Abstract: A quadri-filar helical antenna structure includes a cylindrical body having a relative dielectric constant greater than 4, and four radial metal plates on a distal end of the cylindrical body, and each radial metal plate is extended along the cylindrical body. The ends of every two adjacent radial metal plates are connected to form two antenna structures, and a circuit board is fixed. A ground surface is installed on one side of the circuit board and coupled to one of the antennas. An impedance matching circuit is installed on another side of the circuit board, and one end of the impedance matching circuit is coupled to another antenna. A feeder is installed at another end of the impedance matching circuit. Four radial metal plates having an electric length about odd multiples of a quarter of wavelength of the cylindrical body can receive satellite signals.

Abstract: The method and apparatus in accordance with the present invention provides signal-to-noise ratio improvement through noise reduction by means of spectral averaging and subcarrier based averaging techniques.

Abstract: A quadri-filar helical antenna structure includes a cylindrical body having a relative dielectric constant greater than 4, and four radial metal plates on a distal end of the cylindrical body, and each radial metal plate is extended along the cylindrical body. The ends of every two adjacent radial metal plates are connected to form two antenna structures, and a circuit board is fixed. A ground surface is installed on one side of the circuit board and coupled to one of the antennas. An impedance matching circuit is installed on another side of the circuit board, and one end of the impedance matching circuit is coupled to another antenna. A feeder is installed at another end of the impedance matching circuit. Four radial metal plates having an electric length about odd multiples of a quarter of wavelength of the cylindrical body can receive satellite signals.

Abstract: The present invention discloses a quadri-filar helix antenna structure, which comprises a cylindrical body made of a dielectric material with a relative dielectric constant ?r greater than 4, and four radiating metal plates disposed on a distal end surface of the cylindrical body and extended along the radial direction of the center of the cylindrical body to its periphery and then along the radial direction in a spiral course on the circumferential surface thereof to its periphery on the other end respectively, wherein the ends of every two adjacent radiating metal plates are coupled with each other to constitute two sets of antenna structures, a penetrating hole is disposed at the central position of the cylindrical body and is precisely embedded into a coaxial cable, and a shield cable disposed at the periphery on one end of the coaxial cable is coupled to an end of another set of antenna structure. Therefore, the antenna not only reduces the overall volume, but also greatly lowers its production costs.

Abstract: A quadrature amplitude modulation implementation incorporating a symmetric spherical quadrature amplitude modulation constellation. The symmetric spherical quadrature amplitude constellation, as displayed in a multi-dimensional complex plane, is bounded by a surface comprising all symbol points at a predetermined distance from a center point and coincident with the intersection of at least two axes, and exhibiting correspondence in relative position of the symbol points on opposite sides of the at least two axes.

Abstract: The present invention discloses an improved initialization method for modem communication wherein the timing offset required for synchronization is estimated utilizing an entire received DMT frame and the channel impulse response is estimated utilizing the pilot tones received within the same DMT frames utilized for synchronization.

Abstract: A recording and/or reproducing device (1) includes at least one tape guide (10) having a guide wall (13) and guide flanges (14, 15) projecting beyond the guide wall (13). The guide wall and guide flanges are coated with a coating (21) of zirconium nitride or titanium nitride. This results in the tape guide having a high wear resistance and a high resistance to the deposition of material abraded from the tape.

Abstract: An improved per-tone FEQ method with a noise reduction technique using periodic training pilot tones increases the throughput for long-reached modems. This method can reduce the noise effects in estimating FEQ equalizer coefficients. Each per-tone FEQ can be estimated by using the periodic training signals and an averaging technique to remove noise from each sub-channel (EQN. VI). After solving the system equations (EQN. IV), per-tone equalization coefficients of the FEQ equalizer for each group can be combined to obtain the optimized results in the form of the Toeplitz matrix (EQN. V). Each element within the Toeplitz matrix can be derived from the averaging technique used to remove noise from each sub-channel (EQN. VI). To demodulate a signal with the Toeplitz matrix, an inverse of every element in a row of the Toeplitz matrix is taken and multiplied by the sending signal which creates an N Log N matrix.

Abstract: A transfer system that supports circuit boards as it conveys them through a reflow oven. The system uses a sag support between edge supports. The sag support does not have to move as the circuit board is transferred along the transfer system. The height of the sag support can be easily adjusted. The sag support's mounts can maintain appropriate tension in the sag support even if the sag support expands during operation. The system may use a mechanism to prevent the friction between the boards and the sag support from interfering with the movement of boards along the transfer system.

Abstract: A segmented squeegee blade is provided for optimizing the flow of a depositable material such as viscous liquid or flowable medium such as solder paste, adhesive, or the like through a stepped stencil onto a substrate. The blade has a plurality of segments adapted for substantially independent deflection with respect to each other. The blade segments deflect and conform to a stepped surface or stencil to provide for more consistent deposition of flowable material. The squeegee blade also is adapted for use with stencils having more than two step levels. The segmented squeegee blade enables component density to be increased as compared to conventional methods.

Abstract: Galvanic corrosion of the fuel sender immersed in the corrosive fuel mixture is minimized by supplying the sender with current that periodically switches polarity. The switching rate is selected to prevent or greatly minimize irreversible oxidation buildup. The vehicle body computer responds to current flow through the sender without regard to the alternating polarity drive signal. The switched polarity sender module can thus be employed without necessitating modification of the sender or body computer components.

Abstract: The motor drive circuit has an instrumentation amplifier with a programmable gain set by selectively blowing fuses during initial circuit calibration. The quasi-sawtooth waveform of a relaxation oscillator is compared with the amplified and conditioned signal produced by a pressure responsive Wheatstone bridge circuit. The result of this comparison is a drive signal which controls the pump motor speed. Radio frequency interference is minimized by storing the motor drive current in a capacitor located near the motor. Further interference is minimized by a reactive matching circuit which combines with the motor impedance to result in a purely resistive load.

Abstract: Corrosion of the fuel tank float device by electrolysis is minimized by driving the fuel level sender with short duty cycle pulses instead of a continuous current. While the fuel level sender is energized by a pulse, the analog sample and hold circuit obtains a reading from which fuel level can be determined. A synchronizing circuit controls the sequence in which the fuel level sender is energized and the reading taken, to insure that readings are taken during steady state conditions. An impedance matching circuit compensates for nonlinearities of the fuel level gauge. The impedance matching circuit includes a pair of precision resistors and a voltage multiplier circuit. The impedance matching circuit allows the moving coil fuel level gauge to be energized in a fashion which simulates a continuous current flowing between fuel level sender and gauge.

Abstract: The circuit senses abrupt change in motion of an electromotively-driven part such as the onset of valve seating in a solenoid-operated valve. A constant current source supplies power to the solenoid coil and a pulse detector circuit monitors the voltage across the coil and determines the time rate of change of that voltage. A change in the algebraic sign of the time rate of change in voltage indicates that valve seating has occurred.

Abstract: The power door lock interlock circuit senses the presence of an ignition key in the ignition and also senses when a door is open. When these conditions are met, the power door lock is placed in an interlock condition whereby pressing the power door lock button causes the horn to sound instead of locking the doors. The circuit is thus useful in preventing the driver from accidentally leaving the ignition key in the ignition and accidentally locking all doors. All doors may be unlocked in the usual fashion and all doors may be locked in the usual fashion provided the interlock condition has not been met.

Abstract: The airflow sensor uses a flow sensing bridge having a thermal element which senses airflow as a function of electrical energy applied to the bridge. Energy is applied to the bridge to maintain the thermal element at a constant temperature and constant resistance. A differential amplifier monitors the balanced and unbalanced state of the bridge and controls the application of energy to the bridge to maintain a balanced state. A microcomputer with analog to digital converter senses the level of energy applied to the bridge and converts this energy level to a digital signal indicative of airflow. The raw digital signal is corrected using calibration lookup tables and thermal compensation correction tables in the microcomputer memory circuits. The microcomputer outputs a variable frequency signal indicative of the measured mass airflow. In the alternative to the differential amplifier, the bridge may be balanced using the microcomputer in a sample and hold voltage to current converter configuration.

Abstract: The power door lock interlock circuit senses the presence of an ignition key in the ignition and also senses when a door is open. When these conditions are met, the power door lock is placed in an interlock condition whereby pressing the power door lock button causes the horn to sound instead of locking the doors. The circuit is thus useful in preventing the driver from accidentally leaving the ignition key in the ignition and accidentally locking all doors. All doors may be unlocked in the usual fashion and all doors may be locked in the usual fashion provided the interlock condition has not been met.

Abstract: The programmable telephone screening device routes an incoming call to a selected telephone device, depending on preestablished device priorities and upon access codes dialed by the caller. The device provides call hold, call forwarding and automatic dialing and is capable of testing the telephone utility network to determine DTMF and pulse dialing compatability. The device generates ringer signals for directly energizing the ringer circuits of standard telephone devices.