A system for providing traffic information to a plurality of mobile users connected to a network. The system comprises a plurality of traffic monitors, each comprising at least a traffic detector and a transmitter, the traffic detector generating a signal in response to vehicular traffic and the transmitter transmitting the signal. A receiver receives the signals from the traffic monitors. A computer system is connected to the receiver and is further connected to the network. The computer system in response to a request signal received from one of the users transmits in response thereto information representative of the signals transmitted by the traffic monitoring units. Alternative systems for gathering traffic information are disclosed.

System for providing traffic information

A surface-mount crystal oscillator includes a crystal unit housing and an element housing which is provided on the base side of the crystal unit housing. A crystal blank is accommodated and hermetically sealed in the crystal unit housing. A concavity having an open side is formed in the element housing, and an IC chip is secured to the bottom surface of the concavity by means of face-down bonding. Notch portions or recess portions which are adjoining and connecting to the concavity and which are used for injecting fluid resin are formed in the frame portion at the periphery of the concavity. Fluid resin is injected to the bottom surface of the concavity by way of the notch portions and cured to form a protective resin layer of the IC chip.

Surface mount crystal oscillator

An integrated circuit comprises a microelectromechanical (MEMS) resonator circuit that generates a reference frequency. A temperature sensor senses a temperature of the integrated circuit. Memory stores calibration parameters and selects at least one of the calibration parameters as a function of the sensed temperature. A phase locked loop module receives the reference signal, comprises a feedback loop having a feedback loop parameter and selectively adjusts the feedback loop parameter based on the at least one of the calibration parameters.

Crystal oscillator emulator

A method and apparatus for real time clock brownout detection. A low power real time clock (RTC) operates continuously to keep time in a global positioning system (GPS) receiver while some receiver components are powered down. In various embodiments, a brownout detector circuit detects a loss of RTC clock cycles. If a loss of RTC clock cycles exceeds a predetermined threshold such that the RTC is not reliable for GPS navigation, an RTC status signal so indicates.

Method and apparatus for real time clock (rtc) brownout detection

A surface mount crystal oscillator comprises a crystal blank, an IC chip having an oscillation circuit integrated thereon, and a hermetic package for accommodating the crystal blank and IC chip therein. The hermetic package comprises a substantially rectangular ceramic substrate formed with a metal film which makes a round on one main surface thereof, and a concave metal cover having an open end face bonded to the metal film. The IC chip is secured to the one main surface of the ceramic substrate through ultrasonic thermo-compression bonding using bumps, the crystal blank is disposed above the IC chip, and the ceramic substrate has the one main surface formed as a flat surface.

Surface mount type crystal oscillator

A digital temperature-compensated oscillator comprises a crystal oscillator, a first memory previously storing digital temperature compensation data obtained by previously measuring the relation between the ambient temperatures and the frequency deviations of the crystal oscillator, a second memory for storing frequency offset amounts of the oscillation frequency of the crystal oscillator, a temperature sensor for outputting analog detection data relating to the ambient temperature, an A/D converter for converting the analog detection data to digital detection data, a readout circuit for reading out temperature compensation data corresponding to the digital detection data and stored in the first memory according to the digital detection data and reading out the frequency offset amount stored in the second memory according to the digital detection data, an operation circuit for effecting the following calculation by use of the readout temperature compensation data and readout frequency offset amount to derive digital control voltage, V.sub.c =V.sub.co +(K.sub.00 +V.sub.co K.sub.10 +K.sub.01 T)×(ΔF+ΔF 2 ×K 10 /2) where K 00 , K 01 and K 10 are constants, V co is an initial value of the control voltage, T is an ambient temperature and ΔF is a frequency offset amount, a D/A converter for converting the digital control voltage into an analog control voltage, and a voltage-capacitance converter for receiving the analog control voltage and generating a control signal to be supplied to the crystal oscillator according to the received analog control voltage, wherein the frequency of the crystal oscillator is controlled according to the control signal.

Digital temperature-compensated oscillator

A temperature-compensated crystal oscillator (TCXO) comprises a voltage-controlled crystal oscillator (VCXO) having a crystal unit, a compensating voltage generator for generating a compensating voltage applied to the voltage-controlled crystal oscillator, a low pass filter inserted between the compensating voltage generator and voltage-controlled crystal oscillator, and a switching element connected in parallel with the low pass filter for short-circuiting across the low pass filter. In a manufacturing process of the temperature-compensated crystal oscillator, switching element is brought into a conducting state when an excitation electrode of the crystal unit is irradiated with an ion beam for adjusting the oscillation frequency.

Temperature-compensated crystal oscillator

A digital temperture compensation oscillator for digitally compensating a variation in oscillation frequency due to temperatures, by applying a compensation voltage to a voltage controlled oscillator, comprises temperature detection means, A/D conversion means, memory means, operation means and D/A conversion means. The temperature detection means detects temperatures when the voltage controlled oscillator is operated, and generates a temperature signal. The A/D conversion means receives the temperature signal, digitizes the temperature signal, and generates digital temperature data. The memory means stores compensation data corresponding to the compensation voltage as difference data at corresponding addresses. The difference data includes, when N-stage level difference data (N=a positive integer) are utilized, predetermined reference values of 0th difference data to (N-1)-th difference data of the compensation data and all N-th difference data. The operation means receives the digital temperature data and the difference data, and generates the compensation data on the basis of the difference data in response to the digital temperature data. The D/A conversion means receives the compensation data, converts the compensation data into an analog compensation voltage, and supplies the analog compensation voltage to the voltage controlled oscillator.

Digital temperature compensation oscillator

PROBLEM TO BE SOLVED: To provide a surface-mounting temperature-compensated oscillator which prevents frequency variation by improving temperature compensating operation at start-up SOLUTION: A surface-mounting temperature-compensated crystal oscillator 1 is configured by integrally housing an IC chip in which an oscillation circuit and a temperature compensating mechanism 2 are integrated, and a crystal piece in which a drawing electrode extends from an exciting electrode to both side of one end portion, in a container body made of ceramics The temperature compensating mechanism 2 includes a temperature sensor 2a for detecting at least an ambient temperature, a temperature compensation voltage is generated based on the temperature detected by the temperature sensor 2a, and the temperature compensation voltage is applied to a voltage variable capacitance element 5 in an oscillation closed loop In such a surface-mounting temperature-compensated crystal oscillator 1, a compensation error component in the temperature compensation voltage, caused by heating in starting the IC chip, based on a differential temperature between the detected temperature of the temperature sensor 2a and an operating temperature of the crystal piece is predicted and a start-up correction voltage for correcting the compensation error component is applied to the voltage variable capacitance element 5 COPYRIGHT: (C)2009,JPO&INPIT

Surface-mounting temperature-compensated crystal oscillator

A temperature-compensated crystal oscillator for surface mounting wherein an IC chip into which is integrated a temperature-compensated device having an oscillating circuit and a temperature sensor, which supplies a compensation voltage to a variable-voltage capacitor element of the oscillating circuit, and which also has IC terminals disposed along two edges comprising at least diagonally opposite corner portions of one main surface that acts as a circuit function surface is affixed with the use of bumps to an inner base surface of a main container that is concave in section, and one edge portion of a crystal piece is affixed to an inner wall step portion of the main container; wherein an active element of the oscillating circuit that acts as a heat source and a temperature sensor of the temperature-compensated device are disposed at diagonally opposite corner regions of the IC chip at the greatest distance apart. In addition, IC terminals for thermal dissipation are provided in a central region of the IC chip. The present invention provides a temperature-compensated oscillator for surface mounting in which the temperature-compensation operation at startup is satisfactory and frequency stability is maintained.

Kuichi Kubo

Papers

Digital temperature-compensated oscillator

Temperature-compensated crystal oscillator

Digital temperature compensation oscillator

Surface-mounting temperature-compensated crystal oscillator

Surface mount type temperature-compensated crystal oscillator