Abstract: A battery door latching mechanism comprising two cantilevered posts incorporated in the base housing of a radio receiving device that interface with a headed rib on the base of a battery door. A recessed area in the battery housing surrounds the two cantilevered members, and prevents them from becoming overstressed due to deflection during shock, yet allowing them to deflect enough for attachment of the battery door to the housing.

Abstract: A shock absorbing mechanism for protecting a fragile quartz crystal includes a Teflon coating on the internal surface of the crystal enclosure. The enclosure is provided with a plurality of detents arranged so that when the crystal is shocked in its most fragile plane a plurality of these Teflon coated detents are struck simultaneously to distribute the shock across the surface of the crystal.

Abstract: A shock isolator for a fragile crystal device (20) includes a headed vacuum molded Teflon sheath (10) having rib springs (12) molded on the surface (11) for absorbing the shock of impact with nearby components. An integral spacer (14) is provided and coupled to the shock isolator proper by a living hinge (15). A plurality of keyhole-shaped slots (18) are provided in the spacer for engagement with the crystal leads (22) when the spacer is folded under into its operative position.

Abstract: A frequency synthesizer is provided including a reference frequency generator coupled to one input of a phase detector. The output of the phase detector is coupled via a pair of alternatingly connected filters through a voltage controlled oscillator and a divider circuit to the remaining input of the phase detector to form a phase locked loop. The first filter of the pair is designated for operation on a main channel frequency while the remaining filter is designated for operation on a priority channel frequency. The capacitive elements of each respective filter remain fully charged up for operation on their respective frequencies and thus when such filters are alternately switched between to change frequency from the main channel to the priority channel, the capacitive elements need not be charged to new levels to accommodate such frequency change.

Abstract: An antenna is provided which includes a first closely wound coil spring member of electrically conductive material. A second closely wound coil spring member which is substantially smaller than the first spring member is wound around a portion of the first spring member adjacent one end thereof. The second spring member is anchored to the first spring member by solder which is flowed into the coils of the first and second spring members where they contact each other. The end of the flexible first element to which the second member is attached is situated within a housing of rigid materials having first and second ends which include upper and lower apertures, respectively, the second spring member is fixedly held between the first and second ends of the housing.

Abstract: A supervisory control system for interrogating a large number of remote units. A pseudorandom sequence of bits are generated by central control in cycles and received by the remote units. Each remote unit is provided with a pseudorandom bit sequence generator. Upon coincidence of the pseudorandom bit sequence from the central control and the remote unit and upon detection of the address of remote unit and of the specific point in that remote unit, the remote unit sends back to the central control the status information of the selected point during the next succeeding bit time interval. In this manner the statuses of entire set of remote units are interrogated and reported. In accordance with a further aspect of the present control system, the control system commands the remote units for action and the remote units send back command acknowledge signals.

Abstract: An apparatus and method for determining the period and frequency of a signal intefering with a desired Loran C signal are provided. A sample of the interfering signal is generated at a time corresponding to the peak of the autocorrelation function of the interfering signal with respect to the predetermined pulse tracking reference point of the Loran C signal. Indicia of the period and frequency of the interferer is obtained from the timing of the sample generated at the autocorrelation function peak.

Abstract: An antenna is provided which exhibits a relatively small size and is capable of resonating at two different frequencies. The antenna includes two helically wound elements which resonate at a first resonant frequency. A conductive member extends through and beyond one of the two helical elements to cause the antenna to resonate at a second resonant frequency.

Abstract: A variable impedance synthesis circuit is provided for generating a selected impedance, whether real or complex, at a predetermined port. The variable impedance synthesis circuit exhibits the selected impedance in response to control signals applied thereto.

Abstract: A high efficiency radio frequency amplifier is provided which includes stabilization circuitry which is selectively actuated during periods of time when undesired amplifier circuit operating conditions are present which tend to cause amplifier oscillation. Otherwise, the stabilization circuit remains in effect decoupled from the amplifier so as not to unnecessarily draw power from the amplifier circuit when its action is not required to prevent undesired oscillation of the amplifier.

Abstract: Apparatus is provided for inhibiting the generation of intermodulation products in a radio frequency amplifier coupled to a circulator. A control circuit generates a control signal exhibiting indicia of the amount of isolation provided by the circulator. The control signal is provided to a variable impedance synthesis circuit coupled to the circulation isolation port such that the impedance synthesis circuit exhibits the appropriate impedance to maximize circulation isolation. Intermodulation is thus minimized.

Abstract: A crystal mounting arrangement is provided which achieves central mounting of the crystal on a substrate while not producing frequency changes in the crystal resulting from substantial differential expansion type stress generated over changes in temperature.

Abstract: A symmetrical two pole monolithic crystal filter is combined with appropriate value fixed capacitors and cascaded with other similar filter elements to provide a high order filter with symmetrical transmission zeros and low passband ripple. The filter includes a piezoelectric resonating element having first and second opposite sides with first and second pairs of electrodes thereon. A first capacitor is coupled to an electrode of the first pair located on the first side and a second capacitor is coupled to an electrode of the second pair of the electrodes located on the first side. A shunting capacitor is used between the electrodes of the first and second pairs located on the first side. A fourth capacitor is coupled from both of the first and second electrodes located on the second side.

Abstract: A method and apparatus for attenuating an interfering signal corrupting a desired Loran C signal is provided. An interfering signal sample is determined which occurs at the peak of the autocorrelation function of the interfering signal such that the period of the interferer is known. The sample occurring at the peak of the autocorrelation function is added to or subtracted from the desired Loran C signal sample taken at a predetermined reference point during the pulses thereof such that the interfering signal is cancelled or substantially attenuated.

Abstract: The invention comprises an improved cadmium negative electrode which is less prone to fading, can easily be manufactured by a pasting technique, and which does not require any external cycling to develop a precharge. This is accomplished by the use of irregular knarled cylindroidal cadmium particles of an average size ranging from 8 to 25 microns as measured by a Fisher Subsieve Sizer. The irregular knarled cylindroidal shape of the particles provides a substantial improvement pyrophoric characteristics while stilll providing electrochemical activity within a nickel-cadmium cell.

Abstract: An electroacoustic loudspeaker apparatus is provided including a piezoelectric driver element, the opposed major surfaces of which are acoustically coupled into first and second resonant structures. The first resonant structure exhibits a resonant frequency less than the resonant frequency of the driver and the second resonant structure exhibits a resonant frequency greater than the resonant frequency of the driver thus resulting in a broadened or enhanced frequency response.

Abstract: A mounting structure is provided for electro-optical display character elements. The mounting structure includes first and second electrically insulative substrates, each substrate of which includes an aperture. The aperture of the second substrate is somewhat smaller than the aperture of the first substrate such that when the apertures are aligned, the second substrate exhibits a lip under the aperture of the first structure. A display character element including electrodes on the opposed surfaces thereof is situated in the aperture of the first substrate. Electrode elements on the lower surface of the display character element are electrically coupled to corresponding electrode elements situated on the upper surface of the second substrate extending onto the lip. An interconnecting element electrically couples electrodes on the upper surface of the character element to corresponding electrodes on the upper surface of the first substrate.

Abstract: An apparatus and a method are provided for determining when a moving body assumes a motionless state. A rate of turn sensor is attached to the moving body. A signal indicating that the body is substantially motionless is generated when the rate of turn signal generated by the sensor is substantially constant.