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Old 14-02-2013, 19:32
Nigel Goodwin
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To clarify the above a bit better (with hindsight!), the impact of LTE interference is most likely to be total loss of a multiplex, whether it's from a basestation or a handset. But what I was trying to get at was that basestations will cause more problems than handsets.
I don't think it's ever been suggested that handsets will be a problem at all - it's the transmitter sites that are the potential worry.

However, I'm still dubious about them potentially causing more problems when not in use - surely it's only a phone mast when all is said and done, and they transmit less when not in use.

'Research' isn't a very clarifying answer do you have any links to the research?.
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Old 15-02-2013, 08:15
Staffsyeoman
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As someone in range of Crystal Palace, I am fuming that rather than try to get those who will cause the problem to resolve it, there is this lackadaisical attitude of 'oh, we'll give you a filter, and if that doesn't work you'll have to have cable or satellite'. Pay for the installation, will you? Pay for the new equipment? Thought not.
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Old 15-02-2013, 08:49
Nigel Goodwin
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As someone in range of Crystal Palace, I am fuming that rather than try to get those who will cause the problem to resolve it, there is this lackadaisical attitude of 'oh, we'll give you a filter, and if that doesn't work you'll have to have cable or satellite'. Pay for the installation, will you? Pay for the new equipment? Thought not.
Why are you 'fuming' about something that may never be a problem?, if it happens THEN you can waste your time fuming, but it's even more pointless now
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Old 15-02-2013, 10:06
TallDave
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I don't think it's ever been suggested that handsets will be a problem at all - it's the transmitter sites that are the potential worry.

However, I'm still dubious about them potentially causing more problems when not in use - surely it's only a phone mast when all is said and done, and they transmit less when not in use.

'Research' isn't a very clarifying answer do you have any links to the research?.
Digital Europe think handsets could be an issue with set-top antennas: Document link.

Ofcom have commissioned lots of research, all on their website. One of their reports is referenced in the Digital Europe document.

The "idle" transmitter problem is down to the wide power variations between "idle" and "busy" which causes problems with a DTT receiver's AGC.
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Old 15-02-2013, 10:27
Nigel Goodwin
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Digital Europe think handsets could be an issue with set-top antennas: Document link.
Shouldn't be using set-top aerials

I 'suppose' there is a slight chance of problems, if the signal levels on the set are exceptionally small, and the handset is on full power (distant from a transmitter), and in front of the aerial.

But it seems a long series of unfortunate (and pretty well deliberate) events to cause such a possibility.


Ofcom have commissioned lots of research, all on their website. One of their reports is referenced in the Digital Europe document.

The "idle" transmitter problem is down to the wide power variations between "idle" and "busy" which causes problems with a DTT receiver's AGC.
I would have thought 'idle' would be the lower power, so even less likely to cause problems?.
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Old 15-02-2013, 10:40
TallDave
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Shouldn't be using set-top aerials

......

I would have thought 'idle' would be the lower power, so even less likely to cause problems?.
Agree on set-top aerials, but there are a lot in use!

I'm not an RF expert so I'm getting to the limits of my abilty to explain the idle power issue, but it's not the power at any one moment in time, it's the wide variations in power which affects the DTT receiver's gain control. If the basestation is fully loaded, the power stays constantly high and the DTT receiver's AGC is stable.

As a really poor analogy, imagine someone's trying to talk to you in a quiet voice whilst you're stood next to a PA system that keeps switching on and off loud music. It would be easier to hear them if the level of the music remained constant, regardless of the volume.
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Old 15-02-2013, 10:59
Nigel Goodwin
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Agree on set-top aerials, but there are a lot in use!

I'm not an RF expert so I'm getting to the limits of my abilty to explain the idle power issue, but it's not the power at any one moment in time, it's the wide variations in power which affects the DTT receiver's gain control. If the basestation is fully loaded, the power stays constantly high and the DTT receiver's AGC is stable.

As a really poor analogy, imagine someone's trying to talk to you in a quiet voice whilst you're stood next to a PA system that keeps switching on and off loud music. It would be easier to hear them if the level of the music remained constant, regardless of the volume.
That doesn't make much sense compared with the original idea that whilst idling it will potentially cause more interference - that's implying that most potential problems could occur when it switches power, not when at rest.

Certainly if any interfering signal stronger than the incoming DTT does pass through the receiver - which the IF filtering should stop anyway (much more attenuation than external 'bandpass' filtering), it would upset the AGC levels.

But as far as I'm aware, the main concern for potential problems is overloading of the receivers front end (cross modulation), with TV receivers not designed for excessively high level signals.

As I've repeatedly said, it's pretty pointless so far worrying about a problem that might, or might not, ever occur - and probably only in isolated incidents if it does.

I know phones are on higher bands than TV, but at work our high gain aerial, with high gain amp, feeding a VERY high gain launch amplifier points almost directly at an O2 cell mast about 30feet in front of it. No problems whatsoever.
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Old 15-02-2013, 11:40
TallDave
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I think the government decision to force mobile operators to plough 180m into mitigation activities through DMSL gives us an indication that there's more likelihood of "might" than "might not".

You wouldn't expect problems with your aerial setup and the O2 mast, so no surprises that there are no problems. Buf if O2 fit an LTE basestation there, you might expect problems.

Free filters can fix the problem (although the government strangely decided 1 per household was enough) but the insertion loss of the filter may affect the reception of weaker muxes, meaning some viewers lose some of their services.
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Old 15-02-2013, 11:55
Nigel Goodwin
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I think the government decision to force mobile operators to plough 180m into mitigation activities through DMSL gives us an indication that there's more likelihood of "might" than "might not".
And how much was spent on Y2K


You wouldn't expect problems with your aerial setup and the O2 mast, so no surprises that there are no problems.
High powered RF signals from close range - should cause overloading of the amplifier front end just as 4G could.

There's little filtering on the input of a masthead amp.


Buf if O2 fit an LTE basestation there, you might expect problems.

Free filters can fix the problem (although the government strangely decided 1 per household was enough).
One is all you should need - it goes on the single aerial you should have, and filters before the distribution system.

If you've got multiple aerials, then buy the extra filters yourself - again - IF there's any problem.
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Old 15-02-2013, 13:44
kasg
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And how much was spent on Y2K
Please don't go there again unless you know what you are talking about it. "Y2K" was a massive potential problem, only avoided by the vast amount of money and time that went into preparing for it. Of course some of that money was wasted and some people made a fast buck, but there really is no comparison.
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Old 15-02-2013, 13:56
Nigel Goodwin
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Please don't go there again unless you know what you are talking about it. "Y2K" was a massive potential problem, only avoided by the vast amount of money and time that went into preparing for it. Of course some of that money was wasted and some people made a fast buck, but there really is no comparison.
You've just said 'potential' in that post, and while I'm not denying there were a small number of problems that needed correcting for Y2K it was VERY small.

The situation was VERY similar to 4G, with people running round panicking about something which is very likely to only cause a few problems, and any problems which may occur will be spread out over a VERY extended time.
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Old 15-02-2013, 15:07
kasg
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You've just said 'potential' in that post, and while I'm not denying there were a small number of problems that needed correcting for Y2K it was VERY small.
That was exactly my point, that is absolutely not true, there were a huge number of computer systems that needed to be amended or replaced to work after the year 2000, I know, I was involved, it was a heck of a lot of work but, by and large, the project was completed on time - it pretty much had to be!
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Old 15-02-2013, 15:11
Nigel Goodwin
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Tiny percentage though

Potential problems were mainly software rather than hardware, mostly due to lazy programming in the past.
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Old 15-02-2013, 16:40
kasg
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Tiny percentage though
Possibly, but a much larger percentage needed to be checked.
Potential problems were mainly software rather than hardware, mostly due to lazy programming in the past.
I would say it was more down to short-sighted and cost-obsessed management than lazy programmers. This is all from first-hand experience from the late 70s onwards.
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