Sangamo Weston, Inc.

Schlumberger Industries

Hayes Microcomputer Products, Inc.

Scott C Swanson

John W Jerrim

John A Copeland, Iii

Robert E Dyer

Richard Alan Kramer

Jeffrey P Murray

Robert A Hicks

John A Copeland

An ambient light filter includes light emitting circuitry and optical detection circuitry. The detection circuitry is positioned to detect light from the emitting circuitry. A microprocessor is provided to separately control the light emitting circuitry and the optical detection circuitry. The microprocessor determines whether light from the emitting circuitry has been detected by removing a measured component equivalent to the ambient light present at the optical detection circuitry.

Ambient light filter

A meter sensor light tamper detector includes at least one light emitter and one or more sensors. The sensors have some parameter, i.e., conductivity in the case of phototransistor sensors, to provide an indication that they are in the presence of light. The system also includes a microprocessor which is capable of independent control of the light emitter and the sensors, and can determine the state of the electrical parameter, i.e., conductivity or nonconductivity, of the sensors. The microprocessor determines whether the sensors are being tampered with by checking the state of the sensors when a particular light condition is known to be present or absent.

Meter sensor light tamper detector

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.

Method and system for sensing removal of a utility meter from its socket

A secondary communications device, such as a modem, a facsimile machine, an automatic meter reader or an answering machine, shares a telephone line with a subscriber's telephone and must grant the telephone primary access to the line. The present invention prevents the secondary device from seizing the line when the telephone is already off-hook and will terminate a line seizure by the secondary device if the subscriber picks up the telephone handset during use of the line by the secondary device. An average interval for charging a capacitor to a threshold voltage in response to an on-hook voltage appearing across the telephone line is determined. When the secondary communications device is ready to use the line, circuitry measures an interval for charging the capacitor in response to the current voltage appearing across the telephone line. The secondary communication device seizes the line only if the measured interval does not exceed the average interval by more than a predetermined amount. After seizure by the secondary communication device, a steady-state condition is brought about between the secondary device, the line steady-state impedance, and the central office voltage source. If the line impedance drops from the steady-state value, the circuitry assumes that the subscriber has taken the telephone off-hook and terminates the line seizure by the secondary device.

Parallel off-hook detection for both line-available and phone pick-up

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. Accuracy of detection is improved under microprocessor control by introducing hysteresis in the delay between emitter energization and detection, in the voltage threshold in a comparator connected to the detection circuit, or in emitter energization driving current. The hysteresis is determined in accordance with the memorized state of the last previous detected signal.

System and method for introducing meter sensor hysteresis

A status word modification device. A serial communications device (11) contains two universal asynchronous receiver transmitters (UARTs) (14, 15). Each UART contains a first in, first out (FIFO) buffer (14a), two status buffers (14b, 14c), and a FIFO control register (14d). If the applications program in the host (10) is an enhanced application program which supports the use of the FIFO buffer (14a), then the program will cause FIFO enablement instructions to be written into the control register (14d). In this case, the interface circuit (22) allows the status words to pass unaltered whenever the host (10) reads the status buffers (14b, 14c). However, if the applications program is a standard applications program which does not support the use of the FIFO buffer (14a), then the program will not write to the control register (14d). In this case, the interface circuit (22) will alter the value of selected bits of the status words if the user has enabled the FIFO buffer (14a) and the host reads the status buffers (14b, 14c). The alteration of the status word prevents the standard applications program from treating the FIFO-related bits in the status words as data errors.

Method and apparatus for concealing the enablement of a device by

A bus access controller. An interface circuit (22) controls the access of a host computer (10) and a microprocessor (23) to one or more UARTs (14, 15). The microprocessor (23), which has no provision for waiting for a data transfer, is required to provide a signal of its intent to perform a data transfer prior to beginning the actual data transfer. The signal is identical to the actual data transfer operation. If the host (10) attempts a data transfer operation while the microprocessor (23) is conducting a data transfer operation, or if the host data transfer cannot be completed prior to the time that the microprocessor data transfer will commence, then the interface circuit (22) signals the host (10) that the data transfer will take additional time by deasserting the I/O READY line (12a). Once the microprocessor data transfer is completed then the I/O READY signal is reasserted and the host data transfer is completed. Bus contention problems and data loss are therefore prevented and the host (10) waiting time is minimized.

Method and apparatus for preventing bus contention problems between two

A data flow controller (150) for monitoring and automatically controlling the flow of serial data from a remote transmitter to a host device. A serial communications card (11) provides an interface between a remote transmitter connected to a serial port connector (20) and a host device (10). The card (11) contains a UART (14) which has a buffer. A counter (151) counts the number of bytes received by the UART (14) since the last time that the host (10) read all the data in the buffer. If the number exceeds a predetermined portion of the buffer capacity the counter output (Q11) will go high, thereby disabling the counter and sending a control signal (DTR, RTS) to the remote transmitter to stop sending data. Once the host (10) has read all the data in the buffer the UART (14) provides a signal (-RXREADY) which resets the counter (151), thereby causing the output (Q11) to go low, thereby allowing the remote transmitter to resume sending data. The counter (151) is held in a reset state until the buffer has received at least one byte of data. Data flow control is therefore obtained without the intervention of the host (10).

Method and apparatus for serial data flow control

A data compression method and apparatus particularly suitable for use in electrical power line fault data recorders. The system performs both gain compression and frequency compression. For gain compression, a predetermined number of samples are analyzed to determine a gain setting common to each sample in the set of samples. A reduced data string consisting of a gain code and data words having fewer bits than the input words are transmitted as a compressed data string. For frequency compression, a sample set representing the input signal is decimated until there remain only a sufficient number of data samples to satisfy the Nyquist criterion for the highest frequency component of interest. The frequency compressed output data string comprises a frequency code representing the highest frequency of interest followed by the set of decimated data samples.

Data compression apparatus and method for data recorder

A data compression method and appartus particularly suitable for use in electrical power line fault data recorders. The system performs both gain compression and frequency compression. For gain compression, a predetermined number of samples are analyzed to determine a gain setting common to each sample in the set of samples. A reduced data string consisting of a gain code and data words having fewer bits than the input words are transmitted as a compressed data string. For frequency compression, a sample set representing the input signal is decimated until there remain only a sufficient number of data samples to satisfy the Nyquist criterion for the highest frequency component of interest. Also included is a circuit for reproducing the waveform envelope. Positive and negative peak detectors provide signals representative of the peaks of the waveforms. These positive and negative signals are then compressed with the gain compression circuit, decompressed after transmission or recall, and then displayed as an envelope waveform for allowing trend analysis.

Data compression apparatus and method for data recorder with waveform

An improved temperature transducer for use with a KYZ pulse data recorder. A temperature sensor provides a temperature signal proportional to ambient temperature. An integrator circuit and comparator circuit responsive to the temperature signal provides pulses at a frequency which is proportional to temperature. The pulses are provided over the standard three-wire KYZ pulse cable to the input of the data recorder. The circuit is extremely low power, highly accurate, and requires only the three-wire KYZ connection. No external power supply or cable is required, since the circuit draws its power from the pull up resistors in the KYZ data recorder input. Also disclosed are techniques for improving accuracy and minimizing power consumption in the circuit, and an improved integrator circuit.

Temperature transducer for KYZ pulse recorder

A solid state electricity demand recorder (10) is controlled by a programmable microprocessor (38) to obtain energy demand survey and billing data. The accumulated count of pulses during a record interval is compared with an encoded register reading obtained from an electricity meter (30) at the end of the reord. If there is acceptable correlation between the accumulated count and encoded meter reading, the interval pulse counts associated with that record are deemed verified. Power for the recorder (10) is obtained from the power line, except during power outages in which case a battery (28) provides back-up power. Error conditions such as power outages, meter failure, and low battery condition are automatically detected and communicated to the central computer for remedial action by the electrical utility.

Method of and system for accumulating verifiable energy demand data from

A solid state electricity demand recorder (10) is controlled by a programmable microprocessor (38) to obtain energy demand survey and billing data. The accumulated count of pulses during a record interval is compared with an encoded register reading obtained from an electricity meter (30) at the end of the record. If there is acceptable correlation between the accumulated count and encoded meter reading, the interval pulse counts associated with that record are deemed verified. The recorder then downloads the recorded demand data to a central computer at a preselected time over a communications line. The recorder is receptive to communications and commands from the central computer at times other than the normal preprogrammed data downloading time by detecting a particular number of rings.

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Roswell, GA, United States of America

Scott C Swanson