Abstract: A calibration source (20) for a gamma-ray spectrometer (40) is provided. The calibration source comprises a radioactive material (30) comprising a radioactive isotope having a decay transition associated with emission of a radiation particle and a gamma-ray having a known energy, e.g. Na-22, and a solid-state detector (26A, 26B), e.g. a PIN photodiode, arranged to receive radiation particles emitted from the radioactive material. A gating circuit (32) is coupled to the solid-state detector and is operable to generate a gating signal in response to detection of a radiation particle in the solid-state detector. The gating signal may thus be used as an indicator that an energy deposit in a nearby gamma-ray spectrometer is associated with a decay transition in the radioactive isotope. Since these energy deposits are of a known energy, they can be used as reference points to calibrate the spectrometer response. Thus with calibration sources according to embodiments of the invention, spectral stabilization (i.e.

Abstract: Embodiments are directed to eliminating false audio using an egress gateway in a communications network. At least one false audio packet is received by an egress gateway. The false audio packet includes false audio. A DTMF packet is received by the egress gateway. The DTMF packet is received subsequent to the at least one false audio packet. The false audio in the false audio packet is replaced with a substitute signal by the egress gateway.

Abstract: Example methods, apparatus and articles of manufacture to detect echo during teleconferences are disclosed. A disclosed example method includes collecting first signal data for a first teleconference leg of a teleconference, collecting second signal data for a second teleconference leg of the teleconference, computing an echo detection metric from the first and second signal data, and comparing the echo detection metric to a threshold to determine whether an echo is likely present on the first teleconference leg of the teleconference.

Abstract: Systems and methods to measure the performance of a de-jitter buffer are disclosed. In a described example, a method to measure adaptive de-jitter buffer performance includes transmitting a known audio signal via a plurality of packets over a packet-based network, recording a received signal based on the known audio signal, and analyzing the recorded signal to determine one or more of a lower de-jitter buffer size, an upper de-jitter buffer size, a de-jitter buffer expansion speed, or a de-jitter buffer contraction speed based on the recorded signal and the known signal. The example method further includes comparing the one or more of the lower de-jitter buffer size, the upper de-jitter buffer size, the expansion speed, or the contraction speed to a performance requirement, and correcting communication network performance based on the comparison.

Abstract: Example methods, apparatus and articles of manufacture to cancel echo for communication paths having long bulk delays are disclosed. A disclosed example method includes determining a first location of a first largest magnitude of a first plurality of coefficients of an echo canceller, the first plurality of coefficients separated by two or more sample intervals, and cancelling an echo contained in a received signal using a second plurality of coefficients of the echo canceller and a first offset selected based on the first location, the second plurality of coefficients separated by one sample interval.

Abstract: A method and system for providing a test signal to evaluate the performance of an adaptive jitter buffer are disclosed. For example, the method transmits a test signal into a communication network, and applies a jitter impairment along a path traversed by the test signal in the network preceding a device supporting a Voice over Internet Protocol (VoIP) service, wherein the device having an adaptive jitter buffer. The method then analyzes the test signal that is received from the device to determine a performance of the adaptive jitter buffer.

Abstract: A system and method for recording analog signals exchanged between a telephone device and a VoIP device, capturing packets exchanged between the VoIP device and an IP network, determining analog time values corresponding to analog characteristics of the analog signals, determining digital time values corresponding to digital characteristics of the packets, determining a common reference time for the analog time values and digital time values and determining a processing delay based on the analog time values and the digital time values.

Abstract: A method of identifying radioactive components in a source comprising (a) obtaining a gamma-ray spectrum from the source; (b) identifying peaks in the gamma-ray spectrum; (c) determining an array of peak energies and peak intensities from the identified peaks; (d) identifying an initial source component based on a comparison of the peak energies with a database of spectral data for radioactive isotopes of interest; (e) estimating a contribution of the initial source component to the peak intensities; (f) modifying the array of peak energies and peak intensities by subtracting the estimated contribution of the initial source component; and (g) identifying a further source component based on a comparison of the modified array of peak energies with the database of spectral data. Thus a method for identifying radioactive components in a source is provided which does not rely on comparing template spectra with an observed spectrum.

Abstract: A gamma-ray detector (42, 52, 72, 92) comprising a large-area plastic scintillation body (44, 64, 74, 94) and a photon detector (38, 58, 68, 78) optically coupled to the scintillation body to receive and detect photons (P1, P2, P3) generated by gamma-ray interactions. Selected portions of the scintillation body surface are provided with a reflective layer (46, 60, 80) in planar contact with the scintillation body. Other regions are not provided with a reflective layer. Thus specular reflection is promoted in at the surfaces provided with the reflective layer, while total internal reflection may occur in the regions which are not provided with a reflective layer, hi a scintillation body generally in the form of a plank, the photon detector is coupled to one end, and the regions provided with the reflective layer are the edges of the plank. The scintillation body may be shaped so that it reduced in cross section in a direction away from the photon detector.

Abstract: A portable gamma-ray detector for indicating the intensity of a source of gamma-rays, the nature of the source, and the direction to the source relative to an axis of the detector. The detector comprises a plurality of scintillation bodies arranged around the pointing axis, for example four scintillation bodies in a two-by-two array and separated from each other by aluminium foil. Thus gamma-rays from different directions are shielded from different ones of the scintillation bodies by the other scintillation bodies. The scintillation bodies are coupled to respective photo-detectors and a processing circuit is configured to receive output signals from the photo-detectors and to provide an indication of the direction to a source relative to the pointing axis of the detector based on the relative output signals from the different photo-detectors.

Abstract: A gamma-ray detector (42, 52, 72, 92) comprising a large-area plastic scintillation body (44, 64, 74, 94) and a photon detector (38, 58, 68, 78) optically coupled to the scintillation body to receive and detect photons (P1, P2, P3) generated by gamma-ray interactions. Selected portions of the scintillation body surface are provided with a reflective layer (46, 60, 80) in planar contact with the scintillation body. Other regions are not provided with a reflective layer. Thus specular reflection is promoted in at the surfaces provided with the reflective layer, while total internal reflection may occur in the regions which are not provided with a reflective layer, hi a scintillation body generally in the form of a plank, the photon detector is coupled to one end, and the regions provided with the reflective layer are the edges of the plank. The scintillation body may be shaped so that it reduced in cross section in a direction away from the photon detector.

Abstract: A system that incorporates teachings of the present disclosure may include, for example, an echo measurement device having a controller to transmit a test signal in a communication path which is looped back at an end point identified as having an echo problem. The test signal can be transmitted at a remote location from the end point. The test signal can be represented by a limited burst signal of one or more frequencies operating outside a range of an operating frequency of an echo canceller deactivation signal transmitted in the communication path. Additional embodiments are disclosed.

Abstract: A gamma ray detector (50) comprises a plastic scintillation body (52) arranged to receive incident gamma rays to be detected. Photons are generated in response to the gamma rays by excitation and de-excitation processes in the scintillation body. The photons are detected using at least one photodetector (56) which generates an output signal representative of the energy of the gamma rays. The scintillation body has a detection surface to receive the gamma rays and a thickness in a direction substantially orthogonal to the detection surface that is not greater than 5 cm. Deconvolution techniques can be used to improve the output signal; the thinness of the scintillation body allows sufficiently accurate results to be obtained that individual isotopes can be readily identified. The detector can be usefully employed in portal radiation monitors.

Abstract: A scintillator crystal (26) based gamma-ray camera system is described. The gamma-ray camera system includes a spectra processing component for (34) providing improved energy resolution over that seen in conventional gamma-ray camera systems. The spectra processing component operates to deconvolve detector response functions from observed energy spectra on a pixel by pixel basis. The pixel dependent to detector response functions are obtained by a combination of theoretical simulation, and empirical calibration. By deconvolving pixel specific detector response functions, variations in response of a gamma-ray camera system across its image plane can be accounted for. This offers significant improvements in energy resolution and many of the problems associated with conventional gamma-ray camera systems are reduced. For example, the improved energy resolution allows better rejection of photons associated with Compton scattering events occurring in a source being imaged.

Abstract: A gamma ray detector (50) comprises a plastic scintillation body (52) arranged to receive incident gamma rays to be detected. Photons are generated in response to the gamma rays by excitation and de-excitation processes in the scintillation body. The photons are detected using at least one photodetector (56) which generates an output signal representative of the energy of the gamma rays. The scintillation body has a detection surface to receive the gamma rays and a thickness in a direction substantially orthogonal to the detection surface that is not greater than 5 cm. Deconvolution techniques can be used to improve the output signal; the thinness of the scintillation body allows sufficiently accurate results to be obtained that individual isotopes can be readily identified. The detector can be usefully employed in portal radiation monitors.

Abstract: A method and apparatus for identifying echo sources in a communication path. A system that incorporates teachings of the present disclosure may include, for example, an echo measurement device (EMD) having a transmit module to transmit an echo canceller deactivation signal in a communication path of the communication system, wherein the echo canceller deactivation signal deactivates one or more echo cancellers in said communication path. The transmit module can also transmit a test signal in the communication path which is looped back at an end point identified as having an echo problem, wherein the test signal is transmitted at a remote location from the end point. The EMD can further include a detection module to detect one or more echo signals associated with the test signal. Additional embodiments are disclosed.

Abstract: A scintillation spectrometer provides improved resolution by ensuring that photons generated by scintillation events occurring in different locations within the scintillation material generate similar light profiles on the photo-detector, thereby making the output signal less sensitive to the initial interaction site and enabling more effective de-convolution of raw data. This is achieved in different ways, such as by: limiting the exit window of the scintillation crystal, introducing a spacer between the scintillation crystal and the detector window, or providing a crystal that is longer than necessary to stop gamma rays.

Abstract: A scintillator crystal (26)=based gamma-ray camera system is described. The gamma-ray camera system includes a spectra processing component for (34) providing improved energy resolution over that seen in conventional gamma-ray camera systems. The spectra processing component operates to deconvolve detector response functions from observed energy spectra on a pixel by pixel basis. The pixel dependent to detector response functions are obtained by a combination of theoretical simulation, and empirical calibration. By deconvolving pixel specific detector response functions, variations in response of a gamma-ray camera system across its image plane can be accounted for. This offers significant improvements in energy resolution and many of the problems associated with conventional gamma-ray camera systems are reduced. For example, the improved energy resolution allows better rejection of photons associated with Compton scattering events occurring in a source being imaged.

Abstract: A scintillation spectrometer provides improved resolution by ensuring that photons generated by scintillation events occurring in different locations within the scintillation material generate similar light profiles on the photo-detector, thereby making the output signal less sensitive to the initial interaction site and enabling more effective de-convolution of raw data. This is achieved in different ways, such as by: limiting the exit window of the scintillation crystal, introducing a spacer between the scintillation crystal and the detector window, or providing a crystal that is longer than necessary to stop gamma rays.

Abstract: Different geometries of scintillation spectrometers are disclosed which provide improved resolution over prior art scintillation spectrometers. By ensuring that photons generated by scintillation events occurring in different locations within the scintillation material generate similar light profiles on the photo-detector, the output signal is made less sensitive to the initial interaction site. This can be achieved in a number of ways, such as: by limiting the exit window of the scintillation crystal to a smaller detector, by introducing an optical spacer (94) between the scintillation crystal and detector (99), and/or by making the crystal longer than necessary to stop the gamma rays. A principal advantage of these new geometries is that deconvolution of the raw-data is more effective, thus improving resolution.