High-speed mobile broadband standard LTE, the preferred 4G technology around the world, isn't good enough for critical networks and won't be up to scratch until at least 2018. That's according to the TETRA + Critical Communications Association (TCCA) which promotes the development of communications tech and has been lobbying …
Imagine firefighters inside a burning building, just a few feet/meters/metres away from each other in the smoke, unable to communicate because a base station can't be reached through metal in the walls; police, perhaps in pursuit, whose comms keep dropping off network as they pass obstructions behind which no additional towers had been funded to permit coverage, and all this (as pointed out) where direct voice communication is not designed into the service. Could that be because it isn't billable? Hmm.
Nor do such devices have sufficient power to provide direct comms at the ranges ordinary analog transceivers do, the batteries being only large enough to reach a base station expected to be pretty much line-of-sight to the user and small enough to fit inside an almost matchbook-size enclosure.
Flames, because there there's smoke...
But at least digital isn't as susceptible to interference.
A 500khz AM pirate radio ship off East Anglia can apparently knock out every vital communication system from lifeboats in Cornwall to the RAF in Scotland - or at least that's what's claimed when they are shutting them down,
Because 500kHz is the international distress freq
The pirates on 500kHz were shut down because that was the international distress frequency:
It's not hard to disrupt communications when you are broadcasting on the very frequency in use.
Firstly digital radio is susecptible to interference, it just manifests itself differently, with 'analogue' radio the signal hangs in there gradually becoming less intelligible as the interference increases, 'digital' radio either works or not, it doesn't have the gradual degradation that 'analogue' radio has so has an on/off availability and takes time to recover synchronisation which 'analogue' radio doesn't suffer so serverly with. I would also point out that all radio is analogue and the the analogue/digital bit refers to the format of the information transmitted through the radio.
Some of the other points in the article are also quite interesting particularly the local communication, not something I have really considered but knowing how poor in-building cellular coverage is generally the local communication requirement is a significant issue. How quickly this will get fixed will be interesting as manufacturers help develop standards with a sideline in gaining competitive advantage, it could take a while before the gaps are plugged and equipment is commercially available.
Anyway the only reason why everyone talks about LTE being public safety is a result of the US adopting LTE as the only technology for public safety. This whole topic became a hot potato after 9/11 when the authorities realised how hampered efforts to save people's lives were by the lack of integrated communications between different rescue services.
The US is resistant to TETRA because it's a. not an American system, and b. requires central management. Point (b) is more significant, because there can be significant fragmentation in US agencies, with Federal, State, City and County funded law enforcement (to which you can add Transit and Highway Patrols in some states). Just deciding who should be responsible for operating the network would be a major political headache.
But I think the problem is that they're trying to compare apples and oranges. TETRA is a voice network, and while voice is still by far and away the major requirement for emergency respnonders, there's been an increasing demand for data services too (nothing fancy: just basic mail and web; all those live telemedicine demos that the equipment companies wheel out with the emergency room doctor hanging on the other end of the screen are largely fantasy)
TETRA can do data, but not fast data, and it comes at a high cost relative to other solutions. LTE and 3G are useful for the data part of the solution, but not for the strategic voice comms. Mobile can do voice, but not at anything near the level of reliability or management you need for incident communications.
Basically, it's better to have two good tools that can each do one job well, rather than one tool that does both badly.
Digression continued: Is 500kHz usable on a typical MW radio?
500kHz itself isn't officially in what would frequently be called the AM broadcast band (or Medium Wave), or is it?
I knew of UK-targeted pirates on 531 and 558 kHz, probably others round there I've forgotten, so I *assumed* the reference to 500 meant "around 500" rather than exactly 500.
-- a result of the US adopting LTE as the only technology for public safety --
Say "US politicians and their money-grubbing technologically illiterate capitalist friends adopting ..."
Public safety professionals who know what is needed on the scene? Not so much. Hardly any, in fact.
There are enough "digital" communication system problems already. See for example http://blog.tcomeng.com/index.php/2009/digital-trunked-radio-system-failures/
Most of those problems are the result of skinflint politicians and strapped-for-cash taxpayers being unable or unwilling to fund underlying infrastructure. Some of it is NIMBY on antennas. Some of it is the infrastructure. Some of it is portables' batteries lasting half an hour (a small exaggeration). And some of it is regulators persuaded to make channels so narrow only compressed signals will fit.
Analog FM is actually preferred by folks who enter burning buildings.
LTE will probably be ten times worse. IMO
I'm almost convinced that TETRA only works as well as it does because it uses every radio band going - I don't know exactly what it is designed to operate on (I would Google if I was more interested) but I'm positive from anecdotal evidence that TETRA operates along the lines of "Give me more radio spectrum, I'm hungry, more spectrum" I first became aware of TETRA when the voice of an ambulance driver started coming out of the speakers of the TV, HiFi and Computer all at once - it's actually pretty creepy until you realise what is going on. (and yes for the pedants among you - I am aware that it's caused by poor shielding on the speakers - we are talking pre LCD days) in any case these days there are plenty of complaints from people whose Freeview goes off when TETRA is being used in the vicinity. More info here: http://www.your-book.co.uk/tetra.htm
TETRA band usage
Ummm, no. TETRA, and other PMR (Professional Mobile Radio) systems use a very specifically defined set of frequency bands, and once a system has been provisioned, that's it. The radios are set up to operate in those frequencies and CANNOT operate elsewhere. The most advanced radios in that market can operate on 3 bands: 150MHz, 460MHz, and 800MHz (US - I believe the bands in the UK are similar but not identical).
The reason you hear the traffic coming out of J. Random Electronics is that the radios are very powerful - the hand-helds are 5 watts, the mobiles are 50 watts. Most consumer electronics are crap and do not adequately protect themselves from strong signals in the area, which is why any powerful signal nearby (PMR, Ham, CB) will cause them to freq out (pun intentional).
Tetra, being digital...
As I understand it, TETRA is a digital system, therefore any interference WON'T be voices coming out of poorly-shielded HiFi (that'd be some predecessor analogue system). I have a vague recollection that the radio-interface for TETRA was spawned off of early GSM specs, so you'd expect any interference to audio equipment to be in the form of buzzes and beeps not-dissimilar from GSM....
" I'm positive from anecdotal evidence"
You should have tried well-informed evidence instead. The website you mention seems reasonably well informed, and even points out the difference between RFI from traditional analogue signals and from digital signals.
TETRA works somewhere around 390-395MHz (with 10MHz/channel gaps for uplink/downlink), within the EU.
Besides, given that it's a digital, trunked radio technology, you shouldn't be able to hear anything in terms of audio as interference. (Same deal with GSM, modulo trunking; and UMTS/W-CDMA has its own high-pitched whine - although you can't hear it, unless you tune into a UMTS frequency using an SDR).
Re: TETRA band usage
Mobiles are usually up to 10 watts. Handhelds are up to 2 or so. I work for Sepura.
Re: TETRA band usage
Given that in the EU even consumer electronics must meet RF immunity standards, that is really quite odd. Are you SURE "they" aren't irradiating your brains? (Does that show up first in government?)
Set to fail completely
IMHO LTE doesn't have a fallback mode. If as has been pointed out, the backhaul fails and the whole thing falls over. TETRA in theory has a peer-peer mode (but never implimented by Airwave) and is due to be replaced by something even more flaky.
Most of the required communication will be between "Control" and "Emergency Service Asset/Personnel" and it's much quicker to talk to them. They don't need to be able to send much data, just get whatever asset to such and such location to assist with some incident.
Some of the Emergency services (think blue lights) regret having lost control over their own communications infrastructure and resiliance. TETRA was supposed to have added interoperability into the system but it never actually did, they exist as seperate subnets on the system. LTE could be an even less useful system offering less than adequate system coverage.
I'm not saying much. Mine is one of those phone no's that won't be turned off - they'd call us out to patch up their loss of comms.
Coat. There's a 2m handheld in the pocket.
if they knew what they were doing they wouldn't need to communicate all the time
my friends rarely communicate with me because they can guess what i am doing
my friends rarely communicate with me because they can guess what i am doing
Is it posting random shite on the internet ?
An operator wanting to support voice on 4G has a few options, the "drop to 3G" option is the quickest to implement.
LTE is still pretty new, so alternative approaches will be implemented eventually. Sending voice over IP has the ability to at least improve audio quality.
Tetra was well tested in UK
TETRA was very, very well tested in the UK, in fact virtually every road and track in the country was driven down to check signal strength, there were cases where mini dune buggies were flown by helicopter onto the more remote scottish islands. On top of that there were mobile backpacks to check housing estates and shopping locations etc in inner cities. Farmers, Shotguns and 'get off my land' happened a few times too during testing every square mile of the UK.
So while Tetra may not be good for data the audio quality is as good as GSM and coverage is way, way better than any of the GSM networks in the UK (probably the world). LTE coverage in the UK will be pants for many years to come, and probably still will be in 2018 in comparison.
I don't expect a UK replacement for TETRA till at least 2020, in fact the most likely route to TETRA/LTE would be to replace the current network with one of the 'old' 4G LTE networks (well old in 2020+) only upgraded to REL 12 and with it's coverage extended too. If it's done this way there won't be any sharing of next-gen TETRA with the proles.
There's a spec for high speed tetra data. I say high speed... It's not 4G, but then again it'll probably get through a wall, freq band permitting.
"Most emergency services use TETRA, or one of its predecessors" - yea, that's the problem
Comparing TETRA with LTE is apples and oranges or more precisely - comparing blue-light emergency service with a global consumer comms solution.
TETRA has a horrible evolution history both as a standard and as a service. It should not be the model for standard setting in any forum. For years TETRA UK fought against TETRA France (TETRA Pol), while Motorola in the US with its Agenda 25 service tried to monopolize US Blue-light services. After decades of infighting and the lives of many firefighters, ambulance and police endangered by this politically fraught standard (not to mention huge cost overruns), TETRA is finally delivering some useful services (Motorola is betting on both TETRA and Agenda 25). 3GPP on the other hand has chugged along and rolled out standards at a steady pace. It should not be swayed by anything coming from the TETRA camp. The bullhorn is because that is where TETRA came from.
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