morsamdesa

morsamdesa is a application, written to run on a Raspberry Pi, that periodically retrieves RSS feeds from news websites, and renders the headlines in Morse code.

Features

Audio

• International and American (Railroad) Morse
• Continuous wave (CW): Configurable fundamental and 3 harmonics
• Sparkgap: sample-based, 16 variants
• Telegraph sounder: sample-based, 9 variants
• Double plate sounder: sample-based, 1 variant
• Background noise
• Separate output levels for each audio source

Visual

• LED output via GPIO
• Shows whether audio output is muted, when not sending Morse

Morse command input - light sensitive input, single-letter command

• Mute / Unmute
• Replay last message
• Play next message
• Interrupt current message
• Enable/disable sending of headline mnenonic at transmission start

RSS support

• Multiple RSS feeds
• Filters can be used to suppress headlines
• A 3 character mnenonic associated with a feed is used to select an audio output, so each RSS source can have a distinctive sound

Miscellaneous

• MP3 file generation

Installation

This procedure assumes a base installation of Raspbian Stretch Lite (image date 13-Nov-2018). It has been tested only on a Raspberry Pi model B, rev 2.

Install morsamdesa pre-requisites

Install libconfig

sudo apt-get install libconfig++-dev

Install libcurl

sudo apt-get install libcurl4-openssl-dev

Install pulseaudio

sudo apt-get install pulseaudio
sudo git apt-get install libpulse-dev

Install libxml

sudo get-apt-get install libxml2-dev

Install lame

sudo apt-get install libmp3lame-dev

Grant access to the GPIO pins so that morsamdesa can be run without root privilege

sudo chown root.gpio /dev/mem
sudo chmod g+rw /dev/mem
sudo chmod g+rw /dev/memown root.gpio

Create a directory in which to build morsamdesa, and make it current

mkdir ~/morsamdesa
cd ~/morsamdesa

Download the morsamdesa source zip file from this page and extract the files

unzip -o morsamdesa.zip

Build

make all

Run morsamdesa

chmod 755 run
./run

Use alsamixer to set the master volume.

Build photos

Located here

Demonstration sound files

Examples of morsamedesa output in mp3 format. The text is each case is "hello world". For CW output, the character speed is set to 26 WPM; with Farnsworth spacing the effective speed is 16 WPM. For sounder output, the character speed is 12.5 WPM; with Farnsworth spacing the effective speed is 8.2 WPM.

The demo configuration file used to generate the mp3s is here.

Description	Command	Sound File
CW	./bin/morsamdesa -c demo.conf -p mp3	mp3
CW with harmonics	./bin/morsamdesa -c demo.conf -p cw_harmonics -p mp3	mp3
CW without Farnsworth spacing	./bin/morsamdesa -c demo.conf -p cw_no_farnsworth -p mp3	mp3
CW with a noise 'click' at the start and end of each element	./bin/morsamdesa -c demo.conf -p cw_sound_burst -p mp3	mp3
CW with sampled atmospheric noise	./bin/morsamdesa -c demo.conf -p noisy -p mp3	mp3
Western Electric telegraph sounder	./bin/morsamdesa -c demo.conf -p sounder_we -p mp3	mp3
Western Electric telegraph sounder without Farnsworth spacing	./bin/morsamdesa -c demo.conf -p sounder_we -p sounder_no_farnsworth -p mp3	mp3

Hardware links

Adafruit Mono 2.5W Class D Audio Amplifier - PAM8302

Edimax EW-7811Un N150 Wireless USB Adapter Nano

The TOSLink transmitter was purchased from RS Components

Morse code resources

Wikipedia

International Morse code standard

Learn CW online

A standard for timing using the Farnsworth technique