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Re: New! Satellite Digital Messaging


You mentioned that Kenwood announced a 9600 baud upgrade for the TH-D7. How
do I get the upgrade for my 3 month old TH-D7 ??


Don DeJarnette

----- Original Message -----
From: Bob Bruninga <bruninga@nadn.navy.mil>
To: <amsat-bb@AMSAT.Org>
Cc: Robert Bruninga <bruninga@arctic.usna.edu>
Sent: Sunday, May 21, 2000 11:07 PM
Subject: [amsat-bb] New! Satellite Digital Messaging

> This weekend, coincident with the Dayton Hamvention 2000, ushered in a new
> milestone in personal wireless  world wide amateur satellite message
> communications.  Following several months of on-air testing, and the
> convergence of several new announcements, mobile-to-mobile and handheld
> amateur satellite message communications are now a reality!
> At Dayton, Kenwood revealed the 9600 baud upgrade to their existing
> 1200 baud APRS handheld,  Alinco revealed their new 1200/9600 baud data
> radio, and the South African SUNSAT team announced the availability of
> their satellite for APRS type UI messaging when not in use for scheduled
> voice passes.
> Using the built in 9600 baud TNC's in the Kenwood and ALinco  data radios
> and the effecient APRS messaging protocol, it is  possbile for simple
> mobile or even handheld stations with  simple antennas to communicate
> briefly via SUNSAT or any satellite  that is enabled for UI digipeating.
> ALthough the recent growth in FM voice satelites has sparked
> excitement throughout a new generation of satellite enthusiasts,
> the short, single channel voice operations are highly competitive
> and difficult to share equitably among a large number of users.
> But with one-line APRS messaging, each packet taking less  than a second,
> there is potential for far more stations to share the satellite during
> each pass while also getting short but meaningful communications through
> the bird.
> In addition, being in digital form, any station receiving these packets
> can link them into the worldwide APRServe internet system for
> real-time delivery back to terrestrial RF anywhere on the planet.
> The following example says it all.  During the Dayton Hamvention Sunday
> morning SUNSAT pass, I was trying to demo 9600 baud handheld reception
> in the fleamarket area using nothing but my HT and whip antenna.  Hearing
> nothing but 60-over S9 interemod, I gave up and put the HT in my pants
> pocket and continued my shopping.  A few minutes later I heard the
> tale-tale beep from my HT indicating a new message.
> Thinking it was just another message from my buddies at the
> hamfest, I casually pulled it from my pocket and was surprised
> to see that it was a BULLETIN from SUNSAT!  It was one of the handful
> of Bulletins that SUNSAT downlinks and it was announcing that this
> capability was now open for general use.  There could not have been
> a better and more fulfilling conclusion to our previous testing than this
> serendipitous reception.
> Thus, an Amateur Satellite Message was delivered to a non-optimized
> in-attentive handheld user using EXISTING amateur radio equipment.  What
> makes this possible is the 6 dB stronger downlink transmitter and 9 dB
> better 2 meter path loss  compared to the other 9600 baud UHF downlink
> Although it might appear that the return path on UHF from the HT
> back to the satellite would be impossilbe due to the additional 9 dB
> path loss, the presumption is that an HT user with an outgoing
> message would be aware of the pass and would use a handheld
> beam to make up for the difference.  Thus, we have worldwide amateur
> satellite HT message capability anywhere.  (Note, due to the real
> time digipeating of these messages, there must be groundstation
> somewhere within the same satellite footprint, about 2000 miles
> to send/capture these packets.)
> But even without beams on the uplink OR downlink, we can still do two-way
> messaging to handhelds.... Here's how...
> Some other non-published testing via a 9600 baud satellite has
> taken advantage of the 9dB 2 meter uplink advantage and has demonstrated
> reliable UPLINK of packets from HT's with omni whip antennas and
> non-tracking, un-attentive style message delivery.  THus, if one of the
> existing mode J PACSATS were enabled for UI APRS style messaging, then the
> combined two bird constellation of SUNSAT making message delivery and the
> PACSAT relaying return traffic, gives us a worldwide two way shirt-pocket
> amateur satellite messaging capability!
> The real excitement is that we are doing this now, today.  It requires
> NO new satellites and NO software mods to the existing birds.  Two way
> messaging is possible HT-to-HT and mobile-to-mobile.  Further enhancements
> linking this in to the terrestrial APRS worldwide internet linked
> infrastructure that then gives global real-time  delievery is simply a
> matter of adding simple omni antenna receivers at a few of the existing
> APRS IGates and a little software.
> For details of this exciting new mobile satellite capability and the
> years of UI digipeating testing leading up to it, see:
> http://web.usna.navy.mil/~bruninga/astars.html
> We expect this site to change rapidly as more experimentation is conducted
> on this mode of communications.  SO check back in a week or so when we
> condense all this new info...
> We hope this realtime-messaging capability will provide a  new lifeline
> for amateur stations on-the-go,  in the wilderness, at sea and anywhere
> else that is beyond the reach of terrestrial amateur communications.
> de WB4APR, Bob Bruninga
> Satellite Ground Station, US Naval Academy,  Annapolis, MD
> ----
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