Call Progress Tone Detector

Call Progress Tone Detector (CPD) detects tones derived from the standard North American set of tones (350, 440, 480, 620 Hz) and 400 Hz tone. The tones may come in a pair (any with any) or as a single tone. CPD only reports the onset and removal of a tone. The analysis of timing (if required) shall be responsibility of a higher-level application due to uncontrollable variability of those parameters from country to country.

CPD can be configured on the fly, and such parameters as twists, maximal frequency deviation, spectrum cleanness, and signal duration thresholds can be altered during a call. The granularity of each parameter is about 0.25 dB (and 0.5 Hz for frequency acceptance margins).

CPD provides estimates on the frequency and energy for detected tones, which eases the identification of the PSTN interfacing problems for the given country / administration / LEC. Typical error of frequency estimation is 0.2 Hz RMS. Typical error of energy estimation is 1 dB RMS.

CPD design provides for extendibility when and if required by Licensee.

CPD is designed as a system component rather than a stand-alone algorithm; provides statistics and is capable of non-intrusive monitoring.

The archive with ANSI C, 'C54xx, 'C55xx Source code is available from download page.

    Specs

• Any dual or single tone combined of
  350,400,440,480,620Hz.
  
  
• Dynamic range
  -40...-5dBm
  
  
• Configurable twist
  up to 15dB
  
  
• Noise Immunity typical
  15dB
  
  
• Noise Immunity in special config
  5dB
  
  
• Full Specs (54K)