... approved the following Eagle communications payloads: c. A low rate text message system, like SMS. It will operate on U/V-bands and be usable over 75% of the orbit by a small terminal on the ground.
Sounds just like APRS... <grin>
Of course, I know that they are not talking about APRS, but then when one considers the ten thousand or so D7 and D700 radios with APRS messaging built into the front panel, one wonders why we don't have more APRS satellites to use for this purpose. These days, PCSAT-1 is doing great links to mobiles...
In my mind, one of the best applications of any Amateur Satellite is to serve the mobile operator, since the fixed operator in most cases has access to many other communicaitons paths already, such as the internet and satellites that need beams. But the mobile ham operator could really use a satellite link!
Again, the point of this post is not at all to suggest a change to the Eagle plans, not in any way, but to remind future satellite builders that there is this vast mobile Ham radio community that already has a built-in 1200 and 9600 baud front panel radio message and tiny-web-page display capability out there fully fielded by thousands of operators that could benefit from PCSAT type uplinks and downlinks.
See the Tiny-Web-Page applications of the D7 and D700 radios presented at the TAPR/ARRL DCC 2000: http://www.ew.usna.edu/~bruninga/aprs/TWP.html
We tried to extend the mission of PCSAT-1 with PCSAT2, ANDE and RAFT, but all of those have limited lifetimes. If you have a mobile D7 or D700 and haven't tried PCSAT-1 during this current recovery period, you should try it. On any good pass, I see as many as a dozen stations and messages on my mobile. Simply tune your D7 or D700 mobile to 145.825 and leave it overnight. Next morning, look to see who all you see on the front panel of the radio. Also check the MSG list.
Here are some hints on the best way to do that experiment:
1) Observe call of the last normal APRS station heard (so you can tell what is new and what is old in the morning). 2) Be sure your RANGE LIMIT is set to 0, and not 50 miles or so, because the radio will filter out all satellite packets since they come from 500 to 1500 miles away unless it is set to 0. 3) Check that your radio CLOCK is set so that you can see the packet times of arrival 4) Clear out any old incoming messages to make room for Satellite messages. 5) Park your car to see the sky above about 15 degrees especialy from the Southwest through North East. 6) Please, only do unattended at night so that you do not conflict with command stations during the day.
Next morning, check the station list and message list on the radio and see what you got!
Oh, for unattended operation like that, be sure your TX rate is only one packet per 5 minutes so you will equitably share the channel with dozens of others... If we overload PCSAT-1 in the dark we will kill it. We won't see a positive power budget until March for only a week.
To see everyone live, who is playing on PCSAT-1, see http://pcsat.aprs.org
Good luck!
Bob Bruninga, WB4APR Naval Academy Satellite Lab