[FADCA] Basic Requirement for Demonstration

[bud Thompson]

Deltona
Monday April 1 1340EST

Russ:

I've included the FADCA list so everyone will have a basis of knowledge and
background.

To make a successful demo of getting data files outside the Last Mile
requires an HF digital station running AirMail software. The computer needs
a single comport, but, depending on the radio and data terminal used, a
second comport might make an even more impressive demo.  Airmail will
support total control of radio mode (terminal control0  and frequencies
where the radio has a computer-control input port.  Unless an SCS data
controller (see below) is used, two comports will be required for terminal
and frequency control.

HF Station Includes:

HF SSB RADIO:

Not just any radio will run digital at all, and some that will suck doing
it, but could be used for a simple demo.  (The FT900 I used this week is not
recommended, but will work).  Kenwood 850, 450 and newer Kenwood units with
IF DSP will work.  Many ICOM base station radios are excellent, even the
older units.  I'd also avoid the under-the-dash super-small mobile HF radio
whose heat sink is the size of a quarter.  (I ran the FT-900 at 50w for our
tests. That sucker gets hot just being turned "ON")  Specifically avoid the
ICOM 706 series unless the owner already has it working satisfactorily on HF
digital.

The radio should have 10hz dial readout, and stability of +/- 20hz over
short periods is preferable. It is best if the radio has a data port
(accessory socket) so the controller does not have to be connected to the
microphone jack.

The only ARQ modes that will work with a WL2K station are PacTOR I, PacTOR
II, PacTOR III (under testing), and G-TOR (to only one research station
which will also accept AMTOR.)  PacTOR I or II is recommended for an
impressive demonstration.

DATA CONTROLLER - Pick one.

SCS PTC-II, PTC-E, PTC-Pro,  Kantronics KAM+, KAM-E, KAM-XL, and
AES/TimeWave PK232MBX/PacTOR - in preferential order.  SCS units range from
$600 to $1000, KAMs $350 new, and PK232MBX/PacTOR are available for $200 or
less used.  The SCS PTC-II supports everything including all PacTOR modes,
and full max-FBB binary compression.  The KAM+ supports PacTOR I, G-TOR,
AMTOR  and full max-FBB binary compression.  It takes the latest PK232
firmware to support any binary compression.  PacTOR I is not perfectly
implemented in the PK232, but will work.

Getting a data controller to work with the HF radio is not trivial.  Cabling
between data controller and radio is typical of TNC-to radio cabling.   For
the most part, configuring of the data controller for HF is done using
set-ups in the Airmail program.  The major concern is receiver pass band
response between about 1900 and 2300hz, and preferably with 500hz IF
filters.  Most folks use the present US standard:  2100 Hz center frequency
and 200 Hz shift (Mark 2000 Space 2200).  To do otherwise requires offsets
in dial frequency and/or split operation which complicates matters more.  A
secondary concern is T/R switching times. This must be 20ms or less - or
there could be linking problems.  Most modern HF base station radios will do
this.  Power output beyond 50w is normally not need with a nominal antenna.

It is best if the HF radio can run the narrow (500 Hz) filters in LSB mode,
but not absolutely necessary for a demo. (The FT-900 will not and the
Kenwood 850 only runs one IF with the narrow filter in LSB mode.)

Antenna - what can I say? A good mobile antenna will work, but a full-sized
20m beam up at 70 ft would be better. In the absence of QRM or QSB, S2 to S3
level signals will work well, but S5 level would work better. Beyond S5
throughput maxes out to mode maximum. My recommendation for the demo is an
antenna that will work 40, 30, and 20M w/o need for a manual antenna tuner.
If the internal tuner in the radio is needed that should not be a problem.

While it makes absolutely no difference where the WL2K contact is located,
it is more impressive during a demo that it be at some considerable
over-the-horizon distance.

bud N0IA
386 574 4124