Free DV development ideas

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  • Idea
  • Updated 3 years ago
  • (Edited)
All DV modes have an issue in QSB/QRM/QRN situations: The data stream
gets interrupted and needs awhile to resynchronize.
All methods of error correction etc. won't help much in a dropout.

Digital data modes like PACTOR
work around this by using error correction and resending unacknowledged packets and switching to robust modes until the data packets are acknowledged.
Can't do that to DV in a "normal" QSO situation, or speech would be too much delayed.

I wonder if it wouldn't be possible:

1. To use DV until QSB starts to interrupt the data stream and then switch to SSB and switch back to DV as soon as the connection is reestablished? That should be possible. The human brain rules here and makes it possible to read SSB signals which are almost fading away into the noise.

2. To develop a DV "voicemail" mode, where all you are saying is compressed into voicemail packets, which could be resent until acknowledged by the receiving station, where it would be decompressed and replayed. This mode could be optionally used in difficult QSB/QRN/QRM situations.

BTW we have got a D-Star and a DRM repeater here at Karlsruhe and the same applies to mobile and portable stations: Lots of R2D2 interruptions.
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Alex - DH2ID, Elmer

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  • quite well, thank you

Posted 3 years ago

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Steve - N5AC, VP Engineering / CTO

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Good ideas, Alex.  I've thought about the same things myself.  You might want to join the FreeDV Google Group and discuss that with the folks that are designing this mode.  To date, we've only run others' digital modes rather than creating our own (you didn't want another proprietary digital mode did you?).  I know they are still doing development.  The group is here: https://groups.google.com/forum/#!forum/digitalvoice
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Alex - DH2ID, Elmer

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Thanks, Steve, will look at the DV group.