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Digital Distance, a myth?

dws1900
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Digital Distance, a myth?

In another post, the consumer has been told by an engineer that they go by the digital distance not the actual physical distance.

 

1. The actual physical distance will not change unless openreach rewire the circuit to increase/decrease the line length.

2. The attenuation of the line will change if number 1 is carried out, the wire gauge is change and also if there is resistance due to bad connections, there are probably others.

3. The golden distance for vdsl, according to the only graph I have seen is 800m, I assume this is theoretical and only one line is in use.

4, Throughput between the consumer and the dslam is affected due to errors caused by crosstalk, crosstalk increases due to more subscribers using the multicore cable. This is exacerbated by openreach adding more consumers to the cable by virtue of the addition of a new frame to the side of a dslam.

Assuming a 10% drop, if you are on the maximum speed set by the isp, typically 40Mbs, then you will see a drop of 4Mbs, ie 36Mbs. For those unfortunate to be on longer line (like me) then a 10% drop  on 21Mbs is 2.1Mbs, which means 18.9Mbs.

Of course I still pay the same price as those lucky consumers getting 40Mbs.

FTTP would be a better option, BUT the throughput/latency  will still suffer due to congestion, poor backhaul, equipment, server response and capping.

As faster speeds are required for new service , UHDtv etc there will still be issues.

 

I am sure a more learned person will offer/agree/disagree to my writings Smiley

 

 

 

 

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prettygrim49
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Re: Digital Distance, a myth?

i agree with you, dws1900 but the engineer used the 'digital distance' as opposed to the cable route distance to justify the speed loss. he added in, for good measure and make it seem even more likely that the reason the speed has dropped is because of all the extra connections made into the one cabinet (no new buildings, remember) on the VDSL side, leaving the ADSL side, creating a great amount of cross talk. it's the number of connections that baffles me. why would there suddenly be a massive increase in the number of homes wanting to make this change? why is the limit of connection numbers being exceeded, as it must be, because existing customers are losing speed in order for extra customers to be connected, the typical 'rob Peter to pay Paul' scenario. if this is correct, it's being done for pure greed at existing customers expense and that is dreadful!

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Re: Digital Distance, a myth?

I assume that the engineer was using "digital distance" as a simpler term for attenuation.

dws1900
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Re: Digital Distance, a myth?

@prettygrim49 

Maybe consumers are seduced by faster speeds, and jump onto the bandwagon. This will then increase the number of consumers on the lines from the dslam to the consumers, increasing crosstalk and hence errors reducing throughput.

The connection speed will remain pretty constant, but the amount of traffic passed will reduce.

AFAIK the connection speed is the one used as the benchmark by the ISP's, if this speed drops then they can let you out of the contract, but to where, it's all the same infrastructure to the exchange.

ADSL and VDSL are on different frequencies, hence differing bandwidths, hence different speed ranges.

There are moves to get people off adsl and onto vdsl, which will make the situation worse.

Coupled with that Openreach are apparently focussing on FTTP, but when will we get it,  who knows (Certainly not Boris)

Getting FTTP put in now will typically cost in the region of 20K, (there are reductions for companies/charities in the area to be covered), I looked into it, it worked out to 500 quid per property, thats if they all signed up.

 

There is a market for 4G/5G, but to get a decent price you need to tie in for 24months, and only one suppler will do unlimited.

The unknown is how reliable is it, and whats it like speed wise during peak times. Latency may be a problem for some.

There is a market here for mobile providers as logically going onto 4G with the promise of 5G looks attractive.

 

What is annoying is there are third world countries with better internet services. 

 

As for the mystical 'digital distance', and this is my interpretation,  if a sole user had access the dslam, within the golden 800m, then the 'digital distance' would be 800m.

Add a lot more consumers, more crosstalk on the copper part of the circuit, the speed drops, so to get the same speed as the one user, you would have to physically move close to the dslam, thereby having a different 'digital distance'

Surprisingly I cannot find a reference to 'digital distance' anywhere, quelle suprise!!

 

I am sure someone will correct me Smiley

 

 

 

prettygrim49
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Re: Digital Distance, a myth?

that i cant say, ejs. i dont remember him using it as an alternative term for attenuation. i was of the opinion that attenuation is another name for noise, measured again in db. please correct me if i am mistaken. from what i understood though, he was using each connection on to the line as a place for electrical interference, due, in the main, to those connections getting damp and corroded, increasing the resistance. again, correct me if i'm wrong

prettygrim49
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Re: Digital Distance, a myth?

just had Plusnet use 'digital distance' to me again. i had never heard of it until today but as it seems it can refer to increasing the distance a cable is from home to cabinet, not in length but in interference, i'll bet a pound to a pinch of that it will now become the 'go to words' to use to justify any customer's speed loss! actually doing anything to correct the real problem and cause still wont happen, i'll bet!

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Re: Digital Distance, a myth?

Attenuation is the decrease in the signal, and has nothing to do with noise.

 

Now that I've heard the context, "digital distance" was probably just inventing your own terminology without really defining what it means, to fob off someone who wouldn't know what any of the proper terms meant.

dws1900
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Re: Digital Distance, a myth?

@prettygrim49 

 

If 'digital distance' is a measurement to be used in determining the state of a line/circuit then...

 

1. How is it calculated, where is the formula?

2. How is it measured?

3. Is it registered with a standards authority?

I challenge Plusnet to provide answers to these questions without delay.

prettygrim49
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Re: Digital Distance, a myth?

the info given to me by the engineer was that every connection on to the cable between the cabinet and in this case my home created an electrical resistance. all those resistances, especially if some/all the connections were corroded, when added up constitute a longer line in relation to one that has no connections to it except the start point (the cabinet) and again in this case, my home. as i said previously, i have never heard of this before but as it now gives yet another excuse for poor quality service as well as a reason to NOT correct anything, i'll bet a pound to a pinch that it will be used more and more, even to the extent that it becomes the 'go to' excuse for all speed issues.

i remember reading somewhere a while ago where BT/Openreach were able, should they want to, to do something in the cabinets to eliminate crosstalk. the engineer who was at my home yesterday, given that he is a senior engineer and trains other engineers, had never heard of it, is this something i dreamed or something that can be done? if it is an option (the figure of £5k seems to come to mind), then why isn't it being done? surely it's a better option than having engineers called out over issues that are caused by interference (cross talk), isn't it? or is this simply another option that has been ignored because it would make the service better?

dws1900
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Re: Digital Distance, a myth?

@prettygrim49 

 

Bad joints will increase resistance and attenuation.

On the phone side, this will reduce the line voltage to the point the phone may not function correctly.

On the Adsl/Vdsl side it  will increase attenuation which can cause errors, requiring resending of packets, resulting in reduction of throughput speeds (the one that is the result of a speed check).

The phone line is a twisted pair of wires, running in a cable which has a number of other pairs, and was designed to prevent crosstalk between analogue phone lines.

 

The line (non Exchange Only) goes from the consumer to a distribution cabinet (usually the older non shiny ones) and onto the exchange.

If you are on adsl, then the equipment is in the exchange.

Vdsl lines are split, and the new copper pair goes to the dslam (usually the shiny one close to the not so shiny one).

Here it is then put onto the fibre cable to the exchange.

All connections can cause a drop in voltage/signal, and on an ideal world there wouldn't be any.

Adsl/Vdsl is a radio signal, so if you had a break in the line, it will still work, but the phone would not, it needs both wires to form a loop. *

Interference can be conductive, ie down the wires, or spatial, ie external radio frequency emissions such as radio transmissions, dodgy power supplies and more. Overhead lines tend to be more effected  to the latter type (think big long antenna!!) *

None of this will increase the physical line length (see earlier post)

 

The engineer is correct, but it is his employers (OpenReach) line and responsibility to repair any issues on the line.

Crosstalk is also OpenReach responsibility, and I wonder what is going to happen in the future, I expect they will move the goalposts somehow. 

 

* people in my locality have had all these faults at one time or another.

prettygrim49
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Re: Digital Distance, a myth?

to ejs

i thought it was noise that caused the problems with the signal (attenuation), so i'll stand corrected if that isn't the case.

plusnet actually used this 'digital distance' term to me the day before the engineer visit by saying the distance from my home to the cabinet. i know the cable route and that distance so said she was wrong. when the engineer used the same term when he was here the next day, it seemed pretty strange to me that from never hearing the term before, never seeing it written anywhere before, never having known the term to be used by any other person, engineer or not before, it's suddenly the 'reason of choice'. it makes me wonder if someone, yet again, has dreamed up this term just to give, as i said before, another excuse to be used so as to NOT have to sort problems out?

Baldrick1
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Re: Digital Distance, a myth?

It sounds to me like the latest bussword used to justify a poor line. I guess that a metre of aluminium wire has a longer digital distance than the same length of copper.  Saying your connection has a high digital distance is easier to trot out than admitting that you have a rubbish line and that nothing will be done to improve it.

prettygrim49
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Re: Digital Distance, a myth?

i appreciate that corrosion on joints can cause issues but they are usually, or so i thought, for the property connected by that joint, rather than everyone else up or down the line length. i have never heard of it being used as a means to say a cable is 'longer than it physically is', so that is definitely a new one on me. i wonder if it will be added into the dictionary next time?

as for Openreach moving the goalposts, they're on wheels to make it easier and quicker! while they are allowed to get away with things, including the treatment of customers, either directly or indirectly, they will. individual customers are always poo poo'd off. the only way to get change is for companies that are affected by the way things are to stand up and be counted. most wont because they still get monies from their customers, so the pot is always filling up and only the bottom of the pile customers, us, feel the brunt, are the ones who get the least bang for the buck! in reality, our only hope is with FTTP being installed but i doubt if i'll still be around to see it. i live in hope!