Audio Signal Samples
Generate and listen to real-time radio signals — from Morse code and AM/FM modulation to numbers stations and dial-up handshakes. Each sample includes waveform visualization.
How to Use
- Click Play on any sample to start real-time audio generation and waveform visualization
- Adjust parameters (frequency, speed, depth) before playing to customize the signal
- Compare signals — try white/pink noise alongside AM/FM to hear the difference
- Morse Code — type text and adjust WPM speed, then play to hear your message
- Only one sample plays at a time — starting a new one stops the previous
Morse Code Generator
Converts text to ITU Morse code and plays it via oscillator. Each dot is one unit, each dash is three units, with inter-element, inter-character, and inter-word spacing.
AM Signal
Generates an amplitude-modulated signal. The carrier wave's amplitude varies according to a sine modulating signal. Used in AM broadcast (530–1700 kHz).
FM Signal
Generates a frequency-modulated signal. The carrier frequency deviates proportionally to the modulating signal. Used in FM broadcast (88–108 MHz) for high-fidelity audio.
Numbers Station
Simulates a Cold War–era numbers station broadcasting '1-2-3-4-5' in groups. Uses oscillator tones to approximate synthesized speech digits with atmospheric noise.
56k Dial-up Handshake
Synthesized approximation of a V.90/V.92 modem handshake sequence — DTMF dialing tones followed by training and negotiation signals.
White Noise
Equal energy per frequency — flat power spectral density. Used as a comparison baseline for AM/FM signal analysis.
Pink Noise
Energy decreases 3 dB per octave — mimics natural acoustic environments. Used for audio system calibration and comparison.
About These Signals
Morse Code: The oldest digital encoding scheme, using dots and dashes to represent letters and numbers. Still used in amateur radio and maritime distress signals.
AM (Amplitude Modulation):The carrier wave's amplitude varies in proportion to the message signal. Simple to implement but susceptible to noise, which primarily affects amplitude.
FM (Frequency Modulation): The carrier frequency deviates proportionally to the message signal. More noise-resistant because amplitude noise can be clipped off, providing higher fidelity audio.
Numbers Stations: Mysterious shortwave radio stations that broadcast encrypted messages, believed to be intended for intelligence agents. The synthesized voice and repetitive format are hallmarks of these Cold War relics.
56k Handshake: The iconic sound of a V.90/V.92 modem connecting. The sequence includes DTMF dialing, answer tones, training sequences, and negotiation signals before establishing a data link.