[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

UI packets



On Tue, 9 Feb 1999 Someone asked about UI frames:

> Bob,  Please point me in the direction to find answers to UI's and
> UNPROTO mode of operation.
> 
> I use packet without understanding much about it....
> Am I right in assuming a UI is a oneliner sent unaddressed?

Yes, Your TNC can be in 3 modes: 
  1) Command mode, where your typing talks to the TNC CPU
  2) CONNECTED mode, where your typing gets transmitted to the other stn
               along with many retries, ACKS, and time-out problems
  3) UNPROTO or UI mode where your typing gets sent in a UI packet

To enter UI mode  from command mode, just enter the command CONV
To return to COMMAND mode hit CTRL-C.

When in UI mode, everything you type will be transmitted ONCE when you 
hit the ENTER key.  It will be sent to the address in your UNPROTO
command via any digipeaters there.  You will get no ACKS, but if your
packet was digipeated by a digipeater (R0MIR), then you will see it
and you can assume that everyone else probably saw it too.

UI mode is best when one person is trying to convey informaiton to many
people at the same time.... Such as in this APRS/MIR School Experiment.

Conversly, neither UI mode nor Connected nor any other mode will ever work
effeciently when doing 1-on-1 station-to-station communications via MIR,
SAREX or any other AX.25 satelite.  This is because of the geometry of 
thousands of users coliding on the uplink.  That is why CONNECT packets
are strongly discouraged, and even trying to dialog 1-on-1 is a waste of
everyone's time.
                

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home