Modem Code for Group 3 Fax (TMS320C3x) by ILLICO! Software Overview ILLICO is offering TMS320C3x digital signal processing software modules that implement the CCITT modem standards for Group 3 FAX: V.21, V.27ter, V.29, and V.17. These software modems can replace conventional FAX modem chip sets in applications where a general-purpose TMS320C3x DSP is available on a dedicated or shared basis. Digital sample interpolation permits direct "all digital" interface with 64-kbps PCM data streams and avoids conversion to an analog signal. For analog environments, a simple m- or A-law codec provides the analog interface. Indirect variable addressing allows easy implementation of multiple independent modems in one processor. The target applications for these software modems are FAX relay, interactive voice response systems, store-and-forward FAX servers, and multimedia communications. All available code was created by ILLICO's staff and can be customized to support special interfaces and special signal processing requirements. Features and Benefits • Modem code callable with C-language or assembly-language conventions. • Detection of start and end of echo protection tone. • HDLC coding for both V.21 and image frames (option). • Block-oriented I/O to facilitate processor sharing with other applications. • Receiver interpolation to support fixed sampling rates. • Diagnostic mean-square-error calculation and eye-pattern support. • Detection of V.21 signals in QAM receiver mode. • Highly-optimized transmitters for FAX- broadcast applications. • Transmit speed tracking by sample interpolation (option). • Forty-page Interface Specification to aid installation and application creation. • Zero-overhead context switching for multiple modems in one processor. Processor and System Requirements The following values represent the nominal resource usage. To some extent processing time and program memory require- ments can be traded off against each other to create other resource mixes. The number of independent FAX channels that can be supported on a single processor with a particular MIPs capacity is easily calculated from these numbers. • Data RAM per channel 256 words internal (data variable block) 84 words internal or external (equalizer tap block) 200 words external (V.17 only; trellis decoder block) • Program memory 5 k total for V.21, V.27ter, V.29 8 k total for V.21, V.27ter, V.29, and V.17 • Per channel MIPs loading (Million Instructions per Second, zero wait state) 4.0 MIPs for V.29/V.27ter/V.21 receivers 6.5 MIPs for V.17 receiver Algorithm Verification The ILLICO FAX modem code implements all of the features of CCITT Recommendations V.21, V.27ter, V.29, and V.17 needed to support Group 3 FAX (CCITT T.4 and T.30). Performance measurements and acceptance tests are performed using simultaneous parallel testing against Rockwell modem cards. Test impairments are generated by the T.A.S. Model 182 Network Emulator. A demonstration/evaluation board with integral test capabilities is available for purchase as part of the software license. Availability The TMS320 modem code is available now under a royalty-free licensing arrangement which includes a source-code option. Demonstrations are available at ILLICO's offices in Santa Clara, California. Company Background and Contact Information ILLICO is a software development and licensing firm specializing in the application of digital signal processing to telecommunications product development. We have been active for over seven years with U.S. and international clients, principally in the area of voice band modem design. All ILLICO products were created by ILLICO's staff and are typically modified to meet special client requirements. Contact: Lien Nguyen ILLICO! 2700 Augustine Drive Suite 145 Santa Clara, California 95054 (408) 980-8179 Fax: (408) 980-9327 |