Why do we use two Data Links?

For me, the radio link should be like an unbreakable umbilical cord.

I have flown hundreds of hours with the XLRS system without autopilot years ago when they were not commonly used and I have always felt safe in that regard.
During the flight, it continually checked RF coverage and noise, to know when not to continue or to predict a link loss long before it occurred.

When you fly a lot, it is normal for “good” things to happen to you, such as breaking antennas in flight, passing near the beam of a powerful analog TV repeater, flying near a jammer, etc.

With the first LRS systems, when it passed 3Km from the TV repeater beam, the RF intensity was such that it left my receiver “blind” and the plane went into a spin until it left the beam.
This bothered me a lot because it was about 6 km away and I didn’t feel like looking for the plane in case of a total loss.

Later, in the following weeks, we filtered the receiver until we were able to fly around the repeater at 50 meters and no longer have problems, although some servos would get a little blocked by the RF from time to time.My habit then was to keep the radio control and video power separate.

Video systems

As video systems use higher frequencies, normally 2.4 and 5.8Ghz with modulations of up to 6Mb, the range is smaller and the link is more critical in general, rain, clouds and other causes can reduce the range by half or more.

In the case of analog video at 2.4Ghz with 1W it reaches up to 100Km with a 24dBi dish.

With Full HD digital video up to 150Km but with 8W of power and high gain antennas, 24dBi or more.

To achieve these distances in video with high gain antennas, it is necessary to use an antenna tracker such as SATPRO to aim automatically, with more precision. Manual aiming is not a good option for these distances.