Abstract: Example methods, apparatus and articles of manufacture to cancel echo for a communication path having long bulk delays are disclosed. A disclosed example method includes determining a first location of a first coefficient having a largest magnitude of a first plurality of magnitudes associated with a first plurality of coefficients of a first phase; determining a second location of a second coefficient having a largest magnitude of a second plurality of magnitudes associated with a second plurality of coefficients of a second phase different than the first phase; comparing a difference between the first and second locations to a threshold; and, when the difference is less than the threshold, selecting a first offset based on a greater of the magnitude of the first coefficient and the magnitude of the second coefficient; and cancelling an echo contained in a signal using the first offset.

Abstract: A neutron spectrometer is described. The neutron detector comprises a conversion layer provided on an outer surface of a spherical core of neutron-moderating material. The conversion layer comprises a neutron absorbing material and a phosphor material. The spherical core is arranged to receive photons emitted from the phosphor material of the conversion layer. The neutron detector further comprises a photodetector optically coupled to the spherical core and arranged to detect the photons emitted from the conversion layer.

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: 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: Systems and methods to measure the performance of a de-jitter buffer are disclosed. An example method 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, analyzing the recorded signal to determine one or more of a lower size, an upper size, an expansion speed, or a contraction speed of a de-jitter buffer based on the recorded signal and the known signal, comparing the one or more of the lower size, the upper size, the expansion speed, or the contraction speed to a performance requirement, and correcting communication network performance based on the comparison. Determining the expansion speed includes filling a lower portion of the de-jitter buffer, adding jitter to the plurality of packets, the jitter increasing at a first rate, and identifying the expansion speed as the first rate if no packet loss occurs.

Abstract: A neutron spectrometer is described. The spectrometer includes a first conversion screen (8) comprising a neutron absorbing material and a phosphor material, a first wavelength-shifting light-guide (14) arranged to receive photons from the phosphor material of the first conversion screen and generate wavelength-shifted photons therefrom and a first photodetector (22) optically coupled to the first wavelength-shifting light-guide and arranged to detect the wave-length-shifted photons. The spectrometer further includes a second conversion screen (12) comprising a neutron absorbing material and a phosphor material, a second wavelength-shifting light-guide (16) arranged to receive photons from the phosphor material of the second conversion screen and generate wavelength-shifted photons there-from, and a second photodetector (24) optically coupled to the second wavelength-shifting light-guide and arranged to detect the wave-length-shifted photons.

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: 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: 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: Example methods, apparatus and articles of manufacture to cancel echo for a communication path having long bulk delays are disclosed. A disclosed example method includes determining a first location of a first coefficient having a largest magnitude of a first plurality of magnitudes associated with a first plurality of coefficients of a first phase; determining a second location of a second coefficient having a largest magnitude of a second plurality of magnitudes associated with a second plurality of coefficients of a second phase different than the first phase; comparing a difference between the first and second locations to a threshold; and, when the difference is less than the threshold, selecting a first offset based on a greater of the magnitude of the first coefficient and the magnitude of the second coefficient; and cancelling an echo contained in a signal using the first offset.

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 radiation detector for neutrons and gamma-rays is described. The detector includes a conversion screen (4a) comprising a mixture of a neutron absorbing material, e.g. containing 6Li, and a phosphorescent material, e.g. ZnS(Ag) and a wavelength-shifting light-guide (8) arranged to receive photons emitted from the phosphorescent material and generate wavelength-shifted photons therefrom. The wavelength-shifting light-guide is doped so as to form a gamma-ray scintillator material operable to generate scintillation photons in response to a gamma-ray detection event therein. A photodetector (10) is optically coupled to the wavelength-shifting light-guide and arranged to detect the wavelength-shifted photons and the scintillation photons. Signals from the photodetector are processed to distinguish neutron detection events from gamma ray detection events.

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 calibration source comprises a radioactive material comprising a radioactive isotope having a decay transition associated with emission of a radiation particle and gamma-rays having a known energy and a solid-state detector, arranged to receive radiation particles emitted from the radioactive material. A gating circuit 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 transitions 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 may be performed in real time and in parallel with obtaining a spectrum of observed signal events.

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 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 aluminum 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 spectrometer comprising a scintillation body (34) for receiving gamma-rays and generating photons therefrom and a photodetector for detecting photons from the scintillation body and generating a corresponding output signal is described. The photodetector comprises a photocathode (26), an anode (28), and a reflecting surface (28A). The photocathode is arranged to receive photons from the source and generate photo-electrons therefrom. The anode is arranged to receive photoelectrons generated at the photocathode and is coupled to a detection circuit/amplifier configured to generate an output signal indicative of the photoelectrons received at the anode. The reflecting surface is arranged so as to reflect photons which have passed through the photocathode without interaction back towards the photocathode to provide the photons with another opportunity to interact with the photocathode, thus enhancing the overall effective quantum efficiency of the detector. The reflector may be specular or diffuse.

Abstract: Systems and methods to measure the performance of a de-jitter buffer are disclosed. An example method 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, analyzing the recorded signal to determine one or more of a lower size, an upper size, an expansion speed, or a contraction speed of a de-jitter buffer based on the recorded signal and the known signal, comparing the one or more of the lower size, the upper size, the expansion speed, or the contraction speed to a performance requirement, and correcting communication network performance based on the comparison. Determining the expansion speed includes filling a lower portion of the de-jitter buffer, adding jitter to the plurality of packets, the jitter increasing at a first rate, and identifying the expansion speed as the first rate if no packet loss occurs.

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: 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.