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...

So I went up to 3 frames 60mS (24 bytes) plus the 12 byte overhead per 
transmission....A bit better...

A lost packet hurts more, but the operating bandwidth is less. With the 
diversity operation (I use TWO of the Si4460 chips simultaneously with 
two antennas) , overall the reduction in BW has reduced packet loss.

In the single antenna no diversity option, it is better to have short 
packets and a higher threshold (due to higher bit rate)

It's just I am used to 64kbps... not 3.2kbps.

g








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