spandsp 0.0.6
MFC/R2 tone receiver

What does it do?

The MFC/R2 tone receiver module provides for the detection of the repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol. It is compliant with ITU-T Q.441D.

How does it work?

Basic MFC/R2 tone detection specs:

  • Receiver response range: -5dBm to -35dBm
  • Difference in level for a pair of frequencies
    • Adjacent tones: <5dB
    • Non-adjacent tones: <7dB
  • Receiver not to detect a signal of 2 frequencies of level -5dB and duration <7ms.
  • Receiver not to recognise a signal of 2 frequencies having a difference in level >=20dB.
  • Max received signal frequency error: +-10Hz
  • The sum of the operate and release times of a 2 frequency signal not to exceed 80ms (there are no individual specs for the operate and release times).
  • Receiver not to release for signal interruptions <=7ms.
  • System malfunction due to signal interruptions >7ms (typically 20ms) is prevented by further logic elements.