[amsat-bb] Re: New Satellite Downlink?
bruninga at usna.edu
Thu Aug 26 05:39:06 PDT 2010
> Transits #23 and #25. object nos 19070 and 19419.
Here is a possible application based on the unique nature of the
"navigation" message which is 26 lines of 6 words with each
being 39 bits. But the first 8 lines are changed every 2
minutes by inserting a new line and scrolling off the oldest
one. We can use this for a list of callsigns.
We can get a callsign and extra 8 bit authorization ID into the
39 bits, or 6 calls per line for a total of 48 calls. Then the
remaining 18 lines are available for what I call Quarter-Tweet
messages of 35 bytes each. We will also reserve a few lines for
So here is how it would work.
1) User initiates a login request via internet to the command
2) His call is added to the Login list on the satellite plus an
3) As noted above, this list scrolls down and only the last 48
4) Next he has to tune in the downlink to see his authorization
5) Now with his authorization byte, he can send a Q-tweet via
6) Which now shows up with 18 other Q-tweets in the remaining 18
Your Qtweet can contain a call to another station and when he
responds, you can count a QSO.
Something like that. The above idea lets everyone play, but
requires that they can hear the satllite first (like any other
satelite) before then can send an uplink (via the internet) for
reception (downlink) via RF.
We will use a 5 bit code (like RTTY) but will replace the CR and
LF with the "." and a CAPS shift. SO the 31 possible characters
are a-z plus "." plus CAPS, FIGS and LTRS. This allows normal
mixed case text...
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