Abstract: A DC-DC converter, having multiple outputs, efficiently utilizes its power transformer to provide continuous power output to the outputs except during transitions of the power switches. Energy flow is continuous to one or more outputs during conduction of the power switch and then is transferred to the remaining outputs during its non-conduction. A feedback control, connected to sense only one of the outputs operate the power switch at a controlled duty cycle. Regulation of both outputs is enabled by equalizing transformer volt seconds of the non-conduction and conduction intervals of the power switch and by a clamping circuit which sustains the volt seconds in the power transformer during the non-conduction interval. In a particular embodiment, a converter circuit comprises a transformer having a primary winding and a secondary winding.

Abstract: A capacitor mounting assembly uses a mounting assembly for mounting and aligning a plurality of DC can capacitors on a bulk power system assembly. The mounting assembly includes a metallic base member with a channel cross section having mounting flanges at the longitudinal edges with holes to allow fasteners to pass through and secure the base member to a power system assembly. A top metallic cover plate and a plastic layer cover the top surface of the base member to form a sandwich construction with the plastic layer between the two metallic surfaces. The plastic layer is a polypropylene sheet in the illustrative embodiment. The three layers have holes punched through the sandwich to accept the insertion of the can capacitors.

Abstract: An apparatus and method synchronizes a communication frame of a newly added base station, in a Time Division Multiple Access (TDMA) communication network, to communication frames in the existing communication network of base stations by operating the newly added base station to receive down link signals of a neighboring active base station and synchronize its receive slot in the communication frame with a corresponding forward time slot of the communication frame of that base station. The receive time slot of the newly added base station is shifted by an offset reference time to establish it own forward time slot. The offset reference time is determined by the time interval required for the base station to change from a forward to a reverse channel.

Abstract: A tool for designing the conductors into a PWB includes an audit arrangement for auditing or analyzing crosstalk between electrical conductors to be entered into the PWB. This crosstalk audit may be performed as soon as the initial design is created and before actual manufacture of the PWB. It is operative to identify crosstalk problem areas and to identify impedance mismatches. In particular the audit process defines conduction paths into conduction nets conduction nets are selected one at a time for evaluation and simulated as having an idle current condition. Nearby conduction nets are simulated as being driven in an active condition. The response of the idle network is used to derive a plurality of crosstalk parameters which are used to determine the crosstalk effect on the net under test.

Abstract: A switched mode power converter includes a periodically switched power switch which is switched under the control of a multiple loop feedback controlling the power switch in order to supply a regulated output. The output voltage and power switch current are sensed. An error voltage is generated which is representative of the deviation of the output voltage from a regulated value. A voltage derived from the power switch current is limited in its low frequency response and is then combined with the error voltage. The low frequency response of the current loop gain is used to maintain an advantageously low output impedance for the power supply. This shaped loop gain response advantageously allows accurate adjustment of the current loop gain and reduces the system to a lower order while maintaining adequate loop stability.

Abstract: An isolated MOSFET gate drive includes circuitry to provide a negative gate bias during the off time of the MOSFET to enhance its immunity to inadvertent turn-on. The bias is generated by a self contained two terminal passive network which may be "floated" at any potential with respect to ground. This bias is automatically generated through the action of the network to the gate drive waveform, eliminating the need for an external bias supply to provide this voltage. The bias supply is located locally, thus eliminating the need for long interconnects which may interfere with circuit operation. The bias network in one implementation is a combination of a capacitor and non-linear semiconductor device with a fixed voltage breakdown characteristic. This two-component implementation maintains the capability of producing systems with high packaging densities.

Abstract: Magnetic components are fabricated as monolithic structures using multilayer co-fired ceramic tape techniques. Fabrication of these magnetic components involves constructing multiple layers of a magnetic material and an insulating non-magnetic material to form a monolithic structure with well defined magnetic and insulating non-magnetic regions. Windings are formed using screen printed conductors connected through the multilayer structure by conducting vias.

Abstract: Transitions of a mobile radiotelephone between operating on A band service and B band service are controlled to enable the mobile radiotelephone to utilize the bands of a single service provider over a wide area of cellular service areas in which service is provided on either A or B bands by that single service provider. Each mobile radiotelephone served by a single service provider has an extended home system identification entered into its number assignment module (NAM). When the mobile radiotelephone is operating in a roam mode it scans both the A and B bands searching for the extended home system identification. If the system is successful in locking onto one of the extended home system identification channels the mobile radiotelephone uses that setup channel to establish and receive calls from its original service provider within the present service area. If the lockup can not be made the mobile radiotelephone uses the system I.D. and the A or B band as normally set in the NAM.

Abstract: A switching boost type voltage regulator includes a resonant snubber network connected in parallel with its FET power switch. The snubber includes a FET auxiliary switch that is connected and turned on in order to reduce the voltage across the FET power switch to a zero level at its turn-on transition. A driver circuit, driven by a voltage regulating pulse width modulation (PWM) pulse, initially turns on the FET auxiliary switch to reduce a voltage across the FET power switch and then turns on the FET power switch when the voltage across drops below a threshold level. The FET auxiliary switch is turned off when the FET power switch is turned on. A latch circuit insures the complimentary states of these two switches. The snubber circuit is disabled a near to zero voltage regardless of line and load levels and hence the power dissipation in the snubber is significantly reduced.

Abstract: A dual frequency cellular radiotelephone system, having different service providers, serving mobile subscribers at first and second distinct frequency ranges, uses frequency conversion techniques, to serve both frequency ranges with a minimum of equipment duplication. A first service group is serviced by a first system including a mobile switching center (MSC), a first transmission unit, a first base station controller (BSC), a first base transceiver, a first linear amplifier and first antenna. The entire train of components is designed to support air interface transmissions at the first frequency band at which the first group is served. A signal frequency converter, connected to a transceiver of the first frequency band, converts downlink signals from the first frequency range to the second frequency range and uplink signals from the second frequency range to the first frequency range.

Abstract: In a switch mode power supply the switch current of the power switch is connected to a low pass filter network during the time interval when current is flowing through the power switch. The filter network is disconnected from the power switch when switch current is not flowing. This technique takes advantage of the fact that the average current through the power switch during its conduction interval is either equal to the output current of the power supply, or is proportional with the ratio between the average switch current and the output current being the fixed isolation transformer turns ratio.

Abstract: An estimating circuit for application in estimating or deriving the value V.sub.rms.sup.2 or V.sub.peak.sup.2, of a line voltage V.sub.AC provides fast response time and a substantially ripple free value for these signals by the utilization of a controlled harmonic oscillator whose output precisely tracks the input voltage waveform. Two out of phase (by .pi./2) sine wave signals are derived from the input sine wave and these two out of phase signals are squared and summed to derive or estimate the desired square of the sine waveform signal at a fast response time while substantially excluding ripple of the estimated out of phase sine waves. An estimating circuit, described herein, comprises two integrator circuits series connected into a substantially closed loop. The output of the second integrator circuit is fed back to the input of the first integrator circuit. The output of each individual integrator circuit is a voltage sine wave separated in phase from the output of the other integrator by .pi.

Abstract: A mobile telecommunications system for a large area telecommunications system, including a plurality of different networks, has a directory/network structure for minimizing data storage and transmission and switching capacity requirements for locating roaming mobile terminals. A directory/network structure is provided with a plurality of directory/switching nodes arranged such that only one logical information and transmission path exists between any two nodes.

Abstract: A new communication system merges a voice communication with an image communication into a single transmission channel to provide a virtual voice/video communication service over a limited channel bandwidth. A voice communication path is established between two subscriber communication stations and a desired still picture image is transmitted via the voice channel at the start of the transmission. Portions of the still image expected to be visually active during the communication, such as facial movements (e.g. the lips of the speaker), are replaced at the receiver by an idealized representative image. The voice portion of the transmission is digitally encoded and transmitted from the transmitting station to the receiving station. Synchronous activation of the idealized image (e.g. the lips) are animated by code book coefficients of the digitized speech message.

Abstract: A personal communicator for use in a wireless communication network includes a wireless communications LCD and a multimedia LCD with the communications, mounded on a hinged member, and superimposed on top of the multimedia LCD. The communications LCD is sufficiently transparent to permit viewing of the under multimedia LCD. Each provides visual information to the user relative to the present use of the communicator. The selected use of the communicator is primarily responsive to the open or closed position of the hinged keyboard supporting cover. When the hinged member is closed the communicator operates in a communication mode. When it is open the communicator operates primarily in a multimedia mode. The personal communicator includes a steerable video imager for controllably optimizing image field coverage and adjusting to the orientation of the user relative to the personal communicator.

Abstract: A universal wireless radiotelephone communication apparatus is operative in both a first radiotelephone communication system including a first base station having a wide area of coverage, transmitting radiotelephone signals at a first band of frequencies and in a second radiotelephone communication system including a second base station having a localized area of coverage, transmitting radiotelephone signals at a second band of frequencies higher than said first band of frequencies. The second band of frequencies is optimally selected with an offset of less than twice a frequency contained within said first band. The wireless radiotelephone communication apparatus has a common baseband circuitry for operating with both the first base station covering the wide area and with the second base station covering the local area.

Abstract: A channel assignment system assigns channels to various cells by the optimal partitioning of the available radio frequencies into non-overlapping sets, the optimal grouping of co-user cells, and the best assignment of the former to the latter. The objective is the maximization of traffic handling capacity which, given the multitude of cells, is expressed as the maximization of a bottleneck capacity ratio. The capacity ratio for a cell is defined as the ratio of the number of radio frequencies assigned to the cell over the number of radio frequencies needed to meet blocking probability requirements. The solution to attain an optimal non-regular channel assignment is decomposed into two mathematical programs designated a Master Program and a Subprogram. These are solved iteratively with assistance from a channel set augmentation technique impelmented between solutions of the Master and Subprogram.

Abstract: A power factor control system for a rectifier is operative through the generation of estimators of control input parameters (a peak squared input AC voltage E.sub.m.sup.2 and load power) and by the use of these substantially ripple free signals controls a boost, buck, buck-boost, SEPIC or other related type converter at the input to the rectifier. The generation of these parameters allows the derivation of a programmed current i.sub.p used to control the wave form of the actual input current. The control procedure is based on a quarter cycle averaged power basis. The input power is derived from the rms values of the input voltage and current. Given the output power and its deviations in power due to load changes, the programmed current i.sub.p is determined by deriving an input conductance of the rectifier and combining it with the input voltage.

Abstract: A new insulation system comprising film coated, copper magnet wires covered under NEMA Standards No. MW1000, insulated with single or multiple layer(s) of extruded TEFLON.RTM. (any color) fluorocarbon resin insulation to meet the government or safety agency promulgated performance and construction requirements.

Abstract: A digital block receiver system, in a cellular/wireless FM radiotelephony system, receives and heterodyne a block of cellular/wireless receive channels to a very low block IF signal by analog processing. This block IF signal is applied to a precision high speed A/D converter and converted to a digitized time series. A window function is applied to the digitized time series and a high speed FFT is applied to frequency isolate the individual channels. The active channels are digitally processed by a DSP to recover the FM channel modulation.