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[aprssig] APRS tone encode question

scott at opentrac.org scott at opentrac.org
Wed Aug 25 06:22:27 UTC 2004


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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