[GreenKeys] Mystery RTTY RY Comparison

[B. Smith]

I was curious about Doug's remark that the RY sequence created by the 
555 Square Wave generator might sound "syncopated".  His comment below. 
So  I made a short comparison video of  the 555 generator RYs and 
another RY source.
k4che
http://k4che.com/Tempvideo/RY%20Comparison/555RYComp.mp4

"This would give RYRYRY, but it would probably be rather sensitive to the rangefinder setting.  I'd expect the RYRYRY to sound a bit syncopated, that is, more like RY RY RY RY (not printing spaces, but a little off in the timing)."

T

On 7/8/2023 10:06 PM, Jones, Douglas W wrote:
> From: Harold Hallikainen via GreenKeys [greenkeys at mailman.qth.net] -- Saturday, July 8, 2023 5:49 PM
>
>> So, it seems like we'd get framing errors on a square wave
> Mechanical asynch receivers like TTYs don't detect framing errors, nor do they much care about them.
>
> Here's what I would have expected.
> 1 --- idle line
> 0 - start
> 1 - D0
> 0 - D1
> 1 - D2
> 0 - D3
> 1 - D4
> 0 - stop (framing error, but note*
> 1 --- idle line, note **
> 0 - start
> 1 - D0
> 0 - D1
> 1 - D2
> 0 - D3
> 1 - D4
> 0 - stop
> 1 --- idle line, note **
> 0 - start
>
> Note*: yes, a framing error, but the TTY doesn't care, it's simply insensitive to the state of the line for about 31 ms
> Note**: for 9 ms, the line is ignored as part of the stop bit, the remaining 13 ms of this 1 bit are seen as an idle line.
>
> The net result?  I wouldn't have expected RYRYRY, I'd have expected RRRRRR from just a square wave.
>
> Unless what is happening is the following:
> 1 --- idle line
> 0 - start
> 1 - D0
> 0 - D1
> 1 - D2
> 0 - D3
> 1 - D4
> 0 - stop also sensed as a start bit for the next character ***
> 1 - note ****
> 0 - D0
> 1 - D1
> 0 - D2
> 1 - D3
> 0 - D4
> 1 - stop (not a framing error)
> 0 - start
>
> Note***: framing error, clutch remains engaged, shaft continues to spin.
> Note****: 0-1 transition was 9 ms before expected end of stop bit, too little time for it to matter.
>
> This would give RYRYRY, but it would probably be rather sensitive to the rangefinder setting.  I'd expect the RYRYRY to sound a bit syncopated, that is, more like RY RY RY RY (not printing spaces, but a little off in the timing).
>
>            Doug Jones
>            jones at cs.uiowa.edu
> ______________________________________________________________
> 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 smithab11 at comcast.net