[mythtv-users] Thinking of moving on from MythTV :-( Any suggestions? (for the UK)

[Mike Perkins]

On 01/01/17 21:16, Simon Hobson wrote:
> Damian <myth at surr.co.uk> wrote:
>
>> I meant the Live TV from within MythTV.
>> I don't have a real TV to check signals with, but did have TV guys come out and check the signal a couple of years ago. The signal runs through 2 boosters now.
>
>>From those last 7 words tell me that you have an aerial problem.
> It would be a good idea to have at least one TV connected up as a TV - it gives you a most basic bit of kit to check your signal with, without all the complication of having various layers of hardware and software which may or may not be giving an issue.
>
> But, you shouldn't have 2 boosters. It's a common misconception that chaining boosters will help - in general it won't, because if you have that weak a signal, your boosters will amplify the noise and you'll end up with plenty of signal but with a crap signal/noise ratio (snr). snr is probably more important than signal strength !
>
> Ideally you want an aerial with enough gain that you don't need a booster at all - at least for one tuner. A booster should only be needed to compensate for the loss of signal when it's split amongst several tuners, or for very long cable runs.
> Normally I would recommend getting the highest gain grouped aerial you can - avoid wideband aerials. My normal supplier is http://aerialsandtv.com where there's a good choice, and "proper" information. By proper information, I mean there are graphs of gain because there is no single gain figure for an aerial.
>
> If you look at http://aerialsandtv.com/atvstockaerialtests.html you'll see that they provide graphs for each aerial they sell showing how the gain varies with frequency (RF channel). You need to look up the RF channels used by your local transmitter and select an aerial that provides good gain for those channels.
> The Log36 has a fairly flat gain across the whole band - but it's gain isn't very high, Except for the lower end of group E, you'll see that the Yagi 18 has significantly higher gain within it's band. For the frequencies used by my local main transmitter (Winter Hill), the Yagi 18CD provides something like 6dB higher gain that the Log36. it doesn't sound much, but on a logarithmic scale, 3dB is double the power, and 6dB is 4 times the power !
>
> Many aerial fitters are charlatans and will fit whatever is cheap - often "contract bacofoil" types, of which the least said the better.
>
> And don't forget that the cable degrades as well, especially if it's poor cable or badly installed. If having a new aerial fitted, have new WF100 (check that what they install is real WF100 - many will tell you it is but fit crap) cable fitted, and make sure all the joints are given a good dose of silicone grease (you'll need to provide it) to minimise degradation due to corrosion. Applying it to all the fittings, bolts etc will also mean that they can be undone in a few years time !
>
A point about grouped aerials. They are likely to become less useful in the future as multiplexes 
are moved around.

In the past all analog channels were grouped together so that they could easily be received by an 
aerial tuned to approximately the middle of the range. Other transmitters used other rnages so there 
was little chance of overlap and thus interference.

The digital multiplexes use the old channel frequencies but, as was pointed out in another thread, 
interference is much less of a problem.

However, it seems that some multiplexes are now being allocated on frequencies away from the old 
groups, which means that the old group aerial system will become of less use.

This also means, as I have found, that I can't use a bandpass (or notch) filter any longer to reduce 
interference from other transmitters. I just have to grit my teeth and grind my way through the 
transport scanner, removing those I identify as not being relevant.

-- 

Mike Perkins