20
dBm etc.
To choose auto, manual or dBm range, follow these
steps:
1. From the main measurement screen, select "Range".
2. Select the correct manual, auto or dBm range with
the navigation keys. If you want the selected range to
be the startup value press "Save" or by pressing the
Enter key to return to the measurement screen.
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