My dial-up modem fantasy

My dial-up modem fantasy
NewsGroups | Search | Tools
User Password
Register Now! Lost Password?
 comp.dcom.telecom.tech  Post an article  get this group's latest topics as an RSS feed add this group's latest topics to your My MSN content add this group's latest topics to your My Yahoo content  add this group's latest topics to your Google content  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
My dial-up modem fantasy Green Xenon [Radium] 05-21-2008
Posted by Green Xenon [Radium] on June 14, 2008, 3:32 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
DTC wrote:
> Green Xenon [Radium] wrote:
>> In the real world, what is the maximum amount of bits-per-symbol that
>> can be achieved using PSK without exceeding the dynamic range of a
>> phone line?
>
> Lets dispense with confusing references to bits, symbols, phase shift
> keying, etc. and get down to the nitty gritty....
>
> Answer: About 48 Kbps data rate.
>


I am specifically interested in the bits-per-symbol only. I wasn't
asking about the date rate -- i.e. the 48 Kbps you described. I am
asking only about the bits-per-baud.

Assuming a baud of only 1-symbol-per-second, what is the maximum amount
of bits-per-symbol that can be achieved using PSK without exceeding the
dynamic range of a phone line?

Network Magic 20% Off NMEASY coupon code spring banner 468x60
Posted by R.L. Horn on June 15, 2008, 12:42 am
If you were  Registered and logged in, you could reply and use other advanced thread options
On Sat, 14 Jun 2008 12:32:44 -0700, Green Xenon [Radium]

> Assuming a baud of only 1-symbol-per-second, what is the maximum amount
> of bits-per-symbol that can be achieved using PSK without exceeding the
> dynamic range of a phone line?

I believe the maximum using any encoding should be in the neighborhood of 8
bits. That's assuming an SNR of around 24dB, which is...optimistic. In
practice, a fairly conservative figure of 20dB is often seen, which yields
6.66 (oooh, spooky) bits in 1 Hz of bandwidth (or 26.6kbps in 4kHz).

V.90 manages better than that, but it requires one end be connected directly
to a digital trunk.

Posted by H. Peter Anvin on June 14, 2008, 3:15 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
Green Xenon [Radium] wrote:
> In the real world, what is the maximum amount of bits-per-symbol that
> can be achieved using PSK without exceeding the dynamic range of a phone
> line?

Well, given the fact that most telephone circuits are digitized to
64 kbps at the central office, that is an absolute maximum.

The copper lines themselves are obviously capable of much higher
capacity with a suitable change of equipment at the central office.
This is the technical basis for ISDN and DSL.

        -hpa

Posted by henry cabot henhouse III on May 27, 2008, 9:49 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
sorry, those of us who clone advanced life forms in our supersonic colonic
colliders don't like to talk about such things...ooops gotta run, the
Interociter is whizzing...




> Hi:
>
> My internet-access fantasy involves dial-up modem telecommunications
> technology devices which use PSK [Phase Shift Keying] as the modulation
> scheme. This too-good-to-be-true PSK uses only 1-symbol-per-second but
> with a Graham's-number amount of bits-per-symbol.
>
> http://en.wikipedia.org/wiki/Graham's_number
>
> Now that is a lot of bits-per-baud!
>
> If it were possible for such PSK to exist, what would be the disadvantages
> of it?
>
>
> Thanks,
>
> Radium
>



Posted by R.L. Horn on May 27, 2008, 10:02 pm
If you were  Registered and logged in, you could reply and use other advanced thread options
On Wed, 28 May 2008 01:49:05 GMT, henry cabot henhouse III

> ooops gotta run, the Interociter is whizzing...

Is that a quantum interociter or an n-field multiversal interociter? I've
noticed that the latter really kick up a racket when the neutron-flow
polarity gets out of whack.

Similar ThreadsPosted
maximum number of devices on POTS line? (a tale of dialup woe) August 28, 2005, 4:39 am
Virtual Modem for VoIP March 10, 2005, 9:03 pm
telephone parallel to modem January 15, 2006, 11:45 pm
Alarm on ASMi-52L modem April 21, 2008, 12:19 am
How do I wire up a PC modem to dial a POTS phone line? August 4, 2006, 8:48 am

other useful resources:
The Federal Communications Commission (FCC)
Telecommunications Industry Association
Electronic and Software Security Products and Services
International Telecommunication Union

Custom CGI Perl and PHP programming by 1-Script.com

Contact Us | Privacy Policy
The site map in XML format XML site map