Hi,
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I¡¯ve ben doing a bit more reading on amateur radio digital voice modes used on HF.
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To focus on one possibility for a digital voice mode that may be compatible with nonlinear RF finals, I discovered that D-Star is being experimented with by some hams on HF.
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D-Star uses GMSK, Gaussian Minimum Shift Keying on VHF/UHF. Best I can tell the modulation mode is not changed in the HF world.
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If so, this might be a way to add a voice mode to digital only modes transceivers, with simple nonlinear RF output stages, like the QDX.?
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D-Star uses a proprietary codec, so what I¡¯d suggest is use the frequency shift (GMSK) modulation method but swapping out the D-Star codec for the FreeDV codec.?
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Any major flys in the ointment here? Other than getting ham radio operators interested in yet another voice mode?
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There are, also, multiple frequency shift modes that might offer some advantages. But GMSK seems the likely starting point for experimentation or at least for this conversation.
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I know there are folks that have gained much more knowledge of this area than my beginnings at sorting through this area of knowledge. Hopefully some of those folks will be able to add some practical additional knowledge on the subject.
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Tom, wb6b
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