Oh yeah, you really don’t have much control over when the radio transmits. You 
really don’t even know if it has transmitted anything. If the channel is busy, 
the radios will tend to hold off transmitting, so you don’t walk all over 
everything. But if two radios are both trying to send while someone is talking, 
they both will start at the end of transmission and collide with each other.

D-STAR Low Speed Data has so much promise, but Icom’s serial port 
implementation severely handicaps implementation.

Now D-STAR’s high speed data is totally awesome. It does exactly what I want it 
to.

Ed WA4YIH

From: [email protected] [mailto:[email protected]] On 
Behalf Of mungewell
Sent: Wednesday, May 13, 2009 5:06 PM
To: [email protected]
Subject: [DSTAR_DIGITAL] Re: Compression/encoding on data-only transmissions





Yes, in relation to the size of the actual data sent the FEC will be about the 
same size (of extra bytes) for short messages.

However there are other 'costs' in having resend corrupt data.
1) The message coming back to say retransmit the data or part of it (as D-Rats 
does).
2) Waiting for the channel
3) 'Warm up'/TX wait time on the transceiver
4) The header (48 bytes), plus the 72:24 bit(or byte?) ratio of voice to data 
and any sync frames (1st and every 21st)
5) End sequence
6) Transmit tail




[Non-text portions of this message have been removed]



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