Data processing: speech signal processing – linguistics – language – Speech signal processing – For storage or transmission
Reexamination Certificate
2000-03-29
2004-06-22
Barnie, Rexford (Department: 2643)
Data processing: speech signal processing, linguistics, language
Speech signal processing
For storage or transmission
C704S215000, C704S208000
Reexamination Certificate
active
06754620
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to data processing techniques and, in particular, to a system and method for rendering data indicative of the performance of a voice activity detector that is utilized to control communication across a digital network.
2. Related Art
Many telephony networks are presently employing digital communication techniques to communicate voice signals. In this regard, a user telephone at a customer premises often transmits analog voice signals to a telephone network, which transmits the voice signals to a telephone at another customer premises. The analog voice signals are based on the speech of a user speaking into the transmitting telephone.
At some point in the network, the voice signals are converted into digital data, and the digital data is communicated over at least a portion of the network. Packet switching techniques, such as techniques in conformance with internet protocol (IP), may be used to communicate the digital data. Before a user of the receiving telephone hears the sounds defined by the digital data, the digital data is converted back into analog signals. This conversion back into analog signals may occur within the network or may occur at the premises of the receiving telephone.
The user speaking into the telephone transmitting the analog voice signals to the network often pauses and thereby causes periods of silence. The analog signals transmitted during these periods of silence usually include a small amount of noise but do not include any speech data.
To increase the performance of the telephone network, the network is often designed to refrain from transmitting the analog signals having no speech data through the digital portion of the network. In this regard, a voice activity detector (VAD) is employed by a conversion system that converts the analog signals into digital data for communication through the digital portion of the network. The VAD is configured to detect whether the analog signals received by the conversion system define voice or silence. In other words, the VAD is configured to detect whether the analog signals received by the conversion system include any speech data.
When the VAD detects silence or the absence of speech data, the VAD disables the conversion system, and when the VAD fails to detect silence, the VAD enables the conversion system. When disabled, the conversion system refrains from outputting digital data. Therefore, the analog signals transmitted by the transmitting telephone during silence periods should not be converted into digital data and transmitted through the digital portion of the network.
As a result, the total number of data packets transmitted by the digital portion of the network is reduced, thereby increasing the efficiency of the digital portion of the network. Since the user at the receiving telephone is typically interested in only hearing the speech of the user at the transmitting telephone, the increase in efficiency of the network by preventing the transmission of silence data can be achieved without a decrease in performance.
Unfortunately, there is usually a delay associated with enabling and/or disabling the conversion system when the signals received by the conversion system transition from silence to non-silence or vice versa. The delay in enabling the conversion system in response to the transition from silence signals to non-silence signals causes a portion of the speech data defined by the non-silence signals to be clipped. In this regard, the foregoing delay causes the conversion system to initiate the transmission of digital data packets a short time after the conversion system has begun receiving a set of analog signals defining a non-silent period. Therefore, the user at the receiving end may not hear the first portion (i.e., the clipped portion) of the speech defined by this set of signals. In cases of long delays in enabling the conversion system, a noticeable portion of the speech defined by the foregoing set of non-silence analog signals is clipped and is, therefore, not heard by the user at the receiving telephone. The phenomena of clipping the first portion of a set of analog signals defining a non-silent period due to the delay in enabling the conversion system is known as “front end clipping.”
The delay in disabling the conversion system in response to the transition from non-silence signals to silence signals causes the conversion system to continue transmitting digital data packets a short time after the conversion system has received a set of analog signals defining a silent period. Therefore, a portion of these analog signals are converted into digital data and transmitted through the digital portion of the network by the conversion system. Since this results in the transmission of digital data defining silence, the efficiency of the network is reduced. As the delay in disabling the conversion system increases, more digital data packets defining silence are transmitted through the digital portion of the network, and the efficiency of the network, therefore, decreases.
To ensure adequate performance and efficiency of the telephony network, it is desirable to ensure that the VAD is working properly so that excessive delays in enabling and/or disabling the conversion system are prevented. Thus, a heretofore unaddressed need exists in the industry for a system and method capable of rendering data indicative of the performance of the VAD, such that a user can easily determine whether the delay in enabling and/or disabling the conversion system is excessive.
SUMMARY OF THE INVENTION
The present invention overcomes the inadequacies and deficiencies of the prior art as discussed hereinbefore. Generally, the present invention provides a system and method for rendering data indicative of the performance of the VAD.
In architecture, the system of the present invention utilizes a display device and an interface manager. The interface manager receives data indicative of power levels at various frequencies and times of signals received by a transceiver that is communicating via a conventional telephony communication network. The interface manager then renders a graphical display via the display device based on the received data. The graphical display includes clusters, and each of the clusters is associated with a particular range of power levels. Each pixel of each cluster is associated with a power level within the particular range.
In accordance with another feature of the present invention, the interface manager colors each cluster based on the particular power level range associated with the cluster. By analyzing the colors of the clusters, information pertaining to the amount of delay associated with enabling and disabling the conversion system can be determined.
In accordance with another feature of the present invention, indicators are used to identify when the conversion system is enabled and/or disabled and when the aforementioned transceiver receives a noise pulse. These indicators may be used to easily determine the amount of delay associated with enabling and/or disabling the conversion system.
The present invention can also be viewed as providing a method for use in a telephony communication system. The telephony communication system is configured to transmit signals from a transmitting device to a receiving device and includes a conversion system having a voice activity detector. The conversion system designed to convert analog signals received from the transmitting device into digital data for transmission over a portion of the telephony communication system. The voice activity detector is designed to detect silence periods defined by the signals transmitted from the transmitting device to the receiving device and to disable the conversion system during the silence periods. The method can be broadly conceptualized by the following steps: receiving data indicative of power levels at various frequencies and times of signals received by the receiving device; defining different ranges of the power l
Agilent Technologie,s Inc.
Barnie Rexford
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