What is the content of both transponders? Surely data, but what? Internet by satellite maybe?
"Data" is the generic name, a common umbrella(so to speak) for transponders whose content we cannot determine. It can be of any kind and is transmitted to a recipient with a dedicated device to decode it, such as the satellite internet.
We, simple amateurs, try to find this content but can't access it due to the lack of physical media/HDW support or specific applications.
But, in recent years, some passionate developers have created applications capable of decoding that content, such as radio or video streams.
Thanks to them, we found out that at 27.5W, radio/video programs(IPTV-over-Sat) are transmitted using software(TSReader, for example).
However, we could also detect radio transmissions on this satellite, and we didn't even know they existed with our commercial devices. We don't even smell them, but with the help of some dvb cards with high-performance hardware, we also learned about radio transmissions with impossible-to-find parameters, such as symbol rate below 100 Ks.
Another example is the DAB+ transmissions on various satellites you don't have access to with your equipment. Until you find out their content, they were reported on the satellite lists as Data.
This is what I meant about Data transponders, which is, of course, an amateur explanation.
I'll show what such a transponder on this satellite at 27.5W, which we can't decode, and the one whose content we discovered(IPTV/Radio-over-Sat) looks like:
www.satellites.co.uk
