Decoding Morse Code on a PC

While listening to HF / shortwave, I notice the occasional Morse transmission. Because I do not exactly have a huge desire to sit around and decode the Morse manually, I decided to use software.

The idea is simple, connect the radio to the computer via an audio cable, run the decoder software, and find a CW broadcaster.

I used a 45 meter longwire antenna, a Yaesu FRG-7 receiver, a connection cable between the radio and computer (which may include isolation transformer to cut noise, see below), and CWGet. CWGet is a piece of Windows software which will detect and decode Morse code.

CONNECTION OF RADIO TO PC VIA ISOLATION TRANSFORMER

Noise, Noise, Noise

Modern technology has essentially decimated the HF bands, with a microprocessor continuously ticking in everything from the PC to the remote controlled air conditioning unit and spewing out noise through the air and power lines alike. When I connected the computer to the radio, the amount of noise made the whole setup unusable.

Noise was traveling from the computer through the radio as it found its way to ground. The radio apparently is grounded better than the laptop power supply.

The solution is to install an isolation transformer. It provides an electrical isolation between the radio and computer, preventing ground-seeking currents from flowing. I scavenged this one from an old 28.8k modem. Most modem cards have one of these, to electrically isolate/debalance the modem from the phone line. I used two wires from old sets of headphones, each having a 3.5 mm male plug. One goes into the radio via a 3.5 mm to 1/4" adapter. The other end goes into the line in port on the laptop. And that's it.

ISOLATION TRANSFORMER FOR AUDIO TO ELIMINATE GROUND LOOPS AND CUT COMPUTER NOISE, SWIPED FROM AN OLD MODEM CARD.

CW Stations

A reliable source of Morse transmissions for testing this setup is the American Radio Relay League's W1AW.

CAUSE OF POOR SIGNAL DISCOVERED.

CREATED/WRITTEN: 2010-09-08 00:00