Wireless Waffle - A whole spectrum of radio related rubbish
ADSL: A Daily Service Losssignal strength
Monday 19 November, 2007, 11:53 - Much Ado About Nothing
Posted by Administrator
For the past few months, every evening around sunset, my (ADSL) broadband connection at home has been 'drying up'. By this, I mean that the throughput has got smaller and smaller until eventually there has been no incoming or outcoming bandwidth available at all. If left alone, after an hour or two, the situation tends to correct itself but with sunset currently occuring during the working day, it's annoying to lose internet connectivity at these times.

At first I thought the problem might be to do with my ISP, Sky Broadband, but a quick scan of the rather useful, but unofficial, Sky User Forums didn't seem to indicate that others were suffering the same problems as me (though there were one or two veiled comments about how the connection sometimes dropped at night).

bt adsl filterMy next thought turned to my home installation. I'm quite a way from the local exhange and as such only get a connection speed of approximately 4 Mbps downstream and more like 0.4 Mbps upstream. According to my router, the available signal to noise ratio on the downstream link is only 8dB, that is to say that the ADSL signal on my phone line is only approximately 2.5 times higher than the noise on the line which isn't a great deal. But fiddling around with filters and connections makes next to no difference and the connection remains resolutely poor. During the 'dry periods' the signal to noise falls to 3dB or less (hence the loss of the connection), but re-booting the modem at these times oddly yields a return to 8dB.

Being a radio engineer type, and knowing that ADSL uses radio frequencies, I began to wonder whether the problem might be to do with increased radio interference on the line around sunset. ADSL uses frequencies from approximately 26 to 138 kHz for the upstream connection (i.e. from the home to the exchange) and in the range 138 kHz to 1104 kHz for the downstream connection (from the exchange to the home), though this frequency range is extended to just over 2200 kHz for the faster ADSL2+. Given my distange from the exchange, my connection is resolutely ADSL only (and not ADSL2+) and therefore if there was an increase in interference it would need to be in the frequency range 138 to 1104 kHz. However, as most ADSL modems are capable of running ADSL2+ even if the line is not capable of supporting it, it is likely that the receivers in them are not filtering out unwanted or unused frequencies making them susceptible to interference on frequencies up to 2200 kHz and quite possibly even higher even if those frequencies are not in use.

pole dancerNow as it happens, this frequency range is home, in Europe, to both long wave and medium wave radio transmitters (in the frequency range 148.5 to 285.5 kHz and 526.5 to 1606.5 kHz respectively) and there are many high powered radio transmitters in this frequency range. Could it be that the propagation that exists around sunset causes such a significant rise in the level of signals in this frequency range that it was knocking out my ADSL connection? The telephone connections in my area are via flown cables between telegraph poles (as they are still called despite telegraph having died out eons ago) and as such probably make rather good aerials, so it is quite possible that my modem is susceptible to incoming interference from high power long and medium wave broadcast transmitters.

When first booted up, the ADSL modems at both the exchange and the home end 'train', that is to say that they check all the available frequencies to see which have the best signal to noise and then use just these frequencies for the connection. This would perhaps explain why re-booting the modem during a dry period restores the signal to noise: clearly the frequency on which the interference occurs is one which is clean in the mornings when the modem is first switched on.

microfilter circuit diagramAs yet I have not been able to confirm my theory that interference from high power broadcast transmitters is knocking out my broadband connection, but it does seem eminently reasonable. Next steps are to do some tests (maybe connect a receiver to the phone line - bearing in mind it has 50 Volts on it!) Another option might be to add some filtering to the incoming line: surprisingly ADSL microfilters do not touch the ADSL frequency range they just stop the ADSL signal getting into/out of any phones connected (see the example circuit diagram on the right), which means, incidentally, that if you have nothing other than an ADSL modem connected to any phone socket in your house, you don't need a microfilter on it: you only need microfilters on the sockets where phones are connected. Perhaps, therefore, there's room for an improved microfilter that cleans up the incoming ADSL connection as well as keeping it out of the phones. I'll keep you informed of any progress - and if you experience these problems yourself leave a comment and I'll update you personally if I make any breakthroughs!

Update: 18 Dec 2007 Forcing the modem to use ADSL instead of ADSL2+ whilst reducing the connection speed by less than about 5% has almost eradicated the problem. It seems that purposefully avoiding the use of frequencies above 1.1 MHz does make a worthwhile difference.

Update: 11 Feb 2012 After much messing about Wireless Waffle has designed a filter which cures the ADSL drop-out problem that is described above. It costs next to nothing and can be made in minutes!
14 comments ( 2589 views )   |  1 trackbacks   |  permalink   |   ( 2.9 / 6026 )

Wireless Wobblysignal strength
Thursday 20 September, 2007, 10:10 - Much Ado About Nothing
Posted by Administrator
Wireless Waffle isn't one of a kind. There's another Wireless Waffle on the web. Whilst I claim no originality for the title of this blog, it does irk me that the man who runs the other Wireless Waffle is so upset that I accidentally stumbled across the same name as him that he feels the need to take a poke at this site on many occasions.

wirelesswafflecoukWhen I first launched this site, Keith, who runs the other Wireless Waffle, contacted me with a nice e-mail and suggested that we exchange links. I put up a link to his site with a nice button that I took time to make myself (see right) but when a reciprocal link failed to materialise on his site I took it down, and thought nothing more of it. But putting 'Wireless Waffle' into Google, I recently noted that the <title> of his site has been changed to:
Wireless Waffle - A fine radio site not the blog copying its title

If that's not enough, the description of his site says:
Wireless waffle is a specialist radio site ... it is not to be confused with the blog which is using the same title - this other site is more technical and whilst we do not have the copyright on the word waffle they could have thought of a different title...

Fair enough, I could have thought of a different title, but I didn't, but neither did I specifically pick the name on purpose to upset anyone. I was not aware of Mr. Knight's site until he sent me an e-mail.

But the rhetoric doesn't stop there. In a post he made on his site on 16 September he says,
I am wondering if you would miss the Wireless Waffle site if I decided to close it? ... There is another site, a blog, which insists on calling itself Wireless Waffle which is far more technical than this. The chap who publishes this has pictures of ladies in various poses and states of undress. I am one of those that favours proper websites rather than blogs. Blogs do not demand any knowledge of html and that is part of the fun of operating a site.

Now this is just downright misleading, and in some cases completely wrong. He is insinuating that:

thewirelesswaffle* My use of the occasional saucy picture demeans the content on this site. There are many pictures of men in various states of dress as well as women and anyway this kind of thing has been adorining British seaside postcards for many years. These pictures, with their associated captions are intended to add some levity to what can be rather colourless topics.

* That my use of 'blog' software to publish the articles I write devalues them. I use blog software as it makes presentation look nice and it's easier to find articles and for people to browse around.

* That I know nothing about HTML. This couldn't be further from the truth. Take a look at the other content on the host site for Wireless Waffle, such as my Javascript tools, or my Random Town Name Generator. All of these are written by me, using nothing more than a text editor, and most pages are in XHTML which is notoriously more difficult to write in than HTML. If you're going to level that kind of accusation at someone, at least make sure your own site is valid HTML!

The most serious accusation is that by starting this site, I have damaged the viewership of his site to the extent that he is, in essence, accusing me of forcing him to close his site down.

The reaction of many people to so many unfounded accusations might be to retaliate, but I'm not that kind of person. Mr. Knight's site is an interesting read with content that most of the readers of this site would no doubt find of passing or of direct interest. I suggest you take a visit (click on the button above) and have a look around. And pop back here afterwards and leave a comment on this post to let me know what you think.
5 comments ( 1941 views )   |  0 trackbacks   |  permalink   |   ( 3 / 194 )

Box of Dreamssignal strength
Friday 3 March, 2006, 11:49 - Much Ado About Nothing
Broadband wireless ADSL modem/routers are now available for below GBP50, incorporating, as the name suggests, a WiFi router, ADSL (and now ADSL2/2+) modem and often an Ethernet LAN connection. At this price, there's really no excuse for sticking to wired broadband access unless your house is so large that a single wireless access point won't cover all the various wings and annexes.

But things have gone even further than that so that some of the aforementioned modem/routers now include VoIP (Voice over Internet Protocol) connections. With a VoIP connection you can connect a regular phone to your modem/router and send and receive phonecalls via the internet through services such as Sipgate.

7402vgpI recently came across a 'Wireless ADSL VoIP modem/router' for just over GBP90 including postage and the dreaded VAT so I decided to go for it. The sexily named 'Billion 7402VGL BiPAC' (available from broadbandbuyer.co.uk) provides:

* An ADSL2/2+ modem (backwards compatible with good ole' ADSL)
* A WiFi 802.11g access point (backwards compatible with good ole' 802.11b - both operate at 2.4 GHz)
* 3 100 Mbps Ethernet LAN connections (backwards compatible with good ole' 10 Mbps Ethernet)
and
* 2 VoIP phone sockets (the 'Billion 7402VGP BiPAC' is even backwards compatible with good ole' PSTN as well)

After a bit of a kerfuffle setting it up, I now have a wireless broadband network (so I can use my laptop in the bath); my main PC connected via the LAN; and a phone with a central London phone number sat on my desk that rings like any other phone but for which I pay no additional line-rental (other than that I already pay for the line which brings the ADSL connection into the house). sydneyBeing a central London number I can now pretend to my work colleagues that my office is in a swish, high rent district of the city, rather than the sleepy backwater where it acually is! Oh, and it's possible to call other VoIP users for free, so I can chat to my friend in Dublin for nothing whatsoever.

The whole thing is rather impressive (I guess I am easily impressed) and there's still a spare phone socket on the back of the unit so I could get another phone number in, for example, Australia. Why? I don't really know, it's just a gratuitous and pointless use of technology. Plus, I always fancied living in Sydney!
add comment ( 972 views )   |  0 trackbacks   |  permalink   |   ( 3 / 3938 )

Power Strip Antenna Boostersignal strength
Friday 3 February, 2006, 18:32 - Much Ado About Nothing
antennaboosterMy attention was recently drawn to a product called the 'Power Strip Antenna Booster' (though I believe these devices first came to fame in the USA in about 2001). It was being offered for only 1 pence by a mobile retailer (I won't embarrass them by naming First Phone Shop, oops...) if bought in conjunction with other cellular products worth more than GBP12.

The claims being made for this amazing device are quite impressive, "It dramatically reduces static and increases reception by up to 50%", and "It's like having a FIVE foot antenna on your phone". But what I particularly enjoyed were the descriptions of how the device functioned...

"It is a passive device designed to capture the stray radiation inside the body of the phone and re-direct the signal to improve the phone's performance."

"The Signal Booster captures stray static electricity around your phone and focuses it back to the signal, dramatically improving reception."

"It creates a megnetic [sic] field around the handset and draws in more signal also giving better clarity."

To most people these explanations might seem perfectly plausible. As someone who has handled radio for many years, its utter bunkum. 'Focusing stray static electricity back into the signal' makes about as much sense as 'Gathering stray exhaust fumes and channelling them back into the steering wheel'. Surely the fact that the device can be stuck anywhere on the phone, particularly inside the battery compartment, must at least have raised doubts in some people's minds. How can signals get out better if they are trapped behind the battery?

uhfantennaThere are devices which can 'focus radio signals, increasing reception quality'. These magical devices are known as aerials (or antennas to our North American cousins). However, there is already an antenna inside every cellular phone, otherwise it wouldn't receive any signal at all!

crystalphoneThere are a number of devices around which genuinely try to improve upon the performance of these in-built antennas, however the resulting product looks remarkably like... an aerial. A 'patch' that focuses stray radiation, what will they think of next?

Incidentally, having said all this, I do have a supply of Radio Atomising Crystals. Sprinkling these crystals around your phone, particularly under the key-pad and in that hole where the SIM-card fits has the effect of absorbing nearby interference channels, dispersing weak signals and leaving stronger signals to be more easily filtered by the phone's in-built diplexing separator. These crystals are guaranteed to deliver a massive increase in my wealth and are available for only GBP19.99 for a 5 gram sachet from all bad retailers and some rather gullible good ones who got taken in…
1 comment ( 1278 views )   |  0 trackbacks   |  permalink   |   ( 3 / 3151 )


<<First <Back | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | Next> Last>>