ASTRO FHP2, Руководство по эксплуатации

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FHP2 user manual (release 1.0)
8
2.4 Reference function (REF button):
The REF button allows the value of a level received on a previous occasion to be used
as a basis for additional measurements. The additional measurements then use this
base value as a reference. The current reference threshold is then set to a relative offset
of 0 dB, which appears on the display after the button is pressed. The additional
measurements then show the different in level to this reference threshold in dB.
Example:
You would like to test the continuity of a fibre optic splitter, however have one cable
connected to the optical transmitter and one to the optical level meter leading from the
splitter respectively. To exclude the conductor and insertion losses from the
measurement, proceed as follows:
o
Connect both fibre optic cables to an adapter, and insert one end into the optical
transmitter and the other end into the power meter.
o
Switch on the optical transmitter and use the optical power receiver to measure the
optical level. Check the level meter to ensure that the same wavelength has been
set on the transmitter and level meter. The difference in level between the
transmitter output and the optical receiver is the power loss by the patch cable.
o
Now press the REF button on the FHP2. A value of 0 dB is displayed, which means
that both cables will not be factored into the measurement when the fibre-optic
splitter is connected between them.
o
Now remove the adapter between the two patch cables, and connect the
transmitter to the splitter input and insert the receiver into a splitter output.
o
The net splitter attenuation is now displayed in dB without the cables or plug
connections impacting the test setup.
2.5 dBm/dB/mW button:
Note: Most optical powers are measured in dBm.
The dBm/dB/mW button can be used to switch over the scale from
dBm (10 × log [value
in mW/1mW]

logarithmic power level in relation to 1 mW) to the absolute level in mW .
The dB setting displays the relative change in the level in dB to the reference value set
beforehand. If the levels are lower than the reference value, then a minus sign appears
in front of the relative differences in level; if they are higher than the reference value,
then no sign appears in front of the values.
DRAFT VERSION