Nihon Dempa Kogyo Co., Ltd.

Nihon Dempa Kogyo, Ltd.

Naoki Onishi

Shunichi Wakamatsu

Hiroki Kimura

Yasuo Kitayama

Tsukasa Kobata

Tsuyoshi Shiobara

Nobuo Tsukamoto

Hiroyuki Kukita

Hiroyuki Demura

Tomoya Yorita

Kaoru Kobayashi

Shoichi Tsuchiya

An angular error detecting device detects an angular error in a receiving direction of a frequency signal from a tracking target with respect to a front direction of an antenna based on a phase difference of a first reception signal received at a first receiving unit of the antenna and a second reception signal received at a second receiving unit having a receiving position in the antenna different from a receiving position of the first receiving unit. The angular error detecting device includes a reception signal output unit, a pilot signal supply unit, a pilot phase difference detection unit, a correction unit, and an angular error detection unit. The angular error detection unit detects the angular error based on the one side corrected at the correction unit and the other side that is not corrected of the sum signal and the difference signal.

Angular error detecting device

A signal processing device includes a plurality of converters, a generator, a distributor, a first line, and a second line. A plurality of converters is configured to convert analog signals to digital signals based on a clock signal to output the digital signals. The generator is configured to generate the clock signal based on a reference signal. The distributor is configured to distribute a generated clock signal to the plurality of converters. The first line passes through only a region assigned to each of the plurality of converters to supply the analog signal to the converter. The second line passes through only the region to supply a distributed clock signal to the converter.

Signal processing device

An oscillator includes an oscillator circuit, a crystal filter, a package portion, and a heating portion. The oscillator circuit is configured to output an oscillation signal. The crystal filter has a frequency characteristic where an attenuation at a detuned frequency is larger than an attenuation at an oscillation frequency of the oscillation signal. The detuned frequency is a frequency different from the oscillation frequency. The package portion covers a crystal blank of the oscillator circuit and a crystal blank of the crystal filter. The heating portion is configured to heat the crystal blank of the oscillator circuit and the crystal blank of the crystal filter using a resistor disposed between: a wiring board to which the package portion is secured, and the package portion.

Oscillator

To provide, in a frequency synthesizer including: a variable attenuator provided at a subsequent stage of a voltage controlled oscillator; a detector; and a control unit outputting a control voltage for adjusting an attenuation amount of the variable attenuator via a digital/analog converter in accordance with a detection voltage, a technology with which a spurious due to a change in an output of the digital/analog converter can be suppressed. A low-pass filter is provided between an output side of a digital/analog converter and a variable attenuator to cut a frequency component corresponding to an overshoot generated when an output of the digital/analog converter is changed. Further, a period of time from when a control unit outputs a control voltage to when it reads a signal level detected by a detector is set to a period of time longer than a time constant of the low-pass filter determined by a cut-off frequency of the low-pass filter so that no influence is exerted on an operation of automatically controlling the signal level.

Signal level adjusting device and high-frequency apparatus

A rubidium oscillator or a cesium oscillator is used as a high stability oscillator, and an OCXO being a metastable oscillator which is inferior in a long-term frequency stability compared with the above oscillators but has a high short-term frequency stability is used as a backup. There is prepared a table in which an elapsed time since an occurrence of an abnormality in the high stability oscillator and weighting (use ratio) of use of the both oscillators is corresponded, and by using this table, after the high stability oscillator recovers, an oscillation frequency of the metastable oscillator is used by 100% initially, but thereafter the weighting (use ratio) of use of the metastable oscillator is made smaller and the use ratio of the high stability oscillator is made larger in stages.

Reference signal oscillator

The provision of a technique capable of determining a state where PLL control does not operate normally instantly or in advance in a frequency synthesizer that frequency-divides, A/D converts, and quadranture-detects a frequency signal from a voltage controlled oscillating unit, and extracts a rotation vector rotating at a frequency difference between the frequency signal used for the detection and the A/D converted frequency signal, and integrates a difference between a frequency of the above rotation vector and a set frequency to set an integration result as a control voltage to the voltage controlled oscillating unit. The control voltage to be input to the voltage controlled oscillating unit is monitored, and it is determined whether or not a level of the monitored control voltage deviates from a set range determined in advance, and an unlock detection signal is output. In a structure in which the rotation vector is multiplied by a reverse rotation vector reversely rotating at a frequency determined in rough increments according to the set frequency to reduce a velocity of the rotation vector, a determination result whether or not a length of the rotation vector whose velocity is reduced (a scalar quantity) or a correction signal for gain control deviates from a range set in advance is further considered.

Frequency synthesizer

A frequency synthesizer in which a satisfactory frequency stability can be obtained over the entire long period of service immediately after power activation is disclosed. The reference signal generation circuit includes an OCXO, a TCXO, weight converters which regulate weights with respect to outputs, and an adder which adds up the outputs from the weight converters to output the added output as a reference signal. The CPU controls weight converters B and C so that the weight of the TCXO is set to 100% and the weight of the OCXO is set to 0% at the time of the power activation, so that the weight of the OCXO gradually rises, and so that the weight of the TCXO is set to 0% and the weight of the OCXO is set to 100% after preset time, whereby the frequency can quickly be stabilized after the power activation.

Provided is a PLL circuit improving reliability while suppressing power consumption without degrading noise characteristics. The PLL circuit includes a PLL IC that divides an output frequency Fout from a VCO, compares phase with a reference signal, and feeds back a phase difference as a control voltage to the VCO. A control circuit is capable of finely setting both of a reference frequency Fref and an output frequency Fdds in a DDS circuit, and the DDS circuit generates folding signals of Fdds for Fref and an integral multiple frequency thereof based on the combination of the frequencies. A first AMP amplifies a signal, a variable filter selects a desired Fdds (desired) and a second AMP amplifies the signal and supplies the same to the PLL IC as a reference signal. The control circuit further supplies a division ratio N to the PLL IC.

PLL circuit

In a sensing instrument using a quartz sensor on whose front surface an adsorption layer for adsorbing a substance to be sensed is formed and which changes in natural frequency by the adsorption of the substance to be sensed, the present invention has an object to quickly detect a trouble of the quartz sensor to prevent an operator from recognizing an incorrect measurement result. In the present invention, a level detecting circuit detecting a signal level of an oscillation output of an oscillator circuit is provided, and after the time for stabilization passes after the power-on time, a computer takes a level detection value therein to compare the signal level and a threshold value. Then, when the signal level is lower than the threshold value, the signal level is determined as abnormal and, for example, the abnormality notification is displayed on a display unit, whereby an operator is notified of the occurrence of the abnormality.

Sensing instrument

In adopting a structure in which an oscillator circuit unit and an instrument main body including a measuring unit are separately formed in a sensing instrument measuring the concentration of or determining the presence/absence of a substance to be sensed by using a quartz sensor, the present invention has an object to enable the instrument main body side to know an oscillation frequency of the connected oscillator circuit unit. A plurality of band-pass filters having pass characteristics corresponding to oscillation frequencies of the oscillator circuits respectively are provided in the instrument main body side to sort frequency signals, it is determined whether or not levels of the sorted frequency signals are equal to or higher than a threshold value, and a switching unit is controlled so as to connect a channel having a signal level equal to or higher than the threshold value to the measuring unit, and a reference frequency used in the measuring unit, for instance, is selected according to the frequency of the frequency signal corresponding to this channel.

A VCO driving circuit and a frequency synthesizer wherein the impedance viewed from a VCO control terminal is reduced to prevent the VCO phase noise characteristic from degrading. A VCO driving circuit and a frequency synthesizer having the VCO driving circuit, which comprises a coarse adjustment DAC that receives a digital data, which has a coarse adjustment frequency, to output an analog signal; a fine adjustment DAC that receives a digital data, which has a fine adjustment frequency, to output an analog signal; a low response speed LPFthat removes noise from the output signal from the coarse adjustment DAC and then provides the resultant signal as an input to a VCO control terminal; a high response speed LPFthat converts the output signal from the fine adjustment DAC to a voltage, thereby smoothing the signal; a resistor that connects an input stage of the LPFto that of the LPF; and a capacitor used for providing a capacitive coupling such that the output of the LPFis added to that of the LPF

VCO driving circuit and frequency synthesizer

Provided is an oscillation frequency control circuit for correcting its frequency, keeping the oscillation frequency stable when self-oscillating, and oscillating with a control voltage generated by making a fixed voltage given from outside variable. In the oscillation frequency control circuit, a CPU selects/outputs the control voltage preferentially according to a command of a control voltage selection. If the command is not given and the level of an outside reference signal detected by a detecting circuit is within an adequate range, it turns a select switch on. If the command is not given and the level of the outside reference signal is out of the adequate range, it turns the select switch off and outputs information about pulse generation stored in a memory to a PWM circuit.

Oscillation frequency control circuit

Provided is a PLL apparatus realizing extremely high frequency stability. As a concrete means for solving the problem, an A/D (analog/digital) conversion unit samples a standard signal based on 40 MHz frequency signal, which is a rectangular wave, from an oven controlled crystal oscillator (OCXO), and an orthogonal transformation unit applies orthogonal transformation to a digital signal from the A/D conversion unit to extract a real part (I) and an imaginary part (Q) which are complex expression of a phase vector equivalent to a phase difference between the standard signal and the frequency signal from the OCXO. An angular velocity of this vector is detected and a direct-current voltage according to the angular velocity is generated and supplied to the OCXO via a PWM control unit.

Growing community of inventors

Sayama, Japan

Naoki Onishi