Abstract: A method and apparatus for automatic tuning calibration of electronically tuned filters which comprises a programmable frequency generator for producing a calibration frequency signal, a filter for filtering the calibration frequency signal, a detector for producing a detector voltage, a processor for programming the frequency generator to specific test frequencies and for producing a stepped filter tuning voltage and storing the detector voltage in response to the stepped filter tuning voltage, and a converter for digital-to-analog conversion of the stepped filter tuning voltage. Calibration frequency signal versus tuning voltage responses are stored for a number of calibration iterations within the usable range of the filter and the resulting table can be used to determine the correct tuning voltage for the filter when operating at any frequency within the usable filter range.

Abstract: Security is provided for an inside network (14) by a security host (26). Connection request messages sent from source hosts (22) in an outside network (12) are intercepted (94) in the security host (26) and prevented from being transmitted on the inside network (14). The user of the source host (22) then establishes a connection (78) to the security host (26) where a dialog session (80, 98, 100) occurs to confirm the user's authenticity and authorization. After the user is confirmed, the intercepted connection request message is released (116) for transmission on the inside network (14) where the intended application service will respond and a communication session will commence.

Abstract: An automatic vehicle location system (10) includes a radio positioning system receiver (14) which receives GPS radio signals (18) and includes a two-gimbaled gyroscope (22), which is used by a dead-reckoning positioning system. A controller (43) determines position based upon the radio positioning system when the radio signals (18) are available and upon dead-reckoning when the radio signals (18) are not available. The dead-reckoning process is based upon a compensation factor which is established in response to data received from the radio positioning system (14). The compensation factor acts as an adjustment to an inner gimbal angle to compensate for a minor drift away from level by the inner gimbal (32).

Abstract: A dielectric resonator image reject mixer and method comprises an amplifier for amplifying a receive frequency (RF) signal and outputting a first combined signal comprising a RF signal, a RF noise signal, and an image noise signal. A dielectric resonator image rejector is coupled to the amplifier. The dielectric resonator image rejector receives the first combined signal but outputs only a second combined signal comprising the RF signal and the RF noise signal to a mixer coupled to the dielectric resonator image rejector. The image noise signal is rejected by either reflection or resonant transmission to a resistor-terminated microstrip line. A mixer mixes the combined RF signal and the RF noise signal from the dielectric resonator image rejector with a local oscillation frequency signal, producing an intermediate frequency output signal.

Abstract: A cellular communication network (10) and method operates at frequencies above 2 GHz and achieves widespread coverage within a cell (14) by adapting routing channels, symbol rates, and FEC coding processes (78) to current RF broadcast conditions. A portion of subscriber nodes (16) act as repeaters for a base node (12). If subscriber nodes (16) cannot directly communicate with the base node (12), their communications may be indirectly routed to the base node (12) through one or more repeating subscriber nodes (16'). If current conditions do not support a high data rate, then lower data rates are supported by selection of FEC coding processes (78). If increasingly inclusive FEC coding does not achieve a data rate supportable by current conditions, slower symbol rates may be used. Communications at slower symbol rates may utilize narrower frequency bands thus keeping wider frequency bands available for higher speed usage.

Abstract: A bit stream unpacking circuit (10) parses data fields from a serial bitstream as an initial step in decompression. The protocol of the incoming packed data stream is stored in a control ROM (24). As each packed data field arrives, the control ROM provides size and condition instructions (18) to parse out the fields from the serial data stream and store the fields in data storage (14) for later retrieval. The size instruction determines the length of the field in the incoming data. A counter (26) counts clock signals of the incoming serial bitstream and matches the count with the size instruction to determine when a data field has arrived. The condition instruction determines the next address in the control ROM based on the incoming bitstream. Once the incoming message has been parse out and stored, the individual data field may be read directly from the data storage for decompression.

Abstract: A method and apparatus for power combining or dividing handles high impedance line requirements in n-way combiners (15) and dividers (10) using phase delay networks (12, 14) to transform impedances to a lower, intermediate impedance. Each impedance transformation is accomplished using a stepped impedance or tapered impedance transmission line (26). The method and apparatus provides isolation between input or output ports (11, 22 and 24, 13) in power combining or dividing circuits using an incremental phase delay network (12) of prescribed electrical phase lengths (22, 24) to provide phase cancellation. The power divider (10) and combiner (15) can be used in power amplifiers and in communication devices.

Abstract: A voltage controlled oscillator that completely eliminates the need for any externally mounted coil and capacitor, and an automatic fine tuning circuit for television which is inexpensive and highly accurate are provided.A first loop and a second loop are provided, said first loop for band-limiting an output signal of an amplifier through a bandpass filter to provide oscillation at a frequency of a resonant point of the bandpass filter, and said second loop for controlling the oscillation amplitude, so that a lowpass filter output with a 90.degree. phase is extracted from the first loop, while a bandpass filter output with a 0.degree. phase is extracted from the second loop.

Abstract: A low profile hermetic electrical connector includes a conductive layer with opposite first and second conductive layer surfaces. An inner electrical isolation layer is coupled between the first conductive layer surface and a first contact and an outer electrical isolation layer is coupled between the second conductive layer surface and a second contact. A contact interconnector electrically couples the first contact and the second contact through the inner electrical isolation layer, the conductive layer, and the outer electrical isolation layer without electrically contacting the conductive layer, creating a serpentine, low flow path for vapor through the adhesive layers. In a hermetic electrical cable end connector, the first contact is electrically coupled to a first conductor through a first interconnector and a second contact is electrically coupled to a second conductor through a second interconnector. Two additional electrical isolation layers are required.

Abstract: A sample circuit (10) maintains linear operation over frequency. A switchable diode bridge (12) passes the analog input signal when enabled to one terminal of a sample storage capacitor (14). The second terminal of the capacitor is coupled through a closed FET switch (16) to a reference node (18). Once the analog input signal is stored across the capacitor, the FET switch opens before the diode bridge disables. When the second terminal of the capacitor floats and prevents any further charge from altering the sample voltage across the capacitor. When the diode bridge is disabled, the sample voltage across the capacitor does not change. The sample voltage may be amplified and digitized for further processing in the cellular system.

Abstract: An impedance transforming power divider/combiner includes a first transmission line (60) with a first terminal (65) and N transmission line fingers (65, 66, 68, 70) terminating in N transmission line finger ends. N transmission lines (28, 38, 48, 58) having N first and second ends are positioned in close proximity to the N transmission line fingers (65, 66, 68, 70) in one-to-one correspondences. The N second ends of the N transmission lines (28, 38, 48, 58) are coupled through N individual impedances (20, 30, 40, 50) to N terminals (25, 35, 45, 55). If signal power is provided to the first terminal (64), the signal power is divided into N signal power outputs at the N terminals (25, 35, 45, 55). If signal power is provided to the N terminals (25, 35, 45, 55), a combined signal power results at the first terminal (65).

Abstract: A multilateration location system (12) includes a locatable unit (16) and any number of known-position locators (14). A time of arrival detector (22) determines instants in time when a location signal (20) transmitted by the locatable unit (16) arrives at various known-position locators (14). For each combination of two known-position locators (14) that receive the location signal (20), a pre-estimation process (32) determines whether the difference in arrival times is less than or equal to a maximum propagation duration for the locator pair. The maximum propagation duration is based upon the distance between the locators (14) in the locator pair. If the difference is greater than the maximum propagation duration, the difference is omitted from the data set processed by a multilateration calculation process (34). A post estimation filtering process (36) screens out location estimates that are too distant from a predicted position.

Abstract: A master control station (10) includes a common antenna (12) which drives two, unsynchronized multi-channel GPS receivers (16, 18). The two receivers (16, 18) couple to a controller (24). The controller (24) commands the receivers (16, 18) to identify all GPS satellites in view, and then assigns (48) satellites to various channels in the receivers (16, 18). The assignment includes at least one common satellite between the two receivers. Location data are obtained from the two receivers for the common satellite and used to normalize (66) all pseudorange data from all channels to compensate for the lack of synchronization between the two receivers (16, 18). Differential GPS location resolution (84) may then occur using the normalized data.

Abstract: An arithmetic engine includes a first dual multiplier accumulator (MAC) for receiving input data and for producing first dual MAC output data. A second dual MAC is coupled in parallel to the first dual MAC. The second dual MAC receives the input data and produces second dual MAC output data. An adder array is coupled to both the first dual MAC and to the second dual MAC. The adder array receives the input data, the first dual MAC output data, and the second dual MAC output data and produces arithmetic engine output data. Each dual MAC comprises a multiplier cross point switch, multiplier registers, a register selector, and parallel multipliers. Each adder array comprises a cross point switch, adder registers, a register selector, adder, and condition code determiner.

Abstract: A Global Positioning System (GPS) communications includes a GPS receiver for generating position information, a processor coupled to the GPS receiver by a bus, and a communications multi-interface coupled to both the GPS receiver and to the processor by the bus. The processor presents the position information to the communications multi-interface capable of interfacing with a wide variety of communications systems. Described applications include guided weapons systems, interrogatable tag systems, collision avoidance systems, remote locator/responder systems, beacon location systems, search and rescue transceiver systems, location reporting pager systems, and cellular telephone location systems.

Abstract: A MMIC FET mixer and method includes a RF input port for receiving a RF signal, a feedback control input for receiving a feedback signal, and a LO input port for receiving a LO signal. A feedback controller is coupled to the RF amplifier, the feedback controller for producing a controlled RF signal in response to the feedback signal. A constant current source is coupled to the feedback controller, to the RF amplifier and to the LO input port. The constant current source receives a DC offset voltage, the controlled RF signal, and the LO signal and produces an IF output signal at an IF output port. The IF output signal is proportional to the DC offset voltage, to the RF signal, and to the LO signal.

Abstract: A non-intrusive mounting system and method for coupling microwave instruments to a container flange having an opening into a container. The mounting system includes a microwave transparent window and a mounting flange having a window recess for accommodating the microwave transparent window. The microwave transparent window is compressively fastened over the container opening between the mounting flange and the container flange. Microwave instruments such as radar level sensing apparatus can be mounted on and removed from the mounting flange without breaking the seal to the container.

Abstract: A transmitter (12) broadcasts a PN encoded message (16). A receiver (14) includes a SAW correlator (38) configured to autocorrelate with the PN sequence used in the broadcast signal. A preamble of the message (16) conveys two successive bits (18) that are each encoded with the PN sequence. After the correlator (38) has been preloaded with the PN sequence from the first bit (18), its non-correlation output exhibits reduced amplitude time sidelobes. A timing comparison circuit (60) compares a correlation signal (46) with a timing threshold (72). The timing threshold (72) is established at a very low level to minimize the influence of multipath. False triggering on noise is prevented by disabling the timing comparison circuit (60) until after the first bit (18). At this point in time the correlator (38) has been preloaded with its PN sequence, is again being loaded with its PN sequence, and outputs reduced amplitude time sidelobes.

Abstract: A transmission line filter includes first and second substantially parallel transmission lines (20, 30), with alternate ends grounded and each transmission line (20, 30) coupled through a separate capacitor (50, 60) to electrical ground. A coupling capacitor (70) connects the first and second transmission lines (20, 30). A RF output (40) coupled to the second transmission line (30) outputs a filtered RF signal in response to a RF signal input to a RF input (10) on the first transmission line (20). MIC and MMIC applications using series capacitance to allow for line length to be reduced include versions of a band pass filter (FIGS. 5, 6), band stop filter (FIG. 7), and low pass filter (FIG. 9).

Abstract: A method and apparatus for a probeable substrate substitute for a calibration standard and test fixture. The probestrate includes a dielectric substrate having first and second dielectric substrate surfaces and at least one conductive via hole through the dielectric substrate from the first dielectric substrate surface to the second dielectric substrate surface. A first metalized layer is in contact with the first dielectric substrate surface and the at least one conductive via hole. A second metalized layer is in contact with a first portion of the second dielectric substrate surface and with the at least one conductive via hole. The first and second test ports contact a second portion of the second dielectric substrate surface. An electronic device can be connected to the first and second test ports with bond wires for characterization via contact of the first and second test ports with standard test station equipment.