N0GSG DSP Doppler RDF Kit

N0GSG DSP Doppler RDF Kit

Introduction:
Thank you for purchasing the RDF Doppler Radio Direction Finder kit Version
2.0. This kit contains six circuit boards and all the components required to
assemble them.

Enhancements :
Integrated NMEA GPS port. (The GPS is only needed for computerized mapping).
Integrated RS-232 output port ( 4800, 8, N, 1 ).
Standard Agrelo format DF output messages.
Compatible with numerous software packages such as WinAprs, WinDopp ,
APRS+SA , GPSS and others.

Major Features :
Based upon the N0GSG DSP Doppler design as featured in the November
2002 issue of QST magazine.
Utilizes two Atmel Microprocessors, Timing and Antenna switching is managed
by an ATTINY-2313 microprocessor, Signal processing and RS-232 I/O are
provided by another ATTINY-2313 microprocessor. Both are socket mounted to
allow their removal for firmware updates.
Sixteen LED’s furnish relative directional information and also indicate loss of
signal. With resolution of 22.5 degrees.
RS-232 output resolution 3.6 degrees, truncated to its integer value. For example
3.6 degrees is reported as 3 degrees, 7.2 degrees is reported as 7 degrees.

Total of six boards are used to provide maximum efficiency:
The Main Circuit board contains the Microprocessors, filtering and display
Circuitry, the RS-232 interfaces for both the computer and an optional GPS.
The Antenna Control circuit board is responsible for switching between each of the
four antennas in the proper sequence. It also combines the signals received from
each antenna for presentation to the FM receiver.
Four Antenna Interface boards each contain the necessary switching circuitry for
one ¼ wave whip antenna. Each board each has a female SO-239 UHF connector
to which the ¼ wave whip attaches. The whip antennas can easily be constructed
with a section of 3/32 inch brass brazing rod soldered to the center pin of a PL-259
male UHF connector. Brass brazing rod is easily obtainable at a welding supply
store. The array of four ¼ wave vertical antennas should be mounted between .22
and .25 wavelength apart in a square pattern, on a ground plane.
Antenna rotation rate is user selectable between the standard 800 Hz rate and an
optional 700 Hz rate. The 700 Hz rate allows the location of signals being
modulated by 800 Hz which would interfere with the normal 800 Hz rate.

http://www.byonics.com/dsp-rdf/DSP%20Doppler%20Assembly%20Manual_V201.pdf