DIRECTORY / SANDBOXES / MODEM.TELECOM

ACOUSTIC FSK // V.34 MODEM

Frequency-shift keying (FSK) modulation and acoustic telecommunication handshakes in Web Audio.

NO CARRIER

// ⚡ V.90 HANDSHAKE

// TRANSMISSION DATA STREAM

// MODULATION CONSTELLATION

// OSCILLOSCOPE & SPECTRUM VIEW

AWGN CHANNEL SNR 18.0 dB

SHANNON CAP: 20.5 kbps EFF: 6.0 b/s/Hz

THEORETICAL BER: 1.42e-4 PKT ERR: 0 bits

⚡ PLUS // V.90 TELECOM ANALYZER STANDBY

DEMODULATED ASCII STREAM:

READY FOR HANDSHAKE...

💡 TIP: Type text, sweep AWGN SNR noise, and listen to real-time Bell 202 FSK & QAM audio tones.

📚

Quadrature Amplitude Modulation, Bell 202 Frequency Shift Keying, and ITU-T handshakes.

ACADEMIC & ALGORITHMIC REFERENCE

// HISTORICAL ORIGINS

The ITU-T V.90 recommendation (1998) enabled asymmetric 56 kbps digital downstream transmission over analog twisted-pair copper telephone lines.

// GOVERNING EQUATIONS

s(t) = I(t) \cos(2\pi f_c t) - Q(t) \sin(2\pi f_c t)

// BROWSER IMPLEMENTATION

Synthesizes dual-tone DTMF, 2100Hz V.8 answer tone, V.32bis phase reversals, and scrambler equalizing noise via native WebAudio oscillators.

// GUIDED EXPERIMENTS TO TRY IN THIS SANDBOXNORMAL

1Bell 202 Text Transmission (slowed demo)

🎯 Action:Type 'HELLO WORLD' in the FSK input box and click '📡 TRANSMIT DATA (MODULATE)'.

✨ Observe:Hear the high-frequency chirp tones (1200Hz/2200Hz) as each 8-bit ASCII character is modulated in real-time at a slowed demo rate.

// CURATED PAPERS, RFCS & RESOURCES

Official telecom specification for PCM and analog hybrid modems.