Abstract: A current sensor for sensing alternating current in a current-carrying conductor includes a substantially C-shaped magnetic core having first and second ends with a gap therebetween. A current sensing element, which includes a microresonant element, is positioned proximate the gap between the first and second ends of the magnetic core such that the element oscillates when exposed to an alternating magnetic field. A biasing coil is attached to the micro-resonant element for carrying a bias current. The micro-resonant element resonates, or vibrates, at a standard oscillating frequency when no current is present in the biasing coil, and resonates at a modified oscillating frequency when current is present in both the biasing coil and the current-carrying conductor. The magnitude of current in the current-carrying conductor is determined as a multiple of the product of a ratio of the standard oscillating frequency and the modified oscillating frequency, and the bias current.

Abstract: Magnetic shields for plastic molded electricity meter frames are positioned to substantially block external magnetic fields from adversely affecting operation of meter components. The shield can be utilized with either electromechanical or electronic energy meters. In an electromechanical watthour meter which employs an aluminum disk driven to rotate through a magnetic field produced by a retarding magnet, the meter frame includes an integrally formed retarding magnet shield and an integrally formed bearing shield. The shields are coextensive with the frame, and extend from an inner periphery of the frame toward the retarding magnet and the bearing, respectively. The shields are formed of a magnetically permeable powder, such as a ferrite powder mixed with the plastic material from which the meter frame is molded. The shields divert externally applied fields away from the magnetically sensitive components of the meter without adversely affecting meter accuracy.

Abstract: A retarding magnet assembly includes magnets configured to apply a constant drag on the rotating disk of an electromechanical electricity meter. The assembly includes upper and lower keepers secured to opposing extensions of the meter frame. A spacer is secured, at a first end, to the upper keeper, and a non-magnetic flexure spring is secured to a second end of the spacer. A pair of upper magnets are secured to the flexure spring member at opposing ends. A pair of lower magnets are secured to the lower keeper at opposing ends. The meter rotating disk extends between the upper and lower magnets. The equilibrium point of the flexure spring changes, depending on strength of the upper magnets and their consequent attraction to the upper keeper. Thus, if the upper magnets becomes stronger due to a temperature change, the attraction of the upper magnets to the upper keeper increases, and the upper magnets move closer to the upper keeper.

Abstract: Correlation between a pair of digital signal segments is measured by apparatus including a plurality of multipliers. Each of the multipliers produces the product of a respective sample of each one of the signal segments. The outputs of a plurality of digital-to-analog (D/A) converters are coupled to a summer, while each respective one of the multipliers is coupled to the input of a respective one of the D/A converts. The summer produces an analog output signal equal to the sum of the analog output signals produced by the plurality of D/A converter.

Abstract: A toroidal current transformer magnetic shield includes, in one form, a cup portion and a cap portion. Both the cup and the cap are C-shaped, and when the cap is placed over the cup, the cup and cap define a toroidal sensor chamber. The cup portion and the cap portion are constructed of magnetically permeable material, such as iron or steel. A toroidal current transformer is positioned within the sensor chamber, so that the cap and cup enclose, and magnetically shield, the toroidal current transformer.

Abstract: An encoder functions to perform a modulo-two dot product of an n-bit information word with a succession of n-bit projector words which are n-bit words chosen at random or generated pseudorandomly. These projectors are also known by the decoder. The parity of the successive dot products is sent as the output bits of the coder. The decoder receives the incoming bits which have been generated at the encoder and subsequently passed through a noisy channel. In the decoder, the projectors serve as successive n-bit addresses to a table. If the incoming i-th bit is a zero, the content of the indicated table location is incremented. If the incoming bit is a one, the content is decremented. After the table has been filled, the table contents are considered as a vector, V. The Hadamard transform is then taken. The largest (most positive) coefficient of the transform is identified. The table address corresponding to the location of the largest coefficient is the estimate of the decoded information word.

Abstract: A delta sigma modulator having reduced quiescent power consumption as compared to known delta sigma modulators utilizes no operational amplifiers and includes, in one embodiment, an input CCD and a summing CCD coupled to the output of the input CCD. A readout is connected to receive output signals from the summing CCD. Both an integration/recirculation input CCD and a comparator are provided to receive output signals from the readout. The integration/recirculation input CCD feeds back a charge to the summing CCD, and the output of the comparator is connected to a fill and spill reference CCD, which also feeds back a charge to the summing CCD. The comparator output signal is an oversampled digitized version of the analog signal sampled by the input CCD. The comparator output signal is supplied to a low pass digital filter, and a decimator is connected to the output of the digital filter.

Abstract: Delta sigma modulators for accepting input signals having amplitudes up to -1 dB of full-scale and a center frequency (F.sub.S) in the range ?F.sub.S /90, 44F 90!, and which are not prone to internal overflow, require few circuit parameters, and yield a signal transfer function with the inherent property that the modulator magnitude response is close to unity gain in the frequency region of interest include, in one embodiment, a pair of cascaded integrators, a unit delay element coupled to the output of the second integrator, an analog-to-digital (A/D) converter, and a one-bit digital-to-analog (D/A) converter controlled by output signals from the A/D converter. A first differential summing junction coupled to the output of the D/A converter is responsive to delta sigma modulator input signals. A second differential summing junction, coupled to the output of the first differential summing junction, is also coupled to receive a feedback signal from the second integrator.

Abstract: A mobile local area network (LAN) of tracked assets utilizing minimal power and bandwidth allows a large number of assets to be tracked in a practical manner. The mobile LAN is established between a plurality of tracking units in close proximity. Assets are approximately located according to their connection in the mobile LAN where the exact location of at least one of the network nodes is known. Each tracked asset has capability to independently determine and report its position to a central station, and each asset also has capability to communicate locally with other cooperative assets via the LAN. The LAN is dynamically reconfigurable so that as other cooperative assets come into proximity, they can join the network, and as others move away, they can leave the network. Within the network, a protocol is followed which assigns one of the assets to be the "master" and all others to be "slaves".