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Interference

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Neil Wyatt22/09/2020 13:15:50
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Food for thought:

www.bbc.co.uk/news/uk-wales-54239180

I wonder if any of our workshop equipment causes a dip in broadband quality, especially for wireless routers?

On the one hand this shows it needs to be a big, sustained problem before it will be actively tracked down, but on the other it might be worth comparing our broadband speeds with and without heavy machinery or inverters switched on as a way of finding if they cause an issue.

I'm reminded that our entire road lost broadband for ten days due to a dodgy router in an office nearby.

Neil

Robert Atkinson 222/09/2020 13:34:46
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It just goes to show you can't be sure about interference without measurement. Unless a VFD/inverter explictly states it has built in filters it will need external filters to bring emissions within limits.

Robert G8RPI.

Frances IoM22/09/2020 13:54:11
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I would have liked to see a more technical reason why an old TV set could interfere with broadband - was the village served by an upgraded wifi and this old tv was in line of sight of a mast - if an old TV with a CRT was it breakdown (Corona discharge!) from the high voltage drive to the tube
Bazyle22/09/2020 14:15:53
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Sounds like its filters (capacitors) on the EHT inverter had died of old age and it was putting noise on the mains that then got into the phone line perhaps due to a getting through the modem psu. Kind of sloppy of BT not to have looked at it earlier.

Interference from all sorts of things is a problem for meodems, not necessarily cutting out just reducing speed. Mobile phone base stations signals don't help. I've seen a fish tank heater timer give wifi problems reported as intermittent connectivity. If the owner had been more observant they would have noticed it was only starting at 2pm every day.

I imagine there is a lotof potential for eg a home made rotary converter, failing VFD capacitors, worn brushes on a drill etc, to put noise on the mains that can then get into places it shouldn't.

If you want to get a feel for what noise is around from a motor the simplest thing is a battery long or medium wave radio.

Maurice Taylor22/09/2020 14:30:29
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Nobodies bothered when broadband ,plasma tvs ,and other digital devices make it difficult to listen to medium wave and shortwave radio.

Edited By Maurice Taylor on 22/09/2020 14:30:50

Edited By Maurice Taylor on 22/09/2020 14:36:34

Speedy Builder522/09/2020 14:31:12
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"We'd just advise the public to make sure that their electric appliances are properly certified and meet current British standards," she said.

That sounds a bit daft - it means that we have to change everything for the latest BS. Do I have to upgrade my 1932 Austin 7 to the latest emission regs ? Ahem, I think not.

Samsaranda22/09/2020 15:11:58
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Nearly forty years ago when CB radio was all the rage my middle daughter was addicted to it, had her setup in her bedroom and a large mast on the side of the house. One of our neighbours complained bitterly that her transmissions were interfering with his tv reception, I said that my daughters equipment was in compliance with the necessary specifications and no one else was having problems so to solve the problem he could report the matter to the Post Office Department that dealt with such issues, he did and a Post Office expert duly arrived and checked my daughters equipment and transmissions and found no problems, he then checked the neighbours receiving aerial and found that it was basically old and knackered and apparently there was a very high resistance connection and this was receiving the CB signal as interference. It just shows interference can occur in the most unexpected situations.
Dave W

old mart22/09/2020 15:28:20
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When I fitted the VFD controlled three phase motor to the Tom Senior, I first chose one with filters for interferance supression. The Vfd is in an earthed steel box, and all the cabling is screened, including the low voltage control wiring. We have not noticed any problems with VHF and DAB radio signals, and the wireless router in the workshop runs as expected.

I had been initially concerned by the manual mentioning an earth leakage when using the filters, but there has been no tripping of any RCD when the mill is in use.

Peter G. Shaw22/09/2020 15:35:00
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As Frances has said, I too would like to see more about what the actual problem was. For example, up to a few years ago, we had a CRT 625 line tv dating from 1992. From what I can remember, tv's of that age were likely to suffer from the drying out of capacitors, but even assuming that they were all 100%, that TV would have been designed for an era when 625 line analogue TV ruled supreme and broadband was but a pipedream. So which set of regulations should it adhere to: those of the late 1980's or those of the 2020's? I seem to think that it is axiomatic that a device built and working correctly to the regulations pertaining at that time does not have to be updated. Should that not be so, then where does that leave us with our equipment today?

Whilst I agree that people should not be using equipment which causes interference to other people, I'm not too sure that in this instance we are being told the full story: indeed I do wonder if this is a cover-up by BT.

Peter G. Shaw

Bandersnatch22/09/2020 17:16:47
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Posted by Peter G. Shaw on 22/09/2020 15:35:00:

I seem to think that it is axiomatic that a device built and working correctly to the regulations pertaining at that time does not have to be updated.


I sort of agree but I think it's more likely that older equipment would be grandfathered until their penetration comes down to, what .... 10% ? ; 5% ? and then made illicit.

I also think that the person concerned was pretty dumb. I'd have said (to the cable/internet people) "until you can show me that it's illegal I'll continue to use it ...... of course you could always buy me a new, modern TV (and dispose of the old one)" Which would be by far their cheapest option (not to mention good publicity).

Nick Clarke 322/09/2020 17:39:23
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Posted by Speedy Builder5 on 22/09/2020 14:31:12:

"We'd just advise the public to make sure that their electric appliances are properly certified and meet current British standards," she said.

That sounds a bit daft - it means that we have to change everything for the latest BS. Do I have to upgrade my 1932 Austin 7 to the latest emission regs ? Ahem, I think not.

Actually you do need to comply with the latest emission regs - but these have a section that covers cars like your Austin 7 (emit no visible smoke as far as I recall) - however the fun starts if new legislation does not include clauses to cover an existing situation.

SillyOldDuffer22/09/2020 17:52:02
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Posted by Peter G. Shaw on 22/09/2020 15:35:00:

... up to a few years ago, we had a CRT 625 line tv dating from 1992 ... So which set of regulations should it adhere to: those of the late 1980's or those of the 2020's? I seem to think that it is axiomatic that a device built and working correctly to the regulations pertaining at that time does not have to be updated. Should that not be so, then where does that leave us with our equipment today?

... not too sure that in this instance we are being told the full story: indeed I do wonder if this is a cover-up by BT.

Peter G. Shaw

Old equipment not meeting current standards is usually allowed to fade away. The chance of it causing a problem decreases over time because fewer and fewer people own one. But if an old telly interferes with a service, then it can be shut down, provided someone is annoyed enough to trace it. There will be a rapid response if it wipes out airport communications, the military or an emergency service!

Not difficult to think of exceptions,usually safety related: weapons, certain chemicals, pollution, and use of the radio spectrum come to mind, but chopping stuff off at the knees isn't common in the UK. Not all situations permit shades of grey - if the country decided to drive on the right, there wouldn't be a transition period!

The problem in Wales is likely related to the limited error correction scheme used by some transmission systems.

To guarantee reception, it's necessary for sender and receiver to acknowledge receipt resulting in a constant exchange of messages confirming all is well. As this is wasteful and unnecessary inside a normally reliable network, it's common to use a less perfect scheme called Forward Error Correction. In FEC data is packaged into blocks, arithmetic applied, and magic numbers added allowing the receiver to detect an error in a block with a good chance of correcting it from the magic numbers. Works very well up to a point, but serious noise can mangle blocks so badly the contents can't be recovered. Annoying when it happens to one user, very annoying when if effects everyone, and the whole network can collapse if control information is damaged.

Some sympathy with BT, though one might ask why their local team doesn't have a spectrum analyser, and why it took them 18 months to get one from HQ on site. Interference is so common it's strange the problem wasn't diagnosed earlier : I suspect fumbling rather than this being a technical problem.

Dave

Neil Wyatt22/09/2020 19:42:25
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Looks like we may not begetting the full story from the BBC.

The source below would suggest that 'SHINE' is a big switch on transient that was resetting the local broadband system, but not knocking it out all day...

support.zen.co.uk/kb/Knowledgebase/Broadband-Understanding-REIN-and-SHINE

Neil

Peter G. Shaw22/09/2020 20:22:35
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Dave/SOD,

I understand where you are coming from, but somehow I doubt if the MSM would take kindly to big brother coming down heavily on to a pensioner who was unaware that his tv was causing a problem. It also suggests to me that the tv concerned may be faulty in which case the owner should have been advised to have it repaired, not agreeing to not use it - unless it was an agreement to not use it until it had been repaired. Furthermore, I would suggest that the onus is on the designers of the equipment being interrupted to ensure that their equipment is hardened against such interference - unless of course, they are going to pay to have all the interfering equipment repaired or overhauled. There is, of course, a precedent for this, not an exact precedence I admit, but near enough. Think back to when Channel 5 started up transmitting on (I think) Channel 35. In that instance the broadcasting company was required to pay for the retuning of all the VCR's away from transmitter Channel 36 to avoid interference.

I must admit there is precedence the other way: witness the change to so-called digital tv when everyone was required to update their tv reception equipment, but in that instance it was either do it or lose your tv service - there was no threat of big brother coming down heavily if you didn't comply.

I would still like to know more about how switching a tv can cause such a large transient as to knock out broadband. It suggests to me that the broadband designers have not properly hardened the broadband distribution equipment.

Incidently, whilst writing the above, it has occurred to me just what are we talking about here. Are we talking about FTTC, ie the system whereby a large green box distributes broadband around the locality? Does anyone know?

Peter G. Shaw

Harry Wilkes22/09/2020 21:38:08
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Some time back I had a microwave that when on blew my WiFi away, it was a brand name and talking to a friend who designed induction heating equipment he said microwave were as leaky as a cullender he told me jus to prove a point to take up up the garden which I did it was not so bad but still interfered

H

Mark Rand22/09/2020 23:44:00
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Posted by Harry Wilkes on 22/09/2020 21:38:08:

Some time back I had a microwave that when on blew my WiFi away, it was a brand name and talking to a friend who designed induction heating equipment he said microwave were as leaky as a cullender he told me jus to prove a point to take up up the garden which I did it was not so bad but still interfered

H

I'm surprised that domestic microwave ovens don't cause more issues with domestic WiFi installations. Given that the leakage from an 800W 2.4GHz heating device might well overwhelm the output from a 20mW 2.4GHz WiFi transmitter.

We had a construction Site on the Isle of Grain, in Kent, that I'd installed both the wired and wireless networking in. The folk complained that every now and then, the WiFi to their laptops would drop out for a little while... When the laptop is set to prefer the 5GHz frequency band (usually better) and a ship goes past with it's (5GHz) radar belting out a few KW, the WiFi access points would shut down to avoid interfering with the ship's radar...

Michael Gilligan23/09/2020 07:40:10
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The BBC story is predictably lacking in detail, and I remain unsure whether they really mean ‘Broadband’ or ‘Wi-Fi’

That said: metageek offers some interesting information about interference : **LINK**

https://support.metageek.com/hc/en-us/articles/200628894-Wi-Fi-and-non-Wi-Fi-Interference-Examples

I bought one of their early products [Wi-Spy 2.4i] back in 2009, and learned a lot by using it

[ statement of historical fact, not an ‘endorsement’ ]

MichaelG.

.

Edit: I’ve just  found this, which is a little more informative

 https://www.ispreview.co.uk/index.php/2020/09/18-months-of-village-broadband-disruption-traced-to-old-tv-set.html

Edited By Michael Gilligan on 23/09/2020 07:49:52

not done it yet23/09/2020 08:15:54
5143 forum posts
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Ha ha, I liked the confidence of the last para of that report. It may certainly improve the situation but they omit to inform that the fibre optics will not necessarily help individuals, as all the houses will still be fed by copper, from the optical connection to the village....

John Haine23/09/2020 08:36:37
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So to be clear, the problem was an interference spike which reset the main adsl router at 0700 daily. This caused everyone's routers to have to reconnect which reduced their bit rate because of the DLM mechanism. It wasn't rfi to WiFi or into the adsl cables.

Actually Openreach is rolling out fibre to the premises even in rural areas as its operational costs are significantly better than copper. Here in the Cambs/Essex/Suffolk borderlands they've been putting fibre in the ground and on the poles for a couple of years and we are slowly being connected. Fibre to the cabinet has been in place for at least 5 years iirc.

Michael Gilligan23/09/2020 09:16:29
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Posted by John Haine on 23/09/2020 08:36:37:

So to be clear, the problem was an interference spike which reset the main adsl router at 0700 daily. This caused everyone's routers to have to reconnect which reduced their bit rate because of the DLM mechanism. It wasn't rfi to WiFi or into the adsl cables.
[…]

.

A nice, concise, summary ... Thanks, John yes

MichaelG.

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