Thanks for the picture. I think I saw one in Poland as well. So that's what those are for ! Also, an obvious hack to monitor this "close-circuit" system: just

Thanks for the picture. I think I saw one in Poland as well. So that's what those are for ! Also, an obvious hack to monitor this "close-circuit" system: just attach a satellite transmitter to the output of a receiver. Even cheaper: make a web radio out of one of these. Wait, you need internet access to do that...