Abstract: The present invention describes a bias generator (10) which supplies a temperature stabilizing bias current (72) to a main circuit (90). The bias generator (10) comprises a measurement unit (20) having a similar structure and temperature characteristic as the main circuit (90). Measurement unit (20) supplies a temperature dependent measurement signal (27). A temperature invariant element (40) supplies a temperature independent reference signal (47). These signals (27, 47) are compared in a differential amplifier (30) which controls variable current sources (50, 60, 70). The variable current sources (50, 60) supply the measurement unit (20), the temperature invariant element (40) and the bias current (72) for the main circuit (90) itself. A negative feedback is produced which results in a stabilized transconductance of the main circuit (90). Therefore, the bias current (72) which determines all other currents and the speed of the main circuit (90) is automatically adjusted to the needs.

Abstract: In a method for controlling an electric motor the stator voltage frequency of the motor is determined by adding the optimal slip frequency of the motor and the desired rotational frequency of the rotor. The magnitude of the stator voltage is determined by subtracting the actual rotational frequency and the desired rotational frequency of the rotor. The desired stator frequency and magnitude are inputted into a pulse width modulation unit which controls an inverter to supply the appropriate voltages to the motor. The operation of the motor with optimal slip has the advantage that the efficiency is optimal independent of the load.

Abstract: A circuit (100) comprises a built-in test circuit (150) which verifies the proper operation of input cells (130) when they receive signals at a first level (71) and at a second level (72). The test circuit (160) comprises a first and a second logic (110, 120) which receive power only when a test is performed. Thereby power consumption of the test circuit (160) is reduced. The first and the second logic (110, 120) are conveniently formed by a combination of parallel coupled transistors acting in an logical OR-function.

Abstract: Oscillation of the output (16, 17) of an integrated circuit output buffer (43) is automatically damped by sensing ground lead (18) transients as the buffer output (16, 17) changes, and when the ground lead (18) swing is large enough, using the sensed change to apply a turn-off signal of the appropriate polarity to a transistor (N1) serially placed in the output buffer (43) to add resistance during the transition. The added resistance damps out the oscillations quickly to prevent rebound of the buffer output voltage past the logic transition threshold (Vol). An RC time constant (R1, C1) controls the duration of the added resistance which disappears after the transition is complete. The action of a damping control circuit (45) is speed dependent so that greater damping is provided for fast transitions when oscillations would be more sever and no damping during slow transitions when damping is not needed.

Abstract: A two-way radio having a receiver (20) for receiving a radio signal including a voice message, a storage element (45) coupled to the receiver for storing the voice message received, a voice input device (49) for inputting voice messages, a user-actuable selection input (15) for receiving a user input to change between a transmit mode and a repeat mode and a transmitter (21) selectively coupled to the storage element and the voice input device for selectively transmitting input voice messages when in the transmit mode and retransmitting the stored voice message when in the repeat mode. A detection circuit (47) detects the radio signal and a control circuit (50) coupled to the receiver, the transmitter and the detection circuit operates in the repeat mode for activating the transmitter (21) to retransmit the voice message when the detection circuit (47) detects that the radio signal ends.

Abstract: An amplifier controller (104) is described for operating from a single voltage power supply (105). A switch (103) is coupled between the amplifier (102) and the power supply (105). The controller (104) includes a power conditioning circuit (106) for generating doubled and tripled voltages and positive and negative voltages for operating the controller (104) and the amplifier (102). Internal voltage regulators (138, 142) control the magnitude of the generated voltages. The controller (104) further includes: (i) a circuit (172) for disabling the controller (104) and amplifier (102) in response to an idle signal presented thereto, (ii) a circuit (178) for energizing the switch in response to a turn-on signal (128) so that the amplifier (102) can amplify, and (iii) a circuit (176) for sensing the presence or absence of negative polarity (Vss) on a second lead (188) of the amplifier (102) and, if not present, disabling the switch (103) despite the presence of the turn-on signal.

Abstract: A constellation of satellites which are distributed around the earth serves as a communications infrastructure that supports autonomous position determination and reporting of that position to a remote location. Satellites continuously broadcast acquisition signals. Position determining units are remotely programmed to activate upon the occurrence of an activation event. If PDUs can capture an acquisition signal, then they engage in activities which lead to determining their position and they coordinate their communications with the requirements of the communications infrastructure. To determine position, a location pulse may be transmitted on a regular schedule. The location pulse is transported between a fast moving satellite and a PDU. The movement of the satellite causes different location pulses to have different propagation delays and Doppler characteristics. By analyzing changes in propagation delays and Doppler characteristics, a procedure determines a position for a PDU.

Abstract: A bidirectional communication system for communicating signals between a master device (1) and a slave device (2) connected by a single wire (3), in which the master device (1) includes a voltage signal generator (4) for generating voltage signals to be transmitted to the slave device (2) over the wire (3), a current sensor (6) for sensing current consumed on the wire (3), and a received signal generator (14, 19) for generating received signals corresponding to the sensed current consumption. The slave device (2) includes a receiver (7) for receiving the voltage signals transmitted over the wire and producing received data therefrom, and a current consuming device (8) for consuming current from the wire (3) in correspondence with a signal to be transmitted to the master device (1).

Abstract: A full duplex radio having improved properties is obtained by using asymmetric surface acoustic wave (SAW) filters, the filters are composed of series and parallel coupled SAW resonators. Asymmetry is obtained by covering either of the series or parallel resonators of each filter with a dielectric layer to increase the SAW coupling coefficient of the covered resonators relative to the uncovered resonators. The filters are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts of the frequency response are adjacent. Greater pass-bandwidths can be obtained without adverse affect on transmitter and receiver isolation.

Abstract: A band-gap voltage reference (39) has a regulator portion (70) providing a substantially constant current of predetermined magnitude Ic and a band-gap reference portion (72) receiving Ic. The reference portion (72) has a first branch including a first transistor (52) of a first type serially coupled to a second transistor (55) of a second type, a second branch including a third transistor (53) of the first type serially coupled to a fourth transistor (56) of the second type, the first and second branches forming a current mirror (73) carrying a total current of about Ic/2, and a third branch (57) in parallel with the first and second branches and carrying a current of substantially Ic-Ic/2. Base current (65) in the first two branches is compensated by base current (64) of the third branch.

Abstract: A communication and position locating system (2) suitable for air traffic control is described. Multiple satellites (40) are provided in two geosynchronous constellations. One constellation (e.g., 4 satellites) has a first closed ground track (14). The other (e.g., 2 satellites (161, 182)) has a different ground track (18) or is geostationary, located outside of the first ground track (14). Geolocation information is transmitted by the satellites (40) to aircraft (28) and ground stations (26) so that aircraft (28) can determine their current position. A pseudo range correction map is provided to the aircraft (28) by the base stations (26) to permit differential geolocation measurements. The satellites (40) include communication transceivers (80) so that aircraft (28) can communicate voice and data to other aircraft (28) and to the ground stations (26, 30, 32) and automatically report their position to air traffic control centers (30), e.g., via the satellites (40).

Abstract: A method for managing resource usage within a cellular communications system (10) having at least one satellite (12) and, capable of communicating with the satellite(s) (12), at least one controlling station (28) and multiple ground terminals (26). The controlling station (28) predicts (372, 380) system communication traffic and operating capabilities for a future period; generates (216) a system plan (250) and an individual operational plan (270-30n) for each satellite (12) based on the prediction; distributes (222) each individual operational plan (270-30n) to each corresponding satellite (12); monitors (226) execution of the system plan (250) during the future period to determine (228) whether the plan is operating acceptably and when the plan is not operating acceptably (228), generates (216) a new plan, or portion thereof, to alleviate the unacceptable operation; and repeats the foregoing steps for additional future periods.

Abstract: A shock tolerant fuze includes a detector for determining when fuze timing should be initiated, a movable safe and arm assembly containing a time delay circuit and a firing aperture. The firing train detonator is preferably also mounted on the movable armature. When the fuze is armed, the time delay circuit is coupled to the detector and to the detonator, and the aperture provides a pathway between the output of the detonator and the remainder of explosive firing train of the weapon. Electrical energy storage is provided on the armature for powering the time delay circuit and the detonator in the event that primary power thereto is interrupted by impact. By including the time delay circuit and energy storage on the movable armature, a very shock tolerant fuze is obtained.

Abstract: A tester for multiple types of radios has a first group of generic test elements common to all types of radios to be tested and second groups of test elements specific to each one of the multiple types of radios. Each of the second groups of test elements is mounted within a pluggable module for insertion into the tester where it couples to a common bus accessed by all of the other test elements and by the controlling computer. Each pluggable module contains a specific identifier which, when accessed by the controlling computer initiates a stored program which causes the computer, via the bus, to couple the various test elements into a configuration required to test the radio type associated with that identifier. The system is very compact and conveniently uses a lap top computer as the controlling element.

Abstract: A radio subscriber communication unit maintains an annunciation memory which stores a repertoire of annunciations. When the subscriber unit receives annunciation data messages from a communication network, a particular one of the annunciations is selected and presented to the user of the subscriber unit. An audible segment of the annunciation is passed through a vocoder, amplified, and routed to a speaker for presentation to the user. When annunciations are repeated, a second message may be received to instruct subscriber unit to cease presenting an annunciation.

Abstract: A location system relies upon a non-coherent, FDM/TDM communication scheme to measure location parameters. A locator unit moves relative to the locatable unit. A series of messages are communicated between the locator unit and the locatable unit. Through feedback provided from the locator unit to the locatable unit, the locatable unit adjusts its reference frequency and time base so that signals it transmits arrive at the locator unit on a desired frequency and at a desired time slot. The locatable unit estimates Doppler and propagation duration and transmits the estimates to the locator unit. The locator unit measures offsets between desired frequencies and time slots and actual frequencies and time slots. The offsets are combined with the locatable unit's estimates of Doppler and propagation duration to form an integrated Doppler parameter and an integrated propagation duration parameter. The integrated Doppler and propagation duration are used to determine location.

Abstract: A radio telecommunication system includes a number of satellites in low earth orbits. Any number of subscriber units communicates with the satellites. A single subscriber unit communicates with a single satellite using electromagnetic signals so that a measurement processor can obtain Doppler component, propagation duration, and real time measurements of the signals. A location processor converts these measurements into a geographic location with respect to the earth. A service processor determines which qualifications to apply to communication services offered by the system. These qualifications are based on the subscriber unit's location. A call processor carries out the qualifications when requests to setup calls involving the subscriber unit are received by the system and during calls involving the subscriber unit.

Abstract: A cellular communications network includes satellites which project cells toward the earth. The satellites and cells move relative to the earth. When a call is being set up to a subscriber unit, data describing the subscriber unit's location are sent to a switching office of the network. The switching office generates a schedule which forecasts when movement of the cells will cause the subscriber unit to cross cell boundaries. During an ongoing call, the subscriber unit 5 determines when scheduled boundary crossings occur. So long as an adequate signal is present in a scheduled cell and network capacity exists in the scheduled cell to handle the call, the call will be handed off to the scheduled cell. The subscriber unit also monitors signal strengths to determine when a traffic channel's signal is getting weak and when an alternate cell's signal is stronger.

Abstract: A multichip electronic module comprising a base for holding various components and a lid for sealing the module, is temporarily closed by a reworkable seal made from a thermoplastic material. The seal is hermetic so that the module can be tested under ambient conditions approximating actual use. If the module fails the functional test, the lid is easily removed for repair. The thermoplastic material is located in a special grove near the periphery of the base or lid next to the mating surfaces which form part of a final seal for the module. After a module has been repaired, the lid is finally soldered or welded to the base using portions of these mating surfaces which are free of the thermoplastic material. There is no need to remove the thermoplastic material used for the temporary seal.

Abstract: A non-linear active device (32), such as a FET, multiplies multiplicand signals to generate a product signal. A combining circuit (24) combines multiplicand signals into a combined signal. An input matching and conditioning network (28) couples the combined signal to an input of the active device (32). This network (28) matches impedances between sources for the multiplicand signals and the active device (32) at the frequencies of the multiplicand signals, and desirably shorts the product signal's frequencies. A feedback resistor (36) couples between the output and input of the active device (32) to lower impedance at the output and to stabilize the active device (32). An output matching and conditioning network (40) couples a mixed signal from the output of the active device to an output circuit (42). This network (40) matches impedances between the output circuit (42) and the active device (32) at the frequencies of the product signal, and desirably shorts the multiplicand signals' frequencies.