Abstract: Decrypting synthetic transactions with beacon packets is provided. A probe receives, from a client device, a start beacon packet that identifies a test of a service provided by one or more servers. The probe establishes, responsive to receipt of the start beacon packet, a log for the test. The probe stores, in the log established responsive to the start beacon packet, data packets transmitted between the client device and the one or more servers subsequent to the start beacon packet and encrypted with a key using a security protocol. The probe receives, from the client device, key information used to decrypt the data packets of the test encrypted with the key using the security protocol. The probe provides at least one of the data packets for evaluation or decryption using the key information to determine a performance of the service.

Abstract: Decrypting synthetic transactions with beacon packets is provided. A probe receives, from a client device, a start beacon packet that identifies a test of a service provided by one or more servers. The probe establishes, responsive to receipt of the start beacon packet, a log for the test. The probe stores, in the log established responsive to the start beacon packet, data packets transmitted between the client device and the one or more servers subsequent to the start beacon packet and encrypted with a key using a security protocol. The probe receives, from the client device, key information used to decrypt the data packets of the test encrypted with the key using the security protocol. The probe provides at least one of the data packets for evaluation or decryption using the key information to determine a performance of the service.

Abstract: Systems and methods are described for determining a set of three quality metrics for audio and/or video signals transmitted through a packet network. The set of three metrics provide more insight into which factors are affecting the quality of the received signal as perceived by the end-user. These three quality metrics measure reductions in quality due to lossy media transmission, packet loss concealment from packet loss and/or packet/frame jitter, and long periods of silence and/or frozen video. Because each metric quantifies a different aspect of transmitted quality, a deficiency in the transmitted signal can be identified by reference to the set.

Abstract: This invention relates to a method of defining an optimised set of test sequences for use with a packet based perceptual quality evaluation processor associated with an edge-device that receives packets containing speech data and converts said packets to a speech signal, the method comprising the steps of: defining a set of quality targets which should be produced when a test sequence of packets is processed by the edge-device; determining a value for a degradation parameter for each quality target wherein a test sequence having a degradation according to said value will substantially produce said quality target when said test sequence is processed by the edge-device.

Abstract: This invention relates to an apparatus and method for analysis of packet media streams. In particular for analysis of media streams from different network monitoring points where it is desirable to compare analysis of a particular media packet stream from different monitoring points in the network. The invention provides a method for generating a report relating to a stream of packets in a packet switched network from a monitoring point in said network, comprising the step of: generating a signature from a plurality of packets in said stream; and in which said report includes said signature.

Abstract: A method and apparatus for assessing the perceptual quality of stereo speech signals transmitted via a telecommunications network and recorded acoustically from an acoustic terminal device in which a mono reference signal comprising a single channel is aligned with a degraded stereo signal comprising a left and a right channel; a delay between each channel of said degraded signal and said reference signal is estimated; a noise masking indicator in dependence upon said estimated delays is generated; the level of the stereo signals is adjusted in dependence upon said noise masking indicator; a set of perceptually relevant parameters for each of said reference and degraded signals are generated; the perceptually relevant parameters of the reference signal with the perceptually relevant parameters of the degraded signal to generate a disturbance profile are compared; and a speech quality prediction is generated in dependence upon said disturbance profile.

Abstract: This invention relates to measurement of error characteristics of a communication channel. The invention is of particular use for measuring perceived transmission performance of the communication channel. The invention provides a method and apparatus for measuring the transmission error characteristics of a channel employing frame based transmission in which a frame classification indicator is generated for an expected frame, according to data received via said channel, and in which the following steps are repeatedly performed: generating frame classification data relating to the expected frame; updating a statistical representation of the transmission error characteristics according to said frame classification. The invention also provides a method and apparatus for measuring perceived transmission performance of a communications channel in which the perceived transmission performance is generated according to measured transmission error characteristics.

Abstract: The present invention relates to a method and apparatus for determining channel degradation information in which a known data sequence is compared to a transmitted version of the known data sequence to provide such information. To assess performance of a public land mobile network, it is convenient if assessment apparatus is located in the network rather than in a mobile station. The invention provides a technique for efficiently sending data characterizing channel degradation caused by the network to mobile station communication channel from the mobile station back to the network, where the channel degradation information is reconstructed.

Abstract: A method of measuring the degradation of a data stream owing to the influence of errors thereon is disclosed. Unlike known degradation measures, a measure calculated in accordance with the present invention takes into account the variation in the significance of an error in dependence upon the elements which are affected by it. A particular application of the method to the selection of one of a number of possible speech coding methods for use in transmitting speech across a radio link (20) from a mobile phone (10) to a base station (30) is described.

Abstract: This invention relates to measurement of error characteristics of a communication channel. The invention is of particular use for measuring perceived transmission performance of the communication channel. The invention provides a method and apparatus for measuring the transmission error characteristics of a channel employing frame based transmission in which a frame classification indicator is generated for an expected frame, according to data received via said channel, and in which the following steps are repeatedly performed; generating frame classification data relating to the expected frame; updating a statistical representation of the transmission error characteristics according to said frame classification. The invention also provides a method and apparatus for measuring perceived transmission performance of a communications channel in which the perceived transmission performance is generated according to measured transmission error characteristics.

Abstract: This invention relates to measurement of error characteristics of a communication channel. It is of particular use for measuring perceived transmission performance of the communication channel.

Abstract: The present invention relates to a method and apparatus for determining channel degradation information in which a known data sequence is compared to a transmitted version of the known data sequence to provide such information.

Abstract: A voice activity detector suitable for deployment in a mobile phone apparatus is disclosed. An advantage of the voice activity detector is that it is better able to provide a decision (79) as to whether an input signal (19) consists of noise (which it is not desired to transmit) or comprises speech or information tones (which are required to be transmitted), especially in noisy environments. The voice activity detector includes a number of components, in particular an auxiliary voice activity detector (3). The auxiliary voice activity detector (3) distinguishes between noise and speech on the basis that the spectrum of speech changes more rapidly than that of noise. This results in the auxiliary detector (3) rarely mistaking a speech signal to be a noise signal. Hence, a very reliable noise template (421) is obtained. For this reason, the auxiliary detector (3) is also useful in noise reduction applications. The voice activity detector also uses a neural net classifier (7).

Abstract: Speech is distinguished from noise by a spectral comparison of an input signal with a stored noise estimate. Updating of the noise estimate stored in a buffer is permitted during periods when speech is absent under control of an auxiliary detector. In order to improve operation in the presence of signals with strong harmonic components, e.g., signaling tones, an LPC prediction gain is computed from the input (x(i)) and a residual (y(i)) obtained from the input following filtering by a filter having a response complementary to the frequency spectrum of the input, and if the gain exceeds a threshold, buffer updating is suppressed.

Abstract: Speech is distinguished from noise by a spectral comparison of an input signal with a stored noise estimate. Updating of the noise estimate stored in a buffer is permitted during periods when speech is absent under control of an auxiliary detector. In order to improve operation in the presence of signals with strong harmonic components, e.g., signalling tones, an LPC prediction gain is computed from the input (x(i)) and a residual (y(i)) obtained from the input following filtering by a filter having a response complementary to the frequency spectrum of the input, and if the gain exceeds a threshold, buffer updating is suppressed.