The L-3 / Vigra MMI-4311 is a VMEbus-resident digital audio processor delivering four-channel stereo signal acquisition and playback with full programmable matrix mixing and onboard DSP capability. The board combines an MMI-430 mainboard with a DB-311 daughterboard to provide four independent Motorola DSPs, four stereo microphone inputs with software-selectable preamplifier gain (0 dB, 20 dB, or 40 dB), four stereo line inputs with fixed -6 dB attenuation buffers accepting up to 2 Vrms, and four stereo line outputs. All analog I/O connects via 3.5 mm stereo phone jacks.
## Technical Specifications
• **Audio Channels:** Four stereo channels
• **Digital Signal Processors:** Four Motorola DSPs
• **Onboard Memory:** 4 MB dual-port RAM
• **Sample Rate:** Programmable 1500 Hz to 50,000 Hz continuously
• **Frequency Response:** 20 Hz to 45.5% of selected sample rate
• **Dynamic Range:** Up to 80 dB (Sigma-Delta A/D conversion)
• **Line Input Attenuation:** Fixed -6 dB gain buffers; maximum input 2 Vrms
• **Microphone Preamplifier Gain:** Software-controlled 0 dB, 20 dB, or 40 dB
• **Host Interface:** VMEbus with DIP switch configuration (base address and interrupt level)
## Key Features
• Fully programmable 4-channel matrix mixer routing any input to any output or combination
• Sigma-Delta conversion technology for accurate sound reproduction across dynamic range
• Software-controlled input sensitivity and output level adjustment
• DiSPATCH software development package includes C library (K&R/ANSI standard), device driver, DSP firmware, tone generator, and sample applications
## Typical Applications
Simulators, multimedia workstations, trainers, sonar systems, industrial control, voice synthesis and recognition, sound analysis, and communications systems.
