Morse Code Decoder using an FPGA and VHDL

4/24/2012 - This project was originally taken from a 73 Amateur Radio Today (February 1995) magazine article. The program was originally written in GWBASIC by W6PRO and I am in the process of rewriting the code in VHDL for the ATLYS Digilent Spartan-6 FPGA board. - KC2NDA

5/6/2012 - The bandwidth and frequency of the 567 tone decoder circuit can be calculated by using the form below if you want to change the values for another project or for something specific. The circuit was changed by adding a 20K potentiometer instead of the 8.2KOhm resistor. The Circuit Board traces were first designed using Photoshop and printed to a Heat Transfer paper using a Laser-jet printer. The heat transfer paper was then ironed onto a single sided, copper clad board. The circuit board was then etched using a Ferric Chloride solution to remove the un-needed copper leaving only the traces. The board was then cleaned and cut with a band saw to size. The holes were drilled and the components were soldered into place. - KC2NDA

567 Tone Decoder Calculator

R1 Ohm
C1 Farad
C2 uF
Vin Volts RMS
fo kHz
Bandwidth %
BWf Hz

HTX-242 Ham Radio