Feeds

4G networks can screw up cable TV

I want my MTV, and phone calls too

Providing a secure and efficient Helpdesk

LTE can knock out cable TV, according to new analysis funded by Ofcom, which is bad news for anyone who likes to talk and watch at the same time.

The study confirms suggestions last year that LTE deployments could interfere with cable-TV. Ofcom's research found this could indeed happen if the LTE handset is exactly the same frequency, and operating near full power within a metre of the modem or set-top box. The result the result can be broken-up TV pictures and loss of bandwidth: unless Virgin Media decides to beef up their set-top box line.

The issue lies in the digital dividend spectrum – frequencies that used to be reserved for broadcasting analogue TV, but next year will be up for auction and are expected to quickly fill with 4G (LTE) signals. Cable TV uses the same frequencies squeezed down a wire, but if the LTE signal is strong enough it can sneak into the wire too, generating interference.

Screen shot showing interference

You don't need your phone to watch cricket, so turn it off

The tests were carried out by Cobham Technical Services, who provide a detailed analysis in pdf format, showing that the problem only exists when the signal is transmitted by a handset a metre from the cable-TV kit, at close to maximum power of +25dBm, and on exactly the same frequency. Cobham also found huge variation between the models of set-top box and cable modem tested, complaining that "[a]ll of the STBs were found to have significant rectangular holes (apertures) in the metalwork that can allow unwanted frequencies to pass through" – almost as though the designers wanted some air-flow over the components.

But radio engineers have no interest in heat dissipation, only radio isolation, and several of the set-top boxes tested are insufficiently isolated to ensure interference won't be generated.

That could mean making better set-top boxes, or upping the power of the signal transmitted over the cables, either of which is going to cost Virgin Media (the UK'a dominant cable operator) money. Virgin provided the test boxes, but is still digesting the report and possible mitigation strategies. ®

Providing a secure and efficient Helpdesk

More from The Register

next story
Brit telcos warn Scots that voting Yes could lead to HEFTY bills
BT and Co: Independence vote likely to mean 'increased costs'
Phones 4u slips into administration after EE cuts ties with Brit mobe retailer
More than 5,500 jobs could be axed if rescue mission fails
New 'Cosmos' browser surfs the net by TXT alone
No data plan? No WiFi? No worries ... except sluggish download speed
Radio hams can encrypt, in emergencies, says Ofcom
Consultation promises new spectrum and hints at relaxed licence conditions
Blockbuster book lays out the first 20 years of the Smartphone Wars
Symbian's David Wood bares all. Not for the faint hearted
'Serious flaws in the Vertigan report' says broadband boffin
Report 'fails reality test' , is 'simply wrong' and offers ''convenient' justification for FTTN says Rod Tucker
This flashlight app requires: Your contacts list, identity, access to your camera...
Who us, dodgy? Vast majority of mobile apps fail privacy test
prev story

Whitepapers

Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.