Design and test of a real-time floating point LPC vocoder

This paper introduces problems regarding design and implementation of a real-time floating point LPC vocoder running on a general purpose array processor. The implementation is intended to obtain a 2.4 kbit/s vocoder; the software structure however is designed in order to give the opportunity to change interactively the algorithms' parameters; moreover, it is also possible to change the vocoder microprogram structure including or excluding some functional blocks. A real-time measuring block is inserted as integral part of coder's microprogram; it checks continuously a given quantity, by updating a complete set of its statistical measurements, so constituting a unique tool both in testing and in system characterization phase. Architecture of the software and testing methodologies, are, then, the main novelties of the realization; moreover, the obtained features of the system, execution time and structure flexibility, make the implementation interesting and suggest more general issues too.