I would strongly advise against putting a mast-head aerial amplifier on a TV pre-switch-over. I can tell you this from bitter experience. Aerial amplifiers will do little for digital TV reception, and may actually make it worse (as one did with me). A good aerial installer will know this, and should talk you out of fitting a mast-head amplifier. You may however, benefit from a distribution amplifier elsewhere in the house, if you are feeding two or more TV's, in a position where it can be reached without a big ladder.
The problem with digital TV from its introduction was that the Freeview channels had to be wedged in to an already very crowded TV spectrum. Even the Channel 5 signal had to be on 2 channel numbers only, with powers drastically reduced, to avoid interference in adjacent TV areas. When digital TV came along, they had to find a way of introducing the digitally encoded signals (which typically occupy anything between 5 and 8 analogue channels) without causing interference with analogue TV in other areas. Again, the power of the digital signals had to be kept quite low.
Now, on the day of the digital switchover (actually it may be two days), when all the analogue channels are switched off in your area, some of the Freeview stations will move to occupy the frequencies which were used by the analogue channels and,
they will have their transmitter powers increased by up to a factor of 10 because they already know that these channels won't cause interference in other areas.
Now, this is what caused me the problems. On the day of our full switchover (ours happened over 2 days), I re-tuned the Freeview for the second time (I have a Panasonic Viera with Freeview and Freesat built in), and I was keen to see what Freeview HD looked like, but when I flicked through the channels, suddenly the TV became totally unresponsive to the remote, and remained like that for at least 30 seconds, then there was a click from inside, and the TV reset itself, and then it went into a loop like that. I found that 'normal' operation of the TV could be restored on Freesat if I pulled the aerial plug out.
I phoned the Panasonic helpline, and they told me that the problem was caused because my Freeview signals were too strong, and were overloading the TV. This was not harmful, but it did cause the unusual behaviour. They advised me to get an attenuator, which fits into the aerial socket on the TV, and the aerial plugs into that. My Freeview reception had been OK before, but now I had 3 Freeview 'channels' which were 9 times more powerful than they were pre-switchover. Fitting the attenuator fixed the problem (well, at least for now, because the story isn't completely finished !).
So, when the switchover is complete, you will have 3 or 4 strong Freeview channels, and another 3 or 4 that are still on reduced power, and if you are in a bad area, you may not be able to get all the Freeview channels (yet), but these will only be the more minor channels. Now, when all the analogue channels in the country have been switched off, all the Freeview channels which were on low power until now will be increased in power (that will be sometime in 2013). When that happens, channel numbers will change again, and a Freeview re-tune will be required again.
I hope you've followed all that - it is a bit technical, I know
