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hams use coax to transfer high frequency electromagnetic energy between antennae and receivers and transmitters
Jan 13, 2008
(an archived page, this may contain outdated or broken links)
APRS position beacons via ARISS relay
The view from 200 miles up.
ISS currently in APRS/digi mode - relays beacons.

I will update my website . . .
I will update my website . . .
I will update my website . . .

APRS posit beacon relay in Low Earth Orbit !

We have gotten so accustomed to hearing of the numerous school contacts with the amateur radio station onboard the International Space Station, many have forgotten about the digital mode. The Expedition 16 crew currently has a busy construction schedule, and has not scheduled many school contacts. This actually was welcome news to some hams, as the ARISS station has been in "unattended digipeat" mode recently.

I have a page in here from 2005 describing how this works, but this is a good time for a quick review
. This time I'm using AGWPE & UIView32 with the sound card in the PC instead of an external modem (TNC). These programs provide PTT signaling on the RTS pin of Com1. My longitude and latitude are provided in the beacon text, and the only real change to the program from terrestrial APRS operations, is to specify "ARISS" in the 'unproto' field. This sets the broadcast destination of the beacon packets to request that the ISS digipeater re-transmit your beacon. When a ground-based APRS-IS gateway station hears your beacon on the ISS downlink frequency of 145.825, it will forward that information off to the great global APRS-IS database, making it available to internet portals such as . Once word spread last fall that the ISS digi was back on, hams world-wide started sending their beacons. This is the most activity I've ever seen on the ISS/APRS frequency.

Of course, it helps to know when the station is coming by. I still use Instant Track.
satellite schedule for my location

This tells me when, what direction, and how much doppler shift to expect.
As it happens, I have only a simple vertical in the attic right now for 145.825, so there is no need to aim. I've been heard by ISS when it was as low as 6 degrees above the horizon (over Canada) using only ~15 watts output. Higher gain antenna might require less power, but then it would require some pointing/tracking. Some stations simply set their beacon for every 60 sec, and don't need a schedule, or pointing. Others interact, and acknowlege the other stations heard. I have even received QSL cards . . .  This is really neat ..!.. Thanks NASA !!!

I guess one glorious result of this is seeing your name in lights, so to speak . . .
Here are snips from the FindU page showing who has been recenly heard, as well as the raw packets.
stations heard by ARISS
raw packet display
In addition to the maps (as the example above) you can see callsigns from all over the world, with their location. Using FindU further, and clicking on a callsign, you can get a more detailed and interactive map interface ...
more detailed, interactive map
This simple activity is a good jump point into the world of Amateur Satellites . Take this opportunity to check it out, while the ISS is still in 'digi-mode'. . .
Additional resources for these activities can be found easily :

model antenna in a bottle
All these projects tie together, as my new omnidirectional satellite antennae are also useful for VHF/UHF weak-signal/ssb activities. The EggBeater II from K5OE presents circular polarization for satellites, but is effectively horizontally polarized at the horizon. Not too many choices available for horizontal-omni antennae.
K5OE EggBeater II antenna project
This is the 70cm edition, the 2m version should be done this week.   Thanks Jerry...   73
When All Else FailsHuntsville-Madison County EMA
The local ARES/RACES organizations are consolidating some of the overhead associated with registration and training of the membership. Join us on the 2nd Thursday evening of each month for a good meeting at the HMC EMA EOC (and learn more about this).
Remember, the severe weather season is available year-round.
Huntsville Hamfest - 2008
The Huntsville Hamfest is coming in August.
This year's hamfest is also hosting the ARRL Southeastern Division Convention.
digital radio messaging
Recent discoveries, rants and raves, and experiments :
+ Be sure to check for interesting articles inbetween updates to this page.
+ NBEMS = Narrow Band Emergency Messaging System - check it out (new Yahoo group)
VHF Propagation Map = using APRS beacons to visualize current propagation conditions.
+ APRS.FI = another view of the APRS-IS database, from Finland.
here is an example of an auto-updating view of my immediate area (shows multiple stations !)
+ QSOnet = WoW!  You really should try this. Read my review on SomeNet.
+ CWOP = My weather instruments are still active and logging.
although I'm not yet satisfied with the radiation shield I made for the external thermometer.
The reading is too high in full sun. (check my conditions via FindU). = gradually getting my old logs entered . . .
front porch sunset QSL card

Previous pages from the archives :
2007 . . .
2006 . . .
+ 2005 . . .
Additional organizations, projects and web sites that I continue to support and promote :

location of ISS
This generated image shows the current orbital position of the International Space Station . . .

Thanks to for excellent tracking and visual observation schedules.

I really enjoy stepping outside to watch this beautiful machine fly over. Thanks to Chris Peat's excellent web site, we can know exactly when and where to watch for this and many other satellites.

pc-rf lab
originally licensed as WB5RMG in 1976
pile of ham radios
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