V.34 Modem Handshake Audio Generator

Generates authentic V.34 modem handshake audio based on ITU-T specifications. Produces a stereo WAV file with the calling modem on the left channel and answering modem on the right.

Synthesizes the physical layer signals bit-by-bit, employing the exact scrambler polynomials, differential encoders, and pulse-shaping techniques defined in the official telecommunications specifications.

🎧 Listen and Visualize

• v34_modem_handshake.wav: The resulting synthesized audio (Stereo: Left=Call, Right=Answer).

Spectrogram showing ANSam trellis, probing "combs" and scrambled training sequences (Red = Calling modem, Teal = Answering modem)

Features

• Complete V.34 handshake simulation including:
  • DTMF dialing sequence
  • Ringback tone
  • V.8 protocol negotiation (ANSam, CM/JM exchange)
  • V.34 probing and ranging (INFO sequences, L1/L2 probing)
  • V.34 training phase (QAM modulation)
• Accurate signal generation based on ITU-T V.34, V.8, and V.21 specifications
• GFSK modulation for V.21 signals
• DPSK with RRC pulse shaping for INFO sequences
• QAM with proper scrambling for training sequences

Requirements

pip install numpy scipy

Usage

run directly:

python v34_modem_handshake.py

Output

The generated WAV file is stereo:

• Left channel: Calling modem (originator)
• Right channel: Answering modem (responder)

References

• ITU-T V.34: A modem operating at data signalling rates of up to 33,600 bit/s
• ITU-T V.8: Procedures for starting sessions of data transmission over the PSTN
• ITU-T V.21: 300 bits per second duplex modem

License

MIT License