Voice recognition applications and complex audio signal processing with source recognition used to require complex system designs, including a microcontroller for mode switching, data reading, and running the voice application software in addition to a complete audio device with multiple peripherals and a full range of digital and analog interfaces.
Additionally, the microphone's beamforming technology for clear voice capture - an area which AKM has developed over the past 20 years - plus all the pre-processing required for hands-free, voice interface interactions, and clear calls in the vehicle cabin, require an integrated approach, ideal for a variety of "mic/speaker" module products, including automotive telematics communication units.
The new AKM AK7749 is a highly integrated, RAM-based programmable digital signal processor ideal for these applications, already including AD/DA conversion channels, microphone gain amplifier, line-out amplifier, 4 sampling-rate conversion channels, and input filters. The DSP has a parallel processing power of 4096step at 48kHz sampling frequency with ability to meet complex requirements in critical hands free and audio system tasks.
With this configuration, the AK7749 can be easily configured into a system to add add voice features, with all the advantages of an automatic mode switching of up to 8 modes, performed according to usage scenarios without the need of a dedicate microprocessor. Mode switching is possible in 0.5 miliseconds by automatically loading sequential data from external memory (Flash). This easily meets various standards that require high-speed response.
The new AK7749 device is also equipped with an audio hub that enables input/output in multiple sampling frequencies and data formats, with SPI, I2C-bus (400kHz Fast-Mode) and SPI Master Mode interfaces. It includes a 4-channel 24-bit ADC (S/N: 102dB) and 2-channel 32-bit DAC (S/N: 100dB), four channel digital microphone (DMIC) interface with digital filters, four channels of 24-bit SRC and a full 24-bit digital mixer with two output channels and PLL circuit. The device's offers a full differential / single-ended output, with 2 analog direct paths also available in full differential and SE input/output
The DSP includes built-in echo/noise canceller and other essential functions for in-vehicle voice applications, supporting microphone beamforming (two microphones required for microphone/speaker modules), and highly robust hands-free calling and in-vehicle communication technologies, all proven for in-vehicle applications. Specifications are in conformity with automotive requirements, including an operating temperature range between -40 to 105°C.
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