on most DVB systems polarity is controled by voltage through the coax
if your c-band lnbf can accept votage controlled polarity switching then the DVB receiver can do it....... on older c band lnb's ( using a corotor , polorotor ) then polarity switching is controled with the analog receiver using voltage( supplied by three wires) to control a servo on those type of feedhorns
there are only a few DVB receivers that can control the voltage on a corotor / polorotor type feedhorn.
1) 1 x C-Band LNB with a polariser - polarity is controlled by a servo motor and the receiver 2) 1 x C-Band LNBf - polarity is controlled by voltage switching, typically 18volts and 13volts 3) 2 x C-Band LNBs on a dual feedhorn - 1 LNB is fixed on Ver the other on Hor - this setup requires either a receiver with dual LNB input or an LNB switch that is controlled in the same was as #2
13volts dc on the coax is Vertical 18volts dc on the coax is Horizontal (LNBF)
Normal oldschool feedhorn: One coax going to an lnb or one c and one Ku lnb with 18-20 volts that never changes. a small motor called a servo uses three wires from a receiver to physically move a little wire probe in the feedhorn from vertical to Horizontal or any degree in between (skew control).
Red wire +5 volts dc Black wire Ground White wire +5 volts dc pulse. (pulsed voltage output from receiver) frequency of voltage pulse determine where the motor moves and how far.