Abstract: A method and system is disclosed for indication and prevention of tampering with an electricity meter having control circuitry for automatic remote reading. The control circuitry, provided externally of the meter in a base or base extension, to which the meter is connected, is also used for tamper detection. Embodiments of the invention include use of optical sensing, voltage detection and proximity detection. Ambient light sensing may be performed to detect separation of the meter from the external receptacle. Reflected light to a reflective surface of the meter is sensed to determine if the meter is properly engaged. Presence of a meter connection plug element may be sensed either optically or by position responsive switch. Voltage of the utility supply and meter user output may be monitored to determine tampering.

Abstract: The invention relates to a method and to apparatus for quickly and accurately positioning the rotary magnetic heads of a recorder/reader unit. The support for the magnetic heads includes a turntable and a countertable that are circular and that have a common axis of rotation, each including a peripheral support zone and a central support zone. The magnetic heads are situated around the periphery of the turntable. A screw enables the peripheral support zones to be brought into contact with each other and then the central support surfaces to be brought into contact with each other. The invention is applicable to recording and/or reading information on a magnetic tape.

Abstract: A distributed temperature sensor comprises an elongate ultrasonic waveguide having a number of zones along its length, each zone having a grating formed on it. This is typically achieved by incorporating uniformly spaced notches or bands (or collars) throughout the zone. The grating spacing in each zone is different, so that each grating reflects a characteristic frequency. This frequency varies as the temperature of the zone varies, so if wide-band ultrasonic pulses are launched into the waveguide, the temperature of each zone can be determined from the reflected frequencies.

Abstract: An optical sensor for monitoring position of a movable object comprising a LED and a phototransistor is provided with control circuitry, which is responsive to an output signal generated by the phototransistor for causing the LED to suspend radiation of light. When the light reflected from a reflective area of the object falls on the phototransistor, the control circuitry turns off the LED as soon as the output of the phototransistor goes below a threshold level signifying that the phototransistor has been turned on. When the light is absorbed by a non-reflective area of the object and the phototransistor is not turned on, the control circuitry turns off the LED after a predetermined time period, which is chosen to be slightly larger than the response time of the phototransistor.

Abstract: An electrical measuring device utilizing a shunt, an electronic measuring circuit floating at the potential of the shunt and a first voltage divider connected between the shunt and a neutral point to provide a first voltage signal to the circuit. To obtain the benefit of decoupling the potential between the shunt and the intermediate point of the first voltage divider, the device includes an additional terminal connected to the shunt by a second voltage divider, whose intermediate point supplies a second voltage signal used differentially with the first.

Abstract: The invention relates to a device for encoding and remotely transmitting information concerning the position and the direction of rotation of a rotary element. This device comprises an encoder driven by sensors suitable for producing an analog signal whose amplitude varies on each change of state of each sensor by an amount that depends on which sensor changes state. The invention is applicable to electricity meters.

Abstract: A water level measurement system for use with a pressurized power plant boiler comprises a tubular pressure vessel for attachment to one end of the boiler such that the water level in the pressure vessel is the same as in the boiler. The pressure vessel has a central rod-like conductor which together with the vessel forms a coaxial RF waveguide. A pair of spaced reference discontinuities are provided in the conductor above the maximum level of the water, so that an RF pulse injected into the waveguide is reflected successively by both discontinuities and the surface of the water. The level of the water can then be determined independently of changes in the dielectric constant of the vapor above it, from the ratio between the time intervals between the first and second reflected pulses and between the first and third reflected pulses. The conductor is mounted at the top of the pressure vessel by way of a pressure seal and a ceramic insulator.

Abstract: The invention relates to a communications system suitable for application directly to a national electricity grid and comprising a transmitter for transmitting data over a plurality of transmission frequency bands, a receiver for receiving messages over any one of the frequency bands, means for evaluating the transmission quality of each of the frequency bands, and a way to adapt the system for transmitting and receiving over the frequency band that has optimum transmission quality. The system of the invention may be applied, in particular, to remote reading of electricity meters.

Abstract: A method and system for accurate remote reading of an electricity meter including an optical detection arrangement, including a light emitter and sensor, have positioned in the light path therebetween a cutout portion of the meter shaft. Rotation of the shaft affects the amount of light passed to the sensor. Registration errors which may occur in a linear transition operating range are avoided by provision of detector threshold hysteresis. A microprocessor sets timing pulses for emitter energization, establishes a detection period of uniform length of time for each energizing pulse and produces, during each detection period, a digital signal having a logic level indicative of the presence or absence of light transmitted to said sensor, whereby a correlation between light transitions and power usage can be made.

Abstract: A microprocessor based time-of-use electricity meter register uses an external real time clock powered by a backup battery during a power outage to measure real time elapsed during the outage. Upon detection of a power outage, line power and real time data are transferred by the microprocessor to an external, non-volatile memory, the external real time clock is energized by the backup battery and the clock reset to accumulate elapsed real time (days, hours, minutes, seconds) during the duration of the outage. Upon resumption of line power, the elapsed real time accumulated by the clock and the content of the non-volatile memory are transferred to the microprocessor, the backup battery is disconnected from the external real time clock and the real time previously stored in the nonvolatile memory is updated by the elapsed real time so that no customer billing data are lost during the outage.

Abstract: In pressure sensor systems based upon a micromachined silicon pressure sensor comprising a resonantly vibratable beam supported on a diaphragm, the beam is excited into resonant vibration by directing an optical excitation signal at the beam resonant frequency, via an optical fibre 26, onto a part of the sensor other than the beam, preferably the diaphragm. To detect the vibrations, the underside of the beam 16 and the adjacent upper surface of the diaphragm 18 are together arranged to define a Fabry-Perot cavity, and a continuous optical detection signal is directed at this cavity, also via the optical fibre 26. The optical detection signal is thus modulated at the vibration frequency of the beam 16 by the cavity, and the modulated signal is reflected back into the optical fibre 26.

Abstract: A vent (180) for an electricity metering device (30) having a housing (34) having a generally planar surface thereon with a cavity (35), a plurality of vent openings (182) on the surface of the housing (34) which extend through the surface for allowing passage of air therethrough and a plurality of vent shields (184) positioned on one side of the surface adjacent each of the vent openings (182), preventing access through the vent openings (182) into the interior of the housing (34), the vent shields (184) including a first wall (190) extending generally perpendicular from the surface of the housing, and a second wall (192) attached to the first wall (190) extending generally parallel to the surface.

Abstract: A monolithic pressure and/or temperature transducer comprises at least two sensitive semiconductor layers of III-V material sensitive to pressure and to temperature and supported by a common substrate of III-V material, which two layers comprise: a first layer doped with donor type impurities at a first concentration and having a first resistivity as a function of pressure and of temperature; and a second layer doped with donor type impurities at a second concentration different from the first concentration and having a second resistivity as a function of pressure and of temperature, which second resistivity depends on temperature in a different manner than the first resistivity.

Abstract: A securing mechanism for an electricity metering device (30) including a housing (34) having a cavity, a cover (36) positioned on the housing (34) and enclosing said cavity, the cover (36) including hinge pins (120,122) for attaching the cover (36) to the corresponding hinge slots (80,82) on the housing (34) and a sealing screw (126) connected to the cover (36) for releasably securing the cover (36) to the housing (34). The sealing screw (126) is threaded through a hole (124) in the cover (36), and includes an opening (158), and the cover further includes a lug (162) defining a second opening (164) positioned for cooperation and registration with the first opening (158) when the sealing screw (126) has secured the cover (36) to the housing (34).

Abstract: A relative position transducer for determining the angular position of a first member angularly movable relative to a second member includes a coded track on the first member, a read head mounted on the second member, drive means for oscillating the read head to scan over and read a limited region of the coded track, and a microcomputer for interpreting the code read by the read head as the position. A first sensor detects when the read head is in a predetermined reference position and a second sensor detects the end points and direction of the read head scan. The sensor outputs are connected to the computer for correct interpretation of the read head output. An interplation is used to improve the accuracy of the position determination.

Abstract: In an optically-excited micromachined silicon pressure sensor comprising a resonantly vibrating beam mounted on a diaphragm, vibration of the beam is sensed optically via the same optical fibre through which the optical excitation signal is applied to the sensor. The end of the fibre and the beam are arranged to define a cavity or gap whose width varies with vibration of the beam and which behaves as a Fabry-Perot cavity: thus light from the fibre is directed onto the beam and then reflected back to the fibre, the reflected light being modulated at the frequency of vibration of the beam. In order to overcome the difficulty of setting the gap or cavity width at an optimum value for light of a given wavelength, light of two different wavelengths is used to sense the vibrations, the wavelengths being selected such that the phase difference produced by the gap for one wavelength differs from that for the other wavelength by roughly 90.degree..

Abstract: Separate pulse inputs from respective metering circuits, representing the reactive R and in-phase W power components, are converted to a pulse output V representing the vector sum of those components. The two inputs are applied to increment respective registers, the output V is held in a third register, and a fourth register is provided to store the REMAINDER value (W.sup.2 +R.sup.2)-(V+1).sup.2. The meter includes a processor for incrementing the REMAINDER value by 2W+1 for each increment of W and 2R+1 for each increment of R and for incrementing V whenever the REMAINDER value is zero or positive and at the same time reducing the REMAINDER value by 2V.sub.1 +1, where V.sub.1 is the incremented value of V. The FRACTIONAL error in the value of V is determined by means of a look-up table.

Abstract: The present invention is a method by which a dial inbound MIU is able to provide for connection with a central station computer without the need for any specialized telephone equipment at the telephone company's central office. If the customer's phone has been called, the invention detects whether the customer has answered. It then waits until the customer hangs up, and when the customer hangs up it siezes the line and waits for a modem tone indicative of the presence of the central station computer waiting to establish communication. If that modem tone is present, the MIU will connect to the central computer and permit communication to take place before releasing the phone line.

Abstract: A cable retention mechanism (170) for an electricity metering device (30) including a housing (34) having a cavity, a cover (36) positioned on the housing (34) and enclosing the cavity, and wherein the housing (34) has a cable entry slot (96) adjacent an edge of the cavity for placement of a cable therein. The cover (36) has a first retainer (174) extending outwardly from the housing and positioned adjacent the cable entry slot (96) when the cover (36) is positioned on the housing (34), and a second retainer (176) extending from the cover (36) into the cavity adjacent the cable entry slot (96) when the cover (36) is positioned on the housing (34), whereby the first retainer (174), the slot (96), and the second retainer (176) bend and position the cable in a generally U-shaped configuration when the cover (36) is positioned on the housing (34) and the cable is in the slot (96 ).

Abstract: A sealed utility meter having internal automatic disconnection. The meter contains a battery source of power for energizing the circuitry and is used in its operating environment in a horizontal position. In order to minimize battery drain prior to operation the meter is provided with a tilt switch mounted at a substantially 45.degree. angle to horizontal to energize the meter when it is in its operating position and deenergize the meter when it is removed from that position. The meter is packed in a container with packaging material which determines the packed position of the meter and the packing carton is provided with indicia to indicate the proper shipping and storage orientation of the carton. When the meter is thus packed and the carton thus oriented the circuitry is deenergized.