Merit Network
Can't find what you're looking for? Search the Mail Archives.
  About Merit   Services   Network   Resources & Support   Network Research   News   Events   Home

Discussion Communities: Merit Network Email List Archives

North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: And we thought the text part of the Starr Report would be bad

  • From: Eric Sobocinski
  • Date: Wed Sep 23 17:26:18 1998

On Tuesday, 22 Sep 1998 at 22:43 EDT, Robert Szarka 
        <> wrote:
>At 11:22 AM 9/22/98 , you wrote:
>>	For modem to modem communications, start and stop bits were used
>>	up through 2400 baud when one bit = one tone.  The method of one
>>	bit = one tone was dropped for other forms of encoding when modems
>>	started supporting connection speeds in excess of 2400 baud.  
>I assume you mean 2400 bps modems, i.e., v.22bis?  Admittedly, it's been a
>while since I used one, but my recollection is that 2400 bps modems operate
>at 600 baud, with 4 bits/baud using QAM.

Your memory about v.22bis at 2400 bps is entirely correct.  v.22 at 
1200 bps/baud was the last of the 1 bps = 1 baud dialup modem standards.  However, v.32/v.32bis/v.32ter/v.34/v.34bis all use trellis coding and 
additional tricks to get high bit rates out of 2400 baud.  It is 
technically possible to get 2400 bps at 2400 baud from any of these
latter standards, though realistically the only place you'll find
conditions twisted enough to do that is in the lab.

--eric  (speaking only on my own authority, as usual) 

Discussion Communities

About Merit | Services | Network | Resources & Support | Network Research
News | Events | Contact | Site Map | Merit Network Home

Merit Network, Inc.