Question: how to calculate xpd value?
Answer: Power off the vertical Radio on Site-A. Power on the horizontally polarized ODU on Site-A. Note down the RSL of Site-B (RSL4) on vertically polarized IDU. The calculated XPD (XPD = RSL4 – RSL3) should be 30 dB if not then we have to align the feed horn to achieve the required value on site A.