[GreenKeys] 60 Meters now open to RTTY on USB

[Ralph Mowery]

The term AFSK is being misused by many now.  True AFSK is when you feed audio into an AM or FM transmitter.  

If pure sine waves are fed into a SSB transmitter, you do not have AFSK, but just FSK.  There are no sidebands or carrier, just the mark tone and space tone (one at a time) is transmittted.  All of this is assumed that the transmitter is working as it should.

For someone on the receiving end, there is no way to tell if the tones are injected into the microphone or other audio input to a SSB transmitter.  Well, you might if you looked at a signal many dB down.
It will be sent to the antenna the same as if a single carrier was shifted by the same ammount such as the normal 170 Hz shift.

If you feed audio into an AM transmitter, you get a carier and the two sidebands.  With a FM transmitter, you get lots of sidebands so to speak.

I have not kept up with the rules, but unless maybe on 10 meters, I do not think that True AFSK (AM or FM, not SSB) has ever been legal on the HF bands.  I think it may have been legal on the old 11 meter ham band at one time, but that predates many of us.



  ----- Original Message ----- 
  From: WA5CAB at cs.com 
  To: larryradio at att.net ; wa2hwj at att.net 
  Cc: greenkeys at mailman.qth.net 
  Sent: Tuesday, November 22, 2011 6:40 PM
  Subject: Re: [GreenKeys] 60 Meters now open to RTTY on USB


  Short answer is yes.  Probably for several reasons but one is enough.  AFSK has two sidebands.  The carrier frequency is specified as being at the lower channel limit, so the lower sideband would be below that.  However, AFSK never has been common on the HF bands.

  In a message dated 11/22/2011 16:36:46 PM Central Standard Time, larryradio at att.net writes: 

    So, PSK is RTTY?  Do you think is forbids AFSK therefore?

    lar
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