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Re: [digsstv] Easypal modulation scheme

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  • Jacques Mezan de Malartic
    Joanne, It seems that you are the only one sharing this issue with me in this group and finding that the answer is not simple. Unless no other authority than
    Message 1 of 5 , May 20, 2008
      Joanne,
       
      It seems that you are the only one sharing this issue with me in this group and finding that the answer is not simple.
      Unless no other authority than France update their table of authorized modulation, nothing more will happen.
      It is clear that updating would be better at the IUT level but it will take time and we will have difficulties before.
      Following the legal definition would result in different figures depending on how it is made through traditional transceivers or new SDRs. We are already making a difference between a CW "modulation" depending of how it is generated at the audio input in SSB or at the RF amplifier. It gives exactly the same effet at the other end of the reception side and even on a spectrum analysis but definitions say that they are different !  That's life ...
      So, I will give my own definition based on an audio processing and leave the door open for RF processing for the next century when IUT will clean its table ...
       
      73'
       
      Jacques / F2MM
       
      ----- Original Message -----
      From: jdow
      Sent: Monday, May 19, 2008 3:15 PM
      Subject: Re: [digsstv] Easypal modulation scheme

      I am a night owl. I am just about to go to bed. It's 0611 PDT.

      Do consider that the waveform is not best described by a conversion
      scheme to get it to its final frequency.

      The baseband data is digital. The waveform has multiple carriers. And
      it is simultaneously phase and amplitude modulated. I would start with
      that and try to figure out which description comes closest. I would
      also include notations that describe the actual format. For that you'd
      need somebody else's more exact description than I can give. I hope
      somebody chimes in with that information to help you.

      {^_-} Joanne, W6MKU - part vampire, I suspect.
      ----- Original Message -----
      From: "Jacques Mezan de Malartic" <j.mezandemalartic@ free.fr>
      Sent: Monday, 2008, May 19 05:05

      Thanks Joanne for your quick answer ... What time is it in W6 land ??
      I would be happy with your last remark about the "politics favor" but since
      I am faced to these poeple quite often and due to some possible
      controversial aspect, I prefer to be carefull ant try to find the most
      appropriate answer as much as we can...
      I am licensed with this ham call sign for more than 48 years now, have
      worked for professional radiocommunications more than 40 years and been
      involved in standardisation work groups during more than 15 years but I am
      still confused how to apply definitions from the last millennium to what we
      are digitally doing to day.
      Presently, the "digital SSTV" occupies already about 10 kHz on 80m here with
      at least 3 channels without any IARU recommendation to refer at and no
      official authorization. I fear we can be faced to complaints from old
      fashion analog phone SSB users arguing on the illegal aspect of our
      transmissions.
      Our authorities has open the door for updating the rules up to the end of
      this month and my task is to present the contribution.
      I am trying to be as much accurate as I can !!

      73'

      Jacques / F2MM

      ----- Original Message -----
      From: jdow
      Sent: Monday, May 19, 2008 11:38 AM

      Step back from the mode of generation to the format on the air. It is a
      purely digital format involving elements of both AM and phase modulation
      of multiple carriers.

      You can generate the waveform directly at RF from raw digital baseband
      data using waveform synthesis techniques. You can create it at IF and
      up or down convert, as appropriate, to the transmitted frequency. You
      can do so with multiple conversions. The typical ham case uses a
      frequency in the AF spectrum that passes through a typical SSB
      transmitter' s filters. Does any of these means of generation have some
      magical sticking property that would make the same on the air signal
      sometimes an SSB phone signal and sometimes an exotic digital waveform?

      I believe there is a sort of "none of the above" mode descriptor. And
      odds are that is the one that is the best fit for a multiple carrier
      QAM signal.

      Of course, if politics favor you if you can get away with describing it
      as an SSB voice format and can make the case stick - go for it and snicker
      about the stupidity of the officials who accept your line of BS. {^_-}

      {^_^} Joanne "Cynical" W6MKU (This issue is one my hobby-horses. )

      ----- Original Message -----
      From: "Jacques MEZAN de MALARTIC" <j.mezandemalartic@ free.fr>
      Sent: Monday, 2008, May 19 02:22

      Can someone help ?
      In order to update modulation schemes allowed to amateur radio
      transmissions
      by our authorities in France, we need to understand to which UIT
      definition
      this transmission refer. Since the formal definitions in the RR /UIT (
      section RR4-2/ 269 to 273) were made at a time when digital transmissions
      were not well deployed as it is now, we are always hesitating to which
      standard we should refer.
      For example analog SSB/phone is J3E. Most of digital transmissions Digital
      schemes like PSK can refer to J2B as well as JT65 even if not really CW
      but
      with same automatic decoding process.
      Main application of Easypal is pictures transmission and it may be refered
      to J2C as traditional analog SSTV but I dont know if we can consider that
      there is only one transmission channel or more and it could be also J7C.
      I hope someone has the answer to clarify what we should put in our
      contribution.
      Thanks and 73'
      Jacques / F2MM

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