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...
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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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