Thursday, April 2, 2009

The Siren Song of WSPR...WSPR DSB?

Man, that's the kind of map that I want to find on the screen when I walk into the shack in the morning. Or maybe on my Blackberry at lunchtime. Above you can see the WSPR spots for Jeff, KO7M. You can see Jerry, NR5A, in there, proudly representing South Dakota. Buried under the Northeast calls is K1JT, the only Nobel Prize winner in the group.
This morning I downloaded K1JT's WSPR program and was very pleased to find that it runs nicely on this old, rickety Windows 2000 machine. (I pushed the envelope a bit and tried to get it to run on my recently revived Toshiba Satellite Pro 400CS, but it didn't seem to like Windows 3.1. ) I have on the workbench the plans for W3PM's bare bones WSPR transceiver and the WSPR care package sent over by Jim AL7RV.
Here is my plan: Make W3PM's rig even simpler. TX only (at first) and Double Sideband. Maybe I'll just put an SBL-1 mixer between the oscillator and the RF amp in my current Visual MEPT transmitter. (I'll make it switchable so that I can go back to our beloved visual mode whenever I want.) Then add W3PM's audio amplifiers between line out on the sound card and the audio input port on the SBL-1.
What do you guys think? WSPR DSB? The other sideband should fall FAR outside the band, and it will almost certainly be completely down in the noise for anyone not running ARGO or SPECTRAN-like software.
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3 comments:

  1. PaoloApril 2, 2009 at 8:54 AM

    Bill, have you seen my considerations about a simple WSPR/visual DSB/SSB TX?

    I tried to explain the concept on a blog post

    A DBM mixer (SBL or 602) generates DSB. Then a XTAL filter on the RF port gives USB, but may be added later. I plan to run the WSPR beacon out of an MP3/WAVE player so to get rid of a computer for beaconing. This works also for visual modes, and Paolo IZ1KXQ has already been there, done that.

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  2. Bill MearaApril 3, 2009 at 1:20 AM

    Paolo: I really like your idea of playing the WSPR audio from a simple MP3 player. Maybe I could use the sound features of my Toshiba laptop to play the WSPR audio.

    I also like your block diagrams for simple MP3 rigs. You should look at W3PM's design.

    My idea is a lot like your third design, but without the filter. DSB.

    73 Bill

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  3. Joachim SeibertApril 3, 2009 at 2:07 AM

    Bill,
    why going dsb? You could use a 10.140MHz xtal as filter to only pass the upper side band to the final.
    73, Joachim

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