[drats_users] Simultainious voice and data

[Dan Smith]

> 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.

Well, this isn't quite accurate.  Even if the entire file fits in the
first round, there is still negotiation before and after the actual file
transmission that needs to happen.  A couple of back-and-forths to setup
the session, exchange the file information at the beginning.  After the
file, another couple to confirm receipt of the file (you don't want the
sender to think it was successful when it wasn't) and then to close the
session.

> 	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. 

Not quite, as stated above.

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

That's why I pipeline.  You can keep the block size small, but increase
the pipeline length.  This means that a single bit error will affect a
smaller amount of data, thus requiring less to be re-sent.  The smaller
the block size, the more the overhead, of course, but on a lossy channel
it will pay off.

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