A software/hardware codesigned hands free system on a "resizable" block-floating-point DSP

A hands free telephone application has been implemented on a low-cost, custom-configured, block-floating-point, digital signal processor (DSP). The application consists of an acoustic echo canceller and a spectral subtraction (SS) based noise suppressor. The objective of pursuing a custom configuration was the minimization of hardware cost for the given application. For this objective, implementation has been carried out though a software/hardware codesign design flow on a resizable DSP platform. The intention of exploiting block-floating-point as arithmetic was to remove the burden of time-consuming fixed-point model development, while employing an inexpensive fixed-point DSP. The paper describes an implementation of the application. Signal processing quality evaluation results are also presented for some critical computation modules in the application.