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

Re: Here I go again... Was: Re: UO-14 , FO-29, FO-20,QRM via ISS



On Wed, 6 Jun 2001, Stan Vandiver wrote:

> more?  Who has more "right" to be using this resource?  The 
<SNIP> 
> The 2 APRS-automated stations, W3ADO and WA6LIE, are  providing
> national support to a large audience of users.  I copy 
> both stations here near Chicago on almost every single pass.  I 
> think their support of APRS is very effective.  Could they get by 
> with even fewer transmissions?  Possibly.  But I am not convinced 
> yet that they are "excessive" either....
<SNIP>
> > I also see keyboarders on every pass... including new callsigns 
> almost daily.  Some use APRS for keyboard QSO's too.  People 
> are "saying hi" all over the place out there!  Thats great too!
> 
> These APRS stations also send bulletins to try to help the 
> situation out there, like "Please QRT after pass..."...
<SNIP>
> Rather than encouraging anyone else to become a "super-beacon" 
> and "Voice of the ISS".... let me ask, "Can the ISS TNC be 
> configured to transmit its own APRS position data?"  Once the 
> TNC can get the attention it needs (like a callsign!)... can the 
> NASA folks supply the beacons needed to satisfy BOTH of these 
> large user groups, position beacons for the APRS'ers and 
> information beacons for the keyboarders (or other casual listeners, 
> like school kids perhaps)? 

Yes, that was the original intent.  There would be a GPS connected to
provide ISS position data and the astronauts would compose "meta-beacons"
that would inform everyone of what was going on...

Problem is, it will be YEARS until a GPS is connected (so W3ADO and W6LIE
are providing that service from the ground) and the astronauts do not have
an available laptop nor time to mess with it... (So W3ADO and W6LIE could
be uplinking a "meta beacon" for the same purpose, but we are not, because
we have no direct line to the astronauts to put in what they want to
say...)

> Also, I wonder how many "retries" W3ADO and WA6LIE have to 
> transmit before they get their desired data successfully digipeated? 

W3ADO sends an ISS Position report once a minute... about 7 packets per
pass. (it only sends when ISS is above 2 degrees)  There are no retries.

W3ADO also sends its own POSITION once every 3 minutes on a different
schedule....  and a STATUS TEXT once every 9 minutes that contains the
"bulletin to not QRM other satellites and to QRT after the pass"...

> For these APRS-automated stations to get so many successful digipeats
> seems to indicate that they are using an even higher transmit rate
> (4-6 sec intervals noted by W3ADO at times during the test)...

W3ADO sends about 10 or 11 packets TOTAL per pass and ONLY when ISS is in 
view.  Since there are 3 different types of packets, each with their own
rate, there could have been 2 packets within 4 seconds of each other, but 
that is purely a random occurance.  This does NOT consititute a RATE.

de WB4APR, Bob

----
Via the sarex mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe sarex" to Majordomo@amsat.org



AMSAT Top AMSAT Home