[aprssig] Using APRS Satellites in Hurricane Recovery:

Robert Bruninga bruninga at usna.edu
Thu Sep 1 15:57:48 CDT 2005


This document is NOT a receommendation to
use APRS via ISS in a disaster.  There are many
other Ham Radio Communications capabilities that
are better under any given circumstances.

This document was only written to tell "HOW" 
to use APRS and packet via ISS for emergency 
operations in a disaster area,*IF* such use
was necessary for a given emergent need.

This email describes how to use the ARISS and 
possibly PCSAT2 system (on ISS) for tracking and 
communicating with APRS assets in the Hurricane 
affected areas.  It covers 3 topics:

1) Knowing when the ISS is in view without a PC
2) Settings for ISS and PCSAT2 digipeater
3) How to send an Email from your APRS or
    D7 or D700 APRS mobile/HT or normal packet.


DAILY 1:  At 30 deg latitude (New Orleans),
you will get two contact window periods a day 
and each period will give you 2 or 3 pass 
opportunities.  Today these Windows are 7-10 PM
and 2-6 AM daylight time (applies everwhere at 
this N.latitude).

DAILY 2:  If you hear a pass early in a window, 
then you will hear another one 97 minutes later.  
And if lucky, another 97 minutes after that.

DAILY 3:   Similarly, if you hear a good pass during 
the first window, then you will hear another good 
pass in the second window exactly 8 hours 
(and 2 mins) later.

NEXT DAY:   If you hear a pass on ONE day, then 
you will hear another one the NEXT day  27 mins 
LATER.  (AND/OR 68 minutes EARLIER.)

MULTI-DAY:  For longer range multi-day planning, 
these "window-periods" slide EARLIER by 22 
minutes per day (but the exact times follow
only the "daily" rules above")

WIth these simple rules and keeping a log of
when you hear ISS passes on your dashboard,
it is easy to predict future passes and operating
times for weeks or longer.  You can work up
simple plans like this for ECHO, SO50 and any
other satellite.

NEW-START:  If you are starting new, then all you
have to do is monitor continuously during one
of the windows until you do hear a pass, and
from then on, you can figure your own schedule.
Just remember to slide the window earlier by
22 minutes per day from the times above for
1 Sept.

SETTINGS:  There are two digital assets on ISS
and both digipeat using the path of "VIA ARISS"

ARISS:     145.800 down, 145.99 up
PCSAT2:  435.275 +/- 10 Khz, 145.825 up

Use ARISS in the disaster area and mobile
since it is 10 dB stronger, has 9 dB less path 
loss on the downlink to other omni's, has more 
IGate stations and has no appreciable Doppler.

PBBS:  If you have a portable cross band beam
antenna,  and can remember to TRACK ISS, and 
point the beam, and tune the downlink for Doppler, 
then you are welcome to use the PCSAT2 BBS for 
longer paragraph type trafffic, though you
must remember that maintainig a "connection"
via a satellite is problematic at best.  The PBBS
callsign is MAIL.

Only USA STATIONS IN the disaster area
should logon to the BBS with emergency
or priority traffic.  No other USA stations should 
attempt to use the BBS for ANY purpose even 
emergency or priority traffic to or from someone 
in the  disaster area.  

Instead, Let stations in other parts of the world 
be the gateways for downloading any such traffic.
or sending back replies.

EMAIL:   APRS is a one-line message system.  
But you can send email if you can fit the email 
address and text in the same line.  ANyone
can do this via ISS using the APRS protocol 
if they have either an APRS system, a D7 walkie 
talkie or a D700 mobile, or even a simple radio/TNC.

- Set your path to go via ARISS
- Send the message line TO "email"
- Make the first part of the message be the
email address and then enter your very brief
email text continuing on the same message line.
For any TNC or packet system, simply make
the AX.25 address be APRS and send the
packet as a UI digipeated packet via ARISS.

If you are successful via ISS, your radio will
display "MY MESSAGE" to confirm the packet
got digipeted.  If it did, then cancel the 
remaining message retries to reduce QRM.
Do not expect a message ack.

To do this you must make your packet look
like an APRS message packet:
- Go to converse
- Type :EMAILssss:eeee at eee.eee.eee text
Where the four "ssss" are four spaces
Where eeee at eee.eee.eee is the email address
Where text is your text.

If you see it digipeated, then your email will
probably be successful.  If not, you have
to type the whole thing again, error free
to try again.

This document is *NOT* a recommendation to
use APRS via ISS in a disaster.  There are many
other Ham Radio Communications capabilities that
are better under any given circumstances.

This document was only written to tell "HOW" 
to use APRS and packet via ISS for emergency 
operations in a disaster area, *IF* such use had
any immediate application.

But in any case, unattended packet beacons via 
ISS are NEVER welcome  and especially over the 
USA at this time.

This email is provided for what-it-is-worth, and
is not endorsed nor approved by ARISS at this
time.  I just thought it would be useful to have
it as a baseline...

de Wb4APR, Bob
US Naval Academy
PCSAT2 Grond station

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