Abstract: A full duplex speakerphone for connection to a telephone system employs adaptive FIR filters for acoustic and electrical echo cancellation in a novel combination with analog gain controls responsive to incoming signal levels and a transmit level control responsive to the receive signal power level. The particular combination minimizes the amount of digital signal processing required to maintain full duplex operation by holding the signal dynamic range within predetermined limits.

Abstract: In accordance with the invention, a method for programing or editing, or both, the order of performance of digitally recorded information tracks, such as an audio recording, stored sequentially in an appropriate medium. The method allows a user to program or edit, via keystrokes, a program or sequence of tracks to be played. An apparatus for playing information tracks queued to be replayed in a predetermined sequence includes a key pad, which is used to enter commands and numeric information to establish a program queue, a display, which is used to display program events, and an interface processor, coupled to the key pad and the display, which is used to control the commands received from and sent to the key pad and to send display messages to the display. The apparatus also includes a control processor, coupled to the interface processor, which establishes from information stored on a medium in a sequential order, an ordered sequence of information tracks.

Abstract: A communications protocol for use in a main control processor used in an electronic product, which includes at least a second processor to control the user interface, such as a keyboard and a data display. The protocol gives the main control processor the ability to interpret commands received accurately and to disregard those commands that are erroneous. In addition, the protocol provides the user interface processor with all necessary feedback information it needs to determine its mode of operation or any possible error conditions that may have occurred. Furthermore, the protocol provides each processor the ability to utilize its own resources independently, while at the same time communicating with the coprocessor in a manner that treats the other processors as extended subsets of itself.