BT
- Thread starter Black Hole
- Start date
As long as you didn't short the wires and blow the fuse at the exchange : ) (I'm sure you didn't!)
The other point of the microfilter is to filter out the ADSL frequencies from the 'phone handset. The DSL connection is usually just a pass-through to the original A/B connections from the network. Good filters also have their own ring capacitor and will re-instate the ring wire for the telephone. More expensive ones use transistors too.
One quick way of potentially improving broadband speed is be to remove the ring wire from any extensions (disconnect the extension orange wire at the master socket) then use filters to re-instate the ring wire at each extension - assuming your 'phones actually need it which is less and less common. I played around a lot with the wiring in my house in the old days when the best ADSL speed I could get was around 280Kib/s. Most of my extension wiring is isolated now.
Most Openreach engineers I've worked with have been excellent. The problem usually comes when you get one of the contractors instead - Kelly or Quinn.
OP
Black Hole
May contain traces of nut
Yes, but it's the exact usage of the term 'engineer' that I have a problem with, not their skill as technicians.
I am aware of the ring wire issue, I got my sister's broadband speed up that way (downstream of the disconnect plate!). Once I have service I will see what can be done (I prefer the filtered ring wire route - the ring wire ought to remain connected really).
I am aware of the ring wire issue, I got my sister's broadband speed up that way (downstream of the disconnect plate!). Once I have service I will see what can be done (I prefer the filtered ring wire route - the ring wire ought to remain connected really).
OP
Black Hole
May contain traces of nut
The one is the equivalent of the other.
Yes, but your original statement implied (or I inferred at least) that the filter just enabled the DSL to work. DSL will usually work without a filter whereas the voice side becomes almost unusable unless one is present.
BMAX
Active Member
The line is current limited, (a)- for protection and (b)- to save power on short lines. Before the digital age, the current was limited by two relay coils of about 200 ohms each.
OP
Black Hole
May contain traces of nut
That is totally contrary to my understanding and experience.
Ezra Pound
Well-Known Member
ADSL broadband does not require micro filters for it work, the filters remove ADSL high frequencies that would otherwise be fed to the telephones. The low pass filter supplies the telephones with 300 - 3400 Hz as it was in the POTS days (Plain Old Telephone Services) and also prevents the telephones attenuating the ADSL frequencies when they go 'off-hook'
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prpr
Well-Known Member
If you'd like to soak up mine, I've got 130 quid's worth of it for a fault that was their side. ******g lazy ******d 'engineers' and those despicable ****s in India.
OP
Black Hole
May contain traces of nut
Is that received wisdom or personal experience? When I get a service back I will report what happens when the micro-filters are removed (I'll have a wager that the phones will work fine but the broadband won't).
Trev
The Dumb One
My actual experience is the same as that which EP suggests. You get ADSL noise on the phones. A shushing noise. You may be able to use the phone with this present, but that will depend on how much noise that you are prepared to accept and still call the voice side OK. When I checked the BB when the phone was off the hook, the throughput was considerably reduced, presumably due to 'noise on the line' causing error correction repeat requests or whatever they are called. But of course, my experience may be a load of coincidental s**t
OP
Black Hole
May contain traces of nut
With a phone on-hook there is an AC path through the bell circuit, and I have four in parallel...
OP
Black Hole
May contain traces of nut
My point is that with the (possibly unusual, but within spec) circumstance of four loads in parallel shorting out the ADSL frequencies if there were no micro-filters, the presence of the micro-filters may be essential to my broadband connection when maybe others can get away without them.
I am curious about EP's and AF123's assertion that micro-filters are not essential to ADSL - this would be true if the line were connected to an ADSL modem only, but when diplexed with a POTS service there can be any number of telephone apparatuses on the line up to an REN of 4. Regardless of the "pass through" nature of the micro-filter to the ADSL modem, the components in the micro-filter ensure that the AC impedance of the telephones do not absorb the ADSL signal.
This may not qualify as "essential", but it is certainly "advisable", and in some cases probably "necessary". It probably boils down to a disagreement on the semantics.
As to audible disturbance of unfiltered ADSL on the phone circuit, I don't know but I would have expected the frequencies to be too high to have an effect (unless there is some kind of intermodulation going on). My curiosity is already piqued, I will have a play when I get my service back!
I am curious about EP's and AF123's assertion that micro-filters are not essential to ADSL - this would be true if the line were connected to an ADSL modem only, but when diplexed with a POTS service there can be any number of telephone apparatuses on the line up to an REN of 4. Regardless of the "pass through" nature of the micro-filter to the ADSL modem, the components in the micro-filter ensure that the AC impedance of the telephones do not absorb the ADSL signal.
This may not qualify as "essential", but it is certainly "advisable", and in some cases probably "necessary". It probably boils down to a disagreement on the semantics.
As to audible disturbance of unfiltered ADSL on the phone circuit, I don't know but I would have expected the frequencies to be too high to have an effect (unless there is some kind of intermodulation going on). My curiosity is already piqued, I will have a play when I get my service back!
Telephone wire isn't twisted pair. Fitting Cat5 cable in place of telephone wire will improve the situation upstream of a micro-filter.
Certainly the ring wire can impose an additional impedance, and most modern phone installations do not rely on it, but it is part of the POTS specification and best left in circuit - downstream of the micro-filter.
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OP
Black Hole
May contain traces of nut
At last!
Meanwhile, the problem logging into my BT on-line account (post 1, note not my email account) has received a call back (which went to voice mail), offering interactive help with my email!
BT email said:
Meanwhile, the problem logging into my BT on-line account (post 1, note not my email account) has received a call back (which went to voice mail), offering interactive help with my email!
Ezra Pound
Well-Known Member
That will be an interesting report. Did you see the circuit diagram in #22? If only an ADSL modem is connected, the filter is not required, if only a telephone is connected a filter IS required, so my guess will be your next argument will be that when both an ADSL modem and a telephone is connected which benefits from the filter more, that will vary from installation to installation and would require a count of how many ASDL links fail without the filter and how many users can hear the unwanted ASDL frequencies on their telephones.
BTW
Internal telephone cable is twisted pair
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OP
Black Hole
May contain traces of nut
I have no argument with that, as per post 35. That is not what I would call normal service though.
It is? Maybe I'm getting confused with alarm wire (which I thought used stock phone cable for economy of scale).
Ezra Pound
Well-Known Member
You put the 5 minute editing feature to good use there (previously denying that pre broadband cable was twisted), in the mean time I photographed some 0.5mm solid core cable used by BT (the Post Office) 20 years ago and as you can see it is twisted pair, maybe the fact that your internal wiring isn't twisted, is causing you a problem
