Blipping on high hights

When I looked out of my window today I saw two persons with a strange behavior. One had some equipment with an antenna and the other had some gadget like he was fishing in the blue. I thought they were from Swedish Radiotjänst to check out who hasn't payed the Television license. We was talking about that some days ago.

In the sky I found the answer, a Zeppeline blipper. They used unmanned helicopters and Zeppelines when blipping for "house for sales" advertisements. You can see the cable in the corner, down to the left.