EXFO IQS-1600 High-Speed Power Meter for IQS-500/600 - Manual (Page 36)

Setting Up Your High Speed Power Meter
28 IQS-1600
Selecting the Measurement Unit
Selecting the Measurement Unit
Power measurements can be displayed in dB, dBm, W, or W/W (the latter
indicating the ratio between the power received and the reference for the
current wavelength and channel). When W or W/W is selected, the
software automatically selects W units (pW, nW, μW, mW), depending on
the measured power and sensitivity of the detector.
When a relative unit is selected (dB or W/W), the most recent reference
value used will become the current reference value.
To select the measurement unit (either from the Instrument or
Settings function tab):
1. Select the channel for which you want to set the measurement unit
(if you have a multiple-channel power meter).
2. Use the arrow buttons next to the Unit list to change the value.
3. click Apply to confirm your new setting.
Note: You can also use the All Channels button to modify all channels identically.
If other values were set before, but are different from those you are setting,
any value you change will turn red to indicate that it is different.