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wolfmanii
Contributor
828 Views
Message 1 of 11

Would a speaker near the BTInfinity/Phone Socket affect line quality?

Hi,

    recently had issues with my phone line (but not BT Infinity which is great), where people complained that they could not hear us talking clearly (distortion or buzzing on line) but they were clear as a bell to us. I had a DECT phone connected, but bought a bog standard wired cheapo phone to check it was not the phone, but people still said that it was bad.

 

Because of location, I had a speaker next to the BT Box were the line comes into the house and wonder if this could be the cause of the voice distortion?

 

I have moved the speaker and so far, no complaints (but only 1 call), so I strongly suspect the speaker, just don't understand the mechanics of why it would affect the outgoing part of the line, but not the incoming or the infinity input/output data rates (37Mbit down/8Mbit Up)

 

Thanks

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Distinguished Sage
Distinguished Sage
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Message 2 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

The home hub 3 has a wireless transmitter which can be picked up by some telephones.

 

If you do not use WiFi, then you could turn it off.

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wolfmanii
Contributor
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Message 3 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

Not got HH 3 but HH 2.

 

Also wireless is used in the house. Still does not explain the hard wired phone getting the distortion on outgoing, yet since I have moved the speaker, while wireless in use, the phone was fine.

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Distinguished Sage
Distinguished Sage
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Message 4 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

What was the speaker for?

 

If it was connected as a monitor to  the phone line, then its still possible for it to pick up WiFi from the home hub, and induce interference onto the phone line.

 

See if its still there when you switch the home hub off.

 

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wolfmanii
Contributor
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Message 5 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

No, speaker is connected to Surround sound system. Just that optimum placing is right in front of BT box coming into house.

 

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Distinguished Sage
Distinguished Sage
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Message 6 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

Does turning the home hub off, stop the problem?

 

 

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wolfmanii
Contributor
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Message 7 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

Will check when at home.

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bfg
Aspiring Expert
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Message 8 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

hi wolfmannii,

 

A speaker creates quite a large electro magnetic field because a speaker is just a suspended cone connected to a large electro magnet (which moves the cone to create sound).

 

Any strong elctomagnetic feild can have an 'unusual affects' on other electronic equipment, it is possible that the speaker was distorting the signal genretaed by the landline/phone. In the main socket there is a simple circuit board with capictors, restistors ect and it is possible that the interference is having an affect on the calls.

 

I would have thought the affect would cause problems with both incoming and outgoing, and to check why only outgoing you'd need to record the field frequency of the speaker and the signal frequency, and it would probably explain why only on one way.

 

DO NOT TRY THIS AT HOME:

A great example of this affect is to place a magnet by an old television the field distorts the elctrons in an old CRT TV and changes the colour and position of where the pixels should be displayed, youv'e probable seen this affect in science musems and in school science experiemnts.

 

hope that simple explanation helps.

 

PS it is also possible that the speaker was interferning with the wifi from the hub and in effect 'breaking' the hub(creating a feedback loop through the hub, again would depend on the speaker and frequency it produces) and the noise was being generated by the hub and thats why you also had it on a corded phone.

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wolfmanii
Contributor
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Message 9 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

Thanks for the explanation. My confusion was over the outgoing voice being affected but not data or incoming voice.

 

Turning wifi off made no difference to the problem, moving the speaker seems to have cured it on the few calls that we have made/received since.

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bfg
Aspiring Expert
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Message 10 of 11

Re: Would a speaker near the BTInfinity/Phone Socket affect line quality?

Hi Wolfmani,

 

Its basically caused by whats called an 'anti aliasing' affect, the reason for the affect on one service and not the other is caused by the differences in the two signals used to provide the PSTN and ADSL.

 

The PSTN signal is relatively slow compared to the ADSL signal (lower frequency). The interfernce from the speaker will be at another frequency (i suspect some where between the PSTN and ADSL, but closer to the PSTN, as both are just audio frequencies) and where the two frequencies 'interact' or 'cross over' it cancels that part of the frequency (or causes the frequency to increase and go beyond the tolerences accepted by your phone).

 

This cancellation affect is what you hear (or dont hear) on the calls.

 

Another good(easier to see) example of this would be car wheels on TV/films etc, this affect is why a car wheel appears to slow down and reverse its direction when the car is accelerating (the camera records at 25 frames per second which is a lower frequency than the car wheel actually moves at when at full speed, so cancels part of the frequency/image depending on the speed of the wheel, at slow speeds the wheel moves at a slower frequency, less than 25fps, so the frame rate has no affect on the image, but as the speed increases and reaches the same frequency/frame rate you start to miss part of the image in the recording, i.e very basically if a wheel moves 25r/p/second, you dont loose any image, but if at 50r/p/second you loose one out of two images, 75rp/second you loose two out of 3 images)

 

So for your example, imagine your data is the car and the wheels are the voice signal, the frame rate isnt enough to affect the view of the car but interferes with the wheels.

 

hope that helps clear it up (or possible just confuse the situation  further lol)

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