TV licensing...

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[XAP]Bob
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Re: TV licensing...

Postby [XAP]Bob » 22 Sep 2020, 8:00pm

I can quite easily believe that a defective unit could produce EMF that would really screw with the rather delicate signals relied upon by ADSL.

Particularly if they happened to be near the exit point of the main exchange cable.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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Mick F
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Re: TV licensing...

Postby Mick F » 23 Sep 2020, 10:27am

It was the line oscillator radiations that they vans used to detect. Extra High Tension (EHT) voltages, maybe 15kv buzzing away in there.

The LO was also the local oscillator to convert the received UHF (or previously VHF) signals.
Vision came as amplitude modulated, and the sound as frequency modulated, so there was lots going on in the telly back then.

All valve technology and no doubt radiated all over the place. All it would need is for the telly to be near an overhead wire and the wire would pick it up and upset the broadband.
Mick F. Cornwall

paddler
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Re: TV licensing...

Postby paddler » 23 Sep 2020, 10:48am

I worked on Broadband faults for many years. In the early days we were told how an old Sky TV box knocked the broadband out for several houses either side.
We were also told not to route any cable carrying BB close to any electric cable. Electric fences were another known problem, as were flickering fluorescent lights. One fault I had I couldn't get the speed up when the customers router was connected - then I realised my tester was slow when connected to his cable, but also when it sat where his router was. Turned out that something in the cupboard (hi-fi, alarm eqpt etc), didn't like broadband. Just keeping the router and its feed cable away solved the problem.

Something else we were told, although I never found out if it was true. Older underground cables were 'dry' - that is, they were not grease filled like modern ones. So they could easily get slight damage and water could get in. On it's own, that didn't always cause an immediate fault such as battery, but they said that it would change the electrical properties of that length of cable and thus cause broadband faults. Split pairs were, and presumably still are, a big problem too.
A very experienced Coach once told me, with broadband, suspect everything!

Dave

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NATURAL ANKLING
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Re: TV licensing...

Postby NATURAL ANKLING » 23 Sep 2020, 10:53am

Hi,
Have you got any scientific evidence for this theory?
I'm not dishing it but I'd like to know out of curiosity as I'm interested in such things.
I suppose Mick is probably Maybe likely to know coming from that type of background in the forces?
surely BT would have investigated this if it is common that is that broadband is affected by signal of this type and magnitude?
Or is this simply just made up for a bit of publicity.
The media that's the BBC Inferred that person with the TV would be embarrassed, why should they.
Signal cables are screened aren't they?

Edited- Sorry that was directed at Mick, before I read the comment from DAVE.
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Mick F
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Re: TV licensing...

Postby Mick F » 23 Sep 2020, 11:02am

Just coz a cable is screened, doesn't make it immune.
The screening can pick up signal, and that in turn will effect the inner conductor. Screening is grounded at either end and rarely anywhere else.
The longer the cable, the worse the issue is.

Yes, I was an electronics engineer in the RN.
Radars and radar displays, computers, weapon guidance systems, and communications - MF/HF/VHF/UHF/Satellite.
Mick F. Cornwall

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Re: TV licensing...

Postby paddler » 23 Sep 2020, 11:36am

Not sure about screening, I remember some UG cables had some foil around the bundle, but most didn't. As far as earthing is concerned one leg is connected to the exchange earth and that's it.

I think the main defence against interference was the pairs being twisted, the more twists per foot the better. We had to try and maintain the twist right up to the connection in any joint and socket. The aim was to produce a balanced pair of wires.

Another potential fault was if one leg was in contact with a spare. This caused a serious imbalance, one of the seemingly many things broadband didn't like! These were hard to find as, unlike a contact with a working line, getting a fault location was not straightforward.
One other thing, each broadband carrying pair of wires produced some interference so apparently only a certain percentage of a cable should ideally carry it. In the sticks where I worked most cables were full or very nearly though.

Fibre to the cabinet got over most of these problems just by being closer and therefore having a stronger signal, although in a rural area distance was still a problem. I had to tell several customers they couldn't have broadband.

Dave

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Mick F
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Re: TV licensing...

Postby Mick F » 23 Sep 2020, 11:49am

BT phone cables have a "lazy twist" in the two pairs.

We worked on an connection exchange in the communication centre using a dozen? pairs all with a lazy twist each. We had to peel back the outer plastic sheath with the internal cord, and shake the cable so the twisted pairs separated from each other. All colour coded with one of each of the pairs being dashed. Not unlike normal two-pair BT cable, where they are blue and orange. Blue and blue dashed, and orange and orange dashed, but it's too long ago now for me to remember the colours of all those pairs. 1983! :shock:
Mick F. Cornwall

merseymouth
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Re: TV licensing...

Postby merseymouth » 23 Sep 2020, 12:48pm

Hi, I read somewhere that a Professor* offered the opinion that if a user of a phone stood with one foot in a bucket of water it would greatly improve the quality of transmission! Never tried it myself, but maybe the same could be true about Broadband? Just thought I'd mention it. :roll: :wink:
Keep safe now. MM


* RV Jones WW2 Boffin.

paddler
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Re: TV licensing...

Postby paddler » 23 Sep 2020, 4:09pm

merseymouth wrote:Hi, I read somewhere that a Professor* offered the opinion that if a user of a phone stood with one foot in a bucket of water it would greatly improve the quality of transmission! Never tried it myself, but maybe the same could be true about Broadband? Just thought I'd mention it. :roll: :wink:
Keep safe now. MM


* RV Jones WW2 Boffin.


:D In the days of shared service with earth calling apparently it was common for customers ( subscribers then!) to need a bucket of water to pour over the earth spike during prolonged hot weather otherwise the earth would be useless.

I used to carry water to aid testing for the same reason.

Dave

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Re: TV licensing...

Postby paddler » 23 Sep 2020, 4:16pm

Mick F wrote:BT phone cables have a "lazy twist" in the two pairs.

We worked on an connection exchange in the communication centre using a dozen? pairs all with a lazy twist each. We had to peel back the outer plastic sheath with the internal cord, and shake the cable so the twisted pairs separated from each other. All colour coded with one of each of the pairs being dashed. Not unlike normal two-pair BT cable, where they are blue and orange. Blue and blue dashed, and orange and orange dashed, but it's too long ago now for me to remember the colours of all those pairs. 1983! :shock:



We would never shake a cable like that - a dry concentric cable might flop open and you wouldn't know what was paired with what.

Similarly there were internal cables where each colour was paired with a plain white, very loosely twisted. Care was needed when stripping the outer off - if you lost the lay you had to strip some more back, but only if you had enough! I came across loads where a blue and orange had been used, introducing a split straight away.

Dave

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Re: TV licensing...

Postby Jdsk » 23 Sep 2020, 4:41pm

merseymouth wrote:Hi, I read somewhere that a Professor* offered the opinion that if a user of a phone stood with one foot in a bucket of water it would greatly improve the quality of transmission! Never tried it myself, but maybe the same could be true about Broadband?* RV Jones WW2 Boffin.

"Most Secret War"
https://en.wikipedia.org/wiki/Reginald_Victor_Jones

Highly Recommended.

Jonathan

merseymouth
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Re: TV licensing...

Postby merseymouth » 23 Sep 2020, 6:16pm

Yep, Got my copy back in 1978, on par in value with Alan Turing.
Another book that I have stumbled upon is "Enemy Coast Ahead", by wing Commander guy P Gibson VC, DSO & Bar, DFC & Bar, he of the Dambusters fame.Written not long before he died on active service. Insightful. IGICB MM

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Mick F
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Re: TV licensing...

Postby Mick F » 23 Sep 2020, 7:31pm

paddler wrote:We would never shake a cable like that - a dry concentric cable might flop open and you wouldn't know what was paired with what.
We stripped maybe 2ft or more of the outer plastic off.
Yes, the outer ends would have been open, but over a couple of feet the twisted pairs were fine.
Mick F. Cornwall

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[XAP]Bob
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Re: TV licensing...

Postby [XAP]Bob » 23 Sep 2020, 11:25pm

BT cables around here aren't screened, they're just plain twisted pairs, several pairs in a given cable.

I had a fault where the Band worked, but I got no dial tone... Turns out out one of the conductors had cracked, the higher frequencies of BBand could deal with the capacitance on the line, the phone signal couldn't.

Nearly as bad as a VM failure I had - cold caused a contraction in a tightly bent cable in the cabinet and cut off 1/3 of the houses on the street, of course by the time an engineer came out it was warm and it all worked.

Despite my production of logs demonstrating the problem it took four engineers before one gave me the number of a *network* engineer rather than a customer equipment engineer... We sorted it in about 15 minutes given the evidence I had accumulated.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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Mick F
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Re: TV licensing...

Postby Mick F » 30 Sep 2020, 4:30pm

Threatening Letter No 34 arrived today.
Exactly the same as Letter No 31.
Mick F. Cornwall