# Podcast interference on Atalanta



## Paul Braxton (Jul 21, 2005)

This is a strange one. If anyone has any idea whatsoever about this weird effect I'd be interested to hear.

I have a Marconi 'Atalanta' receiver, in perfect working order. It gets used quite often; surfing the HF waves for amateurs, time signals, all the usual. A couple of nights ago I was running along the 4 to 8 MHz band, and at the same time my wife was about to start listening to a podcast of her beloved "Archers" serial on her laptop. Down at the other end of the house. I was vaguely aware that she had started listening, a bit like someone on the phone that you half listen to but aren't really tuned in to. (I have no interest whatsoever in the 'Archers' and usually 'tune it out' whenever she has it on. It becomes a background thing.) 

It was then that I noticed fairly regularly spaced interference signals, bursts of quite loud static with peculiarly spooky, disembodied and just about unintelligible speech superimposed. Then it dawned: it was the dreaded 'Archers'! Every time somebody spoke it would be simultaneously echoed, modulating the static on the 'Atalanta'.
Very weird and quite disturbing, like someone trying to demonstrate a so-called EVP, or electronic voice phenomenon. 

As soon as I realised that the correlation was indeed some kind of interference from the "Archers" podcast, and not something being transmitted from the outside world, the mystery was partially solved, but of course I was no nearer to being able to understand just how this could possibly be happening.

Not long ago I had an older computer, a laptop, with a hard drive which was on the way out. Any time the laptop was turned on, wherever it was in the house, on mains or battery, the 'Atalanta' would pick up several spots of static interference on HF, a sort of unearthly howling, whining, grating sound, all of which were partially muted when a USB plug was inserted. I noted that if the volume was turned up so that I could hear the receiver output from the other end of the house and I then fiddled with the USB, taking it in and out, the corresponding interference would increase or decrease as I did so. The hard drive did indeed die a few weeks later, as expected.

The new laptop, a Toshiba 'Satellite' running Windows 10, is a new model. No problems with it. The 'Atalanta' is not earthed according to the instruction manual, with the copper strap bolted to the side of the metal enclosure, but I have no easy way of doing this and considered it not strictly necessary as I'm not using an associated transmitter. Probably, if I had done so, the interference would not have occurred. 

I live on a farm, and whenever the farmer turns on his electric fences, no matter which part of the land is in use, or apparently how distant, the good old receiver picks up the unmistakeable regular (1 second pips) faithfully. It also picks up things like the cycles of the washing machine, which is situated out in the garage. 

I suppose some of this is mains borne; the cables probably acting inductively, picking up spurious signals from electrical devices in the house, but from a podcast!! What is that all about?

I am a big fan of Marconi's gear from the old days. It's wonderful having an authentic piece of kit like the 'Atalanta' around the place. It's a wonderful piece of kit alright. Even with a rudimentary wire aerial strung to a nearby hilltop post I routinely pick up signals from long distances. I'm up at about 1400 feet in farming country north of Lake Rotorua in New Zealand, so it's a good, quiet (apart from the electric fence) position for listening out on HF. (Also for looking at the heavens. No light pollution at all and very clear 'seeing') Heard a ham in Austria the other night, talking with a 'VK', Aussie station. He was coming in about strength 3/4 and took my mind back to the early '70's, getting a turn on GKA from the South Pacific with an 'Oceanspan 7' and knowing that I was coming in well over all that distance with just 100 watts output or so. 

Quite an amazing receiver for its time, but its designers didn't know anything about computers and their idiosyncrasies!

So, to end then. Any comments welcome. I will endeavour to make some more observations on this perhaps, as time allows;try to track down the exact frequencies which are being affected and so forth. It seems to me that the laptop's microprocessor must somehow be rebroadcasting the speech from the podcast in some rudimentary, accidental way, which is then picked up by the house wiring or the aerial itself.

What next? Probably anomalous signals from the old "Queen Mary", delayed in time and rebroadcast from some orbiting alien satellite or preprogrammed, unmanned spacecraft. A bit like a certain Duncan Lunan once wrote about in the '70's in the prestigious pages of the British Interplanetary Society's "Spaceflight" journal. Who knows?


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## tunatownshipwreck (Nov 9, 2005)

I can't listen to my shortwave any more due to neighbors using wi-fi instead of hardwired connections.


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## 5TT (May 3, 2008)

Hi Paul,
A modern receiver would usually be able to deal with the impulse type clicks you'd get from an electric fence for example but signals generated by computers, network cables, DSL modems etc. are just there, not much you can do about it except turn the interfering device off if you can or choose a different frequency. It seems like almost everything one buys these days comes with a cheap and noisy power supply and if you're unlucky enough to have a plasma TV on a neighbouring property you can expect to lose huge chunks of spectrum, they emit a very wide and powerful signal, it wouldn't matter what type of receiver is in use it isn't going to be able to deal with that racket.

I found tunatownshipwreck's comment about wi-fi interference on shortwave interesting, it is my experience that with wi-fi signals up in the 2.4 ghz or lately 5 ghz part of the spectrum that there is no h/f interference from those signals at all, in fact one is more likely to get h/f interference from a wired connection and/or from the actual network equipment. 

= Adrian +


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## chadburn (Jun 2, 2008)

5TT, I had a problem with my own Wi Fi when the supplier came to install it, just could not get the signal from the Hub, after some head scratching I asked the installer what frequency the Hub was working on, his answer was 2.4 it was then that I twigged that I had some other equipment emitting a 2.4 signal and asked if there was another frequency available. The Hub was then changed to 5.0 after a telephone call, job done.


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## 5TT (May 3, 2008)

Hi chadburn,

The 2.4 ghz wi-fi allocation is split up into 13 or so channels depending on the region and most equipment when shipped is set up to select the channel automatically. The problem I've found is that the channels overlap somewhat, a strong signal on channel 3 for example will interfere with you on channel 4 but in any case the auto channel selection tends to bunch most users up onto the lower channel numbers. There is diagnostic software available that lets you see the relative strengths of the competing nodes thus enabling you to move away from the stronger signals but even without that it is often sufficient just to manually set a high channel number to be in the clear.

= Adrian +


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## chadburn (Jun 2, 2008)

I use four of the 2.4 channels for other purposes, the decision was made to move to 5.0 to be clear and to get a signal to my i Pad. It was certainly a puzzle for a while as I had no idea that Wi Fi used 2.4, thinking they used another frequency for commercial purposes bearing in mind the amount of equipment the public can buy that uses 2.4. 
Chad.


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## GW3OQK (Jun 10, 2010)

Paul
There's nothing wrong with your Atalanta at all. Your aerial is picking up whatever is being transmitted by the offending equipment. The cure is at that equipment or it's cables. I have my receiving aerials 30m from the house and fed by buried coax. One is a Datong active dipole and another an inverted L with Icom automatic tuner at it's base. 

I have read reports of the plug-top switched-mode psus radiating more than the lap top or router or printer, and the characteristic modulation changes depending how active it was. The cure was to try it on batteries and then replace with a linear psu. Our plasma TV is a dreadful radiator, as are the upstairs 12v lights with their switch-mode "transformers". 

My neighbour's electric fence sometimes radiates a 0.9 sec click, but it never lasts long for he is sure to hear the click of a spark at a bad contact. He only has a chicken run fenced, not a farm.

I like the ease of using my Atalanta and there's a picture on my QRZ.COM page
73, Andrew


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## Paul Braxton (Jul 21, 2005)

Like your photo's on QRZ, Andrew. I know there's nothing wrong with my 'Atalanta', it's a great set - still! I understand something about earthing requirements but didn't know anything at all about all these funky PSU's which are putting out so much QRM/N.

I was just freaked by the set picking up the actual speech from a podcast, and am still faintly mystified by that side of things.

We live in a hugely cluttered RF environment these days, necessarily, it seems. It would be weird if you could actually perceive in some way all this vast interweaving net of electromagnetic waves radiating everywhere. And of course we're not, as a species, adapted for it. We and all the other lifeforms we share this planet with haven't really had time to evolve along with the rapid pace of human EM radiations. Nice to have WiFi on your computer but there is probably a hidden side to it all as recently highlighted perhaps by my own experience.

Takes my mind back to the days of wearing tightly clamped, metal strap headphones and getting an induced RF fizzle on the earholes on certain frequency bands...


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## Varley (Oct 1, 2006)

The SG Brown scalp frazzler eh? Can manage that on most HF with a Crusader. Just forget to connect the aerial and load up into idiot pressing the key.


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