[RTTY] RTTY

[Al Kozakiewicz]

The introduction of intercharacter delays would definitely change the throughput while not altering the timing a bit.

Al
AB2ZY

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On Behalf Of Don Hill AA5AU
Sent: Monday, March 21, 2011 9:07 PM
To: rtty at contesting.com
Subject: Re: [RTTY] RTTY

In MMTTY, there is both a "Character wait" and "Diddle wait" which make your transmission go out slower.  In the TX tab of MMTTY Setup, there is a check box for "Disable Wait".  If it is not checked, then MMTTY uses the values as set in the two slider bars for character wait and diddle wait.  Testing in FSK, revealed that indeed both of these slider settings change the "speed" at which the "characters" or "diddles" are sent.  With both sliders all the way to the left, it appears is the same as checking the "Disable Wait" check box.  As you move either slider to the right, the "speed" appears slower even though it's still decoded at 45.45 baud.
Here's what the MMTTY help file says:

"Transmit Wait Adjustment

There is a transmit wait, or delay, control, that appears by default as "Both Wait" at the far right of the transmit menu. The slider to the right controls the amount of time (wait) between transmission of characters. Select one of four values by clicking the label. 
  
Disable wait - Slider position does not matter, there is no wait. 
Char. wait - Delay character transmission. 
Diddle wait - Delay diddle character transmission. 
Both wait - Delay both character and diddle transmission. "


I don't see a "Both wait" option in version 1.68 so maybe that was left over from a previous version.  Elsewhere in the help file it says something about using "wait" if there is a problem on a slower computer.  I doubt anyone would have a problem these days and everyone should disable wait.

73, Don AA5AU
http://www.aa5au.com
http://www.rttycontesting.com 

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On Behalf Of Al Kozakiewicz
Sent: Monday, March 21, 2011 7:11 PM
To: 'Ktfrog007 at aol.com'; rtty at contesting.com
Subject: Re: [RTTY] RTTY

>What is the effect of the sound card clock adjustment? 

Nothing as far as data transmission/reception is concerned.  With ansynchronous communications. you need a clock at each end running at (in the case of 45.5 baud, close to) the same frequency.  The leading edge of the start bit tells the receiver to start clocking the data bits into individual registers.  The meaningful exchange is over once the agreed upon data and parity bits have been sent.
The stop bit(s) are a vestige of  the electro-mechanical days.  They provided a time slot to imprint the character.

If RTTY is "slow", it can only be due to more stop bits being sent in a character than necessary, or very inefficient shifting.
It's not due to the sender's bit clock being slow - that would just cause the transmission to be indecipherable.

Al
AB2ZY

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On Behalf Of Ktfrog007 at aol.com
Sent: Monday, March 21, 2011 7:51 PM
To: rtty at contesting.com
Subject: Re: [RTTY] RTTY

Hi Don,
 
What is the effect of the sound card clock adjustment?  Is it related  to speed issues?See Calibrate the Sound Card in the Help file and the Misc tab in MMTTY setup.  I've never understood what it is and what the adjustment does.
 
73,
Kermit, AB1J
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