CPE Splitters
Work has begun on producing a PTC Specification for DSL splitters (previously only installed by Telecom Contractors. We are keen to see splitters in the self install arena, as we have observed that the installation of a splitter can often lead to a significant improvement in performance. This is because the balance on most house wiring leaves a lot to be desired, and so it tends to pick up noise from sources such as electronic light dimmers, AC/DC motors (common on food processors), switched mode power supplies as well as external sources such as AM radio stations. Splitters connected as close to the entry point as possible reduce the effect of these noise sources considerably. Two significant changes will be made to the current splitter deployed by Telecom:
1. It will extend to VDSL frequencies. While Telecom does not currently offer VDSL, and has no timetable for doing so, it is inevitable that at some stage in the not too distant future that it will be offered. The future of DSL speeds will probably follow the sort of progression which dial-up modems followed in the 1990s, to the point where V.90 and V.92 modems were often decsribed as "V.everything", because they not only incorporated every modulation type from the past 10 years, but automatically selected the highest speed for the conditions.
As splitters, are essentially low pass filters, extending the specified range of the stop band does not add much to the cost.
2. The splitters will probably be installed by plug and socket, rather than being part of the fixed wiring as they are now. This will allow them to be replaced easily or substituted for residential gateways at some future date. The details of the plug and socket arrangement are still being formulated, but our intention is that it will also become the point where security systems are connected. I hope that we can publish details of this arrangement early in the new year.
ADSL Filters
Work is proceding on writing a new specification for line filters to cover ADSL2+ frequencies. This mainly involves extending the upper frequencies from 1.1 to 2.2 MHz for the appropriate tests. We are also looking at some of the international specifications to see whether we can align more closely with them. One of the significant differences is dealing with the inherently unbalanced 3-wire CPE and wiring we have in New Zealand. PTC280 has a much tighter requirement than most overseas specification which we have looked at for this reason.
Line filters will not be intended for use with VDSL, simply because the effect of premisies wiring on VDSL signals is likely to be sufficiently severe, as to reduce the performance to ADSL2+ or ADSL(1) levels.
Christmas Greetings
Another year of Telepermitting has passed with an increasing flow of products over a wide range of technologies. Voice over IP components have increased (again) by 10%”, PBXs up 48% have been amongst the most prevalent this past year. Broadband modems were down a bit probably because the lifespan of such products is such that the numbers go up every second year. We noticed this in the heyday of dial up modems in the 1990s.
Access Standards will be closed for business until 9th January 2008.
It remains for Alan, Bill and me to wish all our readers a very Merry Christmas and Happy New Year.
Richard Brent
Access Standards
