The compactRIO data acquisition system of National Instruments can be fitted with diverse functionality modules, and thanks to this the product line is outstandingly usable in several cases.
The task was to design a 16 channel analog-to-digital converter module that is compatible with the system. This is different from the currently available modules, because it can sample 16 channels simultaneously and digitizes the signal with 24 bit resolution. According to the plans the module will gather signals from an acoustic sensor-network, where the time differences between the incoming signals are important to measure the precise distances between the sound source and the sensors. That is why the simultaneous sampling was an important consideration.
Two versions of this module were made. After the first version had been designed and assembled I made the driver program for the device and the configuration of the programmable logics. With the help of these I performed measurements needed for the verification of the operation. According to the gathered information and experience I redesigned the module to reduce noise on the analog input channels. I also performed measurements on this version and compared the results of the two devices.
The tests showed that both module versions can be used to measure acoustic signals with up to 16 microphones connected. Beside our planned task this module will be applicable in several other industrial and medical measurement tasks in the future.