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How to use ISS UNPROTO packet

February 27, 2002

How to use the Amateur Radio "Round Table" via the International Space
Station Alpha

By G. Miles Mann, WF1F MAREX
	With contributions from:
Frank Bauer Chairman ARISS
Bob Bruninga WB4APR 

Short Version
(ISS Personal Message System and Voice tips will be published later)

The New Amateur Radio project on the International space Station is now
on line.  

The name of the International Space Station new Amateur Radio experiment
is the "Packet Radio System" or PRS.  The ISS PRS experiment is designed
to allow beginners, easy access to the International Space Stations
educational Amateur Radio experiment.  If you have an existing Amateur
Radio 2-meter packet station at home now, then you may already have all
of the equipment you need to meet new friends around the world or start
a friendship with the Cosmonauts and Astronauts on board ISS.

The ISS Packet Radio System supports three different modes, Personal
Message System, Round Table and APRS. In this article I will describe
the equipment you need to operate the Packet Radio Systems' "Round
Table" mode on ISS. The other supported modes, Personal Message System
and APRS will be covered in separate memos and I will provide URL links
for additional APRS information.

Round Table:
The "Round Table" mode is a keyboard to keyboard form of communication. 
Round Table will allow you to type short messages, which will be relayed
(a.k.a. Digitally Repeated or Digi for short) through the PRS and
retransmitted over a distance in excess of 1000 miles.  Round Table mode
allows many people to participate in a Round Table like environment
while the ISS is in range. The PRS Amateur Radio call sign for the Round
Table mode is ARISS or RS0ISS.

Personal Message System:
The Personal Message System (a.k.a. PMS or MailBox) mode allows you to
place a short personal message directly into the PRS system on ISS. 
Once the message is Saved, the ISS crew can read and or reply to the
message. The ARISS team is working on the Rules on how we will use these
limited resources.  At the present time, the ISS crew is just too busy
to read and replay to any of the messages in the PMS. The ARISS team is
in the process for developing operating procedures for the Personal
Message System. The PMS mode is currently being tested by the ARISS
System operators and selected ARISS support engineers.  The general
public is being asked to refrain from using the PMS mode while the
performance is being evaluated. The PRS Amateur Radio call sign for the
Personal Message System mode is RS0ISS-1.

APRS (Automated Position Reporting System)
The APRS mode is no different from the Round table mode except that APRS
software on the ground is used to preformat the message lines into some
special formats for conveying position data, map objects and other short
messages between users.  For more information on APRS, please refer to
the following URL 

ISS Hardware:
The ISS is currently using an Ericsson portable radio (known as a HT)
which is operating on the Amateur Radio 2-meter band.  The Packet Radio
System (PRS) is using a Paccom Picopacket 1200 baud Terminal Node
Controller (also called a TNC or Packet Radio System).  The radio is
currently connected to a pair of externally mounted co-phased mono band
antennas (2-meter band).  The typical power output is 5 watts, with an
ERP rating of 5 watts. 

To work ISS from your home, you should have at least the following
Amateur Radio equipment.  A 2-meter radio with an output rating of 25 to
50 watts or more.  An omni-directional antenna or small beam.  A short
run of good quality coax (RG-213, 100 feet or less).  And a standard
1200 baud AX.25 Packet modem (TNC). I use an inexpensive KPC-3 modem for
all of my ISS packet connections.

The ISS will use different frequencies, depending on the Mode of
operation and the general location of the Space Station.  Please refer
to the chart below for mode and frequency selection for your country.

The following frequencies are currently used for ARISS general QSO's
Voice and Packet Downlink: 145.80 (Worldwide)
Voice Uplink: 144.49 for Regions 2 and 3 (The Americas, and the Pacific) 
Voice Uplink: 145.20 for Region 1 (Europe, Central Asia and Africa) 
Packet Uplink: 145.99 (Worldwide)
TNC Configuration:
In the Manual for your TNC, the "Round Table" feature is called
"Unproto".  To operate the ISS PRS, you will need to modify some of the
settings on your TNC.  The parameter changes needed for "Round Table"
and "Personal Message System" are the same. The TNC parameter changes 
for APRS are a little different and will be covered in a separate memo. 
Most of the parameter changes required for ISS PRS will be compatible
with terrestrial BBS operations.  Using these suggested parameters will
improve you're success rate and at the same time help reduce
interference (QRM).  Note, for information specifically about ARPS,
please see the URL links below.  This memo is for Unproto and Personal
Message System settings.  You do not need APRS to work ISS Personal
Message System or Unproto (Round Table)

These are the suggested TNC settings for Round Table/Unproto and
Personal Message System modes for ISS PRS.  The settings for the APRS
mode are a little different and will be noted below.

PACLEN  (Round Table and PMS = 72, APRS = 0)
RETRY   6-8
TIME STAMP  (Round Table and PMS = ON, APRS = OFF)
Unproto  CQ V RS0ISS 

Make sure your beacon is disabled.  Unattended beacons on the ISS packet
uplink frequency will just cause interference.  You should only transmit
manually while you are at controls. Please keep beacons turned OFF,
while on the ISS uplink channel.  Only call ISS Round Table Manually

This value seems to interfere with normal ISS BBS operations.  Make sure
LFADD is turned OFF.

This value is normally turned "OFF" for terrestrial BBS connections and
"ON" for connections to the ISS PRS.  This value will allow you to see
packets going to other stations, while you are Connected to Personal
Message System or Attempting to Connect to Personal Message System.  All
courteous operators using ISS will keep this value ON when using the
Personal Message System mode.

Set this value on to monitor all data.
Set this value "ON" if you want to see the details of every single
packet.  This is very useful while monitoring space packets.  But be
sure to turn it off if you run APRS or other specialized software.

Allows monitoring of packets while not connected.

PACLEN:  72 (Characters per line)
Short data packets are less likely to be clobbered or corrupted. Some
APRS software packages may require this value to be set differently,
check your specific APRS application for the correct settings.

You do not want to set this value too high because you may cause
interference (QRM) during your initial connect.  Also, if "RETRY" is too
short, you will time-out during the one of the 4 deep RF signal fades.  
Foot note 2.  During a 10-minute pass, there will be 4 RF polarity
shifts in the signal coming from ISS. This shift is caused by the
apparent position of the antenna on ISS's in relation to your antenna. 

With Time Stamp turned on, you will be able to log data to your disk
while you are away and track the time and duration's of the passes. Some
APRS software packages may require this value to be set differently,
check your specific APRS application for the correct settings.

The UnProto command has two parts.  The first part is the TOCALL and
should be one of the generic callsigns recognized by most other software
programs such as CQ, ALL, APRS, QST.  The second part is the letter V or
VIA and the third part is the PATH.  For ISS this should be ARISS, which
is the digi-repeating alias for ISS.  If your packet is successfully
digi-repeated by ISS, it will substitute its RS0ISS callsign in the
downlink copy.  The PATH field may contain multiple entries, but only
the first PATH is used for ISS, you may insert your Grid square or NAME
in two additional fields for example:

Valid examples for configuring the UNPROTO command in your TNC:

Space Station Call sign:
The Call sign/signal of the PRS on the International Space Station
Alpha, is now RS0ISS or rs0iss (that is "rs 0 iss" the value in the
middle is the integer Zero)
Make sure that when you enter the call sign into your TNC Unproto
command that you enter the correct call sign (Case is not important r =

AX-25 packet frame conventions:
You should try to become familiar with a few of the packet frame
identifiers, this will help you understand, what you are seeing.  Some
of this information should be in your TNC's users manual.

C-Connect request
D-Disconnect request 
DM-Disconnect mode 
UA-Unnumbered Acknowledge 
UI-Unconnected Information frame
I(n)-Information frame (n=0-7).

ISS Round Table procedures:
The ISS PRS (Packet Radio System) also supports the Digital repeating
mode called UnProto / Round Table.   UNPROTO / Round Table mode is a way
of sending packet messages without requiring an acknowledgment (ACK
PROTOCOL) from the other station (hence UNPROTO for Unacknowledged
protocol).  This mode is similar to RTTY in that, you can have several
stations in one big "Round Table" at the same time.  Set your UnProto
command in your TNC as shown above.  Then switch to Converse mode (enter
K at cmd: prompt).  Now everything you type will be transmitted in
UnProto Mode.  If the ISS station hears your transmission, the ISS PRS
Digi will retransmit your information with a range of over a 1000
miles.   Below is a short UnProto / Round Table between a station in
Massachusetts and Pennsylvania, using the ISS Digi Round Table.  The
stations were arranging to meet on HF when the ISS pass was over.

Typical Round Table exchange from via ISS:

N3CXP>CQ,RS0ISS*:Hi all, great sigs here! de Tom in Allentown, PA
WF1F>FN42,RS0ISS*:n3cxp are u on
WF1F>FN42,RS0ISS*:i have the amp on hf 7.215
N3CXP>CQ,RS0ISS*:just copying the mail
N3CXP>CQ,RS0ISS*:ok cu after the pass
WF1F>FN42,RS0ISS*:ok tom
WF1F>FN42,RS0ISS*:monitoring 7.215 lsb

The UnProto mode does not guarantee that your message will be
successful, but if the ISS Digi does retransmit 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, "RS0ISS*/".  If you do not see
the Asterisk, then ISS did not hear your packet.  UnProto does have its
drawbacks, but it is much more efficient to use on ISS than the Direct
two-way connect method. Full two-way packet connects via the ISS PRS are
not recommended because they use up too much resources and excessive
"Retires".  Before you try Unproto on ISS, I recommend that you practice
on a Terrestrial Digi first before attempting to use the ISS station for
Digi-repeating. If you make a few UnProto calls and do not get any
echoes back from ISS, it is probably because the band is too busy. Wait
and try later. 

Related Web pages for additional Information on Amateur Radio projects
on ISS

Ariss web page

Bob Bruninga, WB4APR, US Naval Academy Satellite Lab, ISS APRS web page


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