Dilshan R Jayakody’s Web Log

RDS ( Radio Data System ) is a communication protocol standard used for embedding small amounts of digital information in traditional FM radio broadcasts. It enables radio stations to transmit data such as station identification, program information, and traffic updates.  To capture and decode RDS data, one method involves using a Software Defined Radio (SDR) along with GNU Radio and RFtap . GNU Radio provides a framework for creating software radios, while RFtap acts as a bridge between GNU Radio and conventional network monitoring and packet analysis tools like Wireshark . Decoding RDS data using Wireshark. Unfortunately, as of the time of writing, RFtap is no longer being maintained and does not work with the latest version of GNU Radio (version 3.10.10). This post offers guidelines for rebuild and using RFtap with the new GNU Radio release. This post assumes that the reader has access to DVB-T dongles based on the Realtek RTL2832U and a PC running Ubuntu or Debian Linux. For ...

In this project, we build a simple I 2 S stereo decoder with an amplifier. To decode I 2 S data we use Princeton Technologies PT8211 16bit DAC. KA2206 audio power amplifier is used as the driver stage of this system. The prototype version of I2S stereo decoder Structure of this I 2 S amplifier is self-explanatory from the schematic. We select PT8211 and KA2206 combination due to lower cost and availability. Unfortunately, PT8211 DIP package is not available in the local market and we use SO package in our prototype. We design PCB for the DIP packages, and therefore we solder PT8211 SO package to PCB using " SO8 to DIP8 " converter. We design this system to work with 9V DC power source but at the prototyping stages, we noticed that it works well with lower DC voltage such as 5V. For the output use any 8Ω or 4Ω (5W or higher rated) full range speaker pair. We test this with 8Ω 8W oval speakers which are commonly found on televisions.

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...