ILX Lightwave FPM-8200, User Manual

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FR O N T PA N E L O P E R A T I O N
The FPM-8200 Front Panel
01_10 FPM-8200
11
C H A P T E R
2
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Bar Graph Display
The Bar Graph display shows relative input level as a percentage of full scale for
each gain range. The bright indicator signifies the ones' digit, and the dimmer
indicators signify the tens' value. The tens' indicators are accumulative, while the
ones' are not. Therefore, there is only one indicator lit for the ones' digit.
The bar graph update rate is always FAST. This allows you to monitor shorter-
term fluctuations in measurements while displaying an averaged measurement.
Figure 2.3 Bar Graph
User Calibration
User calibration (USER CAL) sets a multiplication factor that is applied to all FPM-
8200 measurements. The USER CAL indicator (just right of the wavelength
display) illuminates whenever the user calibration factor is any other value than
the factory standard setting of 1.000. The range of USER CAL is 0.500 to 2.500.
This means, for example, with USER CAL set to 0.500, all results are reported at
half of their detected value.
To display or change USER CAL:
1 Press LOCAL/ADR and dB at the same time. The USER CAL factor displays for about
three seconds.
2 While the USER CAL is displaying, press UP or DOWN to change it. The FPM-8200
saves USER CAL in non-volatile memory, so it retains this value the next time you turn-on
the meter.
The most common application of USER CAL is calibrating the FPM-8200 to read
correctly with an external attenuator. For example, if you attach a calibrated 3 dB
attenuator, only 50% of the input signal gets to the meter. In this situation, set
USER CAL to 2.000 and the meter displays correctly. Remember to consider the
accuracy of the attenuator as well as the meter in attenuated measurements.