Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Absolute Timing of International Morse  (Read 3152 times)
W6UV
Member

Posts: 538




Ignore
« on: February 13, 2011, 07:43:11 PM »

I'm trying to determine the length of the basic element of International Morse -- the "dit".

My calculations go as follows:

The duration of the dit is the basic timing element. A dah is 3x the dit. Inter-element spacing is the length of a dit. Inter-letter spacing is 3x dits. Inter-word spacing is 7x dits.

The word PARIS has traditionally been used as the standard "word" when determining WPM speeds. Adding all of the elements of PARIS together yields 43 dit elements.

So, now taking 20 WPM as an example, sending PARIS 20 times will take (20 * 43) + ((20-1) * 7) dit durations. The total is 993 dit times. Dividing this into 60 seconds yields a dit time of 60.4 msec.

If one dit at 20 WPM is 60.4msec, then this generalizes to:

dit time = (60.4msec * 20) /WPM = 1208msec / WPM

Are my assumptions and calculations correct? Is any of this defined in a formal specification somewhere?
Logged
DJ1YFK
Member

Posts: 191


WWW

Ignore
« Reply #1 on: February 14, 2011, 01:08:07 AM »

The common calculations include the last inter-word space of 7 dits, which then yields exactly 1000 dit times for 20 * PARIS, resulting in the formula dit_time = 1200 / WpM. Much easier to remember :-)

I don't know if there's a formal definition anywhere, but I'd be glad to learn if there is one.

73
Logged

N2EY
Member

Posts: 3895




Ignore
« Reply #2 on: February 14, 2011, 03:39:52 AM »

DJ1YFK is correct. "PARIS" is exactly 50 dit-times long, so you get the formula 1200/wpm for the length of a dit in milliseconds.

Of course all such formulas are approximations based on the "average" length of a character (which can vary from the single dit of "E" to the long punctuation such as the comma) and the "average" length of a word (typically assumed to be 5 characters).

73 de Jim, N2EY 
Logged
W6UV
Member

Posts: 538




Ignore
« Reply #3 on: February 14, 2011, 02:28:29 PM »

Thanks.

I need to generate Morse via computer and wanted to make sure I had the basic timings correct.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!