Old TV blamed for modern technology not working

[Electronpusher0]

Originally Posted by Cobaltblue

So my understanding Radiated interference below 30MHz isn't really considered only conducted since.

"Conducted radiation specifications cover emissions in the frequency range of 150 kHz through 30 MHz. A separate set of radiated emissions specifications covers the spectrum of 30 MHz and greater."

"Electromagnetic conducted and radiated emissions are the radio frequency (RF) energy emitted by a product. The level of RF emissions are regulated to ensure that they do not cause unreasonable harm to other electronic products. At low frequencies (less than about 30 MHz) the conductors and cables of most electronic devices are ineffective as antennas and, thus, radiated emissions are not an issue."

In other words there is virtually no requirement for "radiated emissions" below 30MHz

Back "in the day" when I was designing SMPSUs we used a local testing house for electromagnetic combitability testing. As stated above, 150kHz though to 30MHz was tested via conducted emisions. The equipment to be tested was connected to a LISN - Line Impedance Stabilisation Network to which was connected a well shielded communications receiver with an accurate rf level measuring circuit. This was swept through the frequency range and any high levels measured. The comms receiver did have a speaker but just so the operator could separate the emissions from the local radio transmitter!
Above 30MHz the receiver was connected to a log periodic aerial at a set distance in a quiet environment, preferably a shielded room and again swept.

The equipment generally failed first time so we would go back with the report and try and fix it.

Peter

[high_vacuum_house]

May be an opportunity to bring back and re equip the old TV detector vans to find items that are squirting out large amounts of QRM and have the power to do something about it!!

There is a road I occasionally go along in Leicester to get hydraulic fittings from. There is an iffy looking tyre company there and whatever they have in there running permanently completely blots everything out on the radio. Even FM is obliterated. This has been going on for a couple of years now. I am surprised no one has picked up on it.

Christopher Capener

[broadgage]

A few years ago I suffered at sudden loss of internet signal from early December onward, but only during darkness.
A little investigation showed that my own outdoor Christmas lights were to blame, or at least the 12 volt SMPS that powered them.
Earthing the negative side of the 12 volt supply cured the problem. Not connecting to the mains earth but to several small earth rods in the garden.

[Techman]

Originally Posted by high_vacuum_house

May be an opportunity to bring back and re equip the old TV detector vans

Bring them back?

They were never there in the first place!

I find there are a lot of places that obliterate the radio in my car as I drive around - the whole thing has got completely out of control...and who's fault is that?

[Graham G3ZVT]

Originally Posted by Gabe001

Mike, 612 kilohertz keeps getting mentioned in some articles
Gabriel

Indeed it does, but I'm convinced there is no particular significance in this frequency, other than it's a relatively quiet spot on the MW dial, and it makes sense to standardise your measurements when making comparisons.

[Electronpusher0]

Originally Posted by Techman

Bring them back?

They were never there in the first place!

When I was a student at Chichester FE college, must have been early seventies, they brought a detector van round as a PR exercise.
It had real detector gear but most of the van has laid out with seating so the public could be invited in and be scared into buying a licence.
When our class trooped in the technician giving the talk asked us what we were studying and when he found out it was electronics he put aside the handouts and gave us the technical info instead.

It basically worked by picking up the local oscillator so the operator would have to guess what channel was being watched by the target house, 7:30, must be corrie!
The receiver would be tuned to the LO frequency and the two aerials on the roof would be spaced by motor drives so that they gave a 5 or 7 lobe reception pattern.
The receiver output drove the Y axis on an oscilloscope, the X axis was driven by the vehicle wheels so that as the van rolled past the house the display would move along the X axis.
The van would then drive slowly past the house and as the TV came into each lobe the scope gave a response. The main lobe was at right angles to the van so that as the van passed in line with the TV the scope showed maximum deflection. The operator would press a button as the van passed each end of the house, this gave a marker on the scope. If the main reception lobe showed maximum signal within the limits of the house this was considered evidence that there was a TV operating within the house.
The scope image was recorded by means of a polaroid film

The van crew would then knock on the door and see if the owner would confess when presented with the image.
If not they had no right of entry and had to get a search warrent from the court, which would be granted, the photo being considered sufficient evidence for the warrent. This would take about 3 days and as the technician told us if the owner cannot get rid of the set or buy a licence in those 3 days they deserve to be caught.

It was very limited, quite apart from having to guess the channel it would not give elevation so was no use for flats and as it needed a clear, straight, run past the house it was no good for houses on corners or bends.

Its primary function was to be seen and scare people, during the day they used to park it in the nearest shopping centre or high street.

Peter

[emeritus]

The piece on this in Wednesday's "Daily Telegraph" includes a box explaining how this interference can arise:

"Old or faulty household appliances that use a lot of power, such as televisions, fridges, and washing machines, can disrupt broadband connectivity.

The phenomenon is known as Shine (Single High-level Impulse Noise) - a type of powerful radio wave that exists in the same frequency range as that used by a specific broadband device.

It is invisible to the naked eye and cannot usually be heard or felt without specialist equipment."

I am intrigued by "usually" in the last sentence. Ok, so all radio waves are invsible to the naked eye, and you can use a specialist spectrum analyser or even a non-specialist tranny to "hear" a "Shine", but feel?

[AC/HL]

Amid all the criticism, I'm surprised that no one has mentioned the last but one paragraph

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

We know that many importers pay only lip service to this requirement, but even a mention should surely be seen as good news here.

[Oldmadham]

Originally Posted by Radio Wrangler

They obviously went for a depressingly long time before they deployed a powerful enough diagnostic instrument.... A BRAIN!

David

Such wondrous devices are virtually unknown in this enlightened modern time!

[Richard]

They have come out of hiding

[Nickthedentist]

16' eh?

[Tim]

As some of you may know I’m one of the “ van staff” for Openreach.
I have to agree with most of the comments regarding technical training, and wholeheartedly agree. We don’t get enough to properly diagnose occurrences of this nature. Also our work system doesn’t really cater for it( the service providers wouldn’t generally be happy paying for an engineer/s to search for a fault for hours when everything else is testing g OK.
Unfortunately as there are hundreds of service providers, one wouldn’t know faults reported to another. That’s a subject for a different thread though.

[Tim]

On average it would take several visits to find something like this, as these type of occurrences are fairly uncommon. I have only come across three or four in as many years, and then only one was proved. Customers don’t always realise there is anything wrong either, or may only tell the engineer there is a pattern on the fifth or sixth visit!
Rare things happen rarely, which is why Openreach have a specialist team.
I have put myself forward for the next round of REIN training, but have no dates yet.

[Tim]

Some of you may be interested ( & possibly amused) to know that I use a vintage tranny ( an ITT Tiny33)to search for possible sources of interference.

[Tim]

Also any possible REIN reports are triaged, and require certain parameters to be met before a case can be raised( and presumably the budget to do it)

Tim, thanks for the sanity check! It was always going to be a bit dodgy shoving MHz down an audio feed line. I am pleasantly surprised I can get 50Mbs on a POTS* line. I wonder how much the locality suffers (or even notices) when I transmit on 80 (3.8MHz).

*Plain Old Telephone Service.

[Oldcodger]

Tim- there's a few posts on FB about this incident and similar comments on how engineers use an old radio to locate this type of fault.
There's also amusement that there's few engineers who nowadays understand this type of problem . Possibly because there's not the training to understand this sort of problem as a lot of faulting on the nearest to transmission eqpt (PCM/TDM links) can be done monkey fashion by changing cards. But that's so called progress with little understanding of the systems. But again to fault a PCM/TDM system you'd need at the least a scope . I ended up in PO()T) as a TO on transmission duties ( including PCM LINKS) and also worked in GEC on PCM systems, where we faulted systems.
More than a few years ago I returned from Radio to installing telecoms systems ,mainly Panasonic ,where one of the main problems was RFI from welding systems. TIG/MIG in a building and minutes later the system went belly up. Might be interesting to see how much damage a welding shop creates with broadband and how far one welding shop can cause problems.

[Radio Wrangler]

At some point increasing demand for speed will force FTTP and xDSL will go away. So the problem looms of all that digging for areas where distribution is buried.

Money is on them cutting costs by blowing them along sewer pipes..... sorry, Tim.

David

[Tim]

BT( as they were then) were prevented from running fibres to customer premises in the 1990’s by the then regulating authorities. The same authorities who are now complaining this country does not have a sufficiently developed local BB/ fibre network.

[trh01uk]

"The phenomenon is known as Shine (Single High-level Impulse Noise) - a type of powerful radio wave that exists in the same frequency range as that used by a specific broadband device."

This"SHINE" thing is one of the odd things about this incident. Its either one of the engineers showing off his knowledge from a somewhat weird training session - or the news media just making things up.

I spent a long time working in the EMC field, and I never once heard of "Shine". Admittedly I've been retired for 20years, so maybe something new has been discovered and named in the meantime. But thinking about the meaning of this acronym makes it sound like a transient. Its the "single" and "impulse" that in my mind equates with a transients - in fact,just one transient is the implication of "single".

Transients are of course of great concern. They tend to destroy sensitive electronics for one thing - and I spent many hours hitting bits of kit with 4000V spikes, and then redesigning them when they expired rapidly.

But clearly this interference is very unlikely to be a case of a transient - or even many transients. Most likely is the fundamental and harmonics of a SMPS operating frequency leaking out on to the phone network, and then taking out multiple ADSL subcarriers.


Richard