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Author Topic: How much bandwidth do I get over a phone line?  (Read 4742 times)

Offline syhprum

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How much bandwidth do I get over a phone line?
« on: 03/01/2012 07:03:24 »
As correspodents may have guessed some of my ideas about technology are rather outdated; If I make a dialup telephone call to America via one of the fibre optic cables, do I get a 3 or 4KZ bandwidth duplex circuit that I could use for uncompressed  slow scan TV or Facsimile, or is my speech converted to low data-rate digital and switched about as in the TAT1?
« Last Edit: 03/01/2012 09:24:54 by chris »


 

Offline Geezer

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Re: How much bandwidth do I get
« Reply #1 on: 03/01/2012 07:38:55 »
I don't think they are so outdated!

I really don't know, but my guess is that the only time you get any sort of dedicated bandwidth these days is on a local subscriber loop (between your phone and the telephone exchange).

In our case, we don't even have that. Our "land line" phone is Voice Over IP through a cable modem. The only dedicated bandwidth we get is between the handset and the modem in our basement.
 

Offline syhprum

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Re: How much bandwidth do I get
« Reply #2 on: 03/01/2012 08:26:14 »
I miss the old uncompressed TV ,I have a good quality VHS recorder and in the old days you could play back the transmission one frame at a time (You could check out how much marge was expected to pay for the baby at the till) but you can't get frame by frame play back on the MJPG2 stuff that we get today.
 

Offline RD

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Re: How much bandwidth do I get over a phone line?
« Reply #3 on: 03/01/2012 11:35:36 »
... do I get a 3 or 4KZ bandwidth duplex circuit that I could use for uncompressed  slow scan TV or Facsimile

It is possible to Fax via your PC , (sometimes for free) ...
https://www.pcworld.com/businesscenter/article/163630/make_internet_fax_services_work_for_you.html
« Last Edit: 03/01/2012 11:40:18 by RD »
 

Offline syhprum

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Re: How much bandwidth do I get over a phone line?
« Reply #4 on: 03/01/2012 11:55:15 »
I do in fact use it but I wanted to know if I could still use my olde worlde Muirhead machine or at least a simulation of it.
I recieve weather satellite pictures that are in a completly uncompressed format I was wondering how they would fare.
I could do it fourty years ago provided I got a cable connection and not a satellite but I wondered if the compress everthing fanatics had been at work. 
 

Offline RD

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Re: How much bandwidth do I get over a phone line?
« Reply #5 on: 03/01/2012 12:32:19 »
There was a thread on a similar topic: whether it would be possible to convert FSK data for 1980s computer from audio cassette to mp3 (which is a lossy compression format) ... http://www.thenakedscientists.com/forum/index.php?topic=41696.msg374680#msg374680
« Last Edit: 03/01/2012 12:42:00 by RD »
 

Offline syhprum

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Re: How much bandwidth do I get over a phone line?
« Reply #6 on: 03/01/2012 16:47:00 »
I love simulations, apparently you can get a single chip version of an ENIAC 20,000 tube computer with a GUI so that you don't have to swop cables around to program it, what ever next a lap top Babbage differential engine ?
 

Offline SeanB

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Re: How much bandwidth do I get over a phone line?
« Reply #7 on: 03/01/2012 18:01:34 »
Your phone line is analogue till it hits the exchange if you are on POTS, where it then is bandpass filtered from 300 - 3400Hz, then digitised with 8 bit resolution. Some exchange equipment chops off the lowest bit, and then it is sent to the recipient, either direct or via a series of gateways. Along the way it can be compressed and limited further, and on long links is often heavily echo compensated. If the other end is also POTS then the same happens again. If going to a cellular or VOIP system then it is often both heavily compressed and has lossy coding applied, so it may not even handle 2400Baud reliably, even if the speech is intelligible.
 

Offline syhprum

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Re: How much bandwidth do I get over a phone line?
« Reply #8 on: 04/01/2012 01:57:14 »
As far as I can asertain the E Fax is classed as PN2 charge wise ie £0.51 per minute but I will be checking with my service provider (Virgin) as soon as possible.
I like fax people take far more notice of a faxed message than they do an email.
 

Offline syhprum

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Re: How much bandwidth do I get over a phone line?
« Reply #9 on: 04/01/2012 10:32:49 »
I checked with "Virgin" that provide my POTS along with my fibre optic broadband and find that using the 7043* number allocated to me by E Fax sending an A4 page and title sheet taking 1:32 Mins to myself they charged me £1.16 inc VAT.
 

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Re: How much bandwidth do I get over a phone line?
« Reply #9 on: 04/01/2012 10:32:49 »

 

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