The use of designated radio frequency spectra for purpose of private recreation, non-commercial exchange of messages, wireless experimentation, self training, and emergency communication. Though a hobby for many, ham radio has been used effectively in times of crisis and natural disasters as a means of emergency communication when wireline, cellphones and other conventional means of communications fail – recent examples being 9/11, 2003 blackout, Hurricane Katrina, and the Nepal Earthquake. Established by the International Telecommunications Union (ITU).

A method of transmitting text as a series of on-off tones, lights or clicks that can be interpreted by a trained listener/observer. Introduced by Samuel Morse in 1836, but slight changes were made & International Morse Code gained popularity after Still used in the Ham (amateur radio) world for recreation and emergency communication. Still remains the simplest and most efficient way known to send messages via radio.

Write a program to decode multiple Morse code (CW) signals to live text output automatically from a noisy RF band amidst a varying noise floor (poor SNR) in real time using Digital Signal Processing methods to isolate CW signals.

A minimum signal to noise ratio of 10 dB is required for any individual signal that is to be decoded, and no more than the five strongest signals will be decoded at any one time. A simple text display will output which frequencies are being decoded. The maximum acceptable output error rate will be 10% (i.e. at most one out of every ten letters will be incorrect). Any signal that maintains a higher error rate for more than 30 seconds will be considered misread. The speed of Morse code that will be successfully read is to be within an acceptable range of wpm (words per minute) for this software. In order to combat sender error, and bad source signal, the program is only meant to successfully decode signals that fall within a ±20% margin of the International Telecommunications Union’s standard for spacing and length of signals (e.g. the length of a dash should be 3 dots, but can be 2.4 dots to 3.6 dots long for successful interpretation). Finally, to determine that the Morse code signal(s) have been decoded correctly, the text (ASCII) will be displayed on the command prompt. The output may be compared to a hand decoded reference of the same audio file in order to determine accuracy.

1.Receive and read the input audio. 2.Split the input audio into an appropriate amount of frames, perform FFT to translate to frequency domain. 3.Identify peaks in the spectrum; isolate peaks via binary mask. 4.Perform inverse FFT to transform signal back to time domain. 5.Perform automatic gain control to normalize signal. 6.Perform demodulation of the isolated signals and apply low pass filter over each isolated signal to eliminate noise. 7.Threshold at this point to obtain a binary square wave. 8.Detect rising-falling edge pairs in binary square wave, determine length of dots, dashes, and spaces from signal width analysis. 9.Identify elements of Morse code from signal (dots, dashes, inter- character/word spaces). 10.Traverse binary tree with these enumerated values, save results to ASCII string. 11.Output decoded Morse code as live text ASCII string to the user via a GUI, with a 50 character buffer.

Manufacturability: Program should be compatible with existing systems, and work in varied environments under different conditions (noise, input, type of audio file, Morse speed, etc.) Ethical: Use of public-domain open source code in functions and macros that are implemented in project. Use of licensed software and developmental tools. Sustainability: Program should be judicious with resource utilization, and be efficient with processing power. Portability is a desired trait, with hardware application kept in mind (ability to port code to C or other language).

Verification Test Results The UI was also tested to ensure that the loader, transformation window, signal detection window and text console worked as designed. Computer generated audio files were used to test the program. In such synthetic algorithm testing, the algorithm achieved less than a 10% error rate in letter recognition and, on occasion, was able to decode signals that exceeded the ±20% Morse code standard element length error.

Net Cost : $0.00 No additional resources were required (aside from time!). Hardware FlexRadio Systems has already provided a radio. Software Matlab is provided by Texas State University – San Marcos.

Morse Code still remains relevant today, nearly 180 years after its inception with marked use in emergency transmissions, providing fast, inexpensive and efficient communication over long distances. This program seeks to simplify the learning curve for amateur radio operators unfamiliar with Morse code, enabling them to enjoy its several benefits. Possible implementation as an added feature in FlexRadio Systems software defined radio systems (SDRs).