MF and DTMF Detectors

Software Overview

ILLICO is offering TMS320C3x Digital Signal Processing software modules that implement Multi-Frequency (MF) and Dual Tone Multi-Frequency (DTMF) signal detectors. These software modules can replace chip sets in applications where a general purpose TMS320C3x DSP is available on a dedicated or shared basis. Operation at the 8KHz sampling rate permits direct "all digital" interface with 64 Kb/s PCM data streams and avoids conversion to an analog signal. For analog environments, a simple Mu or A-law codec provides the analog interface. Indirect variable addressing allows easy implementation of multiple independent detectors in one processor.

 All offered software was created by ILLICO staff and can be customized to support special interfaces and special signal processing requirements.

Two software packages are available:

1. MF Signal Detection: MF signaling is described in CCITT Recommendations Q310-Q.490. The ILLICO software can be configured at run time to detect one of the four following signaling schemes including North American call progress:

 R1:  700, 900, 1100, 1300, 1500, 1700 Hz (CCITT Q.320)
 R2B: 540, 660,  780,  900, 1020, 1140 Hz (CCITT Q.441)
 R2F: 1380,1500,1620, 1740, 1860, 1980 Hz (CCITT Q.441)
 Dial Tone(350,440 Hz);Ring Back(440,480 Hz);Busy(480,620 Hz)

MF program resource usage:

- Internal data memory: 80 words
- Program memory: 750 words
- MIPs (millions instructions/sec): 1.8 MIPs

2. DTMF Signal Detection: DTMF signaling is described in CCITT Q.23.

 DTMF:  697, 770, 852, 941, 1209, 1336, 1477, 1633   Hz.

DTMF program resource usage:

- Internal data memory: 70 words
- Program memory: 600 words
- MIPs (millions instructions/sec): 2.2 MIPs

Features and Benefits for tone detection software

  • Detectors are callable with C-language or assembly language conventions. 
  • Direct interface with PCM 8KHz sampling rate data. 
  • Zero overhead context switching for multiple detectors in one processor. 
  • Block oriented I/O to facilitate processor sharing with other applications. 
  • Fifteen page Interface Specification to aid installation and application creation. 

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