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Re: APRS capabilities on AO-51



>>> "Gould Smith" <gouldsmi@bellsouth.net>
>Just to clarify some issues for everyone.
>There is no 1200 bps capability on AO-51.

But we are talking about 9600 baud APRS.  And the
easiest way to do this and the most fun is with the
Kenwood TH-D7 HT and TM-D700 mobile radios that 
have 9600 baud satellite APRS built in and with front
panel displays and keypad message entry...

>There is no APRS digipeat capability on AO-51.

That's a pretty broad statement that has enough
ambiguity which is why this question keeps coming 
up.     ECHO runs the  PACSAT protocol on its digital 
channels and that protocol on all prior birds has 
always had the ability to do UI digipeating by the 
simple on/off commanding of the d:0  bit to d:1 which 
prominantly displays in the the PACSAT protocol UI 
Status packet.

Nuts, I just listened this last pass and ECHO was in
high power FM mode, so the digital channel was off.
I havent listened to the digital side in over a year,
but I thought that the "d:0" digi bit is still reproted
in the ECHO downlink STATUS packet.  If it is no longer
there, then I appologize.

The PACSAT transponder has a 9600 baud TDMA 
uplink channel and it has a 9600 baud continuous
downlink.  Both are 100% compatible with 9600
baud APRS handheld and mobile packet.  Saying that 
"ECHO has no digipeat capability" simply means that 
the digipeater ON/OFF bit has not been turned ON.

Now the last we heard a year ago was that the 
command team did turn it on to test it but that the 
"processor was overloaded with interrupts".  This
made no sense because the processor is already
listening to the 9600 baud uplink channels all the
time anyway for 9600 baud packets from stations
wanting to join the queue.  And there is no difference
between a pacsat protocol packet and a UI APRS
packet other than a bit or so indicating that the packet
is UI and a bit indicating it is desired to be digipeated.

And until the processor on board ECHO fully receives
the packet and decodes it, it cannot possibly "apriori"
know that it is an APRS packet instead of a PACSAT
protocol packet.  THus it makse no sense to say that
the reason the DIGI bit is disabled is because when 
the processor listens for UI packets it gets too many
interrupts...  It has to be listening already....

If that is the case, then it would seem that the uplink
processor has some kind of other problem not
related to whether a packet is UI or not.  And if there
is such a problem, that there is plenty of expertise 
to make a software patch to overcome this little
nusance?

>With special software written for AO-51, it can be 
>programmed to provide a Status message at 9600 bps.
>This message could be displayed on the Kenwood 
>APRS radios if  configured for this mode.

Yes, there were several things we can be doing
with the 9600 baud downlink for APRS type handheld
and mobile operations as you indicated.  Such as 
the status you mention and also the ability to send 
bulletins and announcemnets.  But these all require 
effort on the ECHO command team.  Although these 
are neat and we would love to see them, we do 
recognize that they are labor intensive and so we do
not want to add any burden to an already very busy 
team.

But just turning on DIPEAT then users on the ground
can send the bulletins and announcemntes and
status without having to bother the command team.

ANyway, I am not tyring to be a thorn, just I 
would like to explore in a little more depth why
we keep getting the story that ECHO cannot
do 9600 baud digipeating when every previous
PACSAT protocol bird could.    I have been
demonstrating 9600 baud hand-held UI digipeating
through UO-22 since the 1999 AMSAT symposium
in Mississippi, and Kenwood recalled all their early
D7(A's)'s to enable them for 9600 baud APRS and
and cross band Mode J and Mode B packet 
anticipating that we would have more satellites
like UO-22 enabling handheld 9600 baud packet
communincations anywhere on the planet.

But since the demise of UO-22, we have no
9600 baud user-to-user real-time digipeater
even though we now have more than probably
10,000 HAMS with HT's and mobile radios that 
are 100% compatible with the digital uplink and 
digital downlink of ECHO (with no PC needed)
and yet the only thing that ECHO does (which 
runs the same PACSAT protocol as UO-22 and 
wihch did support these radios) has been the 
old style BBS with only a few handfuls of users
operating from their PC's in their shacks.

Compare the public demos of ECHO using HT's
for FM compared to the public demos of ECHO
using the PACSAT protocol channel and one
can see whre I am coming from.   Whereas
if the digipeat bit were simply enabled then
EVERY pass could support:

1) PACSAT protocol users 
2) APRS ht and mobile users
3) FM Voice users

Because all 3 modes can run simultaneously
and independently and with no mutual
interference.  THus maximizing the potential
for ECHO to the community...

Just some thoughts.
de Wb4APR, Bob
----
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