Abstract: A fault indicating circuit for an automobile alternator battery charging system is disclosed. The charging system comprises an alternator providing a rectified battery charging signal in response to alternator field coil excitation which is controlled by a voltage regulator that senses battery voltage. The fault indicating circuit comprises a low voltage detector circuit which provides constant DC excitation for an indicator lamp in response to low alternator output voltage and a high voltage detector circuit which provides intermittent excitation for the lamp in response to an excessively high alternator output voltage, the lamp being maintained in a de-energized state in response to the normal alternator output voltage.

Abstract: A movable electroluminescent display which can be moved relative to its printed circuit board to effect selective viewing of the display apart from the printed circuit board.

Abstract: A detector monitoring the voltage ripple in the rectified electrical output signal of an alternator in a multiphase alternator battery charging system is disclosed. A circuit monitors the undulating alternator output signal and produces a signal level in response. To correct the detector operation for various magnetic phenomena present in the alternator, a first circuit measures the rotational speed of the rotor and produces a proportional signal. A second circuit determines the excitation current supplied to the field coil. The measurement and determination are separately weighted and combined to form a corrected comparison threshold value. A variable threshold circuit combines the signal proportional to the rotational speed of the rotor and the determined field coil excitation current to produce a combined signal level.

Abstract: A detector monitoring the operational status of the field coil circuit in a multiphase alternator and voltage regulator battery charging system is disclosed. Circuit means monitor a first signal at a first terminal of the field coil circuit. Means generate sampling intervals on a repetitive basis. Circuit means interrupt the excitation signal supplied to the field coil by the voltage regulator during the sampling intervals. A second signal is measured during sampling intervals at a second terminal of the field coil circuit. Comparator means compare the first and second signals and produce an output signal when the comparison varies from a predetermined value.

Abstract: An extended AGC circuit renders at least one of a pair of back-to-back diodes, which together form antenna switch, continuously conductive under high RF input signal conditions to the radio receiver to extend the AGC performance of the receiver over a greater range of RF input signal conditions. A local/distant switch function can be easily and economically added to the extended circuit.

Abstract: A digital encoding and decoding system suited for use in a mobile trunked dispatch communication system capable of error correction, error detection, and detection of loss of synchronization. The encoder comprises a cyclic block encoder, an autosynchronization sequence combiner, a convolutional encoder, and a bit interleaver to encode information to be transmitted. The decoder comprises a bit de-interleaver, a convolutional decoder, an autosynchronization sequence combiner, and a cyclical block decoder to recover the transmitted information and also indicates whether any errors are present in the recovered information.

Abstract: A soft quantizer for assigning numerical weights to hard quantized output bits of a binary digital detector in a digital receiver based on the noise energy level of the received baseband data. An analog signal, derived from the discriminator noise level, is digitized by an analog to digital converter for use as an address to look up predetermined numerical weights for soft quantized values in a memory table. The addressed numerical weights are combined with the hard quantized output bits of the digital detector to generate soft quantized data values.

Abstract: A pushbutton switch assembly having a hand-insertable snap-in subassembly comprising the switch chassis and the switch actuator is disclosed. Dome switch electric contacts are contained within a chassis having a plastic wall with a through opening therein. The chassis has a pair of integral flexible retaining tangs projecting into the through opening. A plastic switch actuator having recesses thereon is hand-inserted into the through opening, and the flexible tangs and recesses cooperate to provide a snap-in subassembly. The flexible retaining tangs bias the actuator into a first predetermined position in which an actuating plunger on the actuator is maintained out of contact with the electrical dome switch contacts. The flexible tangs permit inward movement of the switch actuator into the opening such that the actuating plunger can contact and actuate the dome switch electrical contacts.

Abstract: An on channel signal detection system for use in scanning receivers to stop scanning at the desired frequency rather than for an undesired frequency. An amplifier receives IF signal and supplies them to a limiter composed of a pair of diodes. The output of the diodes is supplied to a tank circuit having a sufficiently high Q to provide at least some attenuation. The output of the tank circuit causes a transistor to go into conduction to cause a scanning controller to interrupt the scanning mode in the case of a on channel signal only.

Abstract: A channel selector system in a radio for sequentially selecting one of a plurality of channels and rapidly scanning through any restricted channels such that the restricted channels are not displayed and appear to be skipped. The radio includes a frequency synthesizer for generating a predetermined frequency associated with each selected channel and the channel selector system has a signal generator which causes the frequency synthesizer to sequentially either step or scan through the channels including some channels which may be restricted. The generator provides an output coded signal to indicate selection of a restricted channel which is decoded by decoding circuitry. A scan timer is responsive to the decoded signal to cause the signal generator to rapidly scan through restricted channels. A latching circuit latches a signal generator input during rapid scanning through restricted channels until the system advances to the next unrestricted channel. Related methods are disclosed.

Abstract: A system of the type wherein transmissions of the same information are simultaneously broadcast by spatially removed transmitter sites. A control center establishes transmission links to the transmitter sites. The center includes electronic storage which supplies the required time delay for each signal applied over a predetermined link to assure phase coherency of overlapping transmissions. Upon the establishment of a new link, a new set of time delays is recalled from memory and used to program a bucket brigade to thereby provide the required delay to signals carried over the link.

Abstract: An automotive battery charging system having a voltage regulator circuit with an improved feedback network for controlling the duty cycle and frequency of current in the field coil of the alternator. The feedback network includes a filtering circuit to minimize the effect of voltage spikes and ripple on feedback current. The filtering circuit is in the form of a variety of networks for clamping filtering and regulating.

Abstract: In a high frequency oscillator circuit, or other high frequency circuit, utilizing a crystal, the physical capacitance C.sub.o, of the crystal may be neutralized and the impedance match of the crystal to the remaining circuit achieved over a range of variations in the crystal and varacter parameters by connecting two inductance coils as an auto transformer and disposing them in end to end relationship on a common form across the crystal with a movable metallic slug interiorly thereof for varying the reactance of one coil relative to the other to achieve the desired deviation to reactance response. The overall reactance of the auto transformer remains constant and thus the C.sub.o compensation is not altered.

Abstract: The operational status of equipment located at a base station is reported to a remote control terminal. The same audio channel that is used for sending audio signals and control signals to the base station is also used to carry the report signal. The control signals to the base station and the report signals from the base station are encoded tone burst signals. The report signal provides an indication of the proper receipt and execution of a control signal by the base station equipment. Equipment diagnostic signal and periodic checks of equipment performance are also reported by this system.

Abstract: The reed contact unit comprises a pair of aligned members of magnetizable and electrically conductive material spaced apart endwise from each other with a fillet of non-magnetic electrically conductive material inserted between the spaced ends of the members. The upper surfaces of the members and the fillet are coplanar. An electrically conductive cantilever carries an electrically conductive and magnetizable armature at its free end overlying the fillet and the adjacent ends of the members. Upon magnetization of the members, a contact surface of the armature contacts the members to complete an electric circuit between the cantilever and the members. The members and the cantilever are mounted within a hermetically sealed enclosure.

Abstract: The reed contact unit comprises a pair of aligned members of magnetizable and electrically conductive material spaced apart endwise from each other. A fillet of non-magnetic electrically conductive material may be inserted between the spaced ends of the members. A flat electrically conductive resilient member supported at its opposite ends carries, at its mid-region, a magnetizable and electrically conductive armature and suspends it over the fillet and the adjacent end portions of the magnetizable members. Upon magnetization of the members, a lower contact surface of the armature engages the ends of the magnetizable members and completes an electric circuit from at least one of the magnetizable members through the resilient member to its support. The magnetizable members and the resilient member are mounted within a sealed enclosure.

Abstract: A ground fault detector for an ungrounded electrical distribution system responds to a wide range of ground fault current levels by providing the ground fault sensing circuitry with a high impedance at low ground fault signal levels and a low impedance at higher ground fault signal levels. The varying or nonlinear impedance of the sensing circuitry occurs due to the presence of the series combination of a Zener diode and a resistor connected in parallel with a level sensing means. At ground fault signals below the Zener voltage of the Zener diode, the impedance of the sensing circuitry is that of the level sensing means. When the ground fault signal exceeds the Zener voltage, the impedance of the sensing means is significantly reduced since the Zener resistor is now in effective parallel combination with the impedance of the level sensing means.

Abstract: The contact materials comprise silver with additions of mercury or mercury and tellurium and silver-cadmium oxide compositions with additions of mercury and tellurium. The methods of making the materials include the steps of adding a silver-mercury alloy to molten silver and to a molten silver-tellurium powder mixture. The materials including cadmium oxide are produced by heating a mixture of powders of silver, a cadmium-tellurium compound, cadmium oxide, and mercuric oxide powders in a reducing atmosphere and then reoxidizing.

Abstract: The contact materials comprise silver with additions of mercury or mercury and tellurium and silver-cadmium oxide compositions with additions of mercury and tellurium. The methods of making the materials include the steps of adding a silver-mercury alloy to molten silver and to a molten silver-tellurium powder mixture. The materials including cadmium oxide are produced by heating a mixture of powders of silver, a cadmium-tellurium compound, cadmium oxide, and mercuric oxide powders in a reducing atmosphere and then reoxidizing.

Abstract: A ground fault protective system and method in which an impedance responsive oscillator detects low impedance ground faults on the neutral conductor of an electrical distribution circuit and responds thereto to provide a partially or totally attenuated output signal. A level detector senses the magnitude of the output signal of the oscillator and causes a trip circuit to open contacts in the electrical distribution circuit whenever the attenuated oscillator output signal occurs.