Abstract: The present invention relates to methods, systems, and apparatus for processing audio signals. An exemplary method embodiment includes the steps of: removing silence from an audio signal; determining, for a plurality of time segments of the audio signal, power spectral density values of the audio signal for each of a plurality of N different frequency bins, N being an integer greater than 1; identifying (i) a plurality of dominant frequency peaks based on the determined power spectral density values, and (ii) positions in the audio signal corresponding to the identified peaks; and generating a first audio fingerprint from at least some of the identified plurality of dominant frequency peaks and the identified positions in the audio signal corresponding to the identified peaks. In various embodiments, audio fingerprints are generated from an audio signal of call and then used to determine if the call is a robocall or SPAM call.

Abstract: A method of transporting speech information over a wireless cellular communications system is provided. By determining the existence and compatibility of the destination port with the origination port in a given telephone call, the present invention is capable of using only one compression step and one decompression step. Accordingly, voice signal degradation and delay associated with multiple compression/decompression steps may be reduced.

Abstract: The present invention relates to a system and method for sending and receiving digital signals in a voice communication system. The system includes a data buffer, a tone detector, a speech encoder, and a transmitting unit. The data buffer receives and stores a digitized signal including voice band tone data and speech data. The tone detector detects the voice band tone data and generates at least one tone packet containing data indicative of the voice band tone data. The speech encoder encodes the speech data into a plurality of compressed speech packets. The transmitting unit in communication with the tone detector and the speech encoder transmits a packet message including tone packets and speech packets over an RF channel. The present invention also relates to a receiver including a speech decoder and a tone generator. The speech decoder decompresses speech packets to generate a digitized speech signal.

Abstract: A voice activity detector (VAD) which determines whether received voice signal samples contain speech by deriving parameters measuring short term time domain characteristics of the input signal, including the average signal level and the absolute value of any change in average signal level, and comparing the derived parameter values with corresponding thresholds, which are periodically monitored and updated to reflect changes in the level of background noise, thereby minimizing clipping and false alarms.

Abstract: An echo canceller for use in fixed-wireless telephony networks using low-rate packetized speech coding and DSI is disclosed. An adaptive filter is used to cancel an echo signal of a far-end signal introduced at the near-end by operating to provide a replica signal to cancel the echo signal. The replica signal is updated in the absence of a near-end talker signal presence of near talker signal is detected using an estimated echo-residual loss. The echo replica signal updating process is frozen upon the detection of double-talk. Residual echoes are suppressed without the use of non-linear processing. A residual suppression flag detection and a voice activated switching device are used to detect the absence of near-end signals. The switching device is opened if the signal to be transmitted is not a near-end signal or is noise.

Abstract: A DTMF digit detecting method and apparatus includes signal state identifier (32) for identifying whether the received signal is in a DTMF-digit-detect state, a no-detect high-energy state, or a no-detect low-energy state, digit candidate identification processor (34) for identifying a digit candidate when the presence of a state other than the no-detect low-energy state is detected following a detection of the presence of the no-detect low-energy state for a first predetermined period of time, digit identifier (32) for identifying a DTMF digit corresponding to a sample group in a DTMF-digit-detect state, and valid digit identifier (34) for identifying a valid DTMF digit when at least a first predetermined number of sample groups are all in the DTMF-digit-detect state or in an allowable combination of states.

Abstract: A system is described which integrates terminal traffic in a digital voice cellular radio communication system. Data is conveyed from remote data stations and remote radio telephone stations over a reverse channel TDMA frame. The allocation of time slots in the reverse channel TDMA frame is controlled at the base station. The base station provides priority to radio telephones having digitized voice traffic. The base station assigns time slots within the reverse channel TDMA frame based upon allocation requests received from radio telephone stations and remote data stations. Remote data stations may contend on a random access for a minority of a set of time slots in the reverse channel data frame. Additionally, they may request an assigned slot by inserting an allocation request in a control slot of the reverse channel data frame. The base station allocates time slots on a voice radio telephone priority, and assigns any excess time slots to data stations waiting for access to the reverse channel.

Abstract: A voice activity detector (VAD) which determines whether an input signal contains speech by deriving parameters measuring short term time domain characteristics of the input signal, including the average signal level and the absolute value of any change in average signal level, and comparing the derived parameter values with corresponding predetermined threshold values. In order to further minimize clipping and false alarms, the VAD periodically monitors and updates the threshold values to reflect changes in the level of background noise.