Orban 5750 Technical Manual Technical Data 6-7
Because the 5750 does not digize subcarriers applied to its subcarrier inputs, the 5750’s MPX POWER meter (whi
operates in the DSP domain) cannot indicate the power added by su subcarriers. These usually have conant
power, so it is easy to compensate for them. For example, if an FM subcarrier is injeed at 4% modulaon, it adds
power that can be calculated with an R.M.S. summaon of the subcarrier and the re of the composite signal.
Assuming that the subcarrier and composite signal are uncorrelated and that the composite signal is limited so that
its power is equivalent to a sinewave at 25.3% modulaon, we calculate their R.M.S. sum as follows:
dB81921.11)25647.0(log20
25647.00016.006418.004.00.25333
10
22
−=
=+=+
Recalling that the MPX POWER LEVEL meter is calibrated so that it indicates 0 dB when the composite output of the
5750 is a sinewave at –11.92615 dB below 100% modulaon, we conclude that our subcarrier at 4% injecon will
add 0.10694 dB to the mulplex power. Another calculaon (not shown) indicates that 10% injecon will add 0.62889
dB to the MPX power.
Mulplex Power Threshold: The 5750 provides a means to limit the integrated mulplex power to the ITU andard
by a tenique that allows you to use any preset and to create cuomized presets freely. The mulplex power
controller is adjued in the INPUT/OUTPUT > UTILITIES screen by the MULTIPLEX POWER THRESHOLD control. Set it
OFF if your country does not enforce the andard.
The control is located in the INPUT/OUTPUT > UTILITIES screen because the regulaon applies to operaon of the
processor in a given inallaon.
Figure 6-11: Multiplex power over 15 minute observation interval
with Multiplex power controller active, measured at the Optimod’s composite output
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