[aprssig] APRS tone encode question

[Andrew Rich]

Scott,

So how many "cycles" of 1200 or 2200 fit into the period allowed for 1200
baud ?


  -----Original Message-----
  From: Scott Miller [mailto:scott at 3xf.com]On Behalf Of scott at opentrac.org
  Sent: Wednesday, 25 August 2004 4:22 PM
  To: vk4tec at tech-software.net; 'TAPR APRS Mailing List'
  Subject: RE: [aprssig] APRS tone encode question


  It just means that when you switch from one tone to the other, you stay at
the same place in the waveform.  You get a sine wave that's stretched and
compressed in places, but it doesn't have any jumps or flat spots in it.

  Scott
  N1VG
    -----Original Message-----
    From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Andrew Rich
    Sent: Tuesday, August 24, 2004 10:33 PM
    To: Scott Miller; 'TAPR APRS Mailing List'
    Subject: RE: [aprssig] APRS tone encode question


    what is phase continuous ?


      -----Original Message-----
      From: Scott Miller [mailto:scott at 3xf.com]
      Sent: Tuesday, 24 August 2004 11:41 PM
      To: vk4tec at tech-software.net; 'TAPR APRS Mailing List'
      Subject: RE: [aprssig] APRS tone encode question


      No, it requires that the phase be continuous.  Since 2200 isn't an
even multiple of 1200 baud it wouldn't come out even anyway.  In the
OpenTracker, a pointer to the current sine value is incremented each step.
The size of the increment depends on which tone is being sent at the moment.

      Scott
      N1VG
        -----Original Message-----
        From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Andrew Rich
        Sent: Tuesday, August 24, 2004 1:58 AM
        To: TAPR APRS Mailing List
        Subject: RE: [aprssig] APRS tone encode question


        Does Packet require the tone shift from 1200 to 2200 to occur at a
zero crossing ?

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