MX613

The MX613 is a wide-band, 'N-Tone' non-predictive tone decoder that measures telephone system call progress tones in PABX, Pay/Feature-Phone, Fax and Modem systems.

Adhering to Must/Must-Not Decode limits and able to measure inband frequencies in outband modulation, this MX613 measures the frequency of input signals in the range 300 to 2,150Hz. The result of each measurement is presented to a system µProcessor as a 6-bit serial word.

The decode frequency range, which covers the world's call progress application spectrum, is processed internally as two bands: LO = 300 to 660Hz and HI = 900 to 2150Hz. Frequency measurement is achieved by counting the number of cycles in a set time period

(LO = 39.47ms or HI = 13.16ms). Bad signal/level quality or NOTONE results in a count-abort, timing-reset and no output from the decoder.

Front-end filtering is achieved using our patented Auto-Correlator. Current frequency information is output for the Processor using a Serial Data, Clock and Interrupt interface.

Data from the MX613 should be processed by a µProcessor whose algorithms are able to recognize the frequency, sequence and/or cadence of input signals as national call progress information; e.g.: 'Dial,' 'Busy,''Number-Unobtainable,''Ringing' and automatic tones used by fax and modem systems. Software can be simply configured to reject speech frequencies.

Available in SOIC and PDIP packages, this low-cost, mixed signal IC has a typical power requirement of less than 1mA at 3 volts and utilizes a telecom-system clock input of 3.579545MHz to maintain frequency accuracy.