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How to Digi via Mir and Shuttle






September 29, 1998

Miles Mann     MAREX-NA
(Manned Amateur Radio Experiment, North American Division)
WF1F @ K1UGM.MA
mann@pictel.com

Mir and Packet UnProto mode

The Mir PMS (Personal Mail System) also supports the Digital repeating mode
called UnProto.
I am not going to get into too much detail about UnProto, for more information
check Amateur
radio hand books and back issues of Amateur Radio magazine.  Basically UnProto
is a way of
sending packet messages without requiring an acknowledgment from the other
station.
This mode is similar to RTTY in that, you can have several stations in one big
QSO
at the same time.  Set your UnProto command in your TNC, on my KAM the syntax is

"U CQ V R0MIR".  Then switch to Converse mode (enter K at cmd: prompt).
Now everything you type will be transmitted in UnProto Mode.  If the Mir
station hears your transmission, the Mir PMS Digi will rebroadcast your
information
with a range of over a 1000 miles.   Below is a short UnProto between a station
in
Massachusetts and Alabama, using the Mir Digi.  The stations were arranging to
meet
on Oscar 13 when the Mir pass was over.

WF1F>CQ,R0MIR*/V [04/21/93  22:22:09]: <UI>:
hi Tim can you work OSCAR 13?

N8DEU>CQ,R0MIR*/V [04/21/93  22:22:30]: <<UI>>:
Hi miles, yes what freq?

WF1F>CQ,R0MIR*/V [04/21/93  22:22:40]: <UI>:
145.895

The UnProto mode does not guarantee you message will ever be heard, but if the
Mir
Digi does rebroadcast your line of text, then you can be assured that someone
saw
it.  The line of text you send will be repeated with an Asterisk after it,
R0MIR*/.
If you do not see the Asterisk, then Mir did not hear your packet.
UnProto does have its drawbacks, but it is much more efficient to use on Mir
than the Direct two-way connect method. Full two-way packet connects via the Mir

PMS are not recommended because they use up too much resources and excessive
Retires.
Before you try Unproto on Mir, I recommend that you practice on a Terrestrial
Digi
first before attempting to use the Mir station for Digi-repeating. If you make a

few UnProto calls and do not get any echo's back from Mir, it is probably
because
UnProto is turned off or because of a collision.  Occasionally the System
Operators
may turn off Unproto (Digi = OFF) to improve the Mail Box traffic flow.  The
Mail
box access should always have top priority over other traffic. Also there is a
good
time and a bad time to use the UnProto mode with Mir PMS.
Do not use UnProto when:
1. The Mir crew is operating in Voice mode.
2.   When the Mir PMS is connected to another station that is actively
sending/receiving information from the Personal Message System (PMS).  Any Index
packets going to the R0MIR-1 address.

The only real safe time to use UnProto, is when the Mir PMS is in its 2 minute
time-out mode.  This time-out is caused when the station connected to the Mir
PMS is out of range and cannot log out of Mir.  No one can log into PMS Mail
box (R0MIR-1) until the connected station times out.  Time-outs are the best
time to use UnProto.  Before using UnProto, monitor Mir?s down link to see who
is using the PMS Mail box port R0MIR-1.  If you do not seen any Index packets
from Mir PMS to the ground station using to the R0MIR-1 port for 60 seconds,
you can assume the connected station is out of range of the Mir PMS and its
UnProto time.
The shorter the Unproto sentence, the greater your success of  a PMS repeat.
Long sentences may get clobbered by other stations.  If you are in the middle
of an Unproto QSO and you see someone connect to the PMS Mail box R0MIR-1,
you should end your Unproto QSO and let the Mail box users have access to the
PMS.

Previous Testing of Two-way Connects:
In 1993 WA2GSY in New Jersey (now W2KQ) and I WF1F in Boston made arrangements
to test the efficiency of FULL-TWO-WAY packet connects verses Unroto messages.
Unfortunately I have lost the original logs from the test, but I do clearly
remember the results.  We made arrangements for the Mir Amateur Radio station
to move to a private channel for a weekend.  Then Joe and I attempted a
Full-TWO-WAY
packet Digi connect via the Mir PMS on a perfectly clear channel.  The orbit was
 a
perfect pass, traveling from Texas to Maine.  The 10 minute pass had good
elevation.
Both of our stations were similarly equipped and running high gain antennas with
approximately 1200 watts ERP of transmit power each.  At the beginning of the
pass,
we sent a few Unproto packets, and then Joe issued the full two-way connect to
my
station.  After the initial log-in we each sent each other two simple lines of
ASCII text and then logged out.  Now you must remember we had a perfectly clear
channel.  There were NO other stations on frequency because we had moved the PMS
to a private channel.  There was no interference from any ground stations.
It required over 4 minutes for us to exchange the 2 lines of text.  The total
number of packet transmission from all three transmitters was over 200 packets.
Every packet which I sent, had to be heard, acknowledged and retransmitted by
the Mir PMS.  The same packet was then sent to WA2GSY and had to be heard and
acknowledge.  The acknowledgment from WA2GSY then had to go back to Mir and
Acknowledgement had to be re-broadcast from Mir back to my TNC.  Four
transmission are required for each original packet.  However since my station
in Boston cant hear when Joe?s system in New Jersey was transmitting, there
were dozens of packet collisions. These collisions are what causes the
efficiency of two-way packet to drop.  With a full-two-way connect each
packet sent must be acknowledged.  This causes a tremendous amount of over
head in this particular satellite configuration.  The efficiency of full-two-way
connects via Mir is less than 10% on a perfectly clear channel.  Now if you add
in the normal amount of traffic to the Mir public channel, you can see that
full-two-way connects are a complete waist of time.  The efficiency of
Unproto on the other hand is greater than 50%.  And Unproto is more band
friendly.
The existing design of the Kantronics KPC-9612 does not allow us to filter
out the difference between Unproto and Two-way connects its just all or
nothing.  So we need to rely on  your courteous corporation and for people
to help spread the word on the correct operating procedures.

Good luck and lets be courteous to everyone.

Remember, Only 1 station can connect to Mir's PMS at a time, and try avoid
using UnProto when someone is actively using the PMS Mail Box.

Copyright 1998 Miles Mann, All Rights Reserved.  This document may be
freely distributed via the following means - Email (including listservers),
Usenet, and WorldWideWeb.  It may not be reproduced for profit including,
but not limited to, CD ROMs, books, and/or other commercial outlets without
prior written consent from the author.


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