General Electric Company

Ericsson Gmbh

Ericsson Ge Mobile Communications Inc.

Thomas A Brown

William Peil

Marc A Dissosway

Houston H Hughes, Iii

George D Rose, Jr

Ricky F Bitting

Marcella M Tucker

James E Harris

Vicki J Teel

Charles L Derenge

Thomas A Przelomiec

Spiro Vamvakas

Craig F Szczutkowski

Marvin C Baker

Robert Canada

William K Guzek

A new simulcast dynamic delay adjustment capability for a radio frequency (RF) simulcasting repeater system continually, dynamically adjusts the amount of delay applied to a T1 data stream to ensure common synchronization at multiple simulcast transmitter sites. A Global Positioning System (GPS) distributed time standard provides timing references at a control point and at each transmit site. The control point sends a version of its GPS timing reference signal to each transmit site over links also used to carry signals for transmission over-the-air. The transmit sites compare the arrival time of the land line-distributed reference signal with the output of a version of the same signal produced by a local GPS signal. The result of the comparison is used to adjust an amount of additional delay introduced to equalize delays for different transmission site links. This arrangement eliminates the need for resynchronization of the control point, allows for automatic, dynamic correction/compensation of path delay changes, and can correct delays over a wide range not known ahead of time with the delay amount being independent of over-the-air timing reference signal frequencies--all without loss of service.

RF simulcasting system with dynamic wide-range automatic synchronization

In a wide band radio frequency (RF) simulcast communications system analog voice signals are distributed in a digitized form over high speed data channels and processed as high speed data. A conventional Ericsson, Inc. EDACS.TM. simulcast communications system is improved by altering the apparatus and manner by which 'clear voice' (unencrypted analog voice) is distributed from a control point and 'aligned' at multiple transmitter sites for simultaneous RF broadcasting. In the improved arrangement, the EDACS.TM. simulcast system inherent digital data stream alignment process produces the requisite time domain alignment for the digitized 'clear voice' signals without the need for costly analog audio alignment procedures and equipment.

Auto-alignment of clear voice and low speed digital data signals in a

A downbanded Cellular network (DBC) is provided to supplement an adjacent or coincident standard Cellular network. The control channels used by the DBC and standard Cellular network are synchronized to ensure proper hand-off between the DBC network and the standard network. Synchronization is achieved by monitoring the separation in time between timing pulses transmitted by the DBC network and the standard Cellular network.

Control channel synchronization between DBC and Cellular networks

In a multiple site radio frequency (RF) simuicasting transmission system, voice and digital data distributed via multi-phase modem over 'land-line' inter-site communication links from a control point to the RF transmitter sites exhibit random time delay skew because the modems at each site recover clock signals from an arbitrary one of multiple phases. Reference 'tones' for data alignment, consisting of a high frequency clocking signal and a low frequency 'gating' signal, are generated at each site synchronized to a GPS broadcast reference signal. Similar tones are also provided to transmitter sites along with the distributed data via the land-line inter-site communication links as a backup. The pair of 'backup' reference tones supplied via land-line are automatically aligned at each site to the GPS receiver generated reference tones by individual phase comparison and dynamically-adjusting delay circuits. Consequently, sites can compensate for any land-line path re-routing--so long as the GPS system is operational. In the event of GPS receiver failure or loss of GPS signal lock a delay adjustment inhibit feature is provided to preserve the most recent and accurate delay setting. A site switches over to the land-line backup reference tones once a maximum 'free-running' tolerance time limit for the GPS receiver reference tone generator has been exceeded. In an alternate embodiment, backup reference tone phase comparison is coupled with a circuit for adjustably delaying a composite inter-site link T1-type channel signal. This arrangement automatically aligns the backup reference tones to match analog voice data ('clear voice') signal path latency.

Automatic clear voice and land-line backup alignment for simulcast system

A control channel timing monitor for a simulcast radio frequency (RF) digitally trunked mobile radio communications system continually monitors the outbound control channel timing of each of plural simulcasting transmitting sites. The timing of such monitored signals obtained 'over the air' is compared relative to one another and/or to a reference. Fault indications identifying specific sites having faulty synchronization are produced when such comparison indicates lack of synchronization within a programmable tolerance. Appropriate corrective action (e.g., bringing down the control channel and transferring its function to a frequency formerly used for working channel functions) is taken.

Control channel timing detection and self correction for digitally

Arrangements are disclosed for maintaining time synchronization of simulcast radio frequency communications system transmissions. A circuit continually instructs a modem to use the common system clocking signal, and modems are retrained whenever a channel is taken out of service because of a test call failure.

Self correction of PST simulcast system timing

A 'narrow band' public service trunking (PST) simulcast radio frequency transmission system having high-speed and low-speed digital data access capabilities in addition to analog voice operates in the 900 MHz frequency-range, as distinguished from a conventional 'wide band' PST system that operates in the 800 MHz frequency range. In a narrow band PST simulcast system having digital access capabilities, the handling of low speed digital data must be accomplished differently than high speed data since it becomes unique to each channel. This would ordinarily require providing an additional data path for each channel, or a wider band width audio path neither of which is feasible or cost effective. Arrangements are therefore provided for the routing of low-speed data to each transmit site via the high-speed digital data channel path for each site and for holding the high-speed data resynchronization circuitry at each site at its previous latency during the transmission of low-speed data, which would otherwise cause erroneous triggering of the resynchronization circuitry.

Narrow band simulcast system having low speed data distribution

In a multiple site radio frequency simulcasting RF transmission system, data transmitted from a control point to the RF transmitter sites exhibits random time delay skew because multi-phase modems recover clock signals from an arbitrary one of the multiple phases. The outputs of the modems are temporarily stored at the sites by memory buffers. The control point derives resynchronization signals from a source data clock, this signal containing frequency and timing information. The resynchronization signal is distributed to the various sites via additional phase-stable, delay compensated channels. Each site is provided with a clock recovery circuit that recovers the original source data clocking signal from the resynchronization signal and also extracts read-out timing information from the resynchronization signal. The recovered data clocking signal and the readout timing information are used to synchronize the readout from the FIFO memory buffers--providing approximately simultaneous (coherent) readout of the same data bits from the respective buffers of the different simulcasting transmitter sites.

Public service trunking simulcast system

A digital voter system for a multi-site public service trunking (PST) digitally trunked RF communications system operates on the principle that it is highly likely that messages received during a system redundancy removal period are redundant messages. For a given RF channel, digital receiver is associated with each of multiple sites and receives digital messages reported to it by its associated sites. The multiple digital receivers are connected to a digital selector via a service request line (FSL) and a serial data line (BSL). Digital receivers which have messages to transfer to the digital selector attempt to seize the service request line and, if they successfully seize it, maintain the line in its seized state for the redundancy removal period. Digital receivers which have messages but discover the service request line is already seized simply discard their messages. Since it is likely that two digital receivers may successfully seize the service request line at or near the same time, a windowing technique is used to schedule the times different digital receivers may apply their messages to the serial data line. If a digital receiver sees signals on the serial data line before it is scheduled to begin transmitting, it discards its message and aborts its transmission attempt. The preferred embodiment voter thus handles messages very rapidly (to reduce system latency time) while effectively removing most redundant messages and reducing or eliminating data collision on the shared serial data bus.

Digital voter for multiple site PST R trunking system

A digital voter system for a multiple site digitally trunked RF communications system includes an improved voting arrangement which tests for actual redundancy before removing redundant messages--thereby decreasing retransmission traffic in simulcast and other large coverage area RF trunking systems. Status messages indicating ongoing call reception are generated periodically by each receiver site which receives a given call. The status messages are received by a digital voter, which in a clear voice mode is used to determine (in responses to the status messages) whether an analog voter should maintain a clear voice call.

Voter arrangement for multiple site PST RF trunking system

The invention discloses a control circuit for an electronically commutated motor which performs essential internal commutation and control functions and responds to external controls, usually user operated. The invention is embodied in a ceiling fan which is subject to controls over motor speed or torque and direction of rotation. The control circuit uses a differential transconductance amplifier, which is periodically balanced, for commutation timing, and control logic, which includes a bidirectional counter, designed for uniformity in count duration, irrespective of the count, direction of counting, or changes in direction of counting, and a five rank decoding structure which selects the unenergized winding stage for sensing, selects the energized winding stages for suitably sensed energization, and responds to both direction and energy controls. The internal control includes circuit protection when power is first turned on. The invention also includes an integrated circuit having the foregoing features and a novel method of operating an electronically commutated motor.

Control circuit for an electronically commutated motor, an integrated

An energy efficient lighting unit is described designed for functional similarity to the incandescent light used in the home. The lighting unit utilizes a metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source. The lighting unit includes means for converting 60 hertz ac to dc, and a dc energized operating network containing a three transistor switch. The transistor switch is used to provide dc and low frequency (120 Hz) energization to the filament, and high frequency energization for both filament and arc lamp. The high frequency energization, which starts and transitions the arc lamp, is discontinued after the arc lamp is started. In the final run state, the arc lamp, which is serially connected with the filament across the dc supply, is ballasted by the filament. The transistor switch is controlled in its operation by control logic provided by an integrated circuit, which provides a complex control sequence, optimized for minimum electromagnetic interference for normal starts, 'hot restarts', and a failure state, called 'End of Life' in which starting attempts are discontinued.

Lighting unit with improved control sequence

In a motor control circuit for an electronically commutated reversible motor used in a ceiling fan, a control is used to reduce the voltage supplied to the motor for variable speed or torque operation. At the same time, a substantially smooth control voltage, dependent on the variable voltage supplied to the motor, is produced. This control voltage, which is used to enhance the adjustment rate, is applied to control a pulse width modulator, which produces output pulses which also control the flow of energy to the motor. When the control voltage reaches a value slightly past the desired minimum speed or torque setting, a signal is generated to change the direction of motor rotation. Means are provided to delay the actual reversal to protect the power switches in the control circuit. When power is first applied, the initial direction of motor rotation is set by a switch on the ceiling fan. The control circuit permits control of motor reversal from a wall location. The control circuitry is designed for use in a maximally integrated ECM control circuit. The invention also concerns a method of controlling an ECM, including reversal, and reversal combined with torque or speed control.

Control circuit for an electronically commutated motor including

An energy efficient lighting unit is described designed for functional similarity to the incandescent light used in the home. The lighting unit utilizes a metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source. The lighting unit includes means for converting 60 hertz ac to dc, and a dc energized operating network containing a three transistor switch. The transistor switch is used to provide dc and low frequency (120 Hz) energization to the filament, and high frequency energization for both filament and arc lamp. The high frequency energization, which starts and transitions the arc lamp, is discontinued after the arc lamp is started. In the final run state, the arc lamp, which is serially connected with the filament across the dc supply, is ballasted by the filament. The transistor switch is controlled in its operation by an integrated circuit.

Lighting unit having power supply with improved switching means

An energy efficient lighting unit is described designed for functional similarity to the incandescent light used in the home. The light unit utilizes a metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source. The lighting unit includes means for converting 60 hertz ac to dc, and a dc energized operating network comprising an inverter operating at above audible frequencies (e.g. 30-40 KHz). The operating network produces a sequence for the arc lamp and the standby filamentary light source appropriate to each operating state of the arc lamp.

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Lynchburg, VA, United States of America

Thomas A Brown