[amsat-bb] Re: New Satellite Downlink? (Drawing)

[Robert Bruninga]

Here is more info on how we could use the Navigation message of
these old satellites for a rudimentary satellite Q-Tweet system.
That is, you can send "Quarter-Tweets" for inclusion in the
downlink... But only after you have scheduled a login and
obtained (in the next downlink) your authorization code...  See
the drawing:
http://aprs.org/transit/call-encoding.GIF

Using the scenario below:
Bob, Wb4APR

> -----Original Message-----
> On Behalf Of Robert Bruninga
> Sent: Thursday, August 26, 2010 8:39 AM
> Subject: [amsat-bb] Re: New Satellite Downlink?
> 
>> 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 one word in 
> each of the first 8 lines are changed every 2 minutes 
> by inserting a new word 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 each of the 39 bit words.  Then the rest of 
> thos first 6 lines can be older callsigns and 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 special bulletins.
> 
> So here is how it would work.
> 
> 1) User initiates a login request via internet to 
> the command station.
>
> 2) His call is added to the Login list on the 
> satellite plus an authorization byte
>
> 3) As noted above, this list scrolls down and only 
> the last 48 are visible
>
> 4) Next he has to tune in the downlink to see his 
> authorization byte.
>
> 5) Now with his authorization byte, he can send a 
> Q-tweet via the internet.
>
> 6) Which now shows up with 18 other Q-tweets in 
> the remaining 18 lines downlink
> 
> 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...
> 
> Bob, WB4APR