Most Digital Terrestrial TV (DTT) is using the DVB-t standard. There are many variants so a receiver box bought in one country may not work in another country.

Satellite TV and Cable uses a single transmitter carrier for each Stream of Digital data, which can be any mix of TV, Radio, EPG, Teletext, Interactive data and computer data, in a similar maner to Ethernet TCP/IP, except it is a "broadcast only" mode with no return "handshakes".

On the ground between a Transmitter and Receiver (your TV aerial) there may be trees, hills, moving vechiles, buildings etc that distort the signal and cause reflections visible as "ghosting" on an analog signal. To solve this problem the data stream needs to be very slow so that the DSP software used for reception can "see" the signals arriving at the different times, combine them and reduce the noise and interference (correlation). But we still need the same overall speed.

The solution is to break up the the signal into 500, 1000 or more separate transmissions at slightly different frequencies. If the data is coded with "Forward Error Correction" then if one of the hundreds or thousands of carriers is missing due to interfernce the overall data can be recovered. The normal scheme of doing this is Coded Orthagonal Frequency Division Multiplexing (COFDM pronounced Cough Dee eM).

A disadvantage of COFDM for Irish so called "Deflector" operators is that a normal receiver and transmitter or CATV frequency shifter will not work to rebroadcast the signal. In fact even in the UK most DTT transmitters are directly fed. Only recently has BBC research indicated reliable methods of DTT rebroadcasting or relay stations.

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The newer DVB-T2 standard is similar, but each carrier uses a different (incompatible) Modulation and instead of 1,700 or 7000 apprxo. carriers per channel (Multiplex), there can be 10 times as many in the same space.

Hence a much more powerful DSP chip and a different Tuner decoder are needed. A firmware upgrade or Software on a PC card will not make a DVB-t box or card into a DVB-T2 version.

This is unlike MPEG2, MPEG4 etc where the decoding is simply done by PC.

But on a Set-Box the CPU is like an 1995 PC and can't do MPEG at all, so the MPEG decoding as well as the COFDM reception (DVB-t or DVB-t2) is in the DSP chip.

MPEG4 needs about 10x the resource to decode as MPEG2, so also an MPEG2 setbox or TV can't be upgraded to MPEG4 simply by firmware. New DSP hardware is needed.