Dilshan R Jayakody’s Web Log

This post is about beat frequency oscillator (BFO) module which is used to receive SSB and CW signals from the ordinary shortwave receiver. The original circuit which is related to this post is obtained through the internet and we modify it to get more precise output with commonly available electronic components. ( Unfortunately at the time of writing this original link is no longer accessible due to a dead link. ) This module consists of two general purpose NPN transistors and we select 2SC828 because of its availability in the local marketplace. For the crystal, we use commonly available 455 kHz ceramic resonator. Assembled 455 kHz BFO module. This BFO unit is easy to construct and may not need any test instrument for calibration. To receive the SSB signals, power this unit with regulated 5V or 6V DC power source and place BFO module near to the shortwave radio receiver. To get good results to place output wire of BFO near to the IF amplifier section of the target receiver....

Morse View is an open source software project to convert audible Morse codes to text messages. This application is capable to convert Morse codes from wave files or from the audio line/microphone inputs. Conversion from Morse code to text can perform based on amplitude and frequency decomposition of the input audio stream. Morse View decoding 25 WPM Morse code wave file We extensively test this application using Morse code files available at ARRL - W1AW code practice page . During the testing we may be able to use this application to decode 5WPM – 40WPM Morse code inputs. As per our test result, after 25WPM, accuracy of the decoder is heavily depends on the quality of the sound card / audio capture device (ADC) and with the system configuration. We test this system with few audio adapters, and out of those adapters both Creative Sound Blaster X-Fi and VIA VT1723 generate more accurate results, especially on 25WPM – 40WPM range. We test this software with different noise c...