EXFO PM-1600 High-Speed Power Meter - Manual (Page 27)

Acquiring Power Measurements
High-Speed Power Meter 17
Measuring Relative Power
3. Press dB/W
/
W until the display switches to relative mode in dB (where
the value displayed is equal to the absolute power minus the
previously stored reference power) or in W/W (where the value
displayed is the deviation ratio from the reference). Pressing dB/W
/
W
again switches between dB and W/W measurement units for the
relative power and reference value.
When you access relative mode, the PM-1600 displays the last reference
value entered at the current wavelength (to view the reference value, set
the appropriate channel to reference display mode).
However, to display meaningful relative power readings, it is important to
have an appropriate reference value, using appropriate adapters and test
jumpers, and connecting the optical circuit being referenced to a detector
port.
Note: If you set a reference while a correction factor (CF) is active, the reference
measurement will take the correction factor into account.
To set a reference value, two choices are available.
Entering the Current Power as the Reference Value
To enter the current power,
1. If necessary, select the desired channel (PM-1620).
2. If necessary, press
λ
to select the appropriate wavelength.
3. Press dBm/W to select the desired measurement unit.
4. Press Ref to use the current power value as the new reference.
Note: Pressing Ref switches the display to relative mode.
Acquiring Power Measurements
High-Speed Power Meter 17
Measuring Relative Power
3. Press dB/W
/
W until the display switches to relative mode in dB (where
the value displayed is equal to the absolute power minus the
previously stored reference power) or in W/W (where the value
displayed is the deviation ratio from the reference). Pressing dB/W
/
W
again switches between dB and W/W measurement units for the
relative power and reference value.
When you access relative mode, the PM-1600 displays the last reference
value entered at the current wavelength (to view the reference value, set
the appropriate channel to reference display mode).
However, to display meaningful relative power readings, it is important to
have an appropriate reference value, using appropriate adapters and test
jumpers, and connecting the optical circuit being referenced to a detector
port.
Note: If you set a reference while a correction factor (CF) is active, the reference
measurement will take the correction factor into account.
To set a reference value, two choices are available.
Entering the Current Power as the Reference Value
To enter the current power,
1. If necessary, select the desired channel (PM-1620).
2. If necessary, press
λ
to select the appropriate wavelength.
3. Press dBm/W to select the desired measurement unit.
4. Press Ref to use the current power value as the new reference.
Note: Pressing Ref switches the display to relative mode.