Multi-channel data acquisition for implementation of real time signal processing algorithms

Many signal processing applications like blind source signal separation, audio beam etc. require multi-channel synchronous data acquisition. These applications require signal to be acquired from multiple inputs that digitize the signal synchronously to preserve the phase relationship. In this paper, we present the design and implementation of a multi-channel data acquisition system using a personal computer (PC). Our design does not require installation of any interface card or any other modification in the circuitry of the PC. Rather, we use the analog joystick port, found in most of the personal computers with a sound card to implement our design. Our design replaces the variable resistors of the joystick with a simple circuit that enables us to synchronously digitize four analog signals and store them. Our circuit also changes the DC bias of the analog signals and detects any lost samples due to delayed response of the host computer. To minimize the possibility of losing the samples during data acquisition, we use a modified Linux kernel.