Abstract: This invention is directed toward improving the subjective voice quality of a mobile to mobile phone call having tandem vocoder processing by modifying the spectrum of the voice signal before it is processed by the second vocoder to compensate for digital distortion which is generated by the second vocoder. An adaptive filter can be used to modify the spectrum of the voice signal. With this invention, the voice quality of a call from a first mobile phone to a second mobile phone has a quality that is substantially similar to the voice quality of a call from a mobile phone to a desk phone.

Abstract: The present invention provides a method and an apparatus for real time objective voice analysis. The apparatus includes a sound quality analyzer for receiving at least one first signal and providing at least one second signal indicative of at least one non-intrusive estimate of a sound quality based on the at least one first signal.

Abstract: It has been recognized that in a wireless communication system certain frames of encoded speech data transmitted between a base station and a mobile unit, or between a mobile unit and a base station, are more critical than others. A frame may be determined to be erased by the receiving base station or mobile unit due to noise or interference over the wireless transmission medium. If an erased frame cannot be recreated from one or more preceding frames, then it is more critical than a frame that can be recreated by an extrapolation of data from one or more preceding frames. Accordingly, on a frame-by-frame basis, each frame in a sequence of frames is identified as being critical or non-critical. Each frame that is identified as being critical is then transmitted in a manner that is more robust than the manner in which non-critical frames are transmitted to decrease the likelihood that a receiver will determine that the frame is erased.

Abstract: A method for conveying information-carrying teletype signals over a wireless telecommunication system by encoding the information into a repetitive signal. Teletype information is derived from part of a received signal encoded as a repetitive signal which part has been determined not to have been adversely affected by the wireless telecommunication system.

Abstract: A method for conveying information-carrying teletype signals over a wireless telecommunication system by encoding the information into a repetitive signal. Teletype information is derived from part of a received signal encoded as a repetitive signal which part has been determined not to have been adversely affected by the wireless telecommunication system.

Abstract: An apparatus and method for conveying teletype signals over a wireless telecommunication system. When the apparatus receives a teletype signal, it derives information carried by said signal and represents said information as at least one message. The at least one message and/or the teletype signal is transmitted over the wireless telecommunication system. When the apparatus receives a signal from the wireless telecommunication system that it determines to be a teletype signal, the apparatus of the present invention decodes the teletype information from part of the received signal determined as not having been adversely affected by the telecommunication system.

Abstract: Telecommunications processing is applied to a reference signal to generate a signal under test. A fidelity measure is generated characterizing the fidelity of the signal under test relative to the reference signal. A control signal is generated from the fidelity measure, where the control signal is used as a feedback signal to adjust the telecommunications processing. In one embodiment, the reference signal is a speech signal and the signal under test is a decoded speech signal generated by encoding, transmitting, and decoding the reference speech signal. The fidelity signal is an average mean opinion score (MOS) and the control signal is used to control the speech decoding processing. For example, the speech decoding processing may involve a speech decoder followed by a post filter, and the control signal is the cut-off frequency of the post filter.

Abstract: A fidelity measuring apparatus (103). The fidelity measuring apparatus (103) measures the fidelity of a system (101). A preprocessor (109) receives an input signal. The preprocessor (109) also receives an output signal from the system (101). The preprocessor (109) extracts a feature set from the output signal. An artificial intelligence tool (111), trained in the relationship between fidelity and the feature set, generates an output that is a measure of the fidelity of the system (101). A fidelity measuring apparatus (103b) includes a preprocessor (138) and two or more artificial intelligence tools (111-N). The artificial intelligence tools (111-N) are independently trained by input signals from different sources. An averaging circuit (140) averages the output of each artificial intelligence tool (111-N). The fidelity measuring apparatus (103b) operates to produce accurate fidelity measurements independent of the input signal, the source of the input signal and the technology of the system.

Abstract: The present invention provides a method and apparatus for measuring at least one signal characteristic. Initially, a set of features is selected which characterize a signal. An intelligent system, such as a neural network, is trained in the relationship between feature sets and signal characteristics. The selected feature set is then extracted from a first input signal. The extracted feature set from the first signal is input to the trained intelligent system. The intelligent system creates an output signal based on the feature set extracted from the first input signal. This output signal is then used to characterize the input signal. In one embodiment, the invention assesses voice quality, typically as expressed in MOS scores, in a manner which accurately corresponds to the analysis of human evaluators. For voice signals processed by voice coders, the present invention provides a measurement technique which is independent of various voice coding algorithms and consistent for any given algorithm.