Abstract: An FSK demodulator is provided comprising means for receiving and digitizing an FSK signal (such as a signal comprising two frequencies f1 and f2 in which first and second logic states are represented by first and second periods of different durations). First, second, third and fourth consecutive transitions of the signal are identified and the times of said transitions are identified. A first period between the first and third transitions is calculated, as is a second period between the second and fourth transitions. A change of frequency in the signal is indicated when the first and second periods lie on opposite sides of a first threshold period (.tau.) and no change of frequency is indicated when the first and second periods lie on the same side of the threshold period (.tau.). In a further aspect of the invention, a transition is rejected as illegal when two consecutive transitions occur within a predetermined period of time.

Abstract: A selective call receiver displays messages in at least two scripts. The selective call receiver receives data including an address and a message to be displayed. A decoder decodes the data and recognizes a script select character therewithin. A memory stores at least two fonts corresponding to said at least two scripts, said scripts having different resolutions. A microcomputer is coupled to the decoder and the memory for selecting one of the fonts in response to the script select character, and a display is coupled to the microcomputer for displaying the message in the selected font.

Abstract: Errors in a predetermined digital sequence are detected by utilizing a detector which includes memory elements such as a series shift register, and logic gates for detecting a predetermined subsequence. Errors are detected by comparing each bit in the data stream with the output of the memory. Logic gates inhibit the detection of an error in response to the subsequence detection.

Abstract: A central controller operating as a pager terminal for receiving, handling, and transmitting messages is shown that adaptively alters its message handling characteristics in order to improve the overall throughput of the central controller. The channel loading characteristics, based upon the time of day, are used in order to vary the limitation of the size of message received by the central controller as well as vary the transmission size and age of messages prior to transmission. Additionally, channel loading may be determined by determining the total size of messages within the central controller. In response to the total size determination, the limitation of the message size received by the controller may be varied. Furthermore, the transmission size and age of messages prior to transmission may be varied in response to the total size determination.

Abstract: Accelerated throughput of voice messages is accomplished by first filtering a normal 50-3000 Hz voice signal to a reduced bandwidth 350-1650 Hz (with loss of identifying features), the reduced signal then accelerated X3 and translated downward to bandwidth 50-3950 Hz for transmission. The receiver recovers the 350-1650 Hz signal.

Abstract: A method for generating alphanumeric messages in a telephone-entry selective call system comprises programmable selective call source identification for selected selective call receivers and numerically coded canned alphanumeric messages.

Abstract: A light guide is optically coupled to a light source and engagingly positioned between a liquid crystal display and a printed circuit board for both damping vibrations from and backlighting the liquid crystal display.

Abstract: A single purpose robot arm end effector having a ring shaped frame positioned around the periphery thereof with a plurality of extendable drivers mounted in the frame for movement between a nonfunctioning position and an operative position. Each of said drivers can be tooled up for unique or dedicated applications so that the arm will be performing many different functions during most of a manufacturing cycle, instead of only performing one function for a short period of time during the manufacturing cycle.

Abstract: This ejector mechanism supplies a force to remove an assembly of printed circuit boards (PCB's) from an enclosure. Each PCB in the assembly is electrically connected by a projecting rear portion of the PCB which engages a multiple contact connector attached to the enclosure. The friction associated with such engagement resists sliding the PCB assembly to disengage the connector. In an embodiment, a U-shaped lever is pivotally mounted to the assembly and applies a distributed force through each leg which is substantially adjacent each PCB. This provides force application substantially in the place of each PCB, thereby maximizing the desired force and minimizing undesired torque on each PCB.

Abstract: An antenna is disclosed for increasing the gain of, or shaping the pattern of, a radiated radio frequency signal. The antenna includes a waveguide for directing the radio frequency signal or for receiving directively the radio signal, a first conductive reflector disposed beneath the waveguide and extending beyond the aperture of the waveguide for reflecting certain of the waves emanating from or entering the aperture of the waveguide, and a second reflector, which may be the mounting surface, disposed beneath the first reflector and extending beyond the first reflector for reflecting other of the waves emanating from or entering the aperture of the waveguide.

Abstract: A high speed CMOS divide by 4/5 prescaler circuit comprises first, second, third, fourth, and fifth inverter stages. When a modulas control signal is low, the prescaler operates as five clocked inverters in series having an output which is fed back to the input of the initial stage. That is, the circuit operates as a five stage clocked ring oscillator wherein only one output changes on each clock edge. When a modulas control signal is high indicating that a divide by four is desired, the counter operates as a five stage ring oscillator for seven clock edges. On the eighth edge, feed forward circuitry forces the last three stages to change states simultaneously.

Abstract: A selective call radio receiving system includes first and second receiving means (10 and 10') each having a memory (20 and 20') therein. Paging messages are received by both the first and second receiving means in accordance with their message receiving capabilities, including factors such as: range, memory size, and position relative to the radio frequency transmitter. The contents of the first and second memories (20, 20') are periodically compared (16 or 16') to determine whether a paging message has been missed. In this way, an individual has the best opportunity to receive each paging message transmitted to him.

Abstract: An encased electronic component comprises a casing (10) for protecting the component while exposing electrodes (or terminations) thereof for soldering. The casing includes an aperture for allowing air internal of the casing to exhaust upon heating during soldering so as to oppose the ingress of foreign material into the casing.

Abstract: A switching system operated from switching areas in a housing of an electronic device includes first and second sets of ambient light sensors and switch sensing means secured in the housing. An ambient sensing circuit and averaging circuit means connects to the first set of light sensors to produce a reference signal representing an average ambient light reaching the first set. A shielding sensing circuit means couples to the second set of light sensors to produce a switch sensing signal in response to an operator shielding ambient light therefrom. A comparison means coupled to the averaging and shielding sensing signal and the reference signal to provide an output after a predetermined delay; and a switch connected to said comparison means performs at least one switching function in response to the output from the comparison means.

Abstract: A selective call personal paging radio receiver has audio and visual means to alert the user when he or she receives a selective call transmission. The audio alerting means has low and high volume modes and a three position slide switch selects either the low volume, high volume, or power OFF modes. The switch also has an integral momentary contact push switch function. When the switch is moved from the OFF position to either the low or high volume mode and the push switch function is activated within a first predetermined time after the switch is moved and maintained activated for a second predetermined time, a distinctive alert sequence is generated and then the silent alert mode is entered. In the silent alert mode, the audio alerting means is disabled and the visual alerting means remains active.

Abstract: A data limiter for a radio pager is described in which an analog input signal including a data signal is compared in a comparator with a threshold voltage which is adjusted by means of a feedback network. The network consists of transconductance amplifiers having predetermined input offset voltages related to the amplitude of the analog signal which monitor the departure of the analog signal from a reference voltage to provide output currents which are integrated by an integrator and applied as the threshold voltage to the comparator and as the reference voltage to the transconductance amplifiers.