TagsA3PN250 adc AK5388 antenna breakout board business capacitor components construction CW delta-sigma design FDIM FPGA homebrew iambic IC iTead Studio keyer kit layout Morse code open source hardware PCB power supply ProASIC3 R2 radio receiver reviews schematic SDR Si570 Skywired software-defined radio soldering T2 test equipment theory transceiver tutorial USB vendor Verilog VFO
Tag Archives: Morse code
This year’s Four Days in May at the Dayton Hamvention was full of sights to see. One amazing little piece of amateur engineering was Rich Meiss, WB9LPU’s “QuadraBug”, a mechanical key in the spirit of the Vibroplex Bug, but with … Continue reading
I found another FPGA Morse code keyer project! This one is written in VHDL by Jim Brady. He has posted the source (for a Xilinx Spartan 3A). He also posted his vintage keyer designs from the 1960′s and 1970′s. Jim’s … Continue reading
With just a few tweaks, I brought up the “IambicV” iambic keyer core on one of my A3PN250 breakout boards. I was stunned when it made dits, dahs, and iambic dah-dits perfectly the first time out. Yes, I know that’s what a testbench is supposed to make possible, and yes, I’ve had it happen before, but I still always expect smoke the first time I turn something on.
I made a few changes from last week’s version. Continue reading
If my goal is to build an FPGA-based ham radio, one of the modules I can’t do without is an iambic keyer. I have to confess that I have never been much of a CW (Morse code) operator, but with so many logic gates available, it would be a shame to leave out a keyer.
Writing an iambic keyer turned out to be a good way to get the kinks out of the FPGA toolchain. The code itself is pretty simple and straightforward. One flip-flop keeps track of whether the current symbol is a dit or a dah. Another tracks whether the paddle for the opposite symbol (dah or dit, respectively) has been pressed during the current symbol. Finally, a two-level counter handles the timing of the dits and dahs and operates the key line. There is a simple sidetone, too. Continue reading