On 20/09/16 08:26, glen english wrote:
> He's is an experience to share... and all this I know already but when 
> you experience just how frugal codec2 is on speech bits, it is 
> enlightenment.....
> I am doing a project that uses Codec2 and sends data over Si4460 
> transceiver chips.
> one thing that has become apparent is there is not much data coming out...
> I send a packet every 20mS so that lost packets don't matter so much.
> But.. all there is to transmit is ... 8 bytes ! :-)   there is 12 bytes 
> wrapped around it..... Ha !
> which means the data rate (and BW) has to go up  to cope with the 
> overhead..... and David has worked so hard to get the bits down, and I 
> just throw 1.5x excess in radio overhead...

One option might be to use some forward erasure coding on each Codec2
frame to give you two 8-byte packets, then in each RF frame, you send
packet 2 (or zeros if it's the first packet) from the previous Codec2
frame concatenated with packet 1 from the current Codec2 frame.

You double your data rate, but if an RF frame gets lost, you can still
recover the full message with no delay or loss.
Stuart Longland (aka Redhatter, VK4MSL)

I haven't lost my mind...
  ...it's backed up on a tape somewhere.

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