Emergency Services Network

[Tweed]

I wonder how the EE based 4G Emergency Services Network would fare under
conditions akin to the German floods? Newspaper articles cite the mobile
networks failing. I do wonder if there is still a need for a basic high
power mast on the top of the police station with hand held radios, as in
days gone by, as a backup. Even if the 4G masts hold up, you’ve got all the
backhaul to maintain and the computer systems that control it all.

[Scott]

I can't say I know much about it but I thought 5G on the 700MHz band
was intended to provide longer range coverage from taller masts.

[Tweed]

But if that mast can’t see its backhaul it can’t see the control system.
There’s much more to running a mobile network than the range from mast to
handset.

[Abandoned_Trolley]

Exactly

In theory 900MHZ GSM has a range of over 30km (or whatever 63 x 510
metres is) and it might work if you use higher powered mobile devices -
but you would run out of frequency slots long before you get anywhere
near it.

--
random signature text inserted here

[Tweed]

Just to point out how useless a mast is without control, the mast near us
shared jointly by Vodafone and O2, was acting as a jammer for 6 months.
From January it would accept 4G handsets attaching and show full signal
strength. However it would pass no data nor allow any voice calls. It
worked fine on 3G, so I had to manually force my phone to 3G. If I left it
in 4G I got no incoming voice calls and outgoing ones took 30 seconds to
connect (presumably a handset timeout before the phone tried 3G). This
fault affected both O2 and Vodafone. It took them 6 months to fix it.

[Mark Carver]

We took a river cruise through the affected area 6 years ago.

3/4G coverage was pretty poor anyway I thought, though it was a few
years ago, and I was roaming, so perhaps a long way down the 'food chain'

[Tweed]

I’d sort of expect coverage to be great, as you can roam onto any available
network. I thought your position in the food chain would only affect
throughput rates.

[David Woolley]

On 17/07/2021 09:01, Tweed wrote:

> I wonder how the EE based 4G Emergency Services Network would fare under
> conditions akin to the German floods? Newspaper articles cite the mobile
> networks failing. I do wonder if there is still a need for a basic high
> power mast on the top of the police station with hand held radios, as in
> days gone by, as a backup.

I'm afraid the problem with bean counting is that the resilience, and
the simple radios, just won't the there.

On the other hand, during the 1953 East Anglian floods, radio amateurs
stepped in to fill a similar gap, which led to the formation of RAYNET
<https://www.east-suffolk-raynet.co.uk/tag/1953-floods/>.

The Dutch, at least, have a similar organisation, and it appears they
have stepped in there.
<https://www.iaru-r1.org/2021/amateur-radio-responds-to-flooding-in-western-europe/>

[notya...@gmail.com]

On Saturday, 17 July 2021 at 09:45:44 UTC+1, Scott wrote:
> On Sat, 17 Jul 2021 08:01:39 -0000 (UTC), Tweed
> <usenet...@gmail.com> wrote:
>
> >I wonder how the EE based 4G Emergency Services Network would fare under
> >conditions akin to the German floods? Newspaper articles cite the mobile
> >networks failing. I do wonder if there is still a need for a basic high
> >power mast on the top of the police station with hand held radios, as in
> >days gone by, as a backup.

Yes they had HQ to [mainly] cars on ~100MHz and [a little later] hand held radios on ~400MHz.

> Even if the 4G masts hold up, you’ve got all the
> >backhaul to maintain and the computer systems that control it all.
> I can't say I know much about it but I thought 5G on the 700MHz band
> was intended to provide longer range coverage from taller masts.

Correct - loads of planning applications for 20m masts in now. These give 35km range on 3G. They often have microwave links to neighbouring masts., and some, like the one I can see out of my window, have diesel generators (albeit it is next to a river!). 25m and 30m masts now permitted depending on location.

As for resilience, the backhaul is the internet - it was designed to withstand nuclear war and it is NOT centrally controlled. The only natural event that I recall knocking out a substantial region of wired internet was the Canadian ice storm in 1998. My phone stayed in a call during a brief wide area power cut last November.

In addition the networks can shed airside load in an emergency. AIUI there are three levels. AIR this was done during the 7/7 terrorism incident, but probably to disable phone controlled bombs [as actually used in the Stade de France attack 2015] and avoid panic rather than to prevent congestion.

Who says the police didn't keep radios as a back up?

Officers have orders to phone in from landlines if their radios stop working.

[notya...@gmail.com]

Yes for setting up calls.

[Tweed]

The Internet as currently set up really isn’t nuclear war resistant and
probably not entirely flood resistant. BT were famously caught putting both
legs of a backbone ring down the same tunnel.

[MB]

On 17/07/2021 16:11, Tweed wrote:
> The Internet as currently set up really isn’t nuclear war resistant and
> probably not entirely flood resistant. BT were famously caught putting both
> legs of a backbone ring down the same tunnel.

I would think all telecom company have been caught out in a similar way.
The BBC lost its radio networks because their telecom provider had
everything in one room and a fan failed.

[Mark Carver]

Indeed. Though I seem to recall I never saw any sign of Vodafone.de, so
I suspect that was 'locked out' from my EE roaming choices ?

[Tweed]

I think sims these days contain lists of preferred roaming partners. I
noticed in rural France that my phone would hang onto one network even if
the signal was pathetically weak. Going into the manual network selection
bit of my phone allowed my to select another stronger network. So roaming
to any network allowed but they didn’t really want you to know about it.
With automatic network selection it would pick up a non preferred network,
but only in the absence of the preferred partner network. I’m with
Vodafone, and in days when I flew to mainland Europe I’d always end up with
a variant of Vodafone when coming out of flight mode. So the phone “knew”
who its friends were supposed to be.

[notya...@gmail.com]

SIM possibly, or perhaps one of the consequences of buy a locked phone or even an unlocked one from an MNO / MVNO.

[Tweed]

Unlocked phone from the Apple shop. I think the sim contains a list of
preferred Vodafone roaming partners.

[Chris Green]

notya...@gmail.com <notya...@gmail.com> wrote:
> On Saturday, 17 July 2021 at 09:45:44 UTC+1, Scott wrote:
> > On Sat, 17 Jul 2021 08:01:39 -0000 (UTC), Tweed
> > <usenet...@gmail.com> wrote:
> >
> > >I wonder how the EE based 4G Emergency Services Network would fare under
> > >conditions akin to the German floods? Newspaper articles cite the mobile
> > >networks failing. I do wonder if there is still a need for a basic high
> > >power mast on the top of the police station with hand held radios, as in
> > >days gone by, as a backup.
>
> Yes they had HQ to [mainly] cars on ~100MHz and [a little later] hand held radios on ~400MHz.
>
> > Even if the 4G masts hold up, you’ve got all the
> > >backhaul to maintain and the computer systems that control it all.
> > I can't say I know much about it but I thought 5G on the 700MHz band
> > was intended to provide longer range coverage from taller masts.
>
> Correct - loads of planning applications for 20m masts in now. These give
> 35km range on 3G.

Surely the range is dependent on the frequency band as much as on the
mobile technology. So 3G at 700Mhz will have a different range to 3G
on 2700Mhz,

--
Chris Green
·

[Tweed]

Correct. I don’t think range is an issue here. Reports by civilians in
Germany said the mobile network had stopped working. I’m wondering if an
emergency services network based on sharing the civilian network would
suffer the same fate here.

[Woody]

The network stopped working probably because many sites in Germany -
unlike the street poles we have - are often mounted on
commercial/municipal/block roofs for fillers, or major shared towers on
hilltops/hillsides for wide area coverage. By commercial I mean such as
large shops, care homes, hotels (but funnily enough unlike here quite
rarely on schools or colleges.)

Mind you, 'the mobile system has gone down' is often heard everywhere.
No, the mobile system YOU are using has gone down but it doesn't mean
they all have. Having said that Germany has only D1 which is the state
owned system, and D2 which are the private suppliers and I guess may be
on common sites?

[David Woolley]

On 17/07/2021 20:26, Chris Green wrote:
> Surely the range is dependent on the frequency band as much as on the
> mobile technology

Not really. It is certainly possible that there is correlation because
of the way that the networks have been engineered. In particular, the
size of receive antennas is smaller, so the recovered signal for the
same antenna design will be less, whereas the thermal noise will be
similar. However the ultimate limit is set by horizon distance, which
isn't really frequency dependent.

On the other hand, I think most modern systems have constraints on the
round trip time. I think they compensate for this by shifting the
transmit time but there is a limit to this. That will depend on the
technology.

Actually, according to <http://www.ringbell.co.uk/info/hdist.htm> 20m
should only give a range of 16km, so I suspect the 35km is based on
worst case assumptions about the effects of temperature inversions, and
may be the separation distance between two base stations on the same
frequency, to avoid a mobile seeing both of them.

[Abandoned_Trolley]

.. "and may be the separation distance between two base stations on the

same frequency, to avoid a mobile seeing both of them"

so ... how does the mobile hand over to the next base station when its
on the move if it cannot see it ?

[Abandoned_Trolley]

Having said that Germany has only D1 which is the state
> owned system, and D2 which are the private suppliers and I guess may be
> on common sites?

I believe the "Mannesmann D2 Privat" network was sold to Vodafone around
20 years ago and that there were 2 1800MHZ GSM licences issued in the
90s. One of them was for the "E Plus" network but I cant recall the name
of the other.

There was also a C450 / NMT450 network known as "CNet" which provided
nationwide coverage but I assume that has been dismantled long ago.

AFAIK the current situation over there is 3 networks with national coverage

Telekom (ex D1)
Vodafone (ex D2)
and O2 (assumed to be ex E Plus)


AT

[Abandoned_Trolley]

>
> Surely the range is dependent on the frequency band as much as on the
> mobile technology. So 3G at 700Mhz will have a different range to 3G
> on 2700Mhz,
>

Assuming identical transmit power, identical bandwidth, identical
antenna gain and an identical radiation pattern ?

I appreciate that the last two are interdependent but I think you may be
comparing apples with pears here.

[Tweed]

Assuming all other things being equal, yes 700 MHz will propagate further
than 2.7GHz. As a practical illustration, TV uses the lower frequencies,
and you do not have to be in direct line of sight of the transmitter to
receive the transmission. The service area of a TV transmitter is greater
than its line of sight coverage. 2.7 GHz is very much line of sight. If it
were not TV would have been extended up to there years ago as you’d be able
to cram in many more channels.

I suppose the emergency network has some main node base stations that are
low band and are well provisioned with both backup power and redundant back
haul to redundant control nodes. I’d hope so at least…..

[Abandoned_Trolley]

>
> Assuming all other things being equal, yes 700 MHz will propagate further
> than 2.7GHz. As a practical illustration, TV uses the lower frequencies,
> and you do not have to be in direct line of sight of the transmitter to
> receive the transmission. The service area of a TV transmitter is greater
> than its line of sight coverage. 2.7 GHz is very much line of sight. If it
> were not TV would have been extended up to there years ago as you’d be able
> to cram in many more channels.
>

Comparing TV broadcasting with cellular communications is comparing
apples with pears again.

In cellular comms, excess overage can be a royal PITA for network
planners and sometimes needs to be eliminated.

[Abandoned_Trolley]

On 17/07/2021 09:01, Tweed wrote:

I have just carried out a search of this entire (mostly technology free)
thread and I am surprised that there is not a single mention of TETRA

AT

[Tweed]

I wasn’t comparing them. I was using TV as an illustration of frequency
dependent range. Range is quite often the enemy of a cellular system. It’s
one reason why the mobile companies don’t want any of the lower frequency
TV spectrum. The 700 MHz stuff is probably already on the limit of what is
useful.

[notya...@gmail.com]

1G was FM, so it relied on adjacent cells being on different frequency sets and FM capture effect for base stations on the same set further away. I successfully used a 1G hand held in Calais ~35km from mainland England*, with no possibility of being connected to a nearer cell.

Using Cell Network Info Lite, my O2 phone is currently connected to a base station ~750m away and can "see" 17 others within a 5km radius.

Most base stations are built on high ground or buildings.

* possession of Calais is disputed but has de facto not been English since 1558...

[notya...@gmail.com]

That is because it piggy backs on the cellular networks.

Pre Tetra the emergency services had their own radio spectrum and systems, but people could listen in with scanners (even accidentally with a valve FM radio).

[Tweed]

Why? Tetra otherwise known as Airwave is being replaced by the Emergency
Services Network. The latter is years late and Airwave is being life
extended at huge cost. The fact that they are struggling to deploy ESN
makes me wonder if it is too complicated to work under the strain of a
geographically widespread disaster.

[Tweed]

Tetra does not piggy back on the mobile networks, apart from perhaps a bit
of mast sharing. It’s an independent self contained system. It runs down at
roughly 400MHz.

[notya...@gmail.com]

Not so - early https://en.wikipedia.org/wiki/Nordic_Mobile_Telephone used 450MHz 1G for cells. This gives improved range.

EE and others leapt at 700MHz because of greater range in rural areas and improved reception in buildings in urban areas.

Lower frequency bands are almost completely allocated, and 700MHz itself was only made available by pushing all broadcast TV into lower frequencies.

[notya...@gmail.com]

And the backhaul? Separate lines or just internet?

> It’s an independent self contained system. It runs down at roughly 400MHz.

Correction accepted. Another important advantage in a disaster is that it can be used point to point if the network is down.

[Tweed]

The Nordic system solved a very different problem. In most of Scandinavia
the distances are huge and the population is sparse. They needed long
distance coverage and congestion wasn’t a problem. As mobile phones became
popular congestion in the urban areas did become a problem and they moved
to 900 MHz GSM. In rural areas they built *very* high masts, akin to TV
transmitters and used double range technology where alternate time slots in
the GSM signal were not used, to allow for extended time of flight.

EE and 3 leapt at 700 MHz because they don’t have any 900 MHz allocation.
Yes, low band is great for range and more importantly building penetration,
but as you go down in frequency anomalous propagation becomes an increasing
problem. I’m fairly sure EE would swap their 700MHz allocation for 900MHz
any time.

[Abandoned_Trolley]

>
> 1G was FM, so it relied on adjacent cells being on different frequency sets and FM capture effect for base stations on the same set further away. I successfully used a 1G hand held in Calais ~35km from mainland England*, with no possibility of being connected to a nearer cell.
>

2G also relies on adjacent cells being on different frequency sets

[Tweed]

I’ve no idea how Tetra does backhaul but I doubt it’s the Internet. I very
much doubt that commercial 4G uses the public Internet either. The use of
tcp/ip does not equate necessarily to the public Internet.

Airwave does allow handset to handset calls and allows for a temporary
mobile base station (a sort of comms vehicle) to run an isolated local
network if need be. I think it’s all this stuff that’s causing the headache
with ESN.

[MB]

On 18/07/2021 12:25, Tweed wrote:
> I’ve no idea how Tetra does backhaul but I doubt it’s the Internet. I very
> much doubt that commercial 4G uses the public Internet either. The use of
> tcp/ip does not equate necessarily to the public Internet.
>
> Airwave does allow handset to handset calls and allows for a temporary
> mobile base station (a sort of comms vehicle) to run an isolated local
> network if need be. I think it’s all this stuff that’s causing the headache
> with ESN.

Some Airwave sites were (are?) fed by satellite. There was / is a gas
powered, satellite fed Airwave site near here.

By the way, TETRA is a modulation system and Airwave is just one user of
TETRA, the terms are not interchangeable.

[David Woolley]

On 18/07/2021 13:22, MB wrote:
> By the way, TETRA is a modulation system and Airwave is just one user of
>  TETRA

It's a bit more than a modulation system, but it is true that Airwave is
just one service based on the standard. Dolphin was another, but they
didn't last long. The idea was to address the whole PMR market, not
(e.g. taxis), not just the emergency services.

It looks like the official meaning of TETRA is Terrestrial Trunked
Radio, although I think the E one stood for European.

The idea was that different users could share the same base stations,
and frequencies, as though they had a dedicated frequency, when, in
fact, the system allocated from a pool, for each transmission.

[Woody]

The reason ESN is way behind is because EE naturally assumed that the
quoted coverage base on population would be acceptable, whereas, for
obvious reasons and seemingly surprisingly to EE the emergency services
actually need geographical coverage.

A dig back through The Register will show that about 3 years ago EE
announced they were installing 348 (or was it 384?) new sites
predominately in central Wales and across the North of England. I wonder
why?

Finally, Airwave is not pure Tetra. It was seriously tweaked to make it
suit UK emergency service requirements. I was of the belief maybe 15+
years ago that Tetra stands for Trans European Train Radio - it was
actually designed so that intercontinental trains could talk to their
own or a control wherever they were.

[Tweed]

I don’t think EE was ever under the illusion that it needed to increase
geographic coverage. That was an easily quantifiable and known issue. I
think they saw it as a competitive advantage for their commercial network
which would gain coverage. At the moment the cost overrun in keeping
Airwave going (excluding ESN cost increases) is in the region of 2 billion
pounds. That’s way in excess of any costs of building a few more base
stations that you might have overlooked.

[tim...]

"Abandoned_Trolley" <fr...@fred-smith.co.uk> wrote in message
news:sd0m9a$7nq$1...@dont-email.me...

>
>
> .. "and may be the separation distance between two base stations on the
> same frequency, to avoid a mobile seeing both of them"
>
>
> so ... how does the mobile hand over to the next base station when its on
> the move if it cannot see it ?

because para 1 does not describe the *next* base station

[Mark Carver]

On 17/07/2021 18:18, Tweed wrote:
>
> I think sims these days contain lists of preferred roaming partners. I
> noticed in rural France that my phone would hang onto one network even if
> the signal was pathetically weak. Going into the manual network selection
> bit of my phone allowed my to select another stronger network. So roaming
> to any network allowed but they didn’t really want you to know about it.
> With automatic network selection it would pick up a non preferred network,
> but only in the absence of the preferred partner network. I’m with
> Vodafone, and in days when I flew to mainland Europe I’d always end up with
> a variant of Vodafone when coming out of flight mode. So the phone “knew”
> who its friends were supposed to be.
>
Yes. The only country I've been to, where my phone seemed to freely and
very regularly switch networks was Canada.
I presume neither Rogers, Telus, or Bell have any preferential roaming
details with EE ?

[MB]

On 18/07/2021 14:53, Woody wrote:
> The reason ESN is way behind is because EE naturally assumed that the
> quoted coverage base on population would be acceptable, whereas, for
> obvious reasons and seemingly surprisingly to EE the emergency services
> actually need geographical coverage.
>
> A dig back through The Register will show that about 3 years ago EE
> announced they were installing 348 (or was it 384?) new sites
> predominately in central Wales and across the North of England. I wonder
> why?
>
> Finally, Airwave is not pure Tetra. It was seriously tweaked to make it
> suit UK emergency service requirements. I was of the belief maybe 15+
> years ago that Tetra stands for Trans European Train Radio - it was
> actually designed so that intercontinental trains could talk to their
> own or a control wherever they were.

I think the spec. for Airwave was all (major?) roads which is why there
are often base stations in odd places to cover a bit of road.

I understood that TETRA was originally Trans-European Trunked Radio and
then Terrestial Trunked Radio and not specifically railways.

I think was derived from MPT1327 - lots of similarities, just digital.

There were grandiose ideas about the police being able to use TETRA
anywhere in Europe, I asked an ex-police friend about that - he had
worked often with foreign police and would not trust any of them!

For a time there was a debate about whether to use TETRA or TETRAPOL, as
always the marketing people made lots of wild claims about Airwave /
TETRA - remember every Bobby with a camera in his helmet transmitting
using Airwave. I think they very quickly realised it did not have the
capacity so various data networks are used data.

[MB]

Modulation was a bad choice of words, "Protocol" is probably better.

It was a step up from MPT1327 which was also trunked but analogue.

Doesn't TETRA operate like some mobile phones with users using different
timeslots on a datastream but a long time since I went to a lecture
about it.

[Woody]

I went on a one-week course at Nokia in Paris on Tetrapol. I have to say
that in many ways - particularly under fallback conditions - Tetrapol
was better than Airwave could ever have been.

I know of one UK force that had four UHF quasi-sync systems to cover its
main area, with Airwave this was reduced to three sites. The problem was
when a site lost contact with the main switch, the users logged on to
the site could talk to each other but not to control. They could only
get onto one of the other sites by going far enough out of coverage that
they lost contact with the site they were still logged on to. The force
ended up putting a line controlled mobile - connected to a load rather
than an aerial - on each of the three sites so that said mobile would
only ever work that site and they could thus stay in contact until the
link to the switch was restored. With Tetrapol the user could manually
log off the site with broken comms and select another site/system. Also
if a mobile pressed the panic button whilst out of range of any site any
mobile hearing it would operate in a relay mode back into the main
system - a sort of mesh - which meant that in practical terms comms were
never lost.

[MB]

On 18/07/2021 17:16, Woody wrote:
> I went on a one-week course at Nokia in Paris on Tetrapol. I have to say
> that in many ways - particularly under fallback conditions - Tetrapol
> was better than Airwave could ever have been.

I remember talking to some police techsa short time before Airwave
started installed.

They said that for modest amount of money, their existing network could
have been improved. Many of the features claimed for Airwave were not
needed or never worked so they were sure their system could have been
improved for much less cost.

It was not sour grapes because they eagerly looking forward to getting
early retirement and, like many working for large organisations, would
be glad to get out.

[Martin Brown]

On 17/07/2021 21:09, Woody wrote:
> On Sat 17/07/2021 20:47, Tweed wrote:
>> Chris Green <c...@isbd.net> wrote:
>>> notya...@gmail.com <notya...@gmail.com> wrote:

>>>> Correct - loads of planning applications for 20m masts in now. These
>>>> give
>>>> 35km range on 3G.

The 35km range is timing gate limited. I have antennae with sufficient
gain to run into the problem of working remote line of site base
stations that are too distant for my connection to be accepted. This is
for MiFi pebbles with a pair of phased array yagis attached.

>>> Surely the range is dependent on the frequency band as much as on the
>>> mobile technology.  So 3G at 700Mhz will have a different range to 3G
>>> on 2700Mhz,
>>

>> Correct. I don’t think range is an issue here. Reports by civilians in
>> Germany said the mobile network had stopped working. I’m wondering if an
>> emergency services network based on sharing the civilian network would
>> suffer the same fate here.
>
> The network stopped working probably because many sites in Germany -
> unlike the street poles we have - are often mounted on
> commercial/municipal/block roofs for fillers, or major shared towers on
> hilltops/hillsides for wide area coverage. By commercial I mean such as
> large shops, care homes, hotels (but funnily enough unlike here quite
> rarely on schools or colleges.)

What kills the mobile network assuming its electronics is not under
water is the very finite battery backup in the base stations. Maybe
enough for an hour or two but nothing like landline phone exchanges.

> Mind you, 'the mobile system has gone down' is often heard everywhere.
> No, the mobile system YOU are using has gone down but it doesn't mean
> they all have. Having said that Germany has only D1 which is the state

> owned system, and D2 which are the private suppliers and I guess may be
> on common sites?

I think it is just that once you lose mains power the lifetime of the
mobile base stations is rather short duration under normal load and
becomes even shorter as everyone and their dog tries to do ET phone home.

--
Regards,
Martin Brown

[MB]

On 18/07/2021 19:41, Martin Brown wrote:
> What kills the mobile network assuming its electronics is not under
> water is the very finite battery backup in the base stations. Maybe
> enough for an hour or two but nothing like landline phone exchanges.

Some years before I retired we found a load of batteries dumped inside
one of our sites. We could see they had been left by one of the mobile
phone companies who were a site-sharer but they denied it (despite their
name being on some items) and the department that dealt with
site-sharers (and probably profited from them) would not do anything
about it so our department had to pay for a specialist company to remove
them and I had to drive down to let them in the building.

I spoked to someone anmd he said that particular mobile phone company
had been removing batteries / UPS's because of the high maintenance
cost. So rather than the usual "one working day" backup, they were just
going to have a few minutes backup on each card.

[Chris Green]

MB <M...@nospam.net> wrote:
> On 18/07/2021 19:41, Martin Brown wrote:
> > What kills the mobile network assuming its electronics is not under
> > water is the very finite battery backup in the base stations. Maybe
> > enough for an hour or two but nothing like landline phone exchanges.
>
> Some years before I retired we found a load of batteries dumped inside
> one of our sites. We could see they had been left by one of the mobile
> phone companies who were a site-sharer but they denied it (despite their
> name being on some items) and the department that dealt with
> site-sharers (and probably profited from them) would not do anything
> about it so our department had to pay for a specialist company to remove
> them and I had to drive down to let them in the building.
>

Most batteries in bulk have a significant recycling value.

--
Chris Green
·

[MB]

On 18/07/2021 21:44, Chris Green wrote:
> Most batteries in bulk have a significant recycling value.

It is the cost of checking them regularly and the cost changing
batteries on a hill with no road or track so needing the use of an ATV.
I would have thought the costs of all that easily exceed the scrap value
of the batteries.

[Martin Brown]

On 18/07/2021 14:53, Woody wrote:

> On Sun 18/07/2021 11:51, Tweed wrote:
>> Abandoned_Trolley <fr...@fred-smith.co.uk> wrote:
>>> On 17/07/2021 09:01, Tweed wrote:
>>>> I wonder how the EE based 4G Emergency Services Network would fare
>>>> under
>>>> conditions akin to the German floods? Newspaper articles cite the
>>>> mobile
>>>> networks failing. I do wonder if there is still a need for a basic high
>>>> power mast on the top of the police station with hand held radios,
>>>> as in
>>>> days gone by, as a backup. Even if the 4G masts hold up, you’ve got
>>>> all the
>>>> backhaul to maintain and the computer systems that control it all.

Failure of the base stations battery backup takes them down first.

>>> I have just carried out a search of this entire (mostly technology free)
>>> thread and I am surprised that there is not a single mention of TETRA
>>>
>>> AT
>>>
>>
>> Why? Tetra otherwise known as Airwave is being replaced by the Emergency
>> Services Network. The latter is years late and Airwave is being life
>> extended at huge cost. The fact that they are struggling to deploy ESN
>> makes me wonder if it is too complicated to work under the strain of a
>> geographically widespread disaster.

TETRA was and is a bit of an over priced joke. It might just possibly
work sometimes in major cities on a good day but that is about all. It
was completely FUBAR up here in North Yorkshire and the Dales.

The only thing you could be certain of was total non-functionality in
any kind of valley (and there are a lot of those round here).

>
> The reason ESN is way behind is because EE naturally assumed that the
> quoted coverage base on population would be acceptable, whereas, for
> obvious reasons and seemingly surprisingly to EE the emergency services
> actually need geographical coverage.
>
> A dig back through The Register will show that about 3 years ago EE
> announced they were installing 348 (or was it 384?) new sites
> predominately in central Wales and across the North of England. I wonder
> why?

Because up here there are places right in the middle of villages with
precisely *zero* mobile network coverage (including the ill fated Tetra).

Even on major routes like the A1 and A19 you get DAB radio dropout
because the planners are seemingly unaware of topography which obviously
isn't such a problem in the Home Counties (which is all that matters).

> Finally, Airwave is not pure Tetra. It was seriously tweaked to make it
> suit UK emergency service requirements. I was of the belief maybe 15+
> years ago that Tetra stands for Trans European Train Radio - it was
> actually designed so that intercontinental trains could talk to their
> own or a control wherever they were.

--
Regards,
Martin Brown

[MB]

On 19/07/2021 09:13, Martin Brown wrote:
> Because up here there are places right in the middle of villages with

> precisely*zero* mobile network coverage (including the ill fated Tetra).

>
> Even on major routes like the A1 and A19 you get DAB radio dropout
> because the planners are seemingly unaware of topography which obviously
> isn't such a problem in the Home Counties (which is all that matters).

Not been down the East coast for a long time but DAB certain holds up
well on the West coast - I have driven to Cornwall and hardly lost DAB
from Tarbet to Falmouth (including through mid-Wales) and hardly ever
lost signal.

I can't receive Long Wave here so obviously Long Wave does not work. I
can drive a few miles and lose VHF FM so that does not work either - a
friend not far from here was very pleased when I showed him I could
receive good DAB at his house even though he cannot receive VHF FM.

I think one problem is that is is like mobile phones, we used to specify
a "high gain" antenna on the company vehicle so had a proper whip but
now it must be very rare for anyone to have a proper antenna on their
mobile phone. DAB is similar, most cars seem to have a silly little
antenna - I wonder how much better they would be if they all had proper
antenna but the silly little antenna works OK in the South of England.

[Abandoned_Trolley]

> I think one problem is that is is like mobile phones, we used to specify
> a "high gain" antenna on the company vehicle so had a proper whip but
> now it must be very rare for anyone to have a proper antenna on their
> mobile phone.  DAB is similar, most cars seem to have a silly little
> antenna - I wonder how much better they would be if they all had proper
> antenna but the silly little antenna works OK in the South of England.
>

Theres also a problem with transmit power for the uplink.

In the early days of GSM mobiles, the mobiles had 4 or 5 different
transmit power classifications. Some of the big chunky things about the
size of a small rucksack were transmitting at 8 or possibly even 20
watts - sometimes using a whip style antenna, but as they had a seperate
"receiver" handset thingy, the antenna was nowhere near the users ear.

Later "handy" sized mobiles had much reduced transmit power (possibly
0.8 watts max) which means that a larger antenna might not solve the
problem.

I believe that GSM power control on the uplink was primarily intended to
extend battery life rather than preserve the users brain.

[Woody]

In the the early analogue days there were four power levels
Class 1 7W or about +38dBm
Class 2 2.2W or about +34dBm
Class 3 1W or +30dBm
Class 4 400mW or +26dBm

Power negotiation was in steps of 2dB down to 4mW (+6dBm).
Initiation/call setup was usually done at full power with reduction
taking place when the radio moved to the traffic channel.

I say was, probably still is!

[tony sayer]

In article <f566661c-42dc-4b23...@googlegroups.com>,
notya...@gmail.com <notya...@gmail.com> scribeth thus
>On Saturday, 17 July 2021 at 09:45:44 UTC+1, Scott wrote:

>> On Sat, 17 Jul 2021 08:01:39 -0000 (UTC), Tweed
>> <usenet...@gmail.com> wrote:
>>
>> >I wonder how the EE based 4G Emergency Services Network would fare under
>> >conditions akin to the German floods? Newspaper articles cite the mobile
>> >networks failing. I do wonder if there is still a need for a basic high
>> >power mast on the top of the police station with hand held radios, as in
>> >days gone by, as a backup.
>

>Yes they had HQ to [mainly] cars on ~100MHz and [a little later] hand held
>radios on ~400MHz.

>
>> Even if the 4G masts hold up, you’ve got all the
>> >backhaul to maintain and the computer systems that control it all.

>> I can't say I know much about it but I thought 5G on the 700MHz band
>> was intended to provide longer range coverage from taller masts.

>
>Correct - loads of planning applications for 20m masts in now. These give 35km
>range on 3G.

They might, if its like around here, flat earth! but a few hills will
put paid to that at these frequencies!. ?ns cellular systems don't
really need long distances do they?.


> They often have microwave links to neighbouring masts., and some,
>like the one I can see out of my window, have diesel generators (albeit it is
>next to a river!). 25m and 30m masts now permitted depending on location.
>

Yes if its a LOS path and Gennies?, well i don't know where around here
is but their very rare in the UK as Mr Pikey and his ilk will soon have
them away and their Diesel Oil..

>As for resilience, the backhaul is the internet - it was designed to withstand
>nuclear war and it is NOT centrally controlled. The only natural event that I
>recall knocking out a substantial region of wired internet was the Canadian ice
>storm in 1998. My phone stayed in a call during a brief wide area power cut
>last November.

It may well be designed for a Nuclear war but it won't last anytime at
all as it needs power and that power will soon disappear in a Nuke
attack of any size let alone the effects of EMP which Fibre is very good
at but other tech not so wonderful..

>
>In addition the networks can shed airside load in an emergency. AIUI there are
>three levels. AIR this was done during the 7/7 terrorism incident, but probably
>to disable phone controlled bombs [as actually used in the Stade de France
>attack 2015] and avoid panic rather than to prevent congestion.
>
>Who says the police didn't keep radios as a back up?
>
>Officers have orders to phone in from landlines if their radios stop working.

Yes well seeing that landlines with be a form of VoIP ere long.

Mind you some radios do have cellular and dPMR functions nowadays...
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

[tony sayer]

In article <scvc52$9ol$1...@dont-email.me>, Tweed <usenet...@gmail.com>
scribeth thus

>Chris Green <c...@isbd.net> wrote:
>> notya...@gmail.com <notya...@gmail.com> wrote:

>>> On Saturday, 17 July 2021 at 09:45:44 UTC+1, Scott wrote:
>>>> On Sat, 17 Jul 2021 08:01:39 -0000 (UTC), Tweed
>>>> <usenet...@gmail.com> wrote:
>>>>
>>>>> I wonder how the EE based 4G Emergency Services Network would fare under
>>>>> conditions akin to the German floods? Newspaper articles cite the mobile
>>>>> networks failing. I do wonder if there is still a need for a basic high
>>>>> power mast on the top of the police station with hand held radios, as in
>>>>> days gone by, as a backup.
>>>
>>> Yes they had HQ to [mainly] cars on ~100MHz and [a little later] hand
>>> held radios on ~400MHz.
>>>
>>>> Even if the 4G masts hold up, you’ve got all the
>>>>> backhaul to maintain and the computer systems that control it all.
>>>> I can't say I know much about it but I thought 5G on the 700MHz band
>>>> was intended to provide longer range coverage from taller masts.
>>>
>>> Correct - loads of planning applications for 20m masts in now. These give
>>> 35km range on 3G.
>>

>> Surely the range is dependent on the frequency band as much as on the
>> mobile technology. So 3G at 700Mhz will have a different range to 3G
>> on 2700Mhz,
>>
>
>Correct. I don’t think range is an issue here. Reports by civilians in
>Germany said the mobile network had stopped working. I’m wondering if an
>emergency services network based on sharing the civilian network would
>suffer the same fate here.
>

Almost certainly, it did up in Yorks the other year in the floods thats
why we have RAYNET t'aint it;)

[tony sayer]

In article <scuuh3$9je$1...@dont-email.me>, MB <M...@nospam.net> scribeth
thus
>On 17/07/2021 16:11, Tweed wrote:
>> The Internet as currently set up really isn’t nuclear war resistant and
>> probably not entirely flood resistant. BT were famously caught putting both
>> legs of a backbone ring down the same tunnel.
>
>I would think all telecom company have been caught out in a similar way.
> The BBC lost its radio networks because their telecom provider had
>everything in one room and a fan failed.
>

Yes put BBC Radio 4 Longwave of it did now nuke sub commanders have been
told that if Radio 4 longwave was to go off for any length of time
etc....

[tony sayer]

In article <sd1udl$2d8$1...@dont-email.me>, MB <M...@nospam.net> scribeth
thus

So you took them to the local scrappie and pocked the proceeds;?...

[MB]

On 26/07/2021 17:01, tony sayer wrote:
> So you took them to the local scrappie and pocked the proceeds;?...

The firm got a licensed company to remove them, they seemed to
specialise in batteries. Of course the site sharing people, who get
nice bonuses from site sharers, did not pay. All charged to us.

[MB]

On 26/07/2021 16:58, tony sayer wrote:
> Almost certainly, it did up in Yorks the other year in the floods thats
> why we have RAYNET t'aint it;)

Though when a Chief Constable told them about coverage problems during
COVID, one of his Plods threatened to arrest the RAYNET man who went to
put on a temporary repeater - at the request of the Chief Constable with
a letter authorising him to travel!

[tony sayer]

In article <sd113r$e1o$1...@dont-email.me>, Tweed <usenet...@gmail.com>
scribeth thus
>Abandoned_Trolley <fr...@fred-smith.co.uk> wrote:

>> On 17/07/2021 09:01, Tweed wrote:
>>> I wonder how the EE based 4G Emergency Services Network would fare under
>>> conditions akin to the German floods? Newspaper articles cite the mobile
>>> networks failing. I do wonder if there is still a need for a basic high
>>> power mast on the top of the police station with hand held radios, as in

>>> days gone by, as a backup. Even if the 4G masts hold up, you’ve got all the

>>> backhaul to maintain and the computer systems that control it all.
>>>
>>
>>
>>
>>

>> I have just carried out a search of this entire (mostly technology free)
>> thread and I am surprised that there is not a single mention of TETRA
>>
>> AT
>>
>


>Why? Tetra otherwise known as Airwave is being replaced by the Emergency
>Services Network. The latter is years late and Airwave is being life
>extended at huge cost. The fact that they are struggling to deploy ESN
>makes me wonder if it is too complicated to work under the strain of a
>geographically widespread disaster.
>

A man i know who works in telecoms for a police force reckons that and
he also reckons that they'd be much better off with a system of their
own be much cheaper to run!...

[tony sayer]

In article <sd17c5$tam$1...@dont-email.me>, David Woolley <da...@ex.djwhome
.demon.invalid> scribeth thus

>On 18/07/2021 13:22, MB wrote:
>> By the way, TETRA is a modulation system and Airwave is just one user of
>>  TETRA
>
>It's a bit more than a modulation system, but it is true that Airwave is
>just one service based on the standard. Dolphin was another, but they
>didn't last long.

No in fact we took over a surplus Dolphin site a few years ago, seems to
have been on air all of a couple of weeks if it actually went on air
that is.

Daft idea could not compete with cellular in the UK....

>The idea was to address the whole PMR market, not
>(e.g. taxis), not just the emergency services.

Well thats not been an outstanding success, even Taxis now use an App
on a smartfone for DATA and voice..

>
>It looks like the official meaning of TETRA is Terrestrial Trunked
>Radio, although I think the E one stood for European.

Yep it did..

>
>The idea was that different users could share the same base stations,
>and frequencies, as though they had a dedicated frequency, when, in
>fact, the system allocated from a pool, for each transmission.
>

Thats more or less how a trunked system works like phone lines used to
years ago only so many trunk lines in the pool...

[tony sayer]

In article <sdmn9d$9ps$2...@dont-email.me>, MB <M...@nospam.net> scribeth
thus

LOL! couldn't make that one up could you!!...

[tony sayer]

>>> Why? Tetra otherwise known as Airwave is being replaced by the Emergency
>>> Services Network. The latter is years late and Airwave is being life
>>> extended at huge cost. The fact that they are struggling to deploy ESN
>>> makes me wonder if it is too complicated to work under the strain of a
>>> geographically widespread disaster.
>
>TETRA was and is a bit of an over priced joke. It might just possibly
>work sometimes in major cities on a good day but that is about all. It
>was completely FUBAR up here in North Yorkshire and the Dales.
>
>The only thing you could be certain of was total non-functionality in
>any kind of valley (and there are a lot of those round here).
>>
>> The reason ESN is way behind is because EE naturally assumed that the
>> quoted coverage base on population would be acceptable, whereas, for
>> obvious reasons and seemingly surprisingly to EE the emergency services
>> actually need geographical coverage.
>>
>> A dig back through The Register will show that about 3 years ago EE
>> announced they were installing 348 (or was it 384?) new sites
>> predominately in central Wales and across the North of England. I wonder
>> why?
>
>Because up here there are places right in the middle of villages with
>precisely *zero* mobile network coverage (including the ill fated Tetra).
>


>Even on major routes like the A1 and A19 you get DAB radio dropout
>because the planners are seemingly unaware of topography which obviously
>isn't such a problem in the Home Counties (which is all that matters).

But how can this be seeing that Yorkshire is Gods chosen county???...

>
>> Finally, Airwave is not pure Tetra. It was seriously tweaked to make it
>> suit UK emergency service requirements. I was of the belief maybe 15+
>> years ago that Tetra stands for Trans European Train Radio - it was
>> actually designed so that intercontinental trains could talk to their
>> own or a control wherever they were.

Never heard of that interpretation!..

[MB]

On 26/07/2021 17:15, tony sayer wrote:
> A man i know who works in telecoms for a police force reckons that and
> he also reckons that they'd be much better off with a system of their
> own be much cheaper to run!...

That's what the police radio techs were saying pre-Airwave. They could
have upgraded their own system for a fraction of the cost of Airwave.

But they were looking forward to early retirement!

[David Woolley]

On 17/07/2021 16:03, notya...@gmail.com wrote:
> As for resilience, the backhaul is the internet - it was designed to withstand nuclear war and it is NOT centrally controlled.

ARPANET was designed to be capable of producing networks that are that
resilient. Commercial realisations are unlikely to have that level of
resilience as cost control isn't consistent with doing that.

(The internet was actually designed to connect multiple networks
together, not specifically for resilience.)