TETRA...

[paulears]

The same scroat could do it under a TETRA installation too, though ..........

[LeakyFeeder]

The same scroat could do it under a TETRA installation too, though ..........

You try finding a jammer that does the UK TETRA freqs....

[paulears]

The Chinese suppliers are happy to produce them on additional bands, except, very oddly, some tv channels in the mid band and a chunk of high UHF. These bands are tightly controlled in China as they're used by their military, but these things use pretty crude technology and plus/minus 400MHz is possible. The cellular products they make come in US and EU band versions. Mind you, many of these devices are pretty rubbish because the output is too wide and and therefore too low power. I bumped into someone who had one, to silence phones in theatres they visited, totally unaware it was extremely illegal, and it simply didn't work. Looking at it with its small wall wart power supply made me chuckle.

With RF gear, just ask the Chinese suppliers if you want particular frequencies. It takes them time, but they can usually do it.

[kr0ne]

You may well be able to jam a couple of low powered handsets in a very localised area, but jamming a cellular network is nigh on impossible... that's kind of the point!

I strongly suspect that jamming a single high powered cell tower with one of these little devices would also be tricky, though perhaps not as impossible an ask if you don't mind climbing.

I've certainly never heard of this happening yet, despite the ready availability of these devices. Has anyone else?

[Metradio]

If it had happend I don't think the powers that be would have announced it !!

Mike

[LeakyFeeder]

It doesnt matter what power the cell site is running..
The idea is to flatten the various inputs of said site.. If the cell site cannot 'handshake' with any of the users/terminals then using that particular cell then as far i understand it is a no no..
Im not on about a whole network..jus localised nonsense from scroats...

[Metradio]

Going back a few years an exercise was carried out by the security services to knock out one of the Met Police's Metradio UHF trunked cell sites. The site had 12 channels, 3 of them could be allocated as a control channel, 3 small TX boxes on the control channel inputs were placed within 100yds of the cell site.. The site was rendered inactive by the TX boxes for the duration of the exercise. Despite a search for the boxes by technical and canine means they were not found by the searchers..

Going back to the 70's the then amateur repeater at Crystal Palace - GB3LO was jammed for about 2 weeks by a constant carrier on the input. There were a few characteristics of the jamming signal that were quite strange, the signal appeared around 5am and dissapeared just after midnight, during the day the signal appeared to slowly rise and fall up to about 12 times. The offending signal only stopped when a London Transport bus mechanic found a small box hooked up to the electrics on a bus that travelled to and from Crystal Palace Parade :-)

Mike

[Metradio]

AOR have released the firmware for the AR-DV1 enabling TETRA DMO:

"AR-DV1 FIRMWARE UPDATE v1609D RELEASE NOTES

(c)2016 AOR, LTD.

Sept.29, 2016

This update will correct issues that some customers experienced, it also adds more functionality to the AR-DV1.
AOR is committed to the continuous improvement of its products and will post firmware updates periodically to further extend the capabilities of this receiver.

IMPORTANT!
This firmware update will clear all your channel, bank and configuration memory data. It is therefore advised to make a backup on SD card as described chapter 5-2 of the user manual, and to restore this data after the firmware update.

The following feature has been added:
TETRA decoding:

Named “T-DM” in the mode selection menu.
Compatible Tetra mode: DMO MOBILE TO MOBILE (also called “direct mode”)
Non-compatible Tetra modes: DMO REPEATER and TRUNKING VIA BASE STATION. (These modes are under evaluation).
Command list: Tetra mode is added to the MD command as selection #8.

Please note following limitations:
-TETRA reception only works in manual mode selection. Unfortunately it cannot be part of the AUTO MODE detection mode because Tetra is very CPU intensive.
-In SCAN mode, do not mix TETRA and non-TETRA modes. All frequencies in your SCAN bank should be preset as TETRA (T-DM).
Encryption is not and can never be supported. (Usually governmental operators do use encryption whereas commercial operators don't)

Advice for best performance:
-LEVEL SQUELCH is strongly recommended for Tetra. As the IF bandwidth of Tetra is very large, the “noise squelch” filter is not suitable for that use. (Press and hold the SQL knob for 2 seconds to display SQL settings.)
-It is best to do a “system reset” after loading this firmware (push and hold CLR button when switching receiver ON) after installing the new firmware. Your memory data will stay untouched."

Mike

[radiosification]

It will also mean that the emergency services can use their radios in the Underground system, 7/7 suffered badly from this. A chum of mine in heavy engineering has been using the LTE system for a few months in the bowels of the Underground and he says it works perfectly. Not only can they speak but can exchange pictures and videos in real time, very useful if you need technical advice and don't want to take a 30 minute trip to the surface to get a signal.

I don't know which manufacturer will get the contract, but he is using a Huawei branded handset.

Can't they already use their radios in the underground? I know that BTP can but it seems only rational that Connect would work to allow access to the network for all airwave users.

[kr0ne]

It doesnt matter what power the cell site is running..

Kind of... I could probably have put that better but my point was that a cell site covers a large area with a relatively high powered signal so the only way to effectively jam it with a low powered device, such as a battery operated jammer off eBay, would be to place the device very close to the cell sites receiving antenna... like you say.

If you did this though, any handsets failing to sign on to that particular cell tower should simply connect to the next closest one though, which in a typical urban / metropolitan area will typically not be too far away.

[kr0ne]

If it had happend I don't think the powers that be would have announced it !!

Not sure what you mean by the powers that be but even if the network operators didn't want to draw attention to such an event, if it was at all trivial to do then I am certain we would have heard about it happening by now...