User manual

Configuring the AM700
3-20
AM700 Audio Measurement Set User Manual
Internal series
resistor
User load
resistance
E
out
Figure 3-14: AM700 generator output voltage divider for dBm calculations
Input dBm. This setting defines the external resistance on the input of the AM700
and is used for calculating the input signal amplitude in terms of dBm. Since the
AM700 is measuring voltage, the internal termination load of the AM700, which is
in parallel with the external load, has no effect on the calculation as the applied
voltage is dropped across both in parallel (see Figure 3-15).
NOTE. This is calculated dBm, so if the external load is not as stated in the Input
dBm box, the measured value stated in dBm will not be correct.
AM700 internal
load resistance
E
in
User’s external
parallel resistor
To acquisition
Figure 3-15: AM700 input circuit for dBm calculation
Analog to Digital Conversion Factor. This selection permits measurement results
obtained from digital audio sources to be represented as analog values as if they
were produced by a D/A converter. The scale factor of a hypothetical D/A converter
is specified in this entry.