Abstract: A decoder for use with a compatible AM stereophonic signal utilizes a amplifier and a feedback loop from the amplifier output to control the output of a multiplier circuit which is one input to the amplifier. The amplifier output is thus forced to become the required correction factor used in restoring the stereo program signals.

Abstract: An ethylene-acrylic acid copolymer can be used as a flux or a solder-through conformal coating. The copolymer can be melted and used as a coating or core for solder, or applied directly to a component, or made into a thixotropic gel with mineral spirits and/or alcohol, then applied as a coating to a component or assembly. Terpenes may be added as tackifiers in some applications. Whether used as a flux or simply solder-through coating, the material provides a self-healing moisture barrier which can safely remain on the component.

Abstract: An AM stereophonic pilot tone is detected using two signals derived from a received broadcast signal. One signal is proportional to the phase deviation and one is a two-level signal which is a function of the magnitude of the phase deviation. The detector controls activation of the visual indicator, muting of the stereo channel of mono/stereo mode switching with almost complete elimination of false detections during monophonic transmission and poor stereo transmission.

Abstract: A resilient spacer for use in a membrane switch assembly is formed of an open-cell, non-reticulated foam felt layer, allowing air from the space between the upper and lower switch contacts to move into the foam material surrounding the contacts when a switch contact is made. The switch contacts remain protected from atmospheric contamination regardless of whether the assembly is edge sealed or not.

Abstract: The signal as transmitted is a compatible AM stereophonic signal with amplitude directly proportional to the monophonic signal 1+L+R. The instantaneous phase angle is the quadrature phase angle modified in that high level, high frequencies in the L-R channel are reduced before carrier modulation. The gain in the high frequency L - R channel may be reduced in proportion to the signal level only, or to both level and frequency, or to the percent of distortion introduced into the high frequencies of the L - R signal by RF filtering of the modulated carrier.

Abstract: A crystal is mounted on a low, centrally located pedestal. Connections to the lower side of the crystal are made by way of conductive areas on the pedestal. Multiple wiring connections are made at the edges of the crystal by allowing the bonding tool to depress the edge of the crystal so that the crystal bonding pad is supported by the base structure only during the bonding process, then released thereafter to allow free vibration of the crystal plate. Complex circuitry, possibly involving more than one frequency can thus be put onto one plate.

Abstract: A highly accurate current mirror for IC implementation is comprised of low beta transistors and operates on a low supply voltage by utilizing a bias network with a balance sensing feedback network to control the bias voltage. The output current of one of the mirror transistors is compared with the reference current and the level of the current is then forced to equal the reference by means of the bias voltage adjustment.

Abstract: Apparatus having an integral coaxial antenna coupled via a coaxial connector to its internal circuitry has a coaxial switch/connector for alternatively coupling an external coaxial signal source to the internal circuitry, thus reducing impedance mismatch to a minimum with no impedance matching network required.

Abstract: A yoke mounting assembly provides easy yoke adjustment along the axial direction of the tube with accurate, fixed positioning in the other two dimensions. An extruded sliding support is movable along projections in a housing frame against the applied normal force of a pair of C-shaped retainer springs, the latter being easily rotated to a release position for yoke or camera tube access.

Abstract: A crystal is mounted on a low, centrally located pedestal. Connections to the lower side of the crystal are made by way of conductive areas on the pedestal. Multiple wiring connections are made at the edges of the crystal by allowing the bonding tool to depress the edge of the crystal so that the crystal bonding pad is supported by the base structure only during the bonding process, then released thereafter to allow free vibration of the crystal plate. Complex circuitry, possibly involving more than one frequency can thus be put onto one plate.

Abstract: A function generator as for use in a system of compatible quadrature AM stereo approximates the tangent function curve, allowing for the provision of essentially undistorted intelligence signals. A form of differential amplifier, including additional multiple threshold transistor circuits with common collectors and common bases, has at its input terminals a signal related to an angle of modulation and provides an output signal approaching a signal related to the tangent of the angle of modulation, the accuracy of the approximation depending on the number of circuits included. The function generator has the capability of providing other similar functions and of use in other applications. As used for AM stereo decoding, a tangent function output is derived from the phase modulation components of the stereo signal and, when multiplied by the amplitude modulated signal, the stereo difference signal can be derived.

Abstract: Instant scale shifting by predetermined increments is provided in a musical instrument tuning device by means of a programmable phase locked loop and crystal-controlled oscillator combination. The incremental scale steps are extremely accurate without need for recalibration and with no change in the tone intervals.

Abstract: Channel efficiency in a communications link between a controller and multiple portable units is increased by polling the active units and a set number of inactive units in a sequence where a "poll" consists of sending the binary coded address of the portable unit. The stream of transmitted data bits is only interrupted by a response from the portable unit, then resumed at the end of the response or a given portion of the response. During the reception of the response, certain other types of messages can be sent out by the controller. Portable responses can be automatic responses as to status, etc., or can be data initiated by the operator of the portable unit keyboard and stored in the portable unit memory until "armed" by the operator, then automatically transmitted to the controller when the portable unit address is received.

Abstract: A two-way communications system for use with a host computer includes a control unit, a base station and multiple radio/data terminal units. The control unit interfaces directly with the computer but uses a radio link to the portable units. Voice and data signals can be transmitted and data between units is decoded, sorted, stored, encoded, and sent to its destination in accordance with predetermined protocol in queue discipline. An extensive self-diagnostic system is included. An active redundancy arrangement switches between two control units/base stations on a regular schedule if both units are up, and instantaneously if the "on" unit goes down.

Abstract: A miniature piezoelectric element is conductively mounted on a metal diaphragm having one or two projecting tabs which provide two solderless terminals. An insulating area is screened onto the diaphragm around the piezoelectric element and out onto one tab. A conductive layer is formed on the upper surface of the active element and out onto the insulating area on the tab without contacting the diaphragm. The diaphragm can then be supported within any suitable housing with the tab or tabs projecting for contact by a miniature connector.

Abstract: In a mobile repeater system there can be two priority repeaters at two adjacent locations which are out of range of each other, but not out of range of each other's portable units. Reception of a tone coded signal from a portable raises the squelch threshold in both repeaters, thus decreasing the portable-to-repeater range without decreasing the repeater-to-repeater range. Interferences caused by simultaneous transmission is eliminated since only the appropriate repeater is activated.

Abstract: A battery as for a miniature communication device is retained within a hollow knurled knob captivated within the device housing. The side of the knob projects from the housing to provide thumb control of the switch, and has an open side portion to provide battery access. Spring contacts access the battery terminals through apertures in the knob. Function indicia are provided on the knob and are visible on the projecting portion as appropriate.

Abstract: Dynamic focus circuitry for a CRT data display terminal provides high resolution even in the corners of the screen by means of a dynamic focus voltage which is the product of parabolic waveforms at horizontal line rate and vertical frame rate. The non-linear characteristic of a diode provides the product function at minimum expense.

Abstract: A splash proof housing assembly for a portable two-way data terminal/radio having a waterproof front panel including keyboard and a waterproof seal joining the data terminal housing halves with a unique tongue and groove gasket and housing configuration.

Abstract: A compatible AM stereo broadcasting system is disclosed in which the signal is a carrier having an amplitude directly variable with monoaural or sum (L+R) information, and having an instantaneous phase .phi. varying as a function of the resultant amplitude of the sum information (L+R) and difference information (L-R) which are established in a preselected phase relationship (quadrature). In a stereo receiver, L and R or the sum and difference signals may be restored by dividing the signal by the cosine of the angle .phi., and in a monaural receiver, the sum signal alone is detected.