[aprssig] FW: Cleaning up the Global APRS Satellite ground station network (update a)

Robert Bruninga bruninga at usna.edu
Thu Aug 31 15:10:10 CDT 2017


[Updated in response to feedback from the initial APRS post on 7 Aug]

We need to better organize our APRS satellite  ground stations network. Over
an 18 month review, we found about 330 unique IGATES feeding the APRS-IS and
captured by the two APRS live satellite web pages on FINDU:
http://pcsat.findu.com  and http://ariss.net

A hot topic at SmallSat conferences is always the need for remote ground
station networks.  But for two decades, APRS has always had a global ground
station network with hundreds of SATGATES on the APRS downlinks of 145.825.

Here are some problems that I think we can solve:
1) The black-hole problem of locals direct to Satgates not showing up on the
downlink pages
2) No means for premium stations to self identity
3) No means to easily compare satgate capabilities
4) No means to easily indicate satellite traffic captured on other
frequencies
5) No easy means to visualize the network in real time
6) The problem of distinguishing RX only SATGATES
7) Future potential for remote transmission via a remote SATGATE for
satellite controllers

BlackHole Fix:  Steve Dimse, K4HG, the author of FINDU proposes:  Proper
SATGATEs clients should simply delay any directly heard packet for 15
seconds when operating in satgate mode. If a local station successfully
digipeats via the satellite and is captured either through this satgate or
through another satgate, then the digipeated packet will make it to
ariss.net before the directly heard packet. Putting this into all SATGATE
software clients would solve the problem (in the area of that satgate and in
the area of that user).

There are far too many different APRS IGATE clients to make this work across
the board.

But when combined with our goal to more formally define and identify the
APRS-Satellite Ground station network, it does become a viable approach when
we use a unique symbol just for these new SATGATES.  As previously proposed,
we define a new SATGATE symbol, \] that is currently unassigned for SATGATE
stations that are permanent parts of this network.  Then, when they
implement the 15 second delay on direct-heard packets to solve the
black-hole problem, they can further segregate their major capabilities
using Overlay characters.

Phase 1 begins with identifying all permanent SATGATES intending to
participate with the special \] symbol.

Phase 2 adds blackhole fix to clients which then self-identify their class
overlays on that symbol.

\] For immediate use of 24/7  satgates to identify as part of this network
(but w/o the BH fix)

A] for AMSAT Oscar class tracking station (2-way, 50W typical radio)
L] for Lower gain class stations (think, Arrow antenna, 3 elements on VHF)
O] for Omni antenna coverage (no tracking) H] for HFSAT (that will be our
next one in a few years)
U] for UHF downlinks ( channel TBD) S] for Schools and University class A
stations
R] for future class A remote access satgates (for satellite operators only)
V] for Class A stations scanning and tracking Various other satellite
downlinks APRS traffic
T] for omni stations that similary Tune other satellite downlinks APRS
traffic
P] for Portable stations currently operating in non permanent locations

FINDU shows no current users of this symbol.  But once SATGATE stations
begin to implement it you can see them using the FINDU filter:
http://www.findu.com/cgi-bin/symbol.cgi?icon=\]&limit=200

So you can use \] now, but do not use any of the overlays until the
blackhole fix is implemented.
Maybe later the FINDU search can include a wild card for the overlay so we
can search for *] symbols.

Bob


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