Feeds

Radio amateurs fret over G.fast interference

FM, DAB protected, not ham frequencies

High performance access to file storage

As vendors, carriers, politicians, analysts and advocates of all kind queue to offer their support to the emerging G.fast standard, there's one group watching developments with apprehension: radio amateurs.

Their worry, as outlined by UK interference-watcher forum Interference.org.uk, is that aside from notches for FM radio and Digital Audio Broadcast frequencies, the new fibre-to-the-X standard won't be required to stay away from Ham Radio frequencies.

According to the document on the Interference.org.uk site, the full sampling rate of a top-rate G.fast system would, at 423 MHz, create a sizeable interference footprint.

However, The Register notes that the sampling frequency is something that happens inside the DSLAM: you have to sample an analogue signal at a minimum of twice its baseband frequency.

Making a less-than-crystal-clear attempt to correct the record, the ITU has made this statement: “We want to point out that the highest frequency ever considered for this technology is 212 MHz, with the determined version of the ITU-T G.fast PSD specification being limited to frequencies up to 106 MHz.”

In other words, the current spec only uses frequencies below 106 MHz – although higher rates could well emerge in the future, since the advocates of the technology are very keen to push its boundaries. Bell Labs, for example, has this presentation from 2012 which suggests 424 MHz could be considered in the future.

Certainly, enthusiasm will remain for pushing the transmission frequencies higher. As this ITU presentation states, “gigabit G.fast” speeds touted by the technology's advocates are only achievable on loops shorter than 100 metres, with a performance target in the standard of 150 Mbps at 250 metres.

And given that many aspects of the copper now in the ground – long loops, a lack of shielding, unbalanced cable impedance, and corrosion in terminations – make the cables very leaky in interference terms, The Register will watch radio interference arguments with interest. ®

3 Big data security analytics techniques

More from The Register

next story
A black box for your SUITCASE: Now your lost luggage can phone home – quite literally
Breakfast in London, lunch in NYC, and your clothes in Peru
Broadband Secretary of SHEEP sensationally quits Cabinet
Maria Miller finally resigns over expenses row
AT&T threatens to pull out of FCC wireless auctions over purchase limits
Company wants ability to buy more spectrum space in auction
EE dismisses DATA-BURNING glitch with Orange Mail app
Bug quietly slurps PAYG credit - yet EE denies it exists
Like Google, Comcast might roll its own mobile voice network
Says anything's possible if regulators approve merger with Time Warner
Turnbull leaves Australia's broadband blackspots in the dark
New Statement of Expectations to NBN Co offers get-out clauses for blackspot builds
Facebook claims 100 MEEELLION active users in India
Who needs China when you've got the next billion in your sights?
Facebook splats in-app chat, whacks brats into crack yakety-yak app
Jibber-jabbering addicts turfed out just as Zuck warned
prev story

Whitepapers

Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.