Quote:
Originally Posted by AndyCambs
Do you have any trees in line with the transmitter? A friend has a large tree outside their home and the signal deteriorates during the summer they lose several of the channels despite having a so-called digital aerial.
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There is no such thing as a 'digital aerial'. What you get is a Wideband aerial, which is often marketed as a 'digital aerial' so that Joe Public understands that they may need to change their aerial to receive Freeview.
Aerials are grouped into frequency bands, and the aerial you choose must match the frequency band of your local transmitter. Transmitters send their signals in groups of frequencies so that each transmitter does not interfere with any neighbouring transmitters. This forces TV viewers to use an aerial that is able to receive signals only from a particular frequency group, so that you don't pick up stray signals from a different transmitter that might spoil your TV reception.
In order to send both digital and analogue signals from the same transmitter, it has been necessary to force some of the transmitters to do two things that were not intended when they were originally built:
1. Transmit signals outside of their allotted frequency group.
2. Transmit signals at a lower power than the transmitter is capable of.
2/ is necessary because of 1/, in order to continue to prevent one transmitter interfering with another.
The consequences of this are twofold:
1. If your local transmitter has to broadcast outside of its normal frequency group in order to provide digital services, then you require an aerial that can receive signals from more than just one frequency group. This is why some people require a wideband aerial, sometimes marketed as a 'digital aerial' for the sole reason that it is the launch of digital terrestrial TV that has made this necessary.
2. If there is anything at all about your locality or TV set-up that might affect your digital TV reception, then you will probably suffer for it, because digital signals are not currently running at full power. They cannot do so until after analogue switch-off is complete for your region (in some cases, not until neighbouring regions are complete as well) so as not to interfere with signals on other transmitters.
To cut a long story short, many of these problems will go away by themselves ... eventually ... however in the meantime you need to do everything you can to ensure your aerial has sufficient gain for the signal strength of your local transmitter, and to ensure your own home set-up is as sound as possible.
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