AN-93 HF Modem
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The AN-93 kit (designed by Johan Forrer, KC7WW) provides any PC user with
the capability for operating RTTY, AMTOR, and PCTOR with this simple
modem-only design.  AN-93 is the equivalent of a BayCom, BayPac, or PMP
setup, but for HF digital operations.  This very simple kit should be for
many that have wanted to play on HF, but didn't want to pay the money for an
expensive multi-mode controller.  

With the AN-93, only three components are required for HF digital
communications: a PC-compatible computer, the AN-93 modem, and software that
performs the encoding and decoding.  The AN-93 comes with a tuning indicator
to allow visual tuning and the unit also provides audio output for
oscilloscope display.  

	Modem Specification
	AGC at > 100-mV audio input amplitude
	Prefilter bandwidth > 1 kHz
	Discriminator channel filter bandwidth 120 Hz
	170-Hz channel separation
	Data low-pass filter cutoff 200 Hz
	Automatic threshold corrector
	Tuning indicator
	A/D converter for RsoftS error correction

The TAPR AN-93 allows for both FSK and AFSK output, allowing operations on
all HF radios.  Instead of two separate boards as shown in the QEX article,
the TAPR AN-93 single board dimension is approximately 4Sx3.5".  The AN-93
operates off 12volts DC.  The kit allows for self-tuning and calibration.  A
Digital VOM and a working PC is needed in order to calibrate and test the
modem.  Connections to the RS-232 serial and parallel ports are made through
DB-9 and DB-25 connectors.  Interfacing to the radio is through a DB-9
connector.  The kit will be shipped with the A/D convertor providing
full-memory ARQ capability for PCTOR.  

Shareware software  is included along with Johan's code.  If you decide to
use the shareware software, TAPR requests that you do submit the necessary
registration fee.

For a full description of the AN-93 modem and its specification, refer to
the May, 1994 issue of QEX and PSR issue #55.

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Reference: 
     Forrer, Johan.  (1994).  AN-93, an HF Modem for RTTY, AMTOR, and Pactor
Software.  QEX: The ARRL Experimenter's Exchange.  May, #147. pp. 3-11.
     AN-93.  TAPR, PSR Issue #55.  Spring 1994.  p. 8.