User(s) browsing this thread: [Complete List]
1 Guest(s)

 
Thread Rating:
  • 1 Votes - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
New threat to the radio spectrum: G.fast: 423 MHz
09-11-2013, 10:04 AM
Post: #1
Very Bad New threat to the radio spectrum: G.fast: 423 MHz

It seems that the ITU-Telecoms division has made a conscious choice to sell-out the radio spectrum carte-blanche. I can find no other explanation for the following.

There is a new proposal "Standard" now propagating through the ITU Working Groups which seeks to extract every last drop of usefulness from the existing copper infrastructure. G.fast is currently being explored with a proposed full sampling frequency of 423 MHz. To be clear, this is not the operation frequency but rather the maximum frequency, inside which there is significant risk of radiated emissions. It is a replacement for the current fibre to the cabinet solution for broadband which tops-out at 80Mbit; G.fast seeks to push this to Gigabit. We have already seen the effects of Gigabit PLT.

G.fast is PLT, make no mistake (at least in all but name) and thus all spectrum inside the sampling mask except that outlined for notching holds the potential for enormous interference. Thus far the only proposed notching is for Band ii (VHF FM, which the UK government plans to phase out). Other services are not mentioned at all. That includes civil aviation, amateur, business radio, DAB and a host of other services which occupy this area of the radio spectrum. All frequencies inside the final sample rate stand to be affected, indiscriminately.

I strongly recommend anyone with ITU TIES access, search for question ITU-R221/1 and then start asking some serious questions about the ethics of this proposal. EN50561 has already set a precedent for accomplishing incredible damage to the radio spectrum and clearly this is simply another step along that road.

I regret I am unable to offer any links at this stage but assure you I have seen a hard copy thanks to the visit of an EMC colleague from Cornwall, whilst I was in hospital this last week. Some further exploration of the topic here: http://www.ispreview.co.uk/index.php/201...roval.html

Everyone involved in Standards committees are strongly recommended to investigate this proposal and resist it at any and every opportunity. The ITU-T's inane appetite for data bandwidth must be kerbed if the radio spectrum is to survive.

I have asked the RSGB to comment and strongly recommend that other non-UK radio users press their national societies for commentary -and action on this matter - as a matter of urgency. EN50561 made it through, riding on the back of apathy, let us not make the same mistakes all over again. . .

Nige.

Interference FaceBook; Interference Twitter; Interference G+;
01-12-2013, 08:46 PM
Post: #2
Stop RE: New threat to the radio spectrum: G.fast: 423 MHz
Although also reproduced here, in a highlighted format, we have also added the document here for completeness, this being the original non-highlighted version.


Interference FaceBook; Interference Twitter; Interference G+;Nerd
02-12-2013, 12:24 AM
Post: #3
RE: New threat to the radio spectrum: G.fast: 423 MHz
The CAA were concerned about existing PLT affecting ILS and ATC.

G.fast if it goes ahead presents a much greater threat...

Stewart
03-12-2013, 06:08 AM
Post: #4
RE: New threat to the radio spectrum: G.fast: 423 MHz

G.fast and G.int SG15 meeting currently taking place: http://www.itu.int/events/eventdetails.a...ntid=10663


Interference FaceBook; Interference Twitter; Interference G+;
05-12-2013, 03:17 PM
Post: #5
RE: New threat to the radio spectrum: G.fast: 423 MHz
There has been some criticism off site about the frequency cited in both the topic subject and the text. The argument is that factoring in Nyquist; sampling at twice the analogue bandwidth of the digital domain signals means that the post title is alarmist.

We want to be clear that the upper frequency (give or take 1 MHz) is not only the Nyquist value but continues to remain a target being developed. The following document (starting to age a little now but nonetheless useful) illustrates this point perfectly.

For those who are too busy to read the entire document, page 13 makes a passing comment at a 424 MHz version of G.fast.

http://www.belllabs.be/opendays/archive/...n_maes.pdf

This does not mean that it will come to pass but it does illustrate how the telecoms sector seem to think they have an automatic right of access to the radio spectrum and complete disregard for its users.

Another comment we have observed is that the dynamic notching will counter any potential interference in the VHF region. We weren't aware that this technology was equipped to deal with duplex operation as is often the norm for radiocommunications above 110 MHz. Will this notching allow for a transmit-receive separation frequency of 8 MHz? Let's hope so.

Interference FaceBook; Interference Twitter; Interference G+;


Forum Jump: