[GreenKeys] 66 WWPM ITTY

[Ralph Mowery]

The mark/space tones have been a problem for years.  I think the problem is when the hams started feeding audio into the SSB transmitters.  Due to the way it works, the tones are actually reversed when trnsmitted.  The usage was that the mark tone was the higher frequency and shifted lower for space.  By putting the audio tone of 2125 into the ssb transmitter and then shifting up to the higher space frequency (2295 or 2975) and using lower sideband, the actual radio frequency would be shifted lower.
 
Difficult for me to explain in print.  However when just the audio is used on the FM or AM transceivers the tones will be mark of 2125 and the space will be a higher frequency.

Anyway, going from the way hams and much  comercial tones are sent, one is usually reversed from the other.  Using the most common demodulators require that you use lower sideband and normal for hams and upper sideband and normal for comercial , or you can reverse the sidebands and also the normal and reverse positions of the demodulator.  Slightly confusing isn't it ?





  ----- Original Message ----- 
  From: Martin 
  To: GreenKeys at mailman.qth.net 
  Sent: Monday, February 07, 2011 5:20 PM
  Subject: Re: [GreenKeys] 66 WWPM ITTY


  I sent this yesterday meaning it to go to the list but got it wrong again!


  PS Its not an issue, but am I wrong in thinking the mark and space 
  convention is supposed to be the other way around!

  Martin