Matt Ettus wrote:
DBS small satellite dish systems often have LNB feedhorns capable of
multiple polarizations and/or multiple bands. This is often controlled
by changing the voltage which powers the device. However, some have a
more complex control system involving tones in the 20kHz range if my
memory serves correctly. Is there anyone who has a reference on this
control system, or who knows how it works? I want to use these for
radio astronomy with the USRP and need to know how to control them.
Thanks,
Matt
Polarization is selected either using LNB voltage level (13V and 17V are
typical thresholds), or
using DiSEQC, which is a 22Khz digital code that can be used to
control feed parameters
and also control any mechanical arm on the dish, and also change LO
frequencies on
the LNBF
The specification can be had here:
http://www.eutelsat.org/satellites/4_5_5.html
Maxim also has an app note or two about interfacing to DiSEQC equipment
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