Abstract: A channel priority encoder in a mobile/repeater unit of a two-way communications system allows a low power, detached unit to remotely select a desired channel for high power repeater transmission to and reception from a base station. The selection can be latched-in permanently or can be made to revert to a home channel after a delay. The mobile unit can override a channel selection made by the detached unit, but another mobile unit would provide the repeater function.

Abstract: A circuit for checking a plurality of impedances having a common connection point as for use in an emergency medical ratio, where the impedance of each ECG electrode contact is automatically and sequentially checked during the initial calibration transmission, using the AC non-polarizing signal which is also used as the ECG subcarrier for the medical data telemetry. The ECG telemetry calibration signal is also processed to provide a sequential switching control. Poor electrode contacts are indicated visually to the paramedic in charge and thus can be corrected before ECG telemetry begins.

Abstract: A connecting and latching mechanism in an electronic apparatus is activated by a portion of the housing of a complementary electronic device as it is inserted for interconnection and charging. Varying sizes of devices can be accommodated. Three rotatable elements, two pawls and a connector arm, are mounted on a single base plate. One pawl keeps the connector arm from being damaged before device insertion and helps position the device upon insertion. A connector block on the connector arm is rotated into position for contacting the terminals of the device by a second portion of the device housing. When the connector block is in full contact with the terminals, the connector arm is latched by another pawl. A lock must be deactivated by key or manually operated button to release the latching pawl, the connector arm and the inserted device. Rotatable charging contacts provide scouring motion at the contact points and also accommodate devices of varying lengths.

Abstract: An extendable half-wave dipole is capacitively coupled to a driven resonant helical antenna for use as on a hand-held, two-way portable radio, the helix being end fed. The dipole may be mounted adjacent to or collinear with the axis of the helix. The collinear mounting requires non-conductive portions on each end of the dipole. Optimum dimensional and performance characteristics are available without switching.

Abstract: A modular console system for housing display devices, panel-mounted apparatus, storage facilities, writing surfaces and the like comprises interchangeable parts which can be assembled or replaced on site. The writing surfaces are added or removed from the front and are cantilevered from a V-shaped structural member without occupying otherwise useful space.

Abstract: A multivibrator utilizing two split inverter pairs of MOSFETS and requiring a supply voltage less than the sum of the threshold voltages of the complementary P-N channel devices. The transconductances of each pair are balanced to provide temperature compensation. MOS capacitors can also be utilized. Good frequency stability and low current drain are inherent in the design.

Abstract: A base station encoder is connected to a decoder terminal and paging transmitter by means of a single voice-pair telephone line link. Automatic operations reduce operator fatigue and operating costs. Digital, tone-keyed gain controls automatically compensate for line losses. All dialing, including long distance and overseas calls, and station identification are done automatically.

Abstract: Group call capability is provided as for a digital pager having a two word page address and using asynchronous detection. A group call is initiated by transmitting two identical binary words having an extra bit space between them, the binary word being word one of the individual paging address of each unit in the group to be called.

Abstract: An isolator for ultra-high frequencies provides a broadband characteristic by simulating a carved-out copper block with stacked copper laminates. Internal structures are formed by photolithographic processing of the copper sheets. Ferrite elements and a unilateralizing resistor are captivated within the stack of sheets which provides inductance, capacitance and optimal ground return paths, as well as heat sinking for the resistor. No external matching network or tuning is required.

Abstract: An acoustic telephone coupler for use in transmitting medical data over telephone lines and adapts to accommodate any telephone handset configuration. The slim coupler base further functions as a spool for a lengthy cable, and a dual purpose strap alternatively retains the cable and cable connector on the spool or a telephone handset against the transducers of the coupler.

Abstract: A console for charging a portable communications device and converting it for mobile operation can accommodate portable units of varying lengths. The contacts for the charging current are positioned by the insertion of a portable unit by means of a unique reel mechanism. Interconnection and latching are also activated by the insertion of the portable unit. The converter connector serves as a part of the latching and locking apparatus which makes the unattended portable essentially theft proof.

Abstract: A standard format keyboard provides a paralleled, binary-coded output corresponding to an alphanumeric character or a function when the appropriate key head is depressed. A signal is coupled through the key mechanism to a set of parallel conductors which are positioned to be approached by a portion of the key mechanism. The conductors have minimum or maximum areas corresponding to binary zeros and ones, whereby the level of signal coupled also corresponds to a binary code (such as ASCII) for the character or function key depressed.

Abstract: A variable control, such as for a gain or frequency control, having a delay period and switching function at each end point, with status or level indication, is comprised of two simple switches and appropriate logic circuitry. While a first switch is closed the gain would be reduced, at a predetermined rate, to a minimum point and held there for a brief interval during which a warning tone may be sounded. If the switch is still closed at the end of the interval, an auxiliary function is enabled. When a second switch is closed, the auxiliary function is disenabled and gain increases at the predetermined rate. If the second switch is kept closed until maximum gain is reached and beyond, the warning tone is sounded for an interval, then a different function is enabled. The unit will remain in that mode until the first switch is again closed. Still another function may be enabled by simultaneous closing of both switches. A visual status readout can be activated whenever either switch is closed.

Abstract: DC programmable counters with DC switching provide instant retuning of an entire keyboard of a programmable electronic musical instrument to any one of a plurality of different scales.

Abstract: An improved data terminal utilizing tactile switch assemblies with specialized sound apertures provide reduced panel space requirements and indirect sound paths for miniature electronic apparatus. A maximum number of switches can be accommodated on the instrument panel with no separate speaker/microphone grille required. Non-aligned sound apertures provide maximal weather protection for speaker and microphone mounted behind the switch assembly panel. The switch assembly design seals off the remainder of the unit from weather or dust damage.

Abstract: A wide bandwidth characteristic is provided for use as in a negative feedback amplifier by a deposited resistor arrangement. The arrangement includes a basic feedback resistor having a high resistance value and a narrow elongated shape. Closely positioned on the same substrate and physically parallel are one or more low value resistors having the same length and with adjacent points on the respective resistors being at the same electrical potential. The feedback capacitance is greatly reduced by the extra length. The capacity to ground, and thus the displacement current, is essentially eliminated since most of the stray capacitance is between points of equal potential.

Abstract: A symmetrical duty cycle waveform at twice the input frequency is provided for use as in a programmable tone generator by a quad two-input integrated circuit device using two RC delay circuits. By varying the delay circuits, two separate clock pulses with different duty cycles can be provided at the original clock frequency.

Abstract: An improved mounting arrangement and method of assembly provides for mounting parts on both chassis and board, then mating the two before soldering by means of a twist-tab-and-slot arrangement. The conformation and dimensions of the tab and slot prevent warpage during soldering, enabling the use of the chassis as a board carrier in the wave soldering process.

Abstract: Unusually long life and reliability in a selector switch are achieved by providing long-wearing components which, in turn, contribute to an essentially dust-free environment for the contact portions of the switch. Materials of all parts produce a minimum of abrasion dust and the conformation of the housing structure prevents the entry of exterior dust. A binary coded cam having multiple cam sections causes sliding contact between spring type contact elements and shorting bars. The rotary element and the two main housing portions are molded of a highly wear resistant, low friction material. The detent mechanism is separated from the contact elements and the metal housing clamp locks the housing portions in the mated position, and helps to seal the housing against exterior dust. All components provide maximum life expectancy and low wear properties.

Abstract: A chassis for supporting a printed circuit board and other components is captivated between two plastic housing portions in a suspension mode. The housing provides support for the entire unit, there being no direct support to the chassis or printed circuit board or associated components. The chassis is formed with projecting tabs which are captivated between bosses formed on the upper and lower parts of the housing. A screw penetrates the boss of the upper portion and the chassis tab, then threads into the boss of the lower portion. Wedge bosses formed in the back walls of the housing bias the chassis into alignment with the rear of the housing when the housing parts meet and provide support to the chassis when interconnecting cables are attached. No individual components, other than the speaker, are fixed to either housing part.