Wireless Waffle - A whole spectrum of radio related rubbish
So farewell, then, analogue TVsignal strength
Monday 29 June, 2015, 17:34 - Broadcasting, Licensed, Spectrum Management
Posted by Administrator
A year ago Wireless Waffle posited the notion that we were beginning to see the end for digital terrestrial television. Just over a week ago in Geneva, the ITU celebrated the date on which, in Region 1 (Europe and the Middle East) and Iran, protection of interference for analogue television services ceases, and digital is the only protected broadcasting service. This 'celebration' presented the position from across the region where there is an extremely wide range of 'success' from countries who have already switched off analogue television, to those who are yet to launch any digital services at all. Of the 119 countries that form Region 1, only around 40 have completed switch-over - hardly a 'success' to be 'celebrated'.

digital switch over status

Director of the ITU Radiocommunication Bureau, François Rancy, explains the situation.



Let's stop fooling ourselves - digital terrestrial television (DTT) as a platform for delivery of everyday TV, is already on its last legs in many countries, or at least it has a bad case of arthritis. Like many of today's technologies, it is a fixed point in an evolving market and eventually it will be overtaken. Analogue television had its purpose, but is beginning to be phased out. Digital terrestrial television will do likewise, no matter how strongly bodies such as the EBU argue that it will remain important until 2025 and beyond.

When DTT was launched, its ability to offer dozens of television channels, and use less spectrum and less electricity made great strides forwards. But the digital world is moving ever faster and DTT is beginning to lag behind and will surely, over the next 10 years, become the lame horse of television broadcasting.

Why? Here's 5 good reasons:
  • Televisions are getting bigger and resolution is improving. When DTT launched, standard definition television was the norm. The norm now is becoming High Definition television, which requires double the bandwidth of standard definition, meaning that the DTT platform can now carry only half as many channels. With the move to Ultra High Definition, or 4K, each television transmitter will, at best, be able to carry 2 (and in the future, as video compression improves, maybe as many as 3) channels. Thus the wide range of content currently available on DTT will slowly wane such that even with a half-dozen multiplexes, the DTT platform will only carry 15 to 18 TV channels. Compare this with the hundreds that cable, satellite and even the internet will offer.
  • What's more, the availability of these alternative delivery platforms is increasing. Satellite, of course, provides near universal coverage already, and though it would be fair to say that the coverage of cable TV networks is not growing significantly, the delivery of television over IP networks (IPTV) such as BT Vision in the UK is only dependent on the availability of a broadband internet connection and most countries are investing heavily to make these as ubiquitous as possible.
  • Whilst household screens are getting bigger, not all viewing is on such big screens. Watching TV on tablets and smartphones is becoming commonplace and although DTT proponents argue that DTT receivers could be built into such devices to allow them to view their transmissions, the manufacturers of such devices appear reluctant to do so. The connection to such devices is WiFi, 3G, 4G or even 5G but not DTT.
  • Although national television broadcasters (such as the BBC, ARD or France Televisions) still account for a very high proportion of viewing, an increasing amount of this viewing is non-linear, that is to say that it is not live, but catch-up through platforms such as the BBC's iPlayer. Certain content will always remain linear due to its immediacy, such as sports events and communal television such as talent shows and soap operas where the ability of all to share a common experience is important. But the use of non-linear television for other programmes such as factual programmes or dramas to allow them to be watched at the convenience of viewers will surely become the standard.
  • Finally, the take-up of over-the-top services which do not rely on standard broadcast content but which have a catalogue of material which viewers can watch at their discretion (e.g. Netflix or Hulu) are starting to become the preferred way to relax and watch a programme. Watch what you want, when you want, without being beholden a particular broadcaster's choice of schedule of what you should watch at a particular time of day.
dtt rabbit earsProponents of DTT argue that:
  • it can continue to operate in disaster situations (but no-one will have any power to watch TV, though they may well have batteries in their radios);
  • that it is the cheapest way of delivering mass TV (this is singularly dependent on the number of viewers that use the platform - fewer viewers = higher cost per viewer);
  • that it is the only platform under national control (e.g. that it is not owned by nasty foreigners that might turn the service off, such as the normally docile Luxembourgeous that own the Astra satellites);
  • and so forth...
All these arguments do hold water, but so does a colander, for a short time.

Is it really likely that, in ten years from now, we will all still be sitting down at 10pm to watch the news over terrestrial television, or that at 10:17 after we have finished watching the ninth season of House Of Cards on Netflix, we launch our custom news channel which provides a set of news reports tailored to our interests. As E. J. Thribb would no doubt have it:
tv service goneSo. Farewell then
Digital
Terrestrial Television

Your days were
numbered

With ones and naughts

And now you
are
but naught

At one
with
your analogue
predecessor.

add comment ( 150 views )   |  0 trackbacks   |  permalink   |   ( 3 / 1262 )

Adjø FM Radiosignal strength
Tuesday 28 April, 2015, 15:58 - Broadcasting, Licensed, Spectrum Management
Posted by Administrator
norway wave goodbyeThe Norwegian Communications Authority (NKOM) recently announced that FM radio is to be closed-down in Norway by the end of 2017. The closure will begin at the north of the country, and spread southwards. National broadcaster NRK will wave goodbye to FM radio first, followed by major commercial broadcasters. Some smaller, local broadcasters, will be allowed to continue broadcasting on FM but the rest will continue only on DAB or on other digital platforms (such as television or online).

The switch-over in Norway, follows a similar logic as that used by Ofcom in the UK (as previously discussed by Wireless Waffle). There are a number of specific criteria that the Norwegian government said had to be met for the switch-off to occur:
  • NRK's digital services have to have the same coverage as their FM service, and national commercial services need to cover 90% of the country.
  • There has to be an affordable solution for listening in cars.
  • At least 50% of listeners have to be listening to digital radio every day.
The regulator claims that these targets have been met but broadcaster claim that they haven't. The Norwegian Local Radio Association claims that only 19% of listeners use DAB and that other 'digital' listening is through other platforms. They also argue that an 'all digital Norway' would mean that any tourists driving from a neighbouring country who don't have a DAB radio would be unable to receive local traffic and weather information and that this could prove dangerous. Of course, if those tourists hired a car in Norway, presumably this problem would not occur.

radio snowBroadcasters also fear that driving people away from FM onto, for example, online radio would open up a much wider world of competition from the likes of Spotify. In this respect, FM radio represents a way of limiting listener choice and reducing competition so it is perhaps no wonder that broadcasters are keen to ensure the longevity of the medium.

Norway was one of the first countries to complete the switch from analogue to digital television and is no doubt hoping that it's bold decision to close FM radio will give it similar kudos. However there were good reasons for a digital television switch-over, including the greater choice and higher quality recption that digital offered and, perhaps most importantly from the perspective of the regulator and government, the ability to free up some radio spectrum which could then be sold of to mobile operators for lots of money. Wireless Waffle estimates that the sale of the digital dividend spectrum in the auction that took place in 2013 raised around GBP75 million, which is not that much compared to the very large prices paid in other countries.

nkom trailblazingThe FM band is a different proposition though, because other than for radio broadcasting, there are no other (harmonised) uses for the band. It could be used for mobile radio (e.g. walkie talkies) but there aren't any available that operate in that frequency range. It could be used to extend the aeronautical band (which begins at 108 MHz). It could be used for some, as yet uninvented wireless service. But unless neighbouring countries (and the local FM broadcasters in Norway who continue to use the band) also switch off their transmitters, the levels of interference from these stations would be too high to make the spectrum of any real value.

So what is the real benefit of switching to digital? For Norway, perhaps, a chance to be a trailblazer. For any other country, perhaps none at all.
add comment ( 96 views )   |  0 trackbacks   |  permalink   |   ( 3 / 278 )

DAB Dead Line?signal strength
Friday 30 January, 2015, 14:48 - Broadcasting, Licensed
Posted by Administrator
ofcom logo 1Yesterday was the final day for applications to Ofcom for a new national digital radio (DAB) multiplex licence. The licence was first advertised on 1 July 2014 with a deadline for submissions of 31 October. The deadline was then extended to 29 January to, according to a516digital, "allow a prospective licence applicant sufficient time to obtain information from Arqiva, which owns many DAB transmitter sites."

Two companies have applied for the licence:
  • Listen2Digital: A joint application from Babcock Media Services and Orion Media, a commercial radio group. Babcock Media run the transmitter network for BBC World Service.
  • Sound Digital: A consortium of Arqiva, a transmission company, and commercial radio broadcasters Bauer and UTV Media GB. Arqiva is the monopoly who run the existing UK digital TV, DAB and the majority of FM transmitters.

This year will mark the 20th birthday of DAB radio. According to Ofcom's latest digital radio market report:
...over the full 12 months to June 2014, digital listening (including DAB, DTV and online) accounted for a 36.3% share of all radio listening hours.

Note that this includes listening on digital television (DTV) and online via the web. The same report also states that:
Two-thirds of digital radio listening is through a DAB set.

Taking both of these into account, the report shows that DAB accounts for just under 24% of all radio listening hours. Of the digital-only stations, only 5 have audiences of over 1 million listeners.

Station Audience Audio Quality
BBC 6 Music 1,855,000 128 kbps, stereo
BBC Radio 4 Extra 1,654,000 80 kbps, mono
Absolute 80s 1,168,000 64 kbps, mono
1Xtra from the BBC 1,099,000 128 kbps, stereo
Radio 5 live sports extra 1,039,000 64 kbps, mono

For comparison Absolute Radio reach 1 million listeners in London alone, using one FM station and not a network of dozens of national (and expensive) digital transmitters. Capital Radio, BBC Radio 2 and BBC Radio 4 all have over 2 million listeners in London. The cost per listnener, therefore, for digital services is far, far higher than for older technologies which is in part, forcing the quality of the services down (and into mono). That being said, these digital-only stations have larger audiences than any station outside London (Free Radio in Birmingham, arguably the largest station outside London, reaches around 380,000 listeners).

As is clear from the table above, many services, even the popular ones, are in mono on DAB (though in stereo on-line and on DTV) and use very low bit-rates (remember that these are encoded in mp2 not the more common and higher quality mp3). The low bit-rates and mono signals mean that many of the services sound dull and lifeless compared to their analogue, FM, competitors.

Though Ofcom paint an upbeat picture, in particular citing that digital radio listening has increased by 2.4% over a 12 month period, this hides the fact that digital's share of listening has stagnated over the past year (it was 36.8% in the second quarter of 2013 and exactly the same in the second quarter of 2014).

dab technologyThe new national digital radio licensee, once on-air, will be able to run DAB+ on their multiplex which will at least offer the use of mp4 audio encoding and hopefully, therefore, better quality audio (though it does not stop them using even lower bit-rate mono). The bigger question has to be whether there is really a business case for digital services. The cost of transmission is high, listenership is low (and not growing significantly) and the quality is poor. Which is exactly why medium-wave broadcasting is dying a death.

Ofcom has set criteria that will determine when the time is right to switch-off analogue transmitters and go fully digital. It requires that 90% of the UK has a digital signal and that 50% of listening is on digital radio. With digital radio listening stuck below 40% and no real signs of growth, it looks as if these criteria will never be met. Of course if you applied the same criteria to FM broadcasting, we would be switching off digital radio today.

dabradioUnless something fundamental changes, it's difficult to see how DAB is going to suddenly become the default method of listening to radio. Even listening via the Internet (using apps such as TuneIn) will be unlikely to become the default method of listening to radio given the simplicity and low price of FM radios (and the fact that listening on FM does not use any of your monthly mobile data allowance). The only way this could happen is if there is a ban on the sale of FM radios. It would, however, be political suicide for any regulator to enforce such a ban as both broadcasters and listeners would no doubt complain very vociferously.

So what is the future of DAB? Does it have one at all? Or is it time to set a DAB 'dead-line' and turn it off? Your views and thoughts very welcome!
2 comments ( 396 views )   |  0 trackbacks   |  permalink   |   ( 3 / 275 )

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!

add comment ( 211 views )   |  0 trackbacks   |  permalink   |   ( 2.9 / 7599 )


<<First <Back | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | Next> Last>>