Wireless Waffle - A whole spectrum of radio related rubbish
Martian radio amateurs appeal spectrum allocation decisionsignal strength
Thursday 22 January, 2015, 10:48 - Amateur Radio, Broadcasting, Licensed, Radio Randomness, Spectrum Management
Posted by Administrator
Radio amateurs with designs on operating from the planet Mars are appealing against a decision by the Consultative Committee for Space Data Systems (CCSDS) to allocate the 70 cm amateur band (430 - 440 MHz +/-) for communications between satellites in orbit around the red planet and the numerous rovers that criss-cross its surface.

In a statement, released by the Mars United People for Planetary and Earth Transmissions (MUPPETs), tea-drinking general secretary Arthur Dent said,
MUPPETs have been planning a DX-pedition to Mars for some time. To discover that our officially allocated radio frequencies are already in use is just not fair. It constrains our ability to talk about radio stuff to each other and means other radio amateurs around the solar-system will be denied extra points in the forthcoming 'talking about radio stuff with other radio nuts' contest.

Responding to the accusations, Prostetnic Vogon Jeltz of the CCSDS commented,
prostetnic jeltzThe 70cm frequency band has been used for communications on and off Mars since the Viking lander first set foot on the planet back in 1976. The MUPPETs have had plenty of time to comment. The plans for frequency use on Mars have been available at the local planning office on Alpha Century for fifty of your Earth years, so they've had plenty of time to lodge any formal complaints and it's far too late to start making a fuss about it now. I'm sorry but if they can't be bothered to take an interest in local affairs that's their own regard.

Appallingly obvious references to the Hitch-Hikers Guide to the Galaxy aside, it may surprise many people to learn that there is, indeed, a frequency plan for Mars. And that there are already 5 communication satellites in orbit around the planet! For communication from the rovers on the surface to the orbiting satellites, frequencies in the range 390 to 405 MHz are used. For the link down from the orbiters to the rovers, the frequency range 435 - 450 MHz is used, which falls inside the amateur radio 70cm band.

The choice of the particular frequencies in use (on Mars) is designed to try and stop anyone deliberately causing interference from the Earth, whilst retaining ease of use on Mars (i.e. the ability to use omni-directional antennas). The various satellites orbiting Mars typically get no nearer than around 400 km from the surface and communication with rovers typically takes place when the satellites make their closest pass. The shortest distance between the Earth and Mars is typically around 60 million km. The table below shows the path-loss at 415 MHz of these distances.

Route Distance Path Loss
Satellite to Mars surface 400 km 137 dB
Earth to Mars 60,000,000 km 240 dB

So the difference in path loss is just over 100 dB. For a transmitter to cause interference from the Earth to communication on Mars, it would therefore have to have a radiated transmitter power 100 dB higher than the signals passing between the rovers and the satellites.

mars uhfA very good description of the communications with Mars is provided by Steven Gordon (from whom the diagram on the left is shamelessly plagiarised). The transmitter power used on Mars is 5 Watts (7 dBW), so in order to cause interference from Earth, a transmitter power of around 107 dBW, or 50,000,000,000 Watts (a.k.a. 50 GigaWatts) would be required. Would it be possible to generate such a signal?

Firstly, it ought to be possible to generate at least 100,000 Watts (100 kiloWatts or 50 dBW) of power at the necessary frequencies as television transmitters for the UHF band that reach this level are available. So what is then required is an antenna with a gain of 57 dB. This requires a dish with a diameter of around 150 metres. The largest dish antenna in the world is the radio telescope at Arecibo, Puerto Rico, which is 305 metres in diameter.

muppets cq dxIf a high powered television transmitter was therefore connected up to the Arecibo radio telescope antenna, it ought to be more than possible to jam the transmissions between the Mars rovers and the orbiting satellites during periods where the Earth and Mars were closely aligned. Of course this kind of power level is way beyond the normal licensing conditions of a typical radio amateur and the right conditions would occur roughly every 2 to 3 years when the Earth and Mars come closer together. Nonetheless, commenting on this finding, Arthur Dent of the MUPPETs jeered,
Safe from interference, eh? Who looks silly now then Jeltz!

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Japan's digital spew-oversignal strength
Tuesday 30 December, 2014, 12:48 - Licensed
Posted by Administrator
Japan. Country of Shinto serenity. Where cherry blossom floats down from tree-strewn parks during Hanami. Where tourists come to enjoy peaceful views of Mount Fuji.

Japan. Country of high-technology. Inventors of the pocket calculator, walkman, compact disc player and PlayStation. The first country to launch 3G mobile services.

Japan. Country of very weird pop videos. Where headless pink maids shimmy and where young girls spew out shadowy birds and multi-coloured eyeballs.

So what has all this got to do with anything radio-related. Well, if you can bear to watch it for that long before your brain turns to blancmange (or alternatively just fast forward to the relevant point), you will find in the video of PonPonPon by Kyary Pamyu Pamyu at approximately 2 minutes 30 seconds in (just after the eyeball spewing incident), a video cassette going into a TV, a TV mast growing and the screen of the TV turning snowy. This, believe it or not, is a tribute to the closure of analogue television in Japan.


Kyary Pamyu Pamyu - PONPONPON on Vimeo

Most countries have celebrated the closure of analogue television with announcements ranging from the upbeat to the sombre, montages of classic TV programmes, countdowns to zero hour, or even just snow replacing the picture mid-programme. As there are still a wide range of countries yet to complete the transition to digital TV (most of Africa, South America and Asia), Wireless Waffle challenges those countries (or their pop stars) to come up with an even weirder tribute than that of Ms Pamyu Pamyu!
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What A Waste Of (White) Space!signal strength
Friday 17 October, 2014, 09:14 - Broadcasting, Spectrum Management
Posted by Administrator
There can be no doubt that there is increasing pressure to find radio spectrum for a growing number of applications and uses. At the same time, there is a diminishing amount of spectrum that can be relatively easily re-purposed. It is against this backdrop that various organisations are seeking to find new ways to access the spectrum for new services without unduly upsetting the existing ones. One of these methods is the use of what has been termed 'white-space' spectrum.

So called white-space is comprised of the little 'off-cuts' that are left lying around after big holes have been punched into the radio spectrum by existing users. television white spaceFor example, high powered television transmitters punch great big holes into the spectrum, occupying big pieces of spectrum over very large areas. But the nature of such high powered broadcast services is that transmitters on the same frequency have to be separated by large physical distances so as to avoid neighbouring transmitters interfering with each other. At points roughly half-way between two such transmitters, neither transmitter will provide a signal that is strong enough to deliver a useful service, but the frequency can not be re-used for more broadcasting as doing so would cause interference to viewers in the coverage area of the two transmitters. But a different service (in particular one with much lower power) could be squeezed in without causing such interference. These small off-cuts can, in theory, be sewn together to form a patchwork quilt of spectrum that might just be useable.

For many years, organisations including Google and Microsoft have poured large amounts of money into finding the right thread to stitch the pieces together to make a piece of spectrum big enough to be useful. Thousands of man-hours of research have been poured into radio spectrum white-space and millions of pounds of investment into technology and standards (including Huawei's recent purchase of white-space gurus Neul) have been made, but so far, other than a few technology trials, no 'killer app' for white-space has been found.

ofcom zoocam 1Kudos then, to Ofcom and Google, who have launched 'ZooCam' in which live pictures of animals at London Zoo are being transmitted from their cages directly to somewhere or other using white-space technology and then streamed onto the internet. When Wireless Waffle popped by to share in the excitement, the Otters were asleep, the Meercats were nowhere to be seen and the Galapagos Tortoise was moving so slowly that a daily photo update would have been just as informative as a live feed.

Philip Marnick, group director of Ofcom's Spectrum Policy Group is quoted as saying:
In a world where consumers' demand for data services¹ is experiencing huge growth, it is essential we find the most efficient ways to share the airwaves. White space technology could be one way of meeting this demand.

¹For 'data services' read 'pictures of furry animals on the internet' (which are known to account for over 85% of all internet traffic).

Might we be so bold as to suggest some other uses for this high-cost, leading-edge technology:wales download
  • 'BergCam' - participate in a thrilling, spill-a-minute live stream of global warming in action as the ice caps slowly melt.
  • 'DecorCam' - in which a group of decorators position a camera somewhere different each day after painting a wall so can you watch it dry.
  • 'HerbiCam' - a live-action feed from Lords Cricket ground focussing on a few blades of grass so that you can watch them grow.
  • 'CymruCam' - share the excitement as someone in rural Wales tries to perform Windows updates using their dial-up internet connection.
Whilst programme makers, machine-to-machine communication proponents, smart-everything activists and public safety organisations the world over are screaming for access to more spectrum, it is clear that Ofcom believe that there are far more economically valuable uses for this colourful patchwork of frequencies. Is it just us, or does this new initiative appear to be a complete waste of (white) space?
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PMSE Industry Calls For More Domed Citiessignal strength
Tuesday 9 September, 2014, 04:36 - Broadcasting, Spectrum Management
Posted by Administrator
european commission logoThe European Commission has finally made a ruling on harmonising spectrum for programme making and special events (PMSE) use. PMSE includes things such as radiomicrophones and in-ear monitors that allow performers to hear themselves think whilst on a noisy stage.

You would think that the PMSE community would be cock-a-hoop about the fact that their needs had been recognised at a European level and that spectrum had been safeguarded for their specific use, but it appears that many in the industry believe it is too little. A spokesperson for the Association of Learned Engineers of Sound (Asso.LES) told Wireless Waffle:
All video and audio broadcasts use wireless devices in their production. The paltry and squalid spectrum being offered by the Commission will cause many thousands of creative, cultural and media industry workers to suffer harmful interference leading to infection and death. Add to this the many churches, schools and hotels who use wireless microphones and this ruling could cause a catastrophic failure of society. We could see plagues, widespread rioting and a failure of social cohesion resulting in a cataclysmic new world-order, not to mention the need to put up new antennas in some theatres.

No one from the Commission was available to comment, however Jörg Van Beaulieu who has a name that sounds like they could work for the Commission, was heard to comment:
Asso.LES couldn't see a gift horse if it kicked them in the face. The Commission has done its calculations and as far as we can see, the only events that will require more spectrum than we are offering are the Eurovision Song Contest and one or two occasions when sporting events occur on the same date as One Direction concerts - interruptions to which we believe the socio-economic impact would be low.

eurovision logoThe impact on the Eurovision Song Contest will come as a blow to its millions of fans both in Europe and across the world. Next year's organisers, ORF have already been in crisis discussions with the Austrian government and the European Commission and have issued this statement:
On advice of the Bundesministerium für Verkehr, Innvation und Technologie (BMVIT) we have decided to move the location of the competition next year from Vienna to Attnang-Puchheim. The town's railway marshalling yard will be flattened and a metal cage will be erected around the area to seal in the radio spectrum so it can be used for the Contest. We are sure that this will allow this critical European cultural event to go ahead without problems of interference from mobile phones or potentially dangerous inter-galactic laser beam weapons.

dome home cone

Meanwhile it is understood that the Council of Westminster are considering similarly drastic steps and that plans to demolish the majority of the West End to allow a protective metal dome to be built around London's infamous theatre district are well developed. The spokesperson for Asso.LES said that this move was welcome and rightly recognised the economic importance of radio microphone users above all other members of society.
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