Re: [amsat-bb] AMSAT: 38K4

["John Boudreau" <john@xxxxxxxxxxx>]

Does anyone have any further information on modifying a G3RUH modem to work with the Symek IFD board?

John - VE8EV

-----Original Message-----
From: STEVE DIGGS <steve.diggs@totrbbs.radio.org>
To: amsat-bb@AMSAT.Org <amsat-bb@AMSAT.Org>
Date: Friday, February 04, 2000 8:12 AM
Subject: [amsat-bb] AMSAT: 38K4


 >From: "Stacey E. Mills, M.D." <w4sm@cstone.net>
 >Subject: [amsat-bb] 38k4 baud satellites
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 >
 >
 >If you're tired of the "slow" 9k6 baud sats, now may be a good time to look
 >into what it takes to go to the 38k4 downlinks.  At least two of the
 >current satellites, TO-31 and UO-36 have this capability.  P3D's RUDAK has
 >multiple high speed modems and is likely to be very active at 38k4, as
 >well.  Several of us have been working with Chris Jackson to tweak WISP to
 >function best with these new satellites, and I believe that they (at least
 >UO-36) will be widely available soon.  Even now UO-36 is often transmitting
 >at 38k4 baud over the US (437.025) during daylight hours.
 >
 >The uplink on these satellites is 9k6 baud, so if you're active on
 >UO22/KO25, etc., no changes are needed on the transmit side.  However, the
 >extreme bandwidth of the downlink at 38k4 necessitates some receiver
 >changes as all of the current ham rigs are too narrow banded to handle
 >this.  There is very good, relatively inexpensive solution, however.  Symek
 >(www.symek.com), a German company in Stuttgart, makes a small
 >receiver/demodulator board that intercepts the data stream from your
 >transceiver's IF.  These IFD boards cost DEM 235 (about $122).  They come
 >with excellent installation instructions (in English if appropriate) and
 >are available for most of the major satellite transceivers and receivers
 >used by amateurs.  If you don't see your rig listed, drop them a note and
 >they'll work with you to get you an IFD board.  I ordered using a credit
 >card over the internet and my modules were received in a few days.  I've
 >installed one in a Yaesu FT-736R and another in a Kenwood TS-790A.  The
 >Yaesu installation is very simple and the Kenwood is only a little more
 >involved.  Anyone comfortable making the 9k6 baud modifications should
 >easily be able to handle this.  Importantly, normal function of the radio
 >is not affected.
 >
 >With regard to a modem that will handle 38k4 downlinks, there may be
 >several options.  I've been told that a standard G3RUH 9k6 FSK modem can be
 >adapted to run at this speed.  There's also been discussion that a
 >DSP56002EVM board is capable (just) of running at this rate and some
 >software may be available for this modem on the TAPR web site. I have not
 >pursued either of these solutions, so I can't comment further.
 >
 >Symek has two very high speed modems (up to 614K baud!) that work extremely
 >well.  One is a two port version (TNC3S) and the other, less expensive one
 >is single port (TNC31S).  These can be ordered from the factory in any
 >specified configuration.  I have the less expensive TNC31S.  Mine is set up
 >to wake up in KISS mode with 38k4 downlink, 9k6 uplink, and a 57k6 PC
 >connection.
 >
 >The downlink at 38k4 on UO-36 is really spectacular! Watching the byte
 >counter fly by is quite a treat. Efficiencies of 90-100% are easily
 >obtained with directional antennas and a preamp.  Doppler tuning is not
 >really necessary on the widebanded 435 Mhz downlink.  Downloads of 1.5 Megs
 >are possible on single passes, and all three components of a color image
 >can be captured in short order.  I used to think 9k6 was fast, at least
 >compared to 1k2 on AO-16, now when I look at KO-25/UO-22, the byte counter
 >seems to be moving in slow motion!
 >
 >To me at least, this high speed (internet level) transfer rate, and the
 >ability to grab images on a single pass, really brings some excitement back
 >to the digital sats.
 >
 >STANDARD DISCLAIMER:  I am not an employee of Symek and I receive no
 >compensation from them... just a very satisfied customer wanting to spread
 >the word.
 >
 >Hope to see you in the queue(s) soon.
 >
 >
 >--
 > ________________________________________________________________________
 > Stacey E. Mills, W4SM    WWW:  http://www.cstone.net/~w4sm/ham1.html
 >   Charlottesville, VA    PGP key:      http://www.cstone.net/~w4sm/key
 > 
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