Re: Splitting Freeview signal
- From: Andy Wade <spambucket@xxxxxxxxxxxxxxxxxx>
- Date: Sat, 24 Jun 2006 13:55:15 +0100
Bill (Adopt) wrote:
I wonder if it's a thought that, when trying to amplify signals for a digital set up, it might be worth considering that digital will operate successfully on a far less signal 'strength' than analogue needs to even get itself up off the ground. Typically digital, as I understand it, needs only around one hundredth (1/100th) of the 'strength' applicable to analogue reception.
Yes, but it's (currently) transmitted at correspondingly lower power levels, so the requirements of the receiving set-up are broadly similar.
What a digital signal does need is not 'amplification', but 'clarity'; an uninterrupted flow without, as far as possible, any 'fuzziness' that might encourage it to 'fall off the cliff'.
Sorry, that's just meaningless waffle. Witchcraft isn't needed here; this is a well-understood scientific subject. The first step necessary to get good reception is to get an adequate RF signal-to-noise ratio (carrier-to-noise or C/N, if you like) into the demodulator. C/N is determined by the available field strength and the performance of the antenna and receiver as a system. Ultimately the latter of these comes down to G/T - the ratio of the antenna gain to the system equivalent noise temperature. In other words it depends on the aerial gain and the overall noise figure of the receiver, including preamps, feeders, splitters and what-have-you - exactly the same things as for analogue, in fact. Amplifiers have a vital role to play here, just as for analogue, in overcoming feeder and splitting losses. To ban amplifiers altogether would necessitate unfeasibly large aerials in many situations.
I wonder if it's better to think of masthead (or other) additions as being 'filters' rather than perhaps uneccessary 'amplifiers'.
I think it's best to think of amplifiers as amplifiers and filters as filters. Good amplifier products should of course include appropriate input filtering to keep out out-of-band signals which could cause intermodulation effects ('overloading'). The barn door principle applies, as ever.
Also means that one should also consider, or re-consider, the quality of the cabling between aerial, STB, Monitor and that of any additional peripherals..
Yes, but that part of the message is now well known and accepted in the reception & distribution industry, and here. You're preaching to the converted.
As a comparison, think of the almost nano-watts of power that a microwave dish gleans for a solid satellite reception...
More like a picowatt (per mux). That's the magic of radio...
--
Andy
.
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- Splitting Freeview signal
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- Re: Splitting Freeview signal
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