[GreenKeys] 1 or 1.5 stop bits?

[Stan Voynick]

My attitude here (coming from an Engineering background) is that if you're designing something to transmit, then design it to produce a 1.5 stop bit.  If you're designing something to receive, then design it to tolerate a 1.0 stop bit.  This ends up giving you more "margin" for recovering from sync problems, noise bursts, different pieces of equipment at either end, etc.

Now, as a designer, you may be burdened by other constraints that override this:  for example, if you need to maximize throughput, then transmitting a 1.0 stop bit will give you around a 7% higher character rate (relative to 1.5) on max-speed transmissions. Everything is a design tradeoff of "cost" vs benefit. (I put "cost" in quotes here because it's not just financial - giving up noise immunity is a "cost" that may be worth it for a particular benefit, as in the example above.)

- Stan V
WB7RPG



>     On January 2, 2022 4:20 PM Ralph Mowery <rmowery42 at charter.net> wrote:
> 
> 
> 
>     You should use 1.5 stop bits if possible.
> 
>      
> 
>     Some machines have used only one stop bit and you get a slightly higher number of characters per minute.     I would have to look but not going to but I think that is where the 66 wpm comes from instead of 60 wpm.
> 
>      
> 
>     You may be able to get away with 1 stop bit, but 1.5 is needed and if more than 1.5 such as 2 stop bits all you lose is a few wpm through put. 
> 
>      
> 
>     Ralph ku4pt
> 
>      
> 
>      
> 
>      
> 
>     From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of W2HX
>     Sent: Sunday, January 02, 2022 6:07 PM
>     To: GreenKeys at mailman.qth.net
>     Subject: [GreenKeys] 1 or 1.5 stop bits?
> 
> 
>     Sorry for rudimentary question. If I am configuring a serial port for use with 45.45 baud ITA-2 mechanical teletype operation, should I use 1 stop bit or 1.5? I can’t recall the proper set up. And when RTTY users on the HF bands what do they use?
> 
> 
>     73 Eugene W2HX
> 
>     Subscribe to my Youtube Channel: https://www.youtube.com/c/w2hx-channel/videos
> 
> 
> 
> 
>      
> 
>     ______________________________________________________________
>     GreenKeys mailing list
>     Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>     Help: http://mailman.qth.net/mmfaq.htm
>     Post: mailto:GreenKeys at mailman.qth.net
> 
>     >>> Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
>     >>> 2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
>     >>> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
>     >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html
> 
>     This list hosted by: http://www.qsl.net
>     Please help support this email list: http://www.qsl.net/donate.html
>     Message delivered to svoynick at selmar.com
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20220104/98646bcf/attachment.html>