CMX683

– Call Progress and Voice Detector

Telephony

CMX683

– Call Progress and Voice Detector

Product description

The CMX683 is a general purpose Call Progress tone detector for use in monitoring the progress of calls in Public Switched Telephone System (PSTN) applications.

Dial Tone, Ringing, Busy and Not Available states can be distinguished by using the host µC to qualify the cadence of the CP DETECT output.

The tone detector uses advanced digital techniques to characterise valid Call Progress tones, unwanted tones, line noise and voice or music signals. The CMX683 offers excellent sensitivity coupled with low false detection rates. The response time allows it to operate with almost any Call Progress system.

Voice mail messaging systems ‘stuttered dial tone’ is supported and it can distinguish voice or music activity from DTMF or Call Progress signals.

A single 3.58MHz crystal ensures accurate and repeatable performance and with supply requirements between 2.7V and 5.5V, and a low current consumption, the CMX683 can be easily integrated into a wide range of telecom equipment.

Devices are available through our Distributor Network.

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CMX683

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CMX683 FAQ

Do you have a recommendation for how to best use the CP DETECT and VOICE FAST/SLOW outputs to detect call progress and voice activity?

A. All CMX683 outputs should be examined for cadence information. For example, sometimes a CP (Call Progress) signal will not cause the CP output to go high because the signal has a high harmonic content, or is amplitude or frequency modulated with another tone. Often this will result in ”voice” detection instead, so it is worth examining the VOICE FAST output for a regular CP cadence. Likewise, if you are only looking for “voice” activity, you may want to reduce host microprocessor load by examining the VOICE SLOW output first, which integrates the detection over a longer time. So the strategy could be:

How does the CMX683 determine the difference between Voice Fast and Voice Slow?

A. The Voice Slow output is an integrated output (integrated over time) of the Voice Fast output with hysteresis switching.