Britain dusts off idle spectrum for rail and emergency comms Britain's telecoms regulator wants to repurpose unused mobile spectrum for the upcoming Emergency Services Network (ESN) and to overhaul communications in the railway sector. Ofcom proposes to make the 1900 MHz band (covering 1900-1920 MHz) available for the UK's rail network and the emergency services, maximizing the use of …
Why we need spectral segmentation -
As a radio guy I have t say there are very good reasons we cannot have a one size suits all digital radio network.
Firstly that the ranges needed and bandwidth needs of different systems are very different, so the power levels at the transmission end of things, (100km for air traffic control - 50W at VHF, WIFI within a house, 0.1 watt - mobile phones, less than km to the base station, less than 1 watt.
Then there is the problem of co-siting a receiver trying to scrape up the odd picowattt from afar cannot do so near a transmitter on an adjacent frequency without filters - of the analogue kind, to give many tens of dB of rejection. In a small system you can time multiplex, but as the area gets bigger keeping it in sync gets harder and the time lost to change-over increases...
Then there is physics - different frequencies need different size antennas, and that lends itself to different transmitters and receivers.
Its all tricky and horses for courses. If you have mains supplies you could just use cables.
M,
You're making quite a big category error. Frequency band sits at a different network layer to VPNs. I can completely avoid having to find solutions to the security, congestion and coverage issues raised by using a shared network by simply having my own spectrum. Why abandon dedicated spectrum and move to a shared resource to make network engineering harder? Remember we're talking about critical national infrastructure here, getting it wrong makes bad things happen.
I think I partially see your point - keep it simple, which should (in theory) make it more robust. But by that argument we'd use morse code on a telegraph, or semaphore flags, because they're even simpler and therefore theoretically more robust solutions. But…
Digital comms aren't exactly new at this point - they are robust, and easily replaceable. And they have a significant advantage in bandwidth - so that spectrum can be shared with more users, rather than only being available to a lucky few.
Yes, yes and no.
Reliable? Robust? Then why-ever would El Reg exist?
Do you NOT ever read the articles how the simplest things are always borked because of over-complicated, useless, money grabs? Or just how vulnerable digital everything is? Like ever? You and the other sweet summer child downvotes.
Robust? Reliable? Easily replaceable? Don't blow smoke up my 30 years in the business, ass.
They’ve not been 30 successful years, have they?
Tell the people who have been running the uk PSTN and mobile networks digitally since 1990 (I still have a paperweight on my desk celebrating the closure of the last analogue trunk exchange) that they aren’t reliable or resilient. Network uptime, 35 years and counting.
How do you propose that images, location data, text information, video and voice all be sent in an entirely analogue domain? How would you protect and encrypt that information in an entirely analogue domain? How much will you pay for devices to be developed and built that can do all this in an entirely analogue fashion?
Think better.
The rail needs to be able to eliminate signal cabling if they can't run it underground in ways that thieves won't be able to get at it. I always fume when morning trains are sat at stations due to cable theft overnight. That has to be an issue for companies that want employees to sit in the company office to do work once again that the employees had been doing at home with no need to add a train into the equation.
"Generally 25,000v is a strong disincentive to stealing the wire, at least for re-offenders"
The ones going after live 25kv lines get Darwined out. The problem is the signalling wires that are sometimes laid across the ground or people break into the wiring huts and just whack off what they can find inside. If there are no signals, the trains aren't safe to dispatch, points can't be changed, etc.
Many - twenty? - years ago I went to a honours year dissertation presentation by a student who work for Railtrack. He had developed a GSM fallback which would allow signals to continue operating if cables failed or were stolen. As I recall he had actually been able to test it on a suburban line in Glasgow.
A lot of GPUs have clocks which go this high.
Now it isn't usually a problem but at least with my old card(s) it was possible for them to get affected by mobile phones.
Put the phone near the open case and ring it or even receive a text and the GPU would crash after about a minute.
With sensible case design it isn't an issue though did about someone's AntMiner jamming the phone network.
Are we going to need a special 'Update; that stops the card using forbidden frequencies?
This is interference, and that is not so uncommon as you would believe. Almost all higher-frequency electronic equipment emits and is receptible to some electromagnetic radiation.
EMC conformity can be a pain...
In practice, it makes sense not to put different electronic (transmission) equipment close to eachother, especially when you are not providing decent shielding, hence the "open case".
The agency reveals that BT/EE had originally planned to provide ESN gateways using 1899.9-1909.9 MHz spectrum. However, Ofcom decided this was not optimal because the frequencies had already been harmonized across Europe for FRMCS.
whilst it makes sense to align with others, what if they got FRMCS wrong in Europe?
being able to do things differently is often a strength
Not if you want trains to run across borders. Rail gauge breaks are already a problem, and IIRC Eurostar trains al have two different firefighting water connectors because British and French fire hoses have different designs. Let's not add to communication problems just because we think our system is "better".
Apart from having FRMCS right or wrong, this is about the assignment of the frequency bands over different applications.
If you want trains crossing borders, they have to comply to the basic parameters - like using the frequency bands for the correct reasons and under correct conditions.
The UK has cross-border rail connections to the EU: the Channel Tunnel Rail Link, and not to forget Newry - Dundalk.
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