Antenna / Dish ?

Hagar

Here's a strange one, maybe some of the more technical guys here could throw some light on it.

I was setting up my new TNT (Digital TV) system yesterday and while I was putting up my external antenna bracket I left the antenna lying flat on the table outside. I went inside and started an autoscan and it started picking up what looked like sat idents. Naturally I couldn't pick up any pics on the TV but I wonder was I really picking up sat signals and what would happen if it fed these signals through a sat box? I can't test this myself as my sytem is put away due to an impending move. Do you think I would get anything? Have I accidentally discovered the ultimate mini-dish?

FWIW I can't get good reception on French TV on it but I'm getting RAI1, RAI2, RAI3 and RAIUtile perfectly.

watty

TNT is DVB-t and Satellite is DVB-s. I suppose it's not impossible to have a OFDM Tuner (DVB-t) that can receive QPSK (DVB-S).

It's probably a badly screened coax Sat IF feed cable. I proved I can pick up analogue satellite from poor cable via a TV aerial (even though terrestrial is AM video and Satellite Analogue is FM video, but there is an explination for that too).

I was able to get a watchable picture over 60m away.


A Sat receiver certainly can't decode / receive DVB-t (TNT/Freeview), but I wouldn't be dogmatic that a DVB-t can't receive DVB-s

When the Sat Receiver has selected the 10.6 LO instead of 9.75 LO, the lowest IF will in theory be 150MHz for 10.75GHz transponder instead of the normal 950MHz.

This is why a sat/terrestrial combiner must be very good quality and reject ll signals below 950MHz on the Sat input.

In practice the LNB will only output IF down to about 750..850MHz due to internal filtering, but the Terrestrial Tuner works usually up to 870MHz.

Hagar

Thanks Watty for the very informative response. I'm going to start with a fresh cable run only about 5/6m any advice on the best cable to use. BTW there is a 5v feed inserted into the cable to power the antenna if that is significant.

watty

All copper dense braid + foil outer, moisture proof foam core satellite cable. PF100 etc. (1mm centre core)

Or long runs outdoor the CT125/PF125 or similar (1.25mm core), needs different connectors.

Hagar

I'll get some PF100. The run is less than 5m. Thanks.