Tetra is a badly conceived and applied standard that should never have
existed and only does because of the vast amounts of money and
bureaucracy dedicated to it.

But quite why?..


Clearly Politics, the Home Office wanted a system that was entirely
independent of publicly available networks.

Thats not a bad reason at all. I've seen the public mobile nets jam up
rather badly over the years and fail 'tho not that often..

No matter how badly conceived or developed, with no limit on cost.
With whatever the disadvantage to the public, or even creating unknown
health issues.
(What **** thought it a good idea to multiplex Tetra at only 17.6Hz?!
a frequency known to cause visual epilepsy )

Yes, and has it or does it?..


Not having a entirely independent system not being something that
worried the Scandinavians meant they got a very practical digital system,
(900MHz GSM Pro) years earlier for about one hundredth the price of Tetra.

GSM Pro of course offers closed secure PTT groups and normal
international phone calls, to all emergency services and commercial users.

In the USA PTT over cellular is fast becoming popular for closed
commercial and emergency services groups.
http://en.wikipedia.org/wiki/Push_to_talk
(Maybe cos Tetra with its vested interests doesn't exist there?)


It doesn't seem to be used much or at all in the UK. I believe that its
problematical..

Only Orange offered a hardly advertised PTT over GSM here,
and that was only to business users, such limited offering was
destined to fail.

Why almost non existent offerings from the UK GSM networks?
IMHO it must have been Gov pressure not to affect Tetra
and Dolphin sales and the vast army of bureaucrats it supports


Are there really a vast number that supports it?, last I heard there
weren't that many working on it anyway!..
Steve Terry

--
Tony Sayer

In article , Roy Badami
scribeth thus
On 24/09/10 21:03, tony sayer wrote:

I thought that GSM was well encrypted as it was?..

I think you should assume that most of the crypto in GSM has been broken
to a greater or lesser degree. Remember that:

(1) GSM is really quite old now, and

(2) there were political reasons to limit the strength of the crypto

I'm pretty sure that real time cryptanalysis of an GSM call was
demonstrated at one of the hacker conferences quite a number of years ago.

-roy


Well if you have ever listened to Police traffic theres not a lot of it
thats likely to give any villains any advantages and in most cases its
lost its value after a short period of time anyway and where are the
devices that are generally available for interception anyway?.

You'd need something a sight more sophisticated than a hand held
scanner;!...
--
Tony Sayer

In article , Steve Terry
scribeth thus

"tony sayer" wrote in message
...
In article , Steve Terry
scribeth thus
"Rupert Moss-Eccardt" wrote in message
...
Steve Terry wrote:
"tony wrote in message
...
In , Steve Terry
scribeth thus
"Roy wrote in message
...
On 22 Sep, 11:55, wrote:
"Roy wrote in message



On 22/09/10 11:24, Recliner wrote:
snip
Trower report:
http://www.tetrawatch.net/papers/trower_report.pdf

Some really good science there eh;?....
snip

Yes it's very suspect science, but there is little doubt that unnecessarily
multiplexing at 17.6Hz could have been a completely avoidable health risk

In 2000 whist visiting Sweden i spoke to police officers about
their new GSM Pro personal radios (at the time using waterproof
Ericsson R250s) and they were very satisfied with them.
(retail price for Ericsson R250s at the time was around £100 each)
http://www.gsmarena.com/ericsson_r250s_pro-119.php

These 450 MHz versions?. With PPT I presume?..


900MHz on existing public GSM networks with high priority GSM Pro sims
With closed group PTT

Yes that doesn't seem that clever from what I hear..

And they don't want to rely on public nets either..

Also if required additional encryption can be added to each phone.

I thought that GSM was well encrypted as it was?..

Debatable

Sufficient for practical purposes..



We of course years later had to reinvent the wheel, at the cost of
billions
to the public for the benefit of private companies, and to the detriment
of the public allowing them to share an improved GSM network.

Are you suggesting that the public shared a security network?..
Tony Sayer


Why not, it works for them, and if you think about it, most UK police
personal comms has for years already been over officers personal
GSM phones on the public network, especially still in Tetra poor
signal black spot areas.

And of course mobile phones don't have any then;?..


The added advantage to Scandinavian public, is that areas where
emergency services have poor GSM signal get priority for additional
cells to strengthen the existing network, so everyone wins.

In the early days of Tetra if it wasn't for officers being able to
fall back on their GSM phones, Tetra's many black spot areas,
would have made it fail.

Come on, there are many and still are several areas where GSM is ****
poor..


Also some UK police services have been using Blackberrys over
public GSM networks for collating data.
No one has questioned any security issues about police using the
public networks

The one thing that has worried me about officers unbridled use of
GSM phones is that where their PRs calls are recorded for
evidential later use, of course their phones aren't.

Perhaps that a good thing from the bobbies POV;!..

Steve Terry

--
Tony Sayer

On Fri, Sep 24, 2010 at 12:33:30PM +0100, Rupert Moss-Eccardt wrote:
Steve Terry wrote:
Well done. How about the actual operational needs.
To pick a simple example. Tetra works on the TGV, GSM doesn't
Translation: Steve Terry doesn't understand the issues. Think why I
chose TGV especially, rather than another line. Umm. Perhaps it is to
do with the speed of the handset relative to the basestation.

I've used GSM on a TGV, for both voice and data. And no, it wasn't
stopped, it was zooming along at eleventy squillion miles an hour
between Paris and Strasbourg.

--
David Cantrell | Cake Smuggler Extraordinaire

Seven o'clock in the morning is something that
happens to those less fortunate than me

"Phil W Lee" wrote in message
...
tony sayer considered Sun, 26 Sep 2010 22:16:53
+0100 the perfect time to write:

In article , Steve Terry
scribeth thus

"tony sayer" wrote in message
...
In article , Steve Terry
scribeth thus
"Rupert Moss-Eccardt" wrote in message
...
Steve Terry wrote:
"tony wrote in message
...
In , Steve Terry
scribeth thus
"Roy wrote in message
...
On 22 Sep, 11:55, wrote:
"Roy wrote in message



On 22/09/10 11:24, Recliner wrote:
snip
In the early days of Tetra if it wasn't for officers being able to
fall back on their GSM phones, Tetra's many black spot areas,
would have made it fail.

Come on, there are many and still are several areas where GSM is ****
poor..

See first point above
There probably wouldn't be nearly as many poor GSM areas if a tiny
fraction of the considerable sums spent on TETRA had been spent on
filling in GSM holes.


Clearly there are two distinct points of view, one that stifled cellular PTT
offers cheap and practical closed group comms for the benefit of all users,
and two those with a vested interest in perpetrating the vast bureaucracy
and £Billion budgets of Tetra that didn't exist ten years ago, and are
looking forward to a replay with even bigger budgets and careers
to be made with the future planned Tetra 2.

Meanwhile on the streets, emergency services will continue to fall back
on their mobile phones for calls, and Blackberrys for correlating data.

and with PTT apps appearing on the latest generation of Android phones
no doubt emergency services will find new uses for them too.

Steve Terry
--
"I would like to plead for my right to investigate natural phenomena
without having guns pointed at me.
I also ask for the right to be wrong without being hanged for it."
- Wilhelm Reich, November 1947

Phil W Lee wrote:
[snip]
Surely the cost of filling in the GSM blackspots would have been far
less than the cost of creating an entire additional network.
It would have also had the benefit of providing a massive PR boost as
ordinary users would get the benefit of any spare bandwidth.

Err, not really. One of the important things about Tetra is that, in
the event of being out of coverage (indoors or out) you can still do
handset to handset calls. This is particularly useful on a fireground
and also in remote locations. In the latter case you can use handsets
to relay back to the national network so can provide coverage 'on the
fly' which can also involve an aerial platform.

GSM and Tetra had very different design goals and does mean that they
are best at different things. Tetra is designed to provide PTT to large
"talk groups" (possibly hundreds of people) in a small location. GSM
can't do that, for example. On the other hand, Tetra isn't very good at
providing micro, pico and femto cells when you want to have loads of
people in coverage in a dense urban area. And so it goes.

Steve Terry wrote:

Clearly there are two distinct points of view, one that stifled cellular PTT
offers cheap and practical closed group comms for the benefit of all users,
and two those with a vested interest in perpetrating the vast bureaucracy
and £Billion budgets of Tetra that didn't exist ten years ago, and are
looking forward to a replay with even bigger budgets and careers
to be made with the future planned Tetra 2.

GSM can't do the sort of PTT that is required by the emergency services.
I suppose you could design something on top but it wouldn't really be
GSM anymore. One of the fundamental problems is the fact that GSM takes
a while for call set up.

Meanwhile on the streets, emergency services will continue to fall back
on their mobile phones for calls, and Blackberrys for correlating data.

It is true that reactive police typically carry and use GSM handsets and
Blackberrys but that is only one of many different emergency services or
even functions within the police.

"Rupert Moss-Eccardt" wrote in message
...
Steve Terry wrote:

Clearly there are two distinct points of view, one that stifled cellular
PTT
offers cheap and practical closed group comms for the benefit of all
users,
and two those with a vested interest in perpetrating the vast bureaucracy
and £Billion budgets of Tetra that didn't exist ten years ago, and are
looking forward to a replay with even bigger budgets and careers
to be made with the future planned Tetra 2.

GSM can't do the sort of PTT that is required by the emergency services.
I suppose you could design something on top but it wouldn't really be
GSM anymore. One of the fundamental problems is the fact that GSM
takes a while for call set up.


I believe Orange's PTT ran over GPRS data which is left running
near enough continuously.

Skype on Three i leave running continuously whilst minimised,
sometimes for weeks on end.

Steve Terry
--
"I would like to plead for my right to investigate natural phenomena
without having guns pointed at me.
I also ask for the right to be wrong without being hanged for it."
- Wilhelm Reich, November 1947

Is it possible to hear London Underground radio transmissions on a
regular scanner now?

On Wed, 29 Sep 2010, Steve Terry wrote:

"Rupert Moss-Eccardt" wrote in message
...
Steve Terry wrote:

Clearly there are two distinct points of view, one that stifled
cellular PTT offers cheap and practical closed group comms for the
benefit of all users, and two those with a vested interest in
perpetrating the vast bureaucracy and ?Billion budgets of Tetra that
didn't exist ten years ago, and are looking forward to a replay with
even bigger budgets and careers to be made with the future planned
Tetra 2.

GSM can't do the sort of PTT that is required by the emergency
services. I suppose you could design something on top but it wouldn't
really be GSM anymore. One of the fundamental problems is the fact
that GSM takes a while for call set up.

I believe Orange's PTT ran over GPRS data which is left running
near enough continuously.

Skype on Three i leave running continuously whilst minimised, sometimes
for weeks on end.

Presumably, providing universal 3G coverage to the emergency services
would be an entirely different kettle of fish. Very expensive fish.

tom

--
Mpreg is short for Male Impregnation and I cannot get enough. -- D