Wireless Waffle - A whole spectrum of radio related rubbish
Pirate radio to go digitalsignal strength
Saturday 23 January, 2016, 11:49 - Broadcasting, Licensed, Pirate/Clandestine, Radio Randomness, Spectrum Management
Posted by Administrator
The number of pirate radio stations on-air in London does not appear to have diminished over the past 10 or more years, despite there now being many legal ways in which stations could reach their audiences, most recently though streaming audio on-line.

brighton dab transmitterOfcom has recently proposed that many local radio stations could be accommodated on 'small scale DAB' transmitters which provide a localised service, and it is conducting a number of trials around the UK of such a service. The idea is to use low cost hardware and software to develop the DAB signals, for example using a USRP software radio, and the various software tools provided by the Open Digital Radio project. Using these, it is possible to put a (very) low power DAB station on-air for less than GBP1000 and with a suitable power amplifier (for example a 30 Watt Mitsubishi amplifier module, or how's about a 1.2 kW amplifier module), a DAB transmitter with reasonable coverage can be built for not that much more. Indeed research conducted for Ofcom suggests that a 100 Watt e.r.p. service using such technology could be provided to broadcasters for around GBP1400 per year (at a bit rate of 160 kbps which is far higher quality than most of the existing UK DAB services!)

An article in spectrum newsletter PolicyTracker entitled, 'Can DAB save us from the pirates?' (note - a subscription is required to read the full article), makes the point that the criteria which the UK has set to begin the digital switch-over of radio services (e.g. the turning off of analogue services in favour of digital) is almost upon us. The criteria is that 50% of UK listening should be on a digital platform (whether DAB, on-line, cable, satellite or other) and the latest figures show this is now up to 43%, though as Wireless Waffle has pointed out before, the proportion of digital listening appears to have stagnated. If the UK does set a date for the winding down of FM radio, one of two things could happen:
  1. pirates may move to digital platforms, in order to be found on the same dial as other stations; or
  2. pirates may take the opportunity of an emptier FM band to choose clearer frequencies, increase their power, or just increase the number of services.

The problem is that in either case there is no guarantee that the pirates would do this in a legal fashion. Pirate radio stations are not renowned for co-operating with each other so why would they pay to be on a DAB platform, rather than buy the equipment themselves and set up digital pirate stations? The answer might come in the form of the reduced number of frequencies available. In the FM band, assuming a station every 300 kHz (which is just about OK from an interference perspective), there is room for 68 stations on the dial. Taking into account the 20 or so legal stations already on-air in London (depending on what you count as London), this leaves a potential for 48 pirates. For DAB radio, which requires 1.4 MHz of spectrum to operate, there is room for just 32 transmissions in any one location. In London 4 of these frequency blocks are in use, leaving 28 'available'.

local dab radio"Ah", you say, "but each DAB multiplex can carry 10 or more stations, so really the number is 280". That is true, but this requires the pirates to club together to buy and operate the equipment and, as already stated, they aren't that good at this. Perhaps the business model they employ could change, and a smaller number of illegal transmitter operators could provide services to multiple pirate stations. Or perhaps a small number of legal transmitter operators could provide the same service. The problem here seems to be that in order to legitimise the pirates, they would have to be invited to 'come in from the cold', and Ofcom would have to have a set of licensing policies that were sufficiently lax to permit 24 stations all playing the same kind of electro-shed, play-house or garage-door music onto the dial. It is almost certain that the existing legitimate stations would object to this on the grounds that it would provide unfair competition. But the fact is that such competition already exists on the FM band, and at least if it were done under a licensed framework, there would be some control over what went on, and thus greater protection of the existing 'big boys'.

Maybe Ofcom could take a leaf out of the book of the Lebanese regulator (the TRA) who offered all unlicensed FM operators (which was a large proportion of the country's stations at the time), a licence, if they came forward and provided the necessary details of their transmitting facilities (power, frequency, antenna height and so on). Most stations did this, wishing to gain legitimacy for their service. As soon as they did, however, the TRA could begin to change frequencies, powers and so on to bring the stations in-line, through a proper legal framework that allowed them to inflict penalties if people refused.

pirate surrenderAnother model might be for Ofcom to licence small-scale DAB operators, but not to set any criteria over which stations are carried on the multiplex, other than their normal broadcasting code which is designed, for example, to stop politically motivated stations from using the airwaves in an partial way. Other than a bit of swearing here and there, most pirate stations would probably already meet most of the rules. This is not dissimilar to the way in which Ofcom licenses digital television, with multiplexes being awarded to companies who are then largely at liberty to select which programmes they include.

In either of the above cases, whether the idea that Ofcom could have an 'amnesty' for pirates, if they agreed to go onto small DAB multiplexes, or if the operation of the DAB multiplexes were made flexible enough to accommodate pirate stations being on them, there might be a sufficient increase the listening to DAB services such that the necessary 50% switch-over threshold is reached sooner rather than later. A 'win-win' situation?
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Understanding Spectrum Liberalisationsignal strength
Saturday 21 November, 2015, 12:14 - Spectrum Management
Posted by Administrator
It's been a long time since Wireless Waffle reviewed a new book. That's largely because there are very few books published on the topic of spectrum management. But Lo! a new book has fallen across our desk. 'Understanding Spectrum Liberalisation' has been written by the trio of Martin Sims and Toby Youell (both journalists with PolicyTracker, a journal of the latest radio spectrum news) and Richard Womersley (who is a spectrum consultant with global spectrum experts LS telcom), all pictured below (for some reason in a Warholesque style).

sims youell womersley

understanding spectrum liberalisationSo what about the book itself? It's a surprisingly easy read, yet tackling some relatively complex topics. The authors take the view that the various mechanisms and methods based on 'liberalisation' that have tried to get spectrum from the tight-fisted hands of the regulators, into the free-spirited commercial environment, have either partly failed, or are destined to fail, and that the 'next generation' of spectrum management, which they consider to be sharing, will be the next fad to try and achieve the same thing.

The book is split into four parts:
  • Part 1: Setting the Scene - this section discusses what liberalisation was supposed to achieve, and provides a handy and simple to understand introduction to the technical issues that the reader needs to know in order to understand the rest of the book.
  • Part 2: Liberalisation in Action - discussed how liberalisation has been applied both in different sectors (e.g. broadcasting and satellite) and in technology terms (e.g. UWB and White-space).
  • Part 3: The Limits of Liberalisation - picks out examples of where the liberalised approach to spectrum management has not, maybe, had the positive outcomes expected and explains why this might be the case.
  • Part 4: The New Agenda - looks at some of the newer techniques being introduced such as Licensed Shared Access, 5G and Li-Fi, and suggests that it will require a combination of regulatory relaxation, technical innovation and commercial pressure for truly efficient spectrum use to be yielded.
The book is written in an informative yet informal style, for example:
The Swiss auction showed that the increasing complication [of auctions] could have disastrous consequences, rather like using a bullwhip to swat a fly on a friend's face - a very risky enterprise.

The book concludes with a section on how the ITU works (or doesn't work) and a handy glossary of a wide range of technical and policy terms that regularly crop up throughout the book.

A good read for anyone involved in radio spectrum management, especially those in a regulatory capability, or who have regular interactions with regulators or some of the bigger institutions and organisations that are shaping or defining spectrum policies.
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5 Guiding Principles for WRC-15signal strength
Saturday 31 October, 2015, 12:05 - Spectrum Management
Posted by Administrator
itulogoThis week in Geneva, the next in the series of ITU World Radiocommunication Conferences (WRC) begins. One of the most contentious items on the agenda at the 2015 WRC (WRC-15) is so called Agenda Item 1.1 (AI1.1). AI1.1 will address the identification of new bands for IMT-based mobile broadband services. Over the last 3 years, (since the last WRC) the amount of effort that has been put into estimating how much spectrum is required, identifying suitable bands, and conducting compatibility analyses to determine whether the use of these new bands are viable, is immense. And yet, the results remain inconclusive.Against this backdrop, the GSMA, the industry body which represents mobile operators, is eyeing four main frequency bands to be identified for more IMT services. These include:
  • The UHF television band (470 - 694 MHz)
  • Spectrum at L-band (1350 - 1518 MHz)
  • An aeronautical radar band (2700 - 2900 MHz) and
  • The satellite C-Band (3400 - 4200 MHz)
But the bands proposed by the GSMA for IMT are not 'empty', they have incumbent users who are occupying and making economically viable use of the frequencies, although this situation changes from country to country. Some countries may be able to use some of the proposed bands but others may not. There is not a 'one size fits all' answer, and taking sweeping international decisions for whole regions of the world may not lead to the best outcome. Excessive harmonisation can lead to inefficiencies. Consider the forced allocation of spectrum to maritime services in countries such as Afghanistan, Chad, Hungary, Nepal or Paraguay which have no coastline which would leave bands unused and unusable. But national footnotes can be equally damaging if they are not well thought through.

Identifying more spectrum for IMT could even lead to bigger headaches for administrations in trying to refarm incumbent users and may not lead to a more vibrant and efficient mobile industry. Balancing the World's interests with those of each country is what the WRC and its national delegations should seek to achieve. The optimum outcome is a result which achieves both. In this respect, Wireless Waffle presents...

5 Guiding Principles for those attending WRC-15


PRINCIPLE 1: Act in the national or regional interest
  • Ensure that the services are important to the development of your country are protected.
  • Determine which of these are needed to encourage social and economic growth.
  • Understand your national priorities - more spectrum for IMT or other services such as broadcasting, transport or government services.
shakespearePRINCIPLE 2: Don't be bullied into taking decisions
  • Question the motives of those making bold statements - are they acting in your interest or just their own?
  • Remember that the long-term needs of mobile operators are at best unclear or undefined, and may well be overstated.
  • Consider that "An empty vessel makes the loudest sound" - William Shakespeare
PRINCIPLE 3: Make sure you see the bigger picture
  • Check all the facts that are presented - 81% of statistics are made-up.
  • Make sure you fully understand all sides of the argument - who stands to win and who stands to lose.
  • Understand the implications of any decisions you make - both today and longer-term.
PRINCIPLE 4: Don't assume that more IMT spectrum means more government income
  • Many mobile operators no longer 'want' new spectrum as they have not used that which they already have.
  • 4G (and 5G) spectrum are of no use in countries where data usage remains very low - in these countries 3G - in existing bands - is far more cost effective.

PRINCIPLE 5: Work with your existing mobile operators to allow them to do their best
  • Work at licensing more of the already identified IMT spectrum.
  • Check that your operators are using their spectrum efficiently. If they're not, how can they demand more?
If every administration attending the conference followed these simple yet effective principles, the outcome of the WRC should be both fair and equitable to everyone.

Whatever the outcome is, let us at Wireless Waffle end by saying 'Bon Chance mes amies'!
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Is WiFi hazardous to health?signal strength
Monday 31 August, 2015, 14:13 - Spectrum Management
Posted by Administrator
A number of people claim that they have had adverse medical and psychological responses to the presence of WiFi signals. But can WiFi actually constitute a health hazard? Wireless Waffle investigates...

Let's begin by considering the international rules which establish the limits for which exposure to radio signals is deemed to be detrimental to health as defined by the International Commission on Non-Ionising Radiation Protection (ICNIRP for short). ICNIRP has established a set of limits for the general public which are designed to stop the temperature of an average human body rising by more than 1 degree Centigrade over a roughly 24 hour period. This level of exposure is 50 times below that at which any measurable biological effects on humans have been identified.

These limits, measured in terms of the measured electrical field strength in Volts per metre, are shown below over a range of different frequencies.

icnirp general public

But what do they mean in practice and how does this help calculate whether WiFi could be dangerous. A WiFi transmitter, operating at full power (100 milliWatts, or 0.1 Watts) that is 2 metres (or 6 feet) away, produces an electrical field strength of just over 1 Volt per metre. The threshold of danger at the frequency that WiFi operates - 2450 MHz - is 61 Volts per metre and so at just 2 metres distant, the signal from a WiFi device is 61 times below the safety limit.

laws of physicsThere is another, and maybe more straightforward, way to calculate whether or not a radio transmission is likely to be dangerous. According to the laws of physics (which as everyone knows, canna be changed) 1 Watt of power (equivalent to 1 Joule per second) will raise the temperature of 1 gram (or 1 ml) of water by 1 degree Centigrade in 1 second assuming that all of the power can be focussed into the water. This is effectively how microwave ovens work: radio energy is focussed into the water in whatever is being cooked, heating it up.

If, for the sake of argument, we make the assumption that an 'average' human being weighs 50 kg (110 lb), and that it is made largely of water, it would take 50,000 Watts (or 50 kW) of energy to raise their temperature by 1 degree Centigrade in 1 second. To do the same job over the 24 hour period defined by ICNIRP would require 86,400 times less (60 x 60 x 24) meaning that if our average human absorbed around 0.6 Watts of energy for a 24 hour period, this would be deemed to be unsafe. WiFi transmitters have a maximum transmitter power (limited by law) of 0.1 Watts, which is below this limit. So even if ALL of the power transmitted by a WiFi device were absorbed by a human for 24 hours, it would still be a factor of 6 times lower than the ICNIRP safety limit.

In reality, it would be impossible to absorb all of the power from a WiFi transmitter unless that transmitter was inside the human body. Even if the antenna was placed directly on the skin, as signals from a WiFi transmitter are sent out equally in all directions at least half of the power would radiate away from the body, further reducing the impact on the human concerned.

swallow antennaIf the WiFi transmitter is 2 metres away, the signal from the WiFi antenna will have spread out so much that far less than a tenth of the original signal would wash over the body of a human, putting the exposure at a factor 60 times below the ICNIRP limit - gratifyingly the same as the level of exposure calculated using the graph above.

It is also worth noting that WiFi transmitters do not transmit constantly. At their busiest, they transmit around 50% of the time (they spend the other 50% of the time listening for incoming transmissions). Any exposure will therefore be another factor of 2 times smaller than above.

So what is the conclusion? As long as you don't swallow 6 transmitting WiFi antennas that continue to transmit on full power for a 24 hour period, any radiation from WiFi transmitters is far, far (far) below the established safety limits.
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