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RE: SUNSAT HT success!

Following on from Bobs message:

I have an APRS Satellite gateway running here in Australia.

Any station that is in Sunsat's footprint at the same time as VK3JFK-10 can
uplink at 1200 or 9600 bps and with the right UIPath will be down linked on
to the local VHF channel. The local Igate will then gate your packet to the

You can check the local Igates MHeard list at
http://aprs.cloud.net.au/mheard.cgi to see if you got through the bird.


Remember that in Mode B you must track Doppler on the UPLINK. "This is
REQUIRED or you will only get in on the center of the pass for a minute or
less. Start on 436.280 at beginning and end at .300 at the end." (Bob B)

Any feedback on the success or otherwise of your transmissions would be


> -----Original Message-----
> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
> Behalf Of Bob Bruninga
> Sent: Sunday, 8 October 2000 4:37
> To: TAPR APRS Special Interest Group; amsat-bb@AMSAT.Org
> Subject: [amsat-bb] SUNSAT HT success!
> SUNSAT 1200 baud Mode-B SUCCESS with an HT!
> After last nights failure to get any 9600 packets digipeated
> from a 5W HT
> with WHIP antenna, in mode B, I decided to give in and try
> 1200 baud this
> morning (5:45 AM!) to pick up the other 7 dB.... SUCCESS!
> Yes it can be done with BEAMS and more power, but that is not the
> objective here. We are trying to develop an APRS satellite comm system
> that can communicate to and from HT's with WHIP antennas IN
> and mobiles.
> SUNSAT has demonstrated that ModeB can deliver MESSAGES to
> your HT in your
> pocket and even indoors! ... and that MODE-J can reliably
> receive MESSAGES
> from an HT with whip antenna in your hand.  (IE, what ever
> link is on 2m
> has a 9 dB advantage over UHF and 1200 baud adds another 7 dB).
> Fortunately SUNSAT (and APRSat) is leading up to a 2m
> up-and-down straight
> DIGIpeater mode, but since that would invite bedlam, we are cautiously
> testing each link separately with the MODE-J and MODE-B tests...
> THis is the basis for our APRSat design.  It will have 2m
> up-and-down for
> 5W HT's only.  Mobiles with 50 watts will be strongly
> encouraged to use
> 9600 baud on UHF where their added power can make up for the
> 10 dB worse
> path loss.. Also, this avoids ANY collisions with the HT's.
> Its the best
> of both worlds:
> MODE-B: DOWNLINK is STRONG and requires NO TUNING. (Unattended)
>         Uplink Needs 9 dB more and requires tuning Doppler BLIND
>  *   5 W HT whip 1200 Baud UP  (tracking or traveler message uplink)
>  *       HT whip 9600 baud reception anywhere anytime  (great demos)
>  *   5 W HT portable ARROW 9600 baud UP and DOWN.  THD7(g) only
>  *  50 W Mobile 9600 baud both ways
>  *  Any station IGates with unattended no-tune, OMNI
> horizon-to-horizon
>     coverage.  (Only need one every 1000 miles). ANYONE with a D700
>     and 50' of coax and a whip antenna can do it...
> MODE-J:  Easy 5W uplink, NO TUNING required.  (Unattended)
>          Omni downlink receive of central 30% of pass.  Needs tuning
>  *   5 W HT whip 9600 baud UP (sending your message out)
>  *  50 W Mobile 9600 baud both ways
>  *       HT/Mobile reception with WHIP during central 30% of pass
> In both cases, 1200 baud works 7 dB better than 9600...
> So, Here is what you can do NOW with SUNSAT in MODE-B 145.825
> down 9600
> baud and  uplink 436.290 (-/+ 10Khz doppler) 9600 OR 1200 baud.
> 1)  Transmit 1200 baud with ANY system with 5W or more and
> omni antenna
>                     (but you must anticipate the -/+10 KHz of doppler)
> 2)  Receive with ANY 9600 baud system (THD7  any model with a laptop)
>                                       (THD7g or D700 to front panel)
> 3)  Receive packets by TELNETing to www.aprs.net or
>     Look at MAP at www.aprs.net with any browser for your position.
> Or if you know anyone's call that is uplinking to SUNSAT, go
> this site to see them:
>    http://map.findu.com/wb4apr
> This site shows you were ANY aprs station is REAL TIME if
> they have been
> heard anywhere on the planet within the last few hours.  FOr
> SUNSAT, it
> assumes that someone in your country is feeding the NO-TUNE,
> HORIZON downlink on 145.825 into APRServe (www.aprs.net).
> See ya on the bird..  Remember, anyone with a 1200 baud TNC
> and a UHF FM
> radio can uplink!  You can HEAR it digipeat the 9600 baud burst back
> down..
> de WB4APR, Bob
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
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