Abstract: A signal generator controls power output on the basis of the output from a &Dgr;-&Sgr; modulator or oscillator. That output may be generated in real time by the modulator or oscillator and fed to a switch control logic unit which controls a power switching stage to output switchably switched power from a power supply to an output, preferably via a filter. Alternatively the output of a &Dgr;-&Sgr; oscillator or modulator may be stored in a switchable memory to be retrieved when needed. A further alternative is to control the power switching stage by a processor with a program which reproduces the control effect of the &Dgr;-&Sgr; oscillator/modulator. Feedback from the output may be used to control the &Dgr;-&Sgr; modulator/oscillator and/or the power supply.

Abstract: Method and systems for reducing effects of magnetic field interference that may interfere with a magnetic field signal generated at or near an underground object, where the magnetic field signal is used to monitor the location of the underground object. At least two different moving averages of a plurality of samples that are representative of a detected magnetic field signal strength are produce. Each of the different moving averages is a moving average of a different number of the plurality of samples. A respective quality metric (e.g., variance) is then determined for each of the different moving average. One of the moving averages is selected based on the determined quality metrics. Further signal processing is then performed using the selected moving average. For example, the selected moving average is used to monitor the location of the object.

Abstract: A system and method for detecting a concealed current carrying conductor is presented. A first and a second field strength signal proportional to an electromagnetic field is generated. A value is determined for the first field strength signal. This value is used to divide the second field strength signal and form an indicator signal. A value for the indicator signal is determined. If the value of the indicator signal is equal to or greater than a predetermined value (i.e., not less than the predetermined value), a conductor detection signal is generated and used to alert a user to the presence of a concealed current carrying conductor.

Abstract: A method and apparatus includes a multi-position valve that restricts the air flow when the valve is placed in one position. Pressure tap valves are located are the inlet and outlet ports to measure the pressure differential and thereby determine the airflow rate.

Abstract: The present invention relates (with reference to FIG. 1a) to a method of manufacture of an integrated camera and illumination device. The method comprises assembling together an optical sensor (12), illumination means (17) and associated electronic circuitry (10) into an assembled unit; placing the assembled unit into a mold; introducing an encapsulant in liquid state into the mold to surround the components therein; and the encapsulant solidifying to form an encapsulated assembly of optical sensor, illumination means and associated electronic circuitry.

Abstract: The present invention (with reference to FIG. 2a) relates to an integrated camera and illumination device. The device comprises illumination apparatus having a plurality of light emitting diodes (17) arranged in a circuit which regulates current output by the circuit to an approximately constant level. The device comprises camera apparatus having a CMOS sensor (12) in a circuit supplied by the current regulated by the illumination apparatus.

Abstract: A remotely configurable locator system includes a detection device to locate concealed underground conductors. The detection device is configured to connect to a communications network via a graphical user interface. Also included is a database management tool configured to connect to the communications network and communicate with the detection device via the communications network. A database is included and is adapted to store data related to the detection device wherein the data is configured to be accessed by the database management tool. Finally, the graphical user interface is configured to permit a user to remotely perform one of updating, analyzing, and diagnosing the detection device based upon the accessed stored data.

Abstract: A signal generator controls power output on the basis of the output from a &Dgr;-&Sgr; modulator or oscillator. That output may be generated in real time by the modulator or oscillator and fed to a switch control logic unit which controls a power switching stage to output switchably switched power from a power supply to an output, preferably via a filter. Alternatively the output of a &Dgr;-&Sgr; oscillator or modulator may be stored in a switchable memory to be retrieved when needed. A further alternative is to control the power switching stage by a processor with a program which reproduces the control effect of the &Dgr;-&Sgr; oscillator/modulator Feedback from the output may be used to control the &Dgr;-&Sgr; modulator/oscillator and/or the power supply.

Abstract: Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localised fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes whilst maximising the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronised with each other and so repeating on the same time-base. This synchronisation may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.

Abstract: In order to identify a fiber optic cable (10) a beam (14) of polarised light is caused to pass down the cable to a first site (A) at which an electromagnetic field (24) is applied to the cable (10). The electromagnetic field (24) traverses the cable (10) in an essentially transverse direction and has a time-varying component orientated along the length of the cable (10) at the first site (A), with the component varying so that the line integral thereof along the cable (10) is non-zero. This results in a variation in the polarisation of the light, which can then be detected by a polarisation discriminator (20) at a second site (B), thereby to identify the cable (10).

Abstract: A digital phase-quadrature oscillator generates a series of sine values representative of a sine wave, and a series of cosine values representative of a cosine wave. In each iteration of the oscillator, a sum of the squares of past sine and cosine values is used as a negative feedback term in synthesizing next sine and cosine values, in order to stabilize the amplitudes of the sine and cosine values.

Abstract: A method of and apparatus for identifying fibers of fiber optic cables is disclosed. Waveforms may be generated by integer subdivision of a clock, the waveforms for modulation of a laser beam into a set of unique signals. Preferably, however, each waveform has two states and a different integer X associated therewith. The repeat period of the waveforms is preferably set at 2Y cycles of the clock, Y being an integer greater than the highest value of X, and the waveforms can be generated by counting X mod Y and changing the state of each waveform whenever this counting reaches or exceeds Y. The signals may be applied either successively or simultaneously to individual fibers at one end of a fiber optic cable. At another end of the cable, each signal can be detected as having a frequency by taking a Fourier Transform; the frequencies detected preferably being in arithmetic progression, whereby each fiber can be identified individually.

Abstract: An excavator vehicle has sensors thereon at different heights. Each sensor may have a coil which is generally horizontal and which detects the magnetic field generated by a current in a buried conductor. By detecting the relative magnitudes of the component of the field parallel to the ground, as detected by the sensors, it is possible to determine whether or not the excavator vehicle is proximate the buried conductor. A warning may be generated, or the excavating tool of the excavator vehicle controlled, to prevent the excavating tool damaging the buried conductor.

Abstract: A system and method to locate electronic marker balls includes receiving a signal representative of a detected marker ball. The signal includes the resolved in-phase and quadrature-phase (I and Q) components, each centered about a first frequency. The I and Q components are filtered in order to shift the first frequency to a second frequency and match the second frequency I and Q components to exponential decay characteristics associated with the marker balls. The second frequency I and Q components phase integrated in order to distinguish the components from noise. The integrating is based upon predetermined gain coefficients and produces integrated I and Q components in accordance with the predetermined gain coefficients. Next, a magnitude of the integrated I and Q components is determined to produce an I and Q magnitude vector and a noise variance associated with the magnitude vector is determined. Finally, the recursive coefficients are adjusted in accordance with the determined noise variance.

Abstract: Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localised fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes whilst maximising the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronised with each other and so repeating on the same time-base. This synchronisation may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.

Abstract: A remotely configurable locator system includes a detection device to locate concealed underground conductors. The detection device is configured to connect to a communications network via a graphical user interface. Also included is a database management tool configured to connect to the communications network and communicate with the detection device via the communications network. A database is included and is adapted to store data related to the detection device wherein the data is configured to be accessed by the database management tool. Finally, the graphical user interface is configured to permit a user to remotely perform one of updating, analyzing, and diagnosing the detection device based upon the accessed stored data.

Abstract: A system and method to locate electronic marker balls includes receiving a signal representative of a detected marker ball. The signal includes the resolved in-phase and quadrature-phase (I and Q) components, each centered about a first frequency. The I and Q components are filtered in order to shift the first frequency to a second frequency and match the second frequency I and Q components to exponential decay characteristics associated with the marker balls. The second frequency I and Q components phase integrated in order to distinguish the components from noise. The integrating is based upon predetermined gain coefficients and produces integrated I and Q components in accordance with the predetermined gain coefficients. Next, a magnitude of the integrated I and Q components is determined to produce an I and Q magnitude vector and a noise variance associated with the magnitude vector is determined. Finally, the recursive coefficients are adjusted in accordance with the determined noise variance.

Abstract: A digital phase-quadrature oscillator generates a series of sine values representative of a sine wave, and a series of cosine values representative of a cosine wave. In each iteration of the oscillator, a sum of the squares of past sine and cosine values is used as a negative feedback term in synthesizing next sine and cosine values, in order to stabilize the amplitudes of the sine and cosine values.

Abstract: Methods and systems for digitally generating sound from phase and amplitude information of a narrow bandwidth signal, such as a narrow bandwidth locator signal. Phase-derivative information is determined from the phase information. The bandwidth of the phase-derivative information is spread out, or stretched, over a wider bandwidth, so that the frequency variations will be more perceptible to users. The result is combined with an audio band carrier frequency, the result of which controls an oscillator. The oscillator output is combined with the amplitude information to generate an analog audio signal that is modulated with the amplitude information and the phase-derivative information. The amplitude information wider bandwidth phase-derivative information are used to modulate an audio carrier in both frequency and amplitude.

Abstract: In order to control the sonde of an underground object, such as an underground boring tool, a predetermined sequence of rotation steps is applied to the object and that sequence is detected. The detection of the appropriate sequence causes the sonde to change its function, for example by changing the carrier frequency of the signal transmitted by the sonde on to change the data output sequence or transfer rate, or to change output power. While it is possible to use a single rotation step, the use of more than one step, with each step to be carried out within a predetermined time, reduces the risk of error.