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Re: Mobile Station

Hi Bob,

I waited a few days before answering your message because there are far
more qualified persons than myself that can answer your questions. I am.
however, interested in doing the same thing as you. I have one
suggestion for doppler compensation, and I'd be interested in hearing
from others on this list who have run the digital birds from a laptop.

I have an Icom 821H, Eggbeaters, a Landwher 440 preamp, Kantronics 9612
TNC, and a Toshiba laptop. While I have not yet tried to work the
satellites from the laptop (single serial port problrm you described), I
have run this setup from my desktop computer. I used WISP to control the
TNC and handle data and messages and I used a program called FODTRACK to
control the radio for doppler etc. FODTRACK is a DOS based program that
seems well behaved under Win 95 and runs nicely in the background. WISP
allows events to be scheduled, so a few minutes before a satellite pass,
WISP will call FODTRACK to start things up and set the radio for the
correct frequency and compensate for doppler. I avoided the need for the
CT-17 by building a 1 transistor bit invertor (instructions came with
FODTRACK). It seems that the 821H handles signals from the seriel port
fine but the signal needs to be inverted first. Since you already have
the level converter, you'll be fine.

Rather than buy a second com port, I wonder if there is a way to get
FODTRACK to talk through the parallel port. I was going to look into
that but never got around to it. I'd be interested in hearing from
anyone who has run a microsat station from a laptop.

Bob Hart wrote:

> I am assembling a station in my motorhome to work
> the 9600 baud digital satellites mobile. The hardware
> and software is as follows:
> Icom 820H with CT-17 level converter.
> IBM 360C Thinkpad laptop with a single serial port.
> Pac Comm Tiny 2 TNC with MC-NB96, G3RUH modem.
> J-pole antennas attached to the fiberglass hull of the motorhome.
> Approx 10 feet of coax.
> Wisp software.
> As with any Ham mobile operation it seems that everything
> is a compromise. There are always limitations on space,
> power availability, and antennas. Yes, a rotatable array would
> be nice until you got to the first overpass. So would a desktop
> PC except for the limitations of batteries and solar panels.
> The one thing that has eluded me is what to do about
> doppler tracking for the radio. It would be simple if there
> were a KCTracker in the laptop, but that of course is not
> practical. I must find a package that allows the computer
> to speak directly to the radio at TTL levels or via the CT-17.
> Which brings up another problem. With the computer talking
> to the radio on the one available com port, I will need another
> to talk to the TNC. Does anyone know of a source for a PCMCIA
> serial card? This whole scenario would become mute if there
> were a software package that used a hardware serial port, HSP,
> like we use for APRS.
> I am looking forward to your constructive comments.
> Bob, WA7HRA, Hoodsport, WA