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How to be successful with ISS packet

July 30, 2002

G. Miles Mann, WF1F

How to be successful with ISS packet.

The Unofficial MAREX ISS Packet operations manual, part one of many

The ISS Packet system is now working as a two-way mailbox (Personal Message
System).  This mailbox is only designed as a single user mailbox.  Because
it is a single user mailbox, you must be very careful when attempting to use
the mailbox, in order to prevent unintentional interference to other users.
In this memo, I will try to explain some of the important procedures you
should know before you try to access the ISS Packet mailbox system.  I would
also like to ask that if you do use the mailbox to send a message to the ISS
crew, that you should not expect to get a reply back from the ISS crew.
There are over 2 million amateur radio stations world wide, and many have
potential access to this single user Personal Message System.  I hope you
will all try to be supportive of this proof-of-concept project, which is
also a tool for the ISS crew and not necessarily a worldwide resource.

During the Mir program the SAFEX/MIREX/MAREX clubs ran similar Packet
projects in space.  One of the important things learned was that your
success increased with knowledge.  In countries where Amateur Radio Stations
took the time to learn correct packet procedures, the success rate was very
high when using the PMS on Mir.  In other countries, where people did not
know the correct packet procedures, the success rate was limited only to
station running kilowatts of ERP.   Please help us educate the world.

The Space Station ISS is currently using an Erickson single band 2-meter
radio transceiver and a PacComm Terminal Node Controller AX.25 1200-baud
packet modem (usually just called a TNC or a Modem).  The radio is currently
connected to an externally mounted mono band antenna (two antennas on
opposite sides of the Zarya (FGB), co-phased together and tuned for 147
mHz).  The typical power output of this system is 4-5 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.  
An omni-directional antenna or small beam.  
A short run of good quality coax (RG-213, 100 feet or less).  
A standard 1200-baud AX.25 Packet modem (TNC).  
And that is it for radio equipment.  I use an inexpensive KPC-3 modem for
all of my ISS packet connections and I can even hear ISS with my police

You will need access to a computer or web to tell you when ISS is in range
of your station.  The timing of your contact is the most important part of a
successful contact with ISS.  There are many tracking programs out in the
market place today.  I do not have the space to review all of the programs
in this article.  Some programs are share-ware (STSPLUS); others cost a few
bucks.  I recommend using the DOS InstantTrack, program by Amsat.  This
program is very easy to use and works very well with older style computers
such as 80286 style PC's.  The cost of most tracking software applications
is approximately $50-100.

Doppler Shift:
The ISS Space Station is traveling around the Earth at over 17,500-mph
(28,000 kph).  This great speed will make radio signals appear to shift in
frequency.  This phenomenon is called Doppler Shift.  Many of us have radios
that are Channel locked.  This means you cannot make any fine tuning
adjustments to your receiver or transmitter's frequency.  Most Mobile and HT
radios cannot make any frequency changes less than 5 kHz channel steps (lets
hope that radio manufacturers will add 1 or 2 kHz channels steps in the
future).  This Doppler shift will cause the ISS transmit frequency (145.800)
to look as if it is 3.5 kHz higher in frequency when ISS is approaching your
location.  If you listen on 145.805 or 145.795, your reception may actually
improve (for a 5 kHz radio).  You will need to review the owner's manual for
your radio to learn how to program "Odd-Splits" channel combinations and
program the following consecutive frequencies into your radios' memories.

For VOICE operations in North America
For 5 kHz channel step radios do not try to adjust for Doppler
Channel 1	145.800.0 RX		144.490.0 TX Voice (Region 2)
Channel 2	145.800.0 RX		145.990.0 TX  Packet
Channel 3	145.800.0 RX		145.200.0 TX Voice (Region 1)

For VOICE (Region 2) 2.5 kHz channel step radios
Channel 1	145.802.5 RX		144.487.5 TX
Channel 2	145.800.0 RX		144.490.0 TX 
Channel 3	145.797.5 RX		144.492.5 TX

For PACKET 2.5 kHz channel step radios
Channel 4	145.802.5 RX		145.987.5 TX
Channel 5	145.800.0 RX		145.990.0 TX 
Channel 6	145.797.5 RX		145.992.5 TX

For VOICE (Region 1) 2.5 kHz channel step radios
Channel 7	145.802.5 RX		145.197.5 TX
Channel 8	145.800.0 RX		145.200.0 TX 
Channel 9	145.797.5 RX		145.202.5 TX

Let's assume ISS is approaching your location (QTH) and the packet system is
active.  Use channel #4 at the beginning of the pass, then when ISS is
overhead, use channel #5 and when ISS passes your QTH use channel #6.  For
best results, use an updated tracking program, which displays the current
Doppler shift.  A program such as InstantTrack will display the Doppler
shift in real-time.  This will assist you in determining when it is best to
change channels.

As you may have noticed, I do not recommend adjusting your uplink frequency
for the 5 kHz radios. This is because you may have better results if you
leave your receiver on 145.800 and your transmitter on 145.990 (for packet).
The Doppler shift is only at the +3.5 kHz setting for a few seconds, then it
will slowly begin to approach zero. After 5 minutes or less, the Doppler
shift will be 0 for a few seconds, and then it will begin to swing towards
-3.5 kHz.

TNC Configuration:
To operate the ISS PMS, you will need to modify some of the settings on your
TNC.  Most of the parameter changes required for ISS will be compatible with
terrestrial BBS operations.  Using these suggested parameters will improve
you're connection rate and at the same time help reduce Interference (QRM).

This is a portion of the TNC parameters in my KPC-3; your actual parameters
may vary:
RETRY			8-10

LFADD:  This value seems to interfere with normal ISS BBS operations.  Make
sure LFADD is turned OFF.
MCOM: This value is normally turned "OFF" for terrestrial BBS connections,
and "ON" for connections to the ISS PMS.  This value will allow you to see
packets going to other stations, while you are Connected or Attempting to
Connect.  All courteous operators using ISS will keep this value ON.    
PACLEN:  Lots of short packet lengths are less likely to be clobbered than a
few very long packets.  
RETRY: You do not want to set this value too high because you may cause QRM
during your initial connect.  Also, if "RETRY" is too short, you may
time-out during the one of the 4 deep RF signal fades.  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 change in orientation of the ISS antennas in
relation to your antenna. 

TIME STAMP:  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.
Learn to Read Packet:
There are only a half dozen actual packet headers.  If you take the time to
learn the different headers, you will be more successful in connecting to
the ISS packet system.  If you set your TNC to the correct parameters, you
will be able to monitor all of the data coming from the ISS PMS.  The packet
data you see will typically fall into one of the 6 categories listed below.

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

ISS Packet Command Listing:
It takes a long time to down load the HELP file from ISS.  I have included
an actually copy of the ISS help file.  The commands are similar to most
terrestrial TNC's.  You should review these commands and compare them to
your TNC owner's manual.  

B(ye)     B [CR] disconnects you from PMS.
H(elp)    H [CR] or ? [CR] displays this help file.
J(log)    J [CR] displays a list of callsigns heard (optional date/time)
K(ill)    K n [CR] deletes message number n  (only to/from your callsign).
KM(ine)   KM[CR] deletes all READ messages addressed to your call sign.
L(ist)    L [CR] lists the 10 latest messages.
M(ine)    M [CR] lists the 10 latest messages to/from your callsign.
R(ead)    R n [CR] reads message number n.
S(end)    S (callsign) [CR] begins a message addressed  to (callsign).
SB        Sends Bulletin
SP        Sends Personal
ST        Sends Traffic
          Subject: ending with [CR].
          Text: End each line with [CR]. End message by
           typing /ex [CR]  or  CTRL-Z [CR]
           at the beginning of a new line.
SR(eply)  SR n[CR] Sends a reply to message n prompting only for text.
V(ersion) V [CR] displays the software version of the PMS system.

The only commands the Public should be using are:
Bye, to disconnect.
Kill and KM, to delete your old mail.
List and Mine to see a message list.
Read, Send and SR, for mail

The rest of the commands are for the system operator usage.

Software Version of the Packet System:

International Space Station
(c) Copyright 1985-2001 
PacComm Packet Radio Systems, Inc.

AX.25 Level 2 Version 2.0
  Expanded NMEA 183 (GPS) SUPPORT

Release 5.0.2 May 07, 2001


Practice Practice Practice:
If you want to be successful in sending and receiving packet mail from ISS
you must be fully proficient in using packet mail on Earth first, before you
make any attempt to use the packet mail system on ISS.

Your Goals:
To send and/or receive a message from ISS, as efficiently as possible.
To help teach others to do the same.

Make sure your 2-meter station is fully functional and your TNC, Computer
and Radio connections are 100% reliable.  Practice on Earth before you reach
for space.

Find a local terrestrial packet BBS to use for your practicing.  

Log into your local BBS and try sending a series of packet messages to your
self.  Each message should be less than approximately 500 bytes long. (The
sample message listed below was approximately 500 bytes long) Learn all of
the fast upload features of your TNC program and learn how to upload a
500-byte file from disk into a terrestrial BBS quickly.  Never send a file
larger than 500 bytes (that is bytes NOT kilobytes).  Remember there are
less than 64,000 bytes of memory for the active mailbox.

You will also need to know how to down load all data from a BBS session to
disk, so you can save and read the data later.  You do not want to waste
time reading the messages on your screen while you are connected to the ISS
PMS.  Read all messages and listing AFTER you have logged out and

Time it:
Keep practicing until you can successfully perform all of the following
commands in less than 60 seconds.
Log in to a BBS
Upload a mail message from disk to the BBS
Kill a sample message
Log off the BBS

After you have mastered the above tasks, it is now on to the next step.
Find a distant terrestrial weak signal BBS that you can connect to (signal
level S3 - 4).  Weak signal BBS will be harder to work when the channel is
busy with lots of activity.  You should test with the weak signal
terrestrial BBS first during off hours, and then repeat the test during
prime time, when the channel is full of other packet traffic. Sending data
to a weak signal BBS during peak traffic hours will be similar to working
the ISS PMS, however the ISS PMS is a little harder.
Now repeat the same practice session as before.
Keep practicing on the weak signal terrestrial BBS until you can
successfully perform all of the following commands in less that 60 seconds.
Log in to a BBS
Upload a mail message from disk to the BBS
Kill a sample message
Log off the BBS

Now try for ISS and please be courteous.

Picking A Pass:
Use your computer program to select a good pass with high elevation angles.
When ISS first appears on the horizon, the satellite will be 1500 miles
(2400 km) away.  When ISS is directly over your house, it is only 240 miles
(384 km) away.  
Using your tracking program, pick a pass with a maximum elevation of over 40
degrees.  These are typically the best passes because ISS will be closer to
your QTH.  If you were to try to call ISS when it is low on the Horizon, you
will probably not be successful.  For low elevation angles, your radio
signal will have to travel along the ground, where it will be affected by
trees, buildings and hills.  When ISS is high above the trees, you will have
a clear line-of-site shot to his antenna. A 1000-mile contact on 2-meters is
easy, that is if there is nothing between you and the other station.
A good pass is only 10 minutes long.  Since ISS is low on the Horizon during
the beginning and end of each pass, you will want to avoid calling during
the first two and last two minutes of each pass.  This will still leave you
with a 6-minute window of opportunity.

Calling ISS:
Before you begin calling ISS on packet, make sure you are familiar with the
operations of your packet system.  Try experimenting with a local
terrestrial PBBS or connecting to a friends TNC.  Practice uploading short
files from your disk to another station.  See if you can Login, upload and
logout in less than a minute.  Once you have mastered this technique on a
busy PBBS frequency, you will be ready for ISS.  Most TNC programs will
allow you to save packet files you have read to your disk. You can learn a
lot from perusing your old data files of previous ISS passes.

When ISS first comes over your Horizon, it will usually be already connected
to another Amateur Radio Station.   Before you transmit, monitor the data
coming down from ISS.  If you read the data carefully, you will be able to
determine if another station is logged into the ISS PMS.  If you see any
"Index" packets going from ISS to any other station, then ISS is connected a
station.  An Index packet is any packet from ISS with the tag << I0, I1, I2,
I3, I4, I5, I6 or I7 >>

In this example, the ISS PMS is connected to WF1F and he is in the process
of down loading a Packet Mail message from the ISS PMS.  
Each line contains the call sign of the sender (RS0ISS).  
The call of the receiving station (WF1F).
The Index packet or Information Frame and number sequence 0 - 7.
And then the Data/Information.

RS0ISS>WF1F <<I0>>:Stat   : PR    
RS0ISS>WF1F <<I1>>:Posted : 00/00/00 00:33
RS0ISS>WF1F <<I2>>:To     : WF1F   
RS0ISS>WF1F <<I3>>:From   : RS0ISS 
RS0ISS>WF1F <<I4>>:@ BBS  :        
RS0ISS>WF1F <<I5>>:xID    : 
RS0ISS>WF1F <<I6>>:Subject: HAM- FUN
RS0ISS>WF1F <<I7>>:

You will only see Index packets if the Mailbox is being used.  If you
attempt a connection to ISS while it is busy, you will receive the message
RS0ISS>yourcall <<DM>>: "RS0ISS Busy."  When you receive a "Busy" from ISS,
then you must STOP calling the ISS PMS.  Do not attempt to call ISS until
you see the currently connected station "Log-off"  (RS0ISS>someonescall/V :
<<I1>>:  - Logged off).

If you continue your attempt at connecting to the ISS PMS while it is busy,
the following will happen:
1.  You will be causing intentional interference (QRM)
2. 	The station currently connected may not be able to log off, because
of the QRM generated by your station.  This will cause ISS to go into a
"time-out loop" and prevent anyone from logging into ISS for 1-2 Minutes.
3.  Anyone within 3000 miles of your stations will be able to see ISS
sending DM messages to your station.  If you do not follow the correct
procedures, everyone within 3000 miles will know who is causing the
interference (QRM).

When is it appropriate to call the ISS Packet PMS:

Set your terminal program to save all data to disk.  This will help you look
back and see a lot of good data.  If you are unable to connect to ISS, you
can read what other people were sending.  

This is a sample of a station logging off from ISS:
RS0ISS>WF1F/V [12/30/02 04:20:57]: <<I1>>:  - Logged off

RS0ISS>WF1F/V [12/30/02 04:20:58]: <<D>>:
*** DISCONNECTED [12/30/02 04:20:58]

RS0ISS>CQ/V [12/30/02 04:20:59]: <<UI>>:  - Logged off

This is the only time you can log into the ISS PMS port.  You need to look
for the "RS0ISS>CQ/V - Logged off " packet coming from ISS.

Another packet flag you should be aware of is the "<<D>>" Disconnect Request
message.  This packet message means that ISS is trying to disconnect from
the station currently connected to this port.  This is different from the
"<<DM>>" Disconnect Busy message.  If the station connected to ISS goes out
of range, then an "Idle-timer" will force a log out after 1-2 minutes.  The
ISS PMS will send several <<D>> messages to the connected station.  Then ISS
resets and sends out the desired "CQ, <<UI>>" packet (UI = unconnected
Information frame).

ISS Call sign:
The call sign of the Packet station keeps changing.  This month the mailbox
address is "RS0ISS".  The address may change from time to time between
RS0ISS and RS0ISS-1.

I have connected, now what?
Before you connect, you should have a plan of what you want to accomplish.
Try to keep your connection time limited to 60 seconds or less.  With this
goal in mind, you will be limited to what you can do during one pass.  Here
are a few examples:

1. Login, Send a short message (S RS0ISS or just S) and then Logout.
2. Login, List the last 10 messages (L command).
Read a message addressed to ALL (R n) and Logout.
3. Login, Read mail to your station (R n), Kill your mail (K n) and Logout

After you have connected, keep your mail messages short  (2 or 3 lines).
The TNC on ISS has a very limited amount of memory for mail messages (the
TNC has a 1 Meg RAM, however only 64k is allocated for mail storage in each
mailbox).  If someone sent mail to you via ISS, then make sure you delete
the message before you upload any more mail.  The reason you want to delete
first before you upload, is to make room for your new message.   

Actual Message from ISS.
Here is an actual message sent from ISS commander Valery Korzun to Dave
Larsen N6CO, on June 28, 2002.  It is mandatory that you have your terminal
program configured to save all data to your disk drive.  This will allow you
to read the information after the pass and not tie-up the TNC by slowly
reading the information as it is displayed.  There will be plenty of time
after the pass to review the details of your messages. In this message, I
will point out a few important items in [].
30-Jun-02  09:03:43  CONNECTED to RS0ISS
Logged on to RS0ISS's Personal Message System
on board the International Space Station

You have mail waiting.
[after you login, if there is mail waiting for you,
you will get the 'mail waiting' message and an automatic
listing of all mail to and from your call sign]

Msg # Stat  Date     Time  To     From   @ BBS  Subject
  844 P     00/00/00 00:07 N6CO   RS0ISS        HELLO
  824 BR    00/00/00 00:19 ALL    N6CO          2 Line ISS Keps 6-28
  795 PR    00/00/00 00:40 RS0ISS N6CO          DLYA Valery [RZ3FK]
r 844

[Here, Dave reads his message with the 'r 884' command, which
is R for read, and the message number.  In this example, there
looks like there is a problem with the time clock in the TNC]

Stat   : PR    
Posted : 00/00/00 00:07
To     : N6CO   
>From   : RS0ISS 
@ BBS  :        
xID    : 
Subject: HELLO

Dave, I'm glad to receive mess from you and thanks for your biography. Very 
nice to meet you again, brave pilot. I'm ex-fighter-Mig- 21,Mig-29.I 
served as pilot 12 years, then I was student air force academy, then 
Gagarin cosmonaut training center from1987 to June 2002.Married.One son.
Your Russian is very good. Thanks for support and help. Hope hear you 


[ As soon as Dave has downloaded the message, he immediately deletes the old
message from the ISS mailbox.  This is very important because the selected
mailbox only has approximately 64k bytes of memory available for mailbox

k 844
Message erased
30-Jun-02  09:04:31  DISCONNECTED: RS0ISS

 [Dave has now logged out of the ISS mailbox.
Start time was 09:03:43
End time was 09:04:31
Total time:  48 seconds. ]

I used Dave's message for a few reasons.
First, it was an interesting memo.  It gives us some insight to Commander
Valery Korzuns background.
It shows us that, the commander has a good understanding of the English
language, not all ISS crewmembers are fluent in multiple languages.  It does
help to send email in the native language of the recipient.

Since Dave is a very experienced ham (Mir amateur radio system operator for
10+ years and ISS packet system operator), it shows you a good example of
how to Login and Logout fast, so that the next person can get in. Dave took
48 seconds, this is a little longer than usual because the channel was very
busy and there were many "RETRY" collisions. His hardware for this message
consisted of a Zero "dBd" antenna and 150 watts of power.  When you take
into account the coax loss and you convert this over to an ERP value, it
gave him an ERP value of 75 watts.

PMS Usage:
The PMS can also be used to meet people in other parts of the world.  If you
do send a message looking for a foreign Packet Pen Pal, make sure you
include your return terrestrial packet address or Email address.  Once you
have made friends around the world, you should then keep in touch via
Terrestrial packet/Email methods and do not use the PMS.  One of the few
exceptions may be if you are in a boat in the south pacific and you are out
of range of all other Terrestrial PBBS systems.  Trying to Work All States
or DXCC via ISS is strictly taboo.

The PMS is NOT a Public Bulletin Board System (PBBS).  You should never post
following types of messages on the ISS PMS: For Sale, Equipment Wanted,
Special Event Stations, etc. 

The ISS PMS station also supports the Digital Repeater option called
digi-peating.  This feature should only be used, when no one is using the
PMS mail ports.  The one station actively using the Mailbox has top
priority.  Read in your TNC manual the section on using the UNPROTO option.
Please practice using the option on a Terrestrial packet station first
before going on to ISS.  With Unproto, you can bounce messages off the ISS
PMS and chat with people thousands of miles away.  Two-way full connects
using the ISS digital-repeater are possible, but extensive testing has
proven this feature is not as reliable as Unproto.  The Sysops do not want
anyone to use the digital-repeater for two-way-ack connects.  

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