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 hybrid filter comprising a plurality of removably mountable resonator modules, each constructed of nmicrostrip, and mounted parallel to each other and perpendicular to the substrate so as to isolate the resonators for single mode operation; the inter-resonator coupling is provided by adjustable capacitor coupling gaps on the host substrate.

Abstract: The encoder which preferably produces a transmitted digital word which serves as an activation code for a single receiver or a group of receivers. The activation code effects only the receiver(s) that have previously detected their digital address and are therefore prepared to enter a message receive state. The activation code transmitted by the encoder will cue the receiver(s) simultaneously thereby allowing the encoder to send a single message to a plurality of receivers. The activation code also allows the encoder to interleave messages to receivers by utilizing the customary transmitter down time in a single message transmission. During this down time, the activation code allows the transmitter to begin transmission of a second message to a second receiver. The use of the activation code to interleave messages is especially important in tone and voice transmissions since it significantly increases the efficiency of a heavily loaded system.

Abstract: An embodiment of a unique ceramic bandstop filter is comprised of a dielectric plate having an input electrode disposed centrally on the top surface thereof and a dielectric block fixedly attached to the bottom surface of the plate and having a hole opposite the input electrode. The dielectric material is preferably a ceramic comprised of BaO, TiO.sub.2 and ZrO.sub.2. The dielectric block is entirely plated with copper or silver except for a portion of the top surface surrounding the hole and is essentially a short-circuited coaxial transmission line. In another embodiment of the unique ceramic bandstop filter, a dielectric block has a hole extending between top and bottom surfaces thereof and an input electrode plated on the top surface near the hole. The dielectric block is entirely plated with copper or silver except for a portion of the top surface surrounding the input electrode and hole.

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: Circuitry for synthesizing a busy or reorder tone comprised of a first tone having a frequency of 770 Hz and a second tone having a frequency of 1150 Hz is described. The inventive synthesizing circuitry requires only one clock oscillator, whose output is coupled to a programmable divider. The programmable divider is switched between two divisor numbers at a frequency that is substantially one-half of a frequency selected from a predetermined range of frequencies substantially midway between 770 Hz and 1150 Hz. In the preferred embodiment, the programmable divider output is switched between frequencies of 1250 Hz and 883.3 Hz at a 500 Hz rate. The programmable divider output is then interrupted at a 2 Hz rate to provide the synthesized busy signal. The inventive synthesizing circuitry may be advantageously utilized in mobile or portable radios for providing a busy signal that sounds essentially identical to a fast busy or reorder tone comprised of two tones.

Abstract: A memory system is used to store data and is powered-up by and only during accessing signals, thus using essentially no current when not being accessed. The memory system includes a decoding network using a mixture of NPN and PNP transistors, and a buffer circuit at the input to a memory cell array allows the use of a minimum number of select lines, having low power requirements.

Abstract: A helical resonator includes a helical coil with one end flared out and folded back over a portion of the cylindrical helix made by the coil to create a winding of opposite pitch superimposed over the cylindrical helix. As an alternative design, a resonator is formed of a helical coil of a first length connected to a helical of opposite pitch. This resonator inhibits a third harmonic resonance but re-resonates around the fourth harmonic. When this resonator is used in combination with a conventional helical resonator, the undesired re-resonances are suppressed.

Abstract: An improved moisture and dust seal assembly is disclosed which is especially suited for application in small hand-held radio apparatus or the like which includes a molded plastic enclosure. A vertical wall is provided on one of the mating members forming the enclosure, such as the cover. The wall has essentially right angle corners and is adapted to receive a standard O-ring thereabout. The assembly is completed by affixing a ribbon-like member, in the form of a closed loop, to the top of the verticle wall. The ribbon-like member extends a predetermined distance beyond the edge of the verticle wall to form a groove-like space for retaining the O-ring. The ribbon-like member may be affixed to the top of the wall by a convenient heat staking operation.

Abstract: The invention is directed to a interdigital filter comprising a plurality of conductive strips positioned in a row and electromagetically coupled to one another. A conductive transmission line is positioned with respect to the row of conductive strips such that the two ends of the transmission line are capacitively coupled to the ungrounded ends of two nonadjacent conductive strips. This arrangement gives the frequency response of the filter a transmission zero. The frequency of the transmission zero can be adjusted by trimming the ends of the conductive transmission line so as to effect the capacitive coupling between the non-adjacent strips.

Abstract: A low profile electrical connector assembly for insertion into a mating socket having a connector body whose pin to lead wire input configuration is non-linear. The connector body includes a nose-like projection which acts to reduce the lateral stress imposed on the connector pins when the assembly is removed from its mating socket by a pulling force exerted on the lead wires.

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: A dual deadman timer circuit functions to reset a dual mode microprocessor in the event of loss of program control. The microprocessor has high and low power requirements corresponding to its two operating modes, and the deadman timer circuit also adjusts the output power level of an associated two-level power supply to ensure that sufficient power is available for the full operation of the microprocessor during reset. The deadman timer functions during both microprocessor modes and includes two level-sensitive input sections to ensure that the microprocessor is reset under an error condition.

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: A signal synchronization system is disclosed which samples an incoming stream containing binary information at a sampling rate which is an integral multiple of the bit information rate. This system correlates the sequences of the sampled bit pattern with a predetermined sequence to produce a measure of the dissimilarity between the sampled and the predetermined sequences. Synchronization of a local sampling clock with the incoming binary information is achieved by making phase adjustments to the local sampling clock which are functions of both the magnitude of dissimilarity and the time of measurement.