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

Internet Linked AMSAT Ground Stations




We are building a network of linked ground stations to provide almost
continuous coverage for some of the Amateur Satellites.  The idea is 
that these stations use only OMNI antennas and operate unattended 24 
hours a day worldwide and are linked by the internet so that any 
packets heard by ANY station are all merged together into a single 
internet stream of raw packets for everyone.  This allows the satellite 
operators to manage their satellites by monitoring their downlink even 
when they are out of range of their own station.  It also lets hams on
one continent see how the same satellite is used over the other 
continents.
 
    The internet side of this capability written by K4HG is working fine
and has been on line for more than a year.  It has demonstrated being able
to handle over 2 dozen simultaneous 1200 baud packet feeds and at least
150  simultaneous users without even a slow down.  This example system is
the worldwide APRS server.  To see its raw packets, TELNET to
199.227.86.221 port 23.
 
Steve is now building another system JUST for Amateur satellites.  It
is temporarily on 199.227.86.221 port 10001.  Here is what we need:
 
   *  Good dedicated and knowledgable stations with dedicated 24 hour
      internet access.  One per footprint, per band, per satellite.
      All you need is a mimimum dumb-terminal TELNET access and any
      DOS machine or, any TCPIP Internet service and WIndows or Mac.
 
   *  Dialup access is OK if you want to bother with having to man-up
      for every pass.  THis is fine for special SAREX events, etc.

At this early stage, we do have one site on the USA east coast (The
Naval Academy) that  is feeding MIR packets to its own WEB page and to the
Miami server.  Its WEB page captures the last days worth of packets from
each pass of MIR.  (OOPS, last night we did not have MCOM on, so it only
captured UI frames and not all the other CONNECT-REQUEST/BUSY packets)
 
      http://web.usna.navy.mil/~bruninga/mirex.html
 
SAREX and MIREX are the easiest.  Next would be DOVE when it comes
back to life.  The 1200 baud pacsats are IDEAL but require automatic
control software to aquire unattended.  This is where we really need the
AMSAT expertise.  We will have to gradually ease into the 9600 baud
pacsats, however,  due to their verbosity...
 
A few stations have already responded and are looking into setting
up stations in Mexico, Chicago, Taiwan, and Madrid.  If you are 
interested in setting up such a ground station, please check out the
web page and/or the raw TNC stream.
 
You may feel that omni antennas are not sufficient, but remember, each
station does not need to see all packets horizon to horizon.  It is
not important that each station hear every packet, what counts is
that at least ONE station out of the SUM of all stations heard the 
packet at least once.  Then EVERYONE gets it via the internet link.
Steve's central server removes all dupes.
 
This greatly simplifies the demands on each station individually.
No complex antenna tracking and wear and tear on mechanical systems.
Using only OMNI antennas cuts the usable footprint per station in
about half (6 dB), but all that means is that we need 6 stations 
in the whole USA instead of just 2.  Still quite easy to do...
 
Lots of potential here folks...

de WB4APR (bob)
and K4HG (steve)




AMSAT Top AMSAT Home