raspikeyer/KnowHow.md

Know How

This is just a collection of information useful for this piece of software.

CW speed

We make the following assumptions:

• The basic unit for morse code is the element.
• A dot is one element.
• A dash is three elements.
• A character is a sequence of dots and dashes.
• The space between the dots and dashes within a character is one element.
• A word is a sequence of characters. The characters within a word are separated by three elements.
• The space between two words are seven elements.

So let's look of how many elements the word PARIS consists:

  P = 11 elements + 3 elements
  A =  5 elements + 3 elements
  R =  7 elements + 3 elements
  I =  2 elements + 3 elements
  S =  5 elements + 7 elements
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31 + 19 elements = 50 elements
                   ===========

If we then send this combination 5 times in 1 minute, we have sent at a rate of 5 WPM. Or 250 elements per minute. If we then take 60 seconds and divide it by these 250 elements we get 0.24 seconds/element. We can then say, at 5 WPM, each Element is 240 ms in length.

This can then be broken down into a simple formula for calculating WPM based on the length of a single morse code dot. WPM = dots/min/25 = 2.4 × dots/sec

In the case of 1 WPM, the duration of a dot is 60 seconds / 50 dots per minute = 1.2 seconds per dot. Also, for any other speed, we can define the dot length as equal to 1.2 seconds divided by the speed in WPM. Based on the above we can use the following formulas:

• Speed (WPM) = 1.2 / Dot length (seconds)
• Dot length (seconds) = 1.2 / speed (WPM)