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Trains, Boats, Planes, God, Kylie Minogue, and more Planes
2007-09-22 08:08:00
Years ago I used to know the frequency¹ for the downlink of Capital Radio in London's 'Flying Eye', the aircraft used to scout about for travel blackspots. It was a useful frequency to have as there was no better place to get the latest travel news. I also remembered that there was an uplink from the studio on around 455 MHz too.One quiet afternoon I thought I'd have a tune around to see whether or not the old up and downlink frequencies were still active. Listening around 467 MHz, there seemed to be no sign of the downlink (though being around 25 miles outside of central London and with a downlink power of less than a Watt, this wasn't perhaps, that surprising). The uplink, however, is still active on 455.075 MHz. What was rather odd, however, was to hear dozens of Imam's calling their congregation to prayer on frequencies just below this at around 454.5 MHz. Was this some freak long-distance propagation carrying signals from arabic speaking count...
More About: Kylie Minogue , Boats , Trains , Kylie , Planes

Wireless Wobbly
2007-09-20 11:10:00
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.When 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 titleIf that's not enough, the description of his site says:Wireless waffle is a specialist radio site ... ...
More About: Wireless

Spot the HF Antenna
2007-09-11 15:07:00
OK, so it's not as snappy as 'spot the ball' but the idea is the same. Look at the picture below and see if you can spot the HF antenna. Clue: Look for the 'x's.A bit silly perhaps, but the thing of interest is that this building is the Admiralty Building as seen from Horseguards Parade in Central London and that those really are HF antennas (see the expanded picture below). Whilst it's easy to dismiss good old fashioned short wave communications as outdated, especially in the age of satellites and mobile phones, it's very satisfying to see that those who need some assuredness of communication think it worthwhile to defile historic buildings in the centre of an area of tranquility and beauty with whopping great big, ugly HF aerials.It doesn't necessarily follow, but it might be fair to presume that the people who did this (let's call them the 'military' for want of a better word) will be keen to ensure continued, low-interfere...
More About: Spot , Antenna

How to listen to UFOs
2007-08-31 11:48:00
Since the late 1990's rumours have abounded that it was possible to hack into American military satellites and use them for wide area communication. The satellites, originally the 'FleetSatCom' newtork (often abbreviated to FLTSATCOM) use basic FM modulation and have uplinks in the area of 300 MHz and downlinks in the area of 260 MHz. Stories went that tuning in to the downlinks it was possible to hear illegal pirates, from Brazil in particular, who were usurping these US military satellites to use for wide-area communications. It was also said that 'Smile 93.9 FM' (rumoured to be from Manila) was using one of the channels as a studio to transmitter link and could often be heard on the downlink frequency of 269.950 MHz.This seemed a little far fetched and unbelievable: How could one of the world's most super-sophisticated armed forces allow their multi-million dollar military hardware be taken control of by such an unsophisticated enemy armed with no...
More About: Pirate , Listen , Clandestine , Ufos

Capture Area - Take 1
2007-07-31 16:26:00
Anyone who really knows their stuff when it comes to radio propagation and stuff like that will tell you that any aerial (or an antenna for that matter) has a certain capture area. Its capture area defines, in effect, how much of the signal that is in the ether it can capture and thus present to an attached receiver. The bigger the aerial, the greater its capture area and the stronger the received signal. Obvious really.For some antennas, such as satellite dishes, the capture area is relatively obvious. A satellite dish which covers an area of 1 square metre has a capture area of roughly 1 square metre (ignoring edge effects). For linear aerials, however, the capture area is less obvious. Which has the greatest gain - a 4 element yagi or a 4 wavelength long colinear? Not so easy is it. However, it seemed to me that there ought to be a simple rule-of-thumb which allowed simple comparison between antennas. I therefore hypothesise that:* The gain of a linear aerial ought to be s...
More About: Capture , Area

Oooh, Baby Baby!
2007-06-18 16:31:00
In a previous entry, I discussed the massive security hole presented to their neighbours like a baboon's bottom, by those still using analogue cordless telephones, as they can be easily received with cheap radio scanners, over quite large distances. However this is as nothing compared to the relatively common practise of bugging one's own house; otherwise known as 'installing a baby monitor'. The majority of these low power (10 mW) transmitters operate using basic analogue FM modulation on frequencies between 49.820 and 49.980 MHz (a low-power, short-range, licence-exempt band in the UK). These devices, like their cordless phone counterparts, can be picked up over several hundred metres, if not further. And whilst the owners often switch off the receivers when their child isn't in range of the monitor, they rarely switch off the transmitter meaning that it's often possible to tune-in to your neighbours going ons all day long (though such activities ...
More About: Baby

48 metre Bandana
2007-05-16 15:14:00
There's a term used in the UK which takes its roots from an overgarment worn by many to keep dry on particularly squally days. The aforementioned garment is an 'Anorak', which is a kind of winter jacket which, no matter what you wear it with, will never look fashionable (the possible exception being Paddington Bear who at least looked cute, though it could be argued that Paddington wore a Duffle Coat rather than an Anorak if we're being pernickety). The Anorak is generally rather unpopular, being an ugly but practical kind of a coat; but due to the fact that it is a rather warm item to wear, those who spend a lot of time outdoors but do no exercise and thus are in need of something to stop them freezing whilst standing around have taken the Anorak to heart as their overcoat of choice. But who, I hear you ask, would want to spend all day standing around doing nothing especially if it was cold or raining? A very good question! The Anorak became (and to some ext...
More About: Pirate , Metre , Banda

Wire-More LAN (Part IV)
2007-04-27 15:51:00
Another train journey, another chance to run good ole Netstumbler and do a survey of channel occupancy for 2.4 GHz (that's 802.11b, g and n and not 802.11a in case you were wondering) to see whether my previous analysis of which are the best WiFi channels to use still holds.For those who haven't (or can't be bothered to) read my previous article, I came to the conclusion that if you lived in an area of high WiFi penetration, channel 1 was the best channel to use as it was the least likely to suffer interference from other Wire less LAN users. In areas where there was unlikely to be any other wireless LAN activity, channel 11 (or 12, or 13) would be best, as these are the most free from other interferers (e.g. the military, microwave ovens, radio amateurs and so forth).So what are the results of this train journey? I've plotted them above. I've shown the outbound journey separate from my return journey. As it's highly possible that if I picked up a LAN i...
More About: Part , More

A Noisy Transatlantic Oyster
2007-04-23 16:16:00
In a previous post I discussed the fact that the powers that be in Europe had taken a decision with respect to low power, licence exempt radio equipment that meant that the 'heart' of the 70 centimetres amateur radio band had been ripped out due to a mountain of noisy interference produced by wireless doorbells, weather stations and so on.But that's not the end of the story, or so it would seem. Not content with annoying noisy oysters by wiping out 433.500 MHz (the EU 70cms FM calling channel) as well as the repeater input and output frequencies in the UK (as well as Finland, Slovenia and certain other countries) from 433.000 - 433.375 paired with 434.600 to 434.975, I recently discovered that they have also managed to pull the wool over our eyes with respect to another travesty against 70 cms radio amateurs. But this time, it's not those of us in Europe that are suffering, it is amateurs in the USA and in particular, in areas where European tourists congregate....
More About: Amateur Radio , Trans , Anti , Atlantic , Tran

How accurate are computer coverage predictions?
2007-04-17 16:58:00
These days, a lot of radio planning (broadcasting and cellular for example) relies heavily on the ability to use computers to predict coverage from a site. So I thought it would prove an interesting exercise to do some coverage predictions from my own amateur station and compare them with actual reception. It's probably worth adding that using a single receive antenna in a fixed location for comparison isn't necessarily fair - reflections could mean that there are strong nulls in a particular direction, though with the antenna mounted nice and high and above most nearby obstacles these effects are probably minimised.The prediction tool I used is RadioMobile, which is a freeware tool for radio amateurs and does pretty good VHF and UHF predictions as well as path profiles which can be used to hazard a guess at microwave links too. I decided to use the 70 centimetre amateur band as my test case and use the various repeaters I can hear as the benchmark. Most repeaters have ...
More About: Computer , Comp , Predictions , Rage , Cover

iTrip iNterference
2007-02-21 04:31:02
So you've bought your iTrip , micro FM transmitter, AirPlay, PodFreq or similar and plugged it into your iPod or PSP and managed to get it to transmit somewhere in the FM band. You even manage to find a clear FM frequency at home where you don't suffer interference from local radio transmitters (or your neighbours' iTrips!) Then you decide to go on a road trip and you take it into your car. Driving around the UK you soon find that the FM frequency that was clear at home is home to a neighbouring radio station and that as you drive along, reception of your iTrip is blighted by interference from local radio stations (how dare they!)What you need is a frequency somewhere in the FM band that is clear of licensed stations so that you can drive up and down the country without ever suffering interference or having to re-tune your iTrip. Dream on! There are only nine frequencies in the mainland UK which are not used by high powered local (or national) radio stations, these be...
More About: Inter , Itri , Ferenc , Interference

An Updated Version of the ZS6BKW Multiband Dipole
2007-02-11 04:25:02
So having whet your appetite with details of the ZS6BKW multi-band antenna, I've finally finished my own installation of the antenna and will share my findings with you. The good thing about this particular multi-band antenna is that it covers the majority of the HF amateur bands that I'm interested in, particularly 80m, 40m, 17m and 12m, as well as 20m. 10m coverage (and 80m for that matter) is a bit poor.The original design shows two wires of 14.2 metres fed with 11.1m of 300 Ohm twin-feeder. However having scouted around the internet, I discovered that there is a revised version using 450 Ohm ladder-line feeder (which seems to be as easily if not more easily available than the 300 Ohm stuff). It has the main advantage that it's marginally smaller which, given the rather small size of my back garden meant that it should just squeeze into the available space. One element of the original design that seems odd is the suggestion that no balun is needed at connection b...
More About: Band , Multi , Update , Sion , Pole

Wiki-d Pirate Site
2006-12-23 03:48:02
Was doing a bit of 'Googling', as you do, and came across an attempt by Anthony Page (of Radio Nemesis fame), to start a pirate radio Wiki .The page at freeradio.wiki-site.com mostly recounts the history of many of the pirate radio stations who graced the airwaves in the South Yorkshire and Derbyshire areas in the 1980's and 1990's; but it's also not a bad attempt to try and define some of the terms such as 'stereo' and 'link' so it get's an 'A' for effort, though at present probably no more than about a 'C' for achievement. With help from people such as you (yes, you) then maybe it could get a lot better. There's also a good description of a number of the pirate stations that used to broadcast in that area including: * Rebel Radio 105.2 (with Scooter Jones) * Ocean FM 106.3 from Rotherham (which is nowhere near the sea!) * WLNG 104.9 of Scunthorpe (who get a mention here) * Radio Britannia from Barnsley with ...
More About: Pirate , Site , Rate , Irate

Skywave Striptease
2006-12-20 03:46:07
Here at Wireless Waffle, we have spent the last month tracking down the perfect Christmas present for the radio enthusiast. Something classy and stylish that would enhance even the lamest of radio installations and make them sparkle and gleam. Something that will make everyone look at your aerial with amazement, requiring double and triple takes in order to believe the awesomeness (yes, that is a word!) of your antenna.And after literally minutes of research, we have discovered the 'Antenna Doll' - an authentic plastic pole dancer who is already stripped to her undies and is ready and willing to spruce up the season with her sexy moves. According to the packaging, special features include:* Fits on Standard Car Antennas* Heavy Duty Plastic* Moves with Motion of VehicleWhat's more, this must-have gift for the wireless wayfarer comes in several different variants guaranteed to make your pole stand to attention including the ravishing dark haired damsel 'Raven...
More About: Trip , Strip , Ease , Wave , Teas

Antenna Plural Bugbear
2006-11-14 21:54:17
Aaaaargh... Why is it that so many people insist on using the wrong plural for antenna? It's soooo annoying. There are two plurals of the word 'antenna':Antenna s - a technical term meaning more than one antenna or aerialAntennae - a zoological term meaning more than one antenna of an insect natureDon't confuse the two! I often see articles where people say that they have erected 'antennae' at home. Really? They've spent an afternoon mounting insect feelers on their house? Interestingly the entomological community rarely make the same mistake. It's not common for them to claim to have found a new kind of bug with aerials growing from its head!If you don't believe me, take a look at the screen-shot above taken from answers.com which clearly defines the two different plurals and their different meetings.To avoid all confusion, try using 'aerial' to mean a radio antenna, that way there's no confusion as the plural is quite ob...
More About: Plural , Al B , Ural , Bear

A noisy noise annoys a noisy oyster
2006-11-09 21:48:02
When I'm at home, my receiver is usually switched on monitoring one frequency or another, commonly 145.500 or the local 70 cm repeater. Yesterday I was doing the latter and it soon became apparent that there was some active tropogation around. In addition to my local repeater, other amateur repeaters from typically 300km distant were fading in and out with regularity. What I noticed, however, was that the audio for all these distant repeaters (and, mysteriously, the local ones too) was accompanied by a rather annoying crackle.My first thought was that the coax cable feeding the antenna must have a dry joint in it somewhere and the gentle wind blowing it back and forth was causing an intermittent connection. But I checked reception of repeaters on 2 metres and these were clear of the crackling noise which indicated that the effect was real, and was being received right across the 430-440 MHz band. The next port of call was the various items of household equipment that could c...
More About: Noise , Anno

London Airport Frequencies
2006-11-02 21:42:02
As if this site isn't littered with enough useless information already, here's a load more. Having travelled to and from the various London airports on a number of occasions, I thought it would be nice to have an up-to-date list of the various air traffic control frequencies used at them (so that whilst en-route to the airport or waiting in the lounge I could tune-in to see exactly how delayed my flight is). Using the all-knowing Google proved rather confusing as lots and lots of differing lists appeared, so I decided to compile the lists together and then take a listen to see which channels were clearly active and which were now obsolete.The results are posted below and only those frequencies heard to be active during random monitoring sessions in October 2006 are listed. The frequencies shown in italics were listed on a number of sites (sufficient to believe that they are for real) but monitoring showed that there was no activity, so they're listed just in case! ...
More About: Airport , Port , Ondo

ITU Frequency Allocation Tables
2006-10-20 10:21:03
Something that's always been a nuisance is that the International Telecommunications Union (ITU) has made it's frequency allocation tables (i.e. the table which shows which frequencies are allocated to which services in which countries) something that has to be paid for if you want a full copy. The 'ITU Radio Regulations' is a large set of documents that describe radio usage and the heart of it is a set of 3 regional tables that allocate frequencies to specific uses and currently costs 252 Swiss Francs (about GBP107 at today's exchange rate). If you just want to know whether fixed links have an allocation at 8 GHz in France, that's rather a lot to pay.I was delighted, therefore, to discover that the Region 1 (Europe, Africa, the Middle East and Asiatic Russia) and Region 3 (Asia and Australasia) information can now be access for free on the web-site of telecommunications consultants 'InterConnect Communications'. Their Electronic Frequency ...
More About: Cat , Tables , Location , Tabl , Loca

Wire-More LAN (Part III)
2006-10-20 10:21:03
Looking back at the analysis of WiFi antenna performance I conducted recently, it struck me that to maximise the performance of a Wire less LAN there are two factors at play. One is the strength of the signal, clearly enhanced by the higher gain antenna. The other is the amount of background noise. It is not for nothing that the quality of the link from the wireless access point to the computers is measured in terms of 'signal to noise'. Wireless LANs (at least variants 802.11b and 802.11g) operate in the frequency range 2400 - 2483.5 MHz (this extends to 2495 MHz in Japan only, and not all of the band is available in all countries, noteably France which does not have access to frequencies below 2450 MHz), known as the 2.4 GHz band. This band is not exclusively set aside for use by WiFi equipment, but is in fact shared with many different users. The transmitters of each of these users will increase the overall background noise in the band and if strong enough, will ca...
More About: Part , More

Sporadic-al-E
2006-10-20 10:21:03
Driving along the M4 motorway yesterday evening, I was trying to listen to the news on BBC Radio 4. As usual, the RDS Alternative Frequency (AF) service was doing a good job at re-tuning my radio to a new transmitter once I disappeared out of the coverage of the one I was tuned to. Not long into my journey I noticed that my radio was struggling to find a clear frequency and that even the best it could find was swamped by interference. Having experienced this before, I wondered whether there might be Spor adic-E propagation around. A quick tune to the low end of the FM band confirmed there was.Sporadic-E propagation exists when the sun's radiation ionises layers of gas in the 'E'-layers of the ionosphere. These ionised layers refract radio signals, often up to high VHF frequencies, enabling signals from far afield to be easily received. Usually such ionisation forms in relatively small 'clouds' such that the signals which are refracted in any one area mi...

Mystery No. 29612 - Solved!
2006-10-20 10:21:03
Tuning around the amateur bands during recent sporadic-E openings, I regularly stumbled across voice traffic in a slavic language on 29612.0 kHz USB (upper side band). The format of the traffic was clearly not amateur, and given this, and the fact that it is right in the middle of the relatively active 10 metre FM section of the band but was not FM made me wonder what it might be. Enjoying a mystery I managed to make a short recording of some of the traffic [304kB windows media file] at around 14:15 GMT on 17 July 2006.Not speaking whatever language it is I posted a message on the Utility DXers Forum message board. What a great set of individuals! Within half a day I'd received a response that the most likely culprit of the signal I heard was the Russian Air Defence (the Protivovozdushnoy Oborony or PVO) who track all aircraft through their airspace giving a continuous read-out (quite literally!) of the sector quadrant and the corresponding coordinates of each aircraft.It tur...
More About: Mystery , Myst

2dBi or 2dBd, that is the question
2006-10-20 10:21:03
Something that I found confusing when first learning about the 'black art' of radio is that there seemed to be some argument about the gain figures quoted for antennas. Take a look at this example: The gain figure quoted for this Comet GP-3 dual-band 144/432 MHz antenna is shown as 4.5 and 7.2 dB respectively for the two bands. But any 11th grade physics student will tell you that dB or 'deciBel' is just a ratio between two numbers. So a figure of 4.5 dB is meaningless unless it is 4.5 dB with respect to some reference or other - and this is where the confusion arises...To circumvent this confusion, an additional letter or letters is usually added after the dB to indicate what the reference point is. So 'dBuV' is 'dB relative to 1 microVolt (uV)', and 'dBm' is 'dB relative to 1 milliWatt (m)' and 'dBW' is 'dB relative to 1 Watt'. So what is the reference point for our antenna gain, and why is there p...
More About: Question , Hat , Quest , That

All-band Antennas for Skinflints
2006-10-20 10:21:03
With apologies to anyone who may be offended: radio amateurs tend to be a tight-fisted bunch. Often this attitude perpetrates from having other priorities in life (family, holidays, beer etc); sometimes it stems from wishing to prove the age-old maxim 'any fool can do for a pound, what a good engineer can do for a penny'; sometimes it is as a result of having grown up scrimping and saving for the latest hi-spec transistor (which are now available for 5 pence from RadioShack); and sometimes, to be fair, it's just because they don't have much money.However, it's equally fair to say that radio amateurs tend to be very ingenious. They have often been at the forefront of the development of new radio technologies, and even today, when technology has massively overtaken the capability of most amateurs, they still find clever solutions to a range of radio problems. One problem which amateurs have been finding solutions to for years, is the problem of installing a...
More About: Band , Skin , Antenna

The Digital Dividend: How does that work then?
2006-10-20 10:21:03
As anyone who has bought a new television in the UK in the past year or so will know, it is the Government's intention to close down all analogue TV transmitters by the end of the year 2012. It's main reason for doing this is to release some of the channels used for broadcasting so that they can be used for 'new users' (presumably ones that they see as being more lucrative!)The plan is for a rolling conversion of all television transmitters in the country to change from analogue to digital. In doing this, of the four existing analogue frequencies used to carry BBC1, BBC2, ITV1 and Channel 4, only three of these will continue to be used - one will be freed for the aforementioned mysterious new users. The three frequencies still in use will carry three digital mulitplexes ensuring national provision of all BBC, ITV, Channel 4 services including CBBC, BBC News 24, ITV2, ITV3, E4 and so on, so there's no need to worry about people losing their favourite progra...
More About: Work , Hat , Digital , Digi , That

Tropogation
2006-10-20 10:21:03
Most day-to-day 'DX' propagation experienced by radio users at VHF and UHF frequencies relies on some interaction between their signal and the troposphere (the troposphere is the lower layers of the atmosphere extending up to about 10 miles above sea level). For anyone wanting to find out more about the different modes of tropospheric propagation, there is an excellent article by William Hepburn that describes them all. The same web-site also gives 5 day predictions as to the possible level of tropospheric propagation that can be expected too - very interesting.Having recently installed a simple VHF antenna on my house, I thought I'd do the usual thing and tune around the various amateur repeaters to see what kind of coverage I was achieving. According to predictions that I had done, I expected to be able to just about receive transmitters from a maximum of 80 miles away (my location is nothing special). I was a bit surprised to discover that I could regularly hear...