[drats_users] Simultainious voice and data

[Dave Cooley]

Yes that is what happens. When the block size is too short DRATS sends the
first part of the transfer and then waits for block status from the distant
end. If the transmission time is enough to accomodate the entire file then
all is well. Confirmation is received from the distant end and a file
transfer complete is sent.  If not, the handshake occurs and any bad blocks
are re-transmitted along with the next pipeline. This will continue until
all of the data is transmitted and confirmed.
The ultimate goal is to set the block size to accommodate the transferred
file size so that when the voice transmission is finnished only the ack
(confirmation) is sent back. Should a re-transmitt be required it would be
triggered at that point. 
Case in Point:
	Net control wants to send a radiogram to a DRATS station. The form
is filled out and ready to be sent. A DRATS equipped station states they are
ready to take the traffic. Net control acknowledges and during the voice
conversation, sends the radiogram form. If the block size and pipeline
blocks are set to the size of the entire form,  a single transmission will
pass the radiogram to the receiving station in a single transmission. The
receiving DRATS station will check the blocks for errors and request a
resend of bad blocks. If no bad blocks were revceived the transmission is
complete. 
If the block size and pipleine is set too small several transmissions will
be required.

It is understood that the larger the block size the greater chance for
errors and this must also be taken into consideration.







-----Original Message-----
From: drats_users-bounces at lists.danplanet.com
[mailto:drats_users-bounces at lists.danplanet.com] On Behalf Of Dan Smith
Sent: Thursday, December 11, 2008 10:38 PM
To: Discussion of D-RATS
Subject: Re: [drats_users] Simultainious voice and data


> Comments Dan?

I'm not exactly sure exactly what you're trying to say here.  If you make
your block size longer, then it will give you longer to talk while the data
is transmitting, that's true.

However, if you make it longer, then it will keep the radio keyed to finish
the data even if you stop talking.  If you keep the data too short, D-RATS
will send it in the first part of your conversation and then expect to be
hearing back about the status of the block while you're finishing the voice
part.  Since I have no reliable way of telling when you've got the radio
keyed for voice, it's nearly impossible for D-RATS to know what you're
doing.  Since I can't tell if you're talking with voice, I also can't tell
the difference between you talking on the voice channel, and a packet
getting lost due to interference.

As far as intermixing voice and data, it's generally a bad idea.  It will be
much more efficient if you just keep quiet and let the data transfer happen
at maximum speed and then go back to talking when it is done.

-- 
Dan Smith
dsmith#danplanet.com, s/#/@/
www.danplanet.com
KK7DS
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