Long Line ADSL

Satellite Broadband

2007-05-10T00:47:00.001Z

Satellite Broadband can be a last resort for you if you are unable to get ADSL delivered to your premises.

There are two basic forms of satellite technology - one way and two way.

One way satellite broadband requires you use a normal modem for dial up access to an ISP plus a box which links your PC to a satellite dish. This dial up link is used to communicate all of your information TO the ISP. The ISP processes your requests and then sends the data you requested down to your PC over a satellite link. As most of the data created when surfing is coming from the Internet to your PC this can work well for some users. Some systems can even take their satellite feed from an existing Sky dish.

Whilst the one way system can be OK for people doing a few mainly text emails and casual browsing for business users with requirements for higher upload rates a two way link might be more appropriate. With a two way link a slightly larger dish is installed which has a transmitter for sending data up to your ISP. Both sets of traffic are therefore travelling via this path. Two way satellite connections are also always on, unlike the one way links which require you to initiate the dial up connection.

Unfortunately the laws of physics dictate that even at the speed of light it does take a significant fraction of a second to reach the satellite from the ISP ground station and to get back down to your PC from the satellite. This does not affect big file downloads for instance as much as web browsing because software will start sending all of the requested file immediately whilst every image or object in a web page must be separately requested - each having it's own delay. Most satellite ISPs have software to try to work around the issue.

Two way satellite also requires expensive hardware to be installed (from just under £2,000 but grants might be available) and this includes a broadcast licence for the dish (you may have trouble if you are close to an airport). Rentals start from about £59 per month plus VAT.

My own personal experience was that satellite was a huge improvement over dial up, but once I could move to ADSL I did and the improvement was well worth while. I would describe satellite as a car with a high top speed but poor acceleration whilst ADSL is much nippier off the mark (and cheaper too). I would have no hesitation in recommending my old ISP Remote data Services.

In all satellite broadband, even two way, is not as fast as terrestrial ADSL but it is a damn site faster than dial up and if it is the only game in town then it might just be right for you.

Old Zen Line Stats

2007-03-02T14:40:00.000Z

I just stumbled across the line stats for my old St Albans line from the days when we briefly had a Zen broadband connection.

ADSL 512 63.5dB loss, 2.5dB margin

Broadband over Powerlines (BPL)

2007-02-27T07:37:00.000Z

Broadband Over Power Lines (BPL) is a technology for distributing broadband internet over the high voltage electricity lines. It seeks to exploit the established network of powerlines for broadband distribution - avoiding the need to lay new or upgrade existing telecom cabling.

Broadband over Powerlines faces various challenges due to the noise created by high voltage power and the blocking effect of trasnformers.

Broadband over Powerlines should not be confused with HomePlug technology where network signals are distributed throughout domestic wiring in s house.

The effect of internal wiring on ADSL and faceplate splitters

2007-02-12T20:48:00.000Z

To get a good, high speed ADSL connection you want to minimise the line loss between your ADSL modem and the telephone exchange where the DSLAM (the exchange based broadband controller) is located.

The loss of signal is measured in decibels and you really want to keep the loss below about 60dB to pretty much be guaranteed to have a good ADSL signal. It is possible to get a connection with higher losses but is rare and the connection is likely to be slow and/or unstable.

Most of the factors that affect line loss (line length, the quality of the cable used by BT, whether the cable is underground or up poles) are outside of your control. One area that you can change that does impact line loss is the internal wiring and the devices you have connected to the internal wiring.

Most recent BT installations should have a master socket and possibly several extension sockets. The extension sockets are smaller and don't have a removable bottom half to the front panel. The wiring from the exchange to the back of the master socket belong to BT and you mustn't monkey about with it.

You can remove the bottom of the master socket faceplate and you will see it just plugs into a telephone socket (known as the test socket) in the back of the master socket. The wiring from the master socket, including the bottom half of the faceplate you are allowed to monkey about with.

If you are plugging your ADSL modem into an extension socket then you are obviously on a longer total line length than if you simply plugged into the master socket - this will increase line loss. If the wiring is poor or is complicated in layout then the line loss may be even greater.

There is anecdotal evidence that plugging too many devices or certain 'poor quality' devices into your phone sockets can also increase the loss. I have specifically heard that DECT phones can have quite an impact.

The good news is you can test all of this quite easily and you have a good chance to rectify the problems. You should learn how to read the synchronisation speed of your modem and hopefully the line characteristics (including the line loss). You will need to refer to the documentation for your ADSL device to find this information. You can also run a speed test by following the instructions here. Whenever you make a change force your modem to renegotiate the connection (which will make it connect at the best available speed) by switching it off for a few moments and then restarting it.

Your first step should always be to ensure every non-ADSL device plugged into your phone line is plugged into an ADSL filter.

Then try removing everything connected to you telephone wiring except the broadband device. If this results in a much better connection plug the devices back in one at a time, rebooting each time and see if one of the devices causes a significant degradation in signal - consider replacing this device or simply using less devices.

Try plugging your broadband modem directly into the master socket. If this improves the signal you should consider improving the internal wiring or fitting a faceplate filter (see later).

Finally try removing the bottom of the master socket and plugging your broadband device directly into the test socket behind the faceplate. At this stage none of your telephone extensions should be connected to the phone circuit and you have the best possible connection without BT making any adjustments.

If this final step results in a much better signal then you need to either review the internal wiring for replacement or re-routing or better still fit a faceplate filter. A faceplate filter separates the ADSL signal from the phone signal at the point it enters the domestic wiring. Telephone extensions can then be connected without the possibility of them interfering with the ADSL signal.

Unfortunately the master socket may not be located in the best position for you to connect your broadband device and PC. In this instance you may want to consider using a broadband router to handle the ADSL connection and create a home network, which is not as complicated as it might sound.

You could create an Ethernet network around the home using network cable and sockets (which is probably the most reliable), you could install a wireless broadband router and then use wireless adapters to connect your PCs to the broadband connection or you could use powerline networking to run the broadband network over the power sockets in your house. I will cover some of these options in a later article.

Solwise have a good article about filtering and home networking.

Re-provisioning a line from another exchange

2007-01-31T02:11:00.000Z

I have been told after the last engineer visit that we are simply too far from St Albans exchange for ADSL to work.

Whilst I would query the 'too far' bit, I do accept that the quality of the lines are so poor that I am unlikely to get a service from St Albans at the moment.

I am frustrated that the 'V' cable to my local cabinet is so poor that at just over 4km the line loss is 61dB. I also do not quite understand how myself and neighbours have had service (for significant periods of time) but it now appears impossible to provide one now.

The engineers that visited to check my line did state that we are actually closer to the Garston exchange than St Albans and he had got a neighboor working from that exchange just recently.

We are going to try and get the line re-provisioned from Garston rather than St Albans

Limiting ADSL to 512Kbits

2007-01-23T22:11:00.000Z

Andrews and Arnold are trying to lock my ADSL service down to 512K in the hope this will enable my modem to synchronise. I have power cycled the modem and am now waiting to see if this has had any effect.

Home 250 - A last resort for BT ADSL?

2007-01-22T22:08:00.000Z

Most ADSL offerings these days are 'rate adaptive' - they train to the highest speed possible on your telephone line. BT offers their ADSL MAX product which will give speeds up to 8Mbit/sec depending upon line length & quality.

Unfortunately some very long or poor quality lines just cannot support this service and ADSL will fail to synchronise even at 512kbit/sec. Sometimes the BT Home 250 product which is tied down to working at 250kbit/sec will work on these lines. It is possible that if the Home 250 service works then line statistics can be measured and it may be possible for an ISP to get enough information about your line to make some improvements with BT and achieve an upgrade to 'full' ADSL.

Home 250 is supplied by the following ISPs and probably a few more besides.

Andrews & Arnold
Zen Internet
Merula
Zetnet

Urban Wimax active in London

2007-01-22T18:44:00.000Z

I am quite hopeful about the prospects for WiMAX as an alternative to wires for the last mile delivery of broadband services to premises outside the reach of current ADSL implementations.

Whilst they don't yet cover St Albans, Urban WiMAX offer WiMAX (IEEE 802.16) based broadband services to (business) customers in London, UK. I am a bit confused as to why they don't offer service here as WiMAX has a stated range up to 30 miles and last time I checked we are only about 16 miles from central London.

Urban WiMAX provide symetric broadband up to 10Mbit/s (range dependent) and offer 'carrier c;ass' SLAs with minimal contention (according to their webiste).

The price (£99/month according to this document) is nearer to SDSL than ADSL and means it is suited to businesses which need the high service levels and symetric bandwidth rather than being a general replacement for ADSL at the moment. Hopefully the cost will fall over time.

Andrews & Arnold ADSL Tech Support

2007-01-16T14:35:00.000Z

We are currently working with Andrews & Arnold to install ADSL.

Whilst we are not actually getting anywhere with the ADSL installation I am very impressed with the A&A technical support team. I have spoken with a couple of their engineers and they are always technically knowledgeable. One engineer seems to be assigned to a case so I can always talk to the same person rather than explaining over and over that I have already rebooted the router.

Currently BT have placed a fail against the line even though the length is listed as just 5.3KM which should be within limits for ADSL.

They are also great at calling me with status updates - even if it just to say that they have not heard anything from BT yet but they are chasing. A&A are reluctant to let this go and are pursuing BT for further investigation and still have some options to pursue.

I obviously cannot comment on the quality of their broadband (yet) but I can say they give excellent Technical Support!

Another visit -another failure

2007-01-12T21:54:00.000Z

We have had an ADSL engineer out again to the premises and it is not looking hopeful.

He seemed pretty competent - he even tried bunching pairs from the exchange to the cab to try and get a better signal. So far no synch light though.

He confirmed there are 'issues' with customers served from the cabinet (cabinet 96 apparently) and they are beginning to suspect a problem in the cabinet itself. I know that there is only a 'V' cable to the cabinet (whatever this is) and that means there is a poor signal even at the cabinet. Given that there is possibly 2KM more (poor quality) cable to our house I am not sure we are ever going to get ADSL unless they fix the wiring to the cabinet or start installing miniDSLAMs in the cabinets.

ADSL Over 5kms

2007-01-11T12:59:00.000Z

OK, I have been struggling to get ADSL at my address on the outskirts of St Albans (BT exchange LBNSTB) for several years now.

We are just south of St Albans and live about 1km down a lane serviced by cable up poles (with a couple of dives underground to avoid overhead power cables). Unfortunately the BT exchange is located just on the north side of town and therefore our measured line length is about 5.3km.

I wanted a spot to document my efforts to get ADSL, partly to help me remember what I have tried, but I also hope it may help others to get ADSL on their marginal line.

I want to make it clear I am not in this to bash BT - I think they do a good job (I also still own a few shares from the old privatisation days). It is just that with the current state of the market and the technology it is not feasible to make ADSL available to all.

I want to understand the factors that might prevent you getting ADSL on a long line and what you can do to mitigate these factors.

I currently have broadband - via a two-way satellite link which cost about £1800 to install, £69 per month to rent and is probably not as good as a £14.99 512Kb/s ADSL link. I am happy with satellite compared with the old dial up connection I had, but to run an it consultancy and internet educational toy store from home really requires something a little quicker.