In reply to a post by blfamily:

Have the same problem with a Talk talk router next door, constantly follows my wifi signal, which then annoys my son on his laptop in his room.

????

I don't understand what you are saying there.

Take a good look in your own house for anything, usually substantial, that has been added, moved etc.

One example particularly is mirrors, due to the metallic "silvering" required to achieve the reflections.

It might not be in the same room.

My WiFi Repeater stopped working recently when a metallised crisp packet was placed in the waste basket alongside.

Taking that packet out of the basket, without moving or disturbing anything else, let the repeater start working again.

I wonder if anyone has experience of the metal foil backing on plasterboard etc.

In reply to a post by blfamily:

Have the same problem with a Talk talk router next door, constantly follows my wifi signal, which then annoys my son on his laptop in his room.

manually change the wifi channel using a wifi analyzer as a test tool.

Having 2 wifi routers on the same channel is generally not an issue. When you say it annoys him, is there really any noticeable issues or just the son notices they're on the same channel and becomes annoyed?

Often times, the routers on AUTO do choose the same channel as one another, and often this is intentional. There can be worse interference on the other channels such as baby monitors, microwave ovens, wireless doorbells, cordless landlines, wireless HDMI transmitters, bluetooth keyboards, bluetooth headphones, bluetooth mice, bluetooth fitbit fitness trackers etc. You do not see these devices in operation. If 2 routers are close by and are selecting the same channel, chances are there is other interference in the area causing that. You are probably just forcing your own device to use a channel swamped with those devices you are not seeing & all of these apps inssider, android apps etc are generally ignoring, as they only look at the wifi being broadcast.

wifi analyzer will not map out every device using 2.4ghz, it only maps out the wireless routers, as such it often causes you to choose a bad channel. Routers on the same channel do not cause the major issues at 2.4Ghz, it is the often analog devices such as a baby monitor which cause the mayhem. AUTO generally does a decent job at avoiding this, but the milage varies router to router.

Edited by ukhardy07 (Sun 26-Jun-16 00:19:07)

To follow on from UKHARDY's excellent explanation.

There are only 13 Channels in the 2.4 GHz WiFi Band.

Whilst the range or distance covered is relatively short, if you take a laptop or suchlike with inSSIDer or some other WiFi monitoring program to the business area of any town, you will see that by name/SSID there can be hundreds of separately identifiable WiFi circuits in operation, in very close proximity, clearly limited to those 13 channels, presumably successfully.

If there was any great amount of interference of any sort, would there not be a great outcry?

Even in metal-bodied trams and busses, travelling through the streets, hundreds of WiFi circuits can be seen waxing and waning as the vehicles move along, with the vehicle's own WiFi being the only "fixed" one.

Edited by deleted (Sun 26-Jun-16 07:49:38)

The Gadget Show did a test with microwaves, baby monitors and Christmas tree lights and found little or no effect on wireless signals.

I suspect with microwave cookers, it would need dirty door-seals to create a "leakage" path.

Having assisted in the development of cavity magnetrons, the RF source in such cookers, back in 1954 and 1955, I have a particular interest in them.

I am surprised how clean the microwave cooker door seals remain over the years, compared with their interiors, when things go awry.

Have any forum members experienced this particular form of interference and been able to examine the source cooker in any detail?

Yes it is usually a rogue device that causes the issues, not a baby monitor etc in general. 9/10 it is fine, but too often these devices do perform poorly. You see much more often things like wireless TV transmitters causing issues than routers themselves at 2.4Ghz. By no means does a baby monitor, bluetooth device running etc equate to a poor wifi network everytime, if it did there would be a lot of issues, it is just a small amount of the time. Needless to say the point is that choosing a channel yourself often misses interference. Then again, some routers also do not account for this interference either on AUTO (and some do).

I concede eckidoo's greater experience of microwave technology. However it's still notable that you see clusters of routers on a few channels, usually 1 and 6 in my experience. I have also definitely improved wifi by switching to apparently clear channels.

Without a spectrum analyser (or at least a scanning receiver) it isn't possible to see what else is occupying the same RF spectrum. I doubt it's possible to make the wifi radio in a smartphone do this job but happy to be proven wrong. Perhaps a software defined radio device that covers the 2.4GHz band might give a fairly low cost solution.

The wavelength of 2.4GHz is about 12cm. So bits of metal that are that size, half that size and possibly a quarter of that size could have profound effects on the wifi signal if close to either the router or the phone/tablet etc. One day i'll take my router out of the cupboard where it's close to the consumer unit, burglar alarm and see if makes a difference.

As an electronics engineer with much experience (admittedly not much with RF and antennas) I still find it pretty mriaculous that you can put multiple radios and their antennas in a tiny box, hold it at a random angle with proximity to conductive elements (humans!) and get them to work fairly reliably. But that's exactly what our phones, tablets etc do.

Thank you.

I generally agree with your technical comments, particularly the need for a genuine spectrum analyser or a software one to run on a PC. Must try the latter again, unsuccessful in previous attempts.

Agreed particularly with your final paragraph. I wonder how many realise the miniscule scale of most WiFi Tx/Rx "units" - about a very tidy wrist watch; and Bluetooth ones being even smaller.

Combine with the very unusual design of the typical WiFi aerial usually hidden inside the screen part of laptops.

Again being of the size of a very thin wrist watch; and many resembling a squared version of the "Isle of Man" symbol.

------

My Bright Box 2 is set to AUTO Channel Select and to extend DOWNwards if necessary, on both WiFi Bands, 2.4 GHz and 5 GHz.

At home, there are relatively few other WiFi systems to compete with; and I am uncertain as regards other potential interference sources, other than the reasonable assumption of one microwave cooker per household; and there may or may not be a baby monitoring system "two doors along".

Occasionally, busses equipped with WiFi have shown up - very rare as although there are about 3 services passing the house, they are all local, so generally less likely to have WiFi on board - although the facility is clearly increasing.

Using ACRYLIC on an older laptop but which also has 5 GHz band facilities, the situation is-

Chan SSID
11 My Brightbox 2
11 My WiFi Extender, one of the BT range
40+44 My Brightbox 2

There are two other SKY WiFi systems on Channel 6

Plus a third SKY, 9 BT and 1 "Direct DB" all on Channel 1.

Two of those BT have "with FON"

All of the 2.4 GHz have a "Max Speed of 144.4 Mbps, the Direct DB being 72.2 Mbps

TalkTalk has just appeared on Channel 3, 270 Mbps.


So clearly not approaching the quantities I have noted in town etc.

Strictly speaking, a microwave oven should use 2.450GHz while wifi uses 2.412 GHz to 2.472GHz. But microwave ovens aren't designed for frequency stability so even fairly small leakage could muck up wifi. Even if it's spot on frequency if there's a lot of leakage from the oven I suppose it could saturate a wifi receiver where the front end selectivity won't be sufficient to reject 2.450GHz

Useful information about usage of the 2.4GHz ISM band:
https://en.wikipedia.org/wiki/List_of_2.4_GHz_radio_use