Abstract: A digitally controlled PLL oscillation circuit has a VCO, a frequency divider, a reference oscillation circuit, an A/D converter, a phase comparator, a digital filter, a D/A converter, and an analog filter. A reference signal supplied from the reference oscillation circuit is output through a narrow-band crystal filter (MCF) to the A/D converter to cancel noise, jitter and a spurious wave included in the reference signal, making it possible to prevent the phase noise characteristic and spurious characteristic of a VCO output from being degraded.

Abstract: An object of the present invention provides a frequency synthesizer having a broad frequency entraining range which can finely set a frequency over a broad band by a novel principle. As s specific solving means, a sinusoidal signal of an output frequency of a voltage-controlled oscillator is subjected to orthogonal detection, a vector rotating at the differential frequency (speed) between the output frequency and the frequency of the frequency signal used for the detection is created, and the frequency of a vector when the output frequency of the voltage-controlled oscillator is equal to a set value is calculated in advance. The voltage signal corresponding to the difference between the frequency of the vector and the calculated frequency is fed back to the voltage-controlled oscillator when the voltage-controlled oscillator is driven, and PLL is formed so that the difference is equal to zero.

Abstract: An object of the present invention is to perform measuring work easily when detecting the presence or absence of an object to be measured or the concentration thereof using a plurality of quartz sensors equipped with a Langevin type quartz resonator. As a concrete means for solving the problem, a quartz sensor 3 equipped with a quartz resonator 30 forming an adsorbing layer to adsorb a target component to be measured on one surface side and coming into contact with an airtight space on the other surface side is installed in a printed circuit board 4 via a base 5. A plurality of quartz sensors 3 is detachably installed respectively in a plurality of connecting terminal units provided in a horizontal arrangement on a side surface 21 of the measuring device main unit 2 via a connecting terminal unit 41 formed on an end of the printed circuit board 4 in a state that the above-described adsorbing layer faces upward.

Abstract: Disclosed is a frequency synthesizer capable of preventing occurrence of a frequency shift upon occurrence of a change in the level of an input to an A/D converter by preventing PLL control from being properly operated. The frequency synthesizer includes a carrier remove, an inverse rotational vector multiplier, a phase time difference detector, an adder, a phase difference accumulator, a loop filter, a parameter output part, an amplitude information detector, a filter, and a multiplier configured by an FPGA. Unlock detection means monitors the value of amplitude information detected by the amplitude information detector. When the value lies within a proper range, a lock (synchronization) process is performed under PLL control, whereas when the value is off the proper range, an unlock state in PLL control is detected.

Abstract: An object of the present invention is to provide a sensing instrument capable to detect a substance existing in a very small quantity, such as environmental pollutants, instantly with a high degree of precision. As a specific means for solving the problem, a frequency signal from a crystal oscillator is sampled using a frequency signal from a reference clock generating part, the sampling value is outputted in a digital signal, quadrature detection is conducted with the digital signal for a frequency signal corresponding to the output signal, the rotational vector rotating at a frequency corresponding to the difference between the frequency of the frequency signal and the frequency of a sinusoidal wave used for the quadrature detection is taken out, and the variation of the frequency is detected by detecting the velocity of the rotational vector based on the respective sampling values.

Abstract: It has been difficult that conventional PLL circuits have a suppression characteristic of suppressing the phase noise which is free of variation due to temperature and individual difference and stable in a wide frequency band. The present invention provides a PLL circuit which can absorb variation of phase noise characteristic due to temperature and individual difference and has a phase noise suppression characteristic stable in a wide frequency band.

Abstract: An object of the present invention is to provide a sensing instrument capable to detect a substance existing in a very small quantity, such as environmental pollutants, instantly with a high degree of precision. As a specific means for solving the problem, a frequency signal from a crystal oscillator is sampled using a frequency signal from a reference clock generating part, the sampling value is outputted in a digital signal, quadrature detection is conducted with the digital signal for a frequency signal corresponding to the output signal, the rotational vector rotating at a frequency corresponding to the difference between the frequency of the frequency signal and the frequency of a sinusoidal wave used for the quadrature detection is taken out, and the variation of the frequency is detected by detecting the velocity of the rotational vector based on the respective sampling values.

Abstract: An object of the present invention is to perform measuring work easily when detecting the presence or absence of an object to be measured or the concentration thereof using a plurality of quartz sensors equipped with a Langevin type quartz resonator. As a concrete means for solving the problem, a quartz sensor 3 equipped with a quartz resonator 30 forming an adsorbing layer to adsorb a target component to be measured on one surface side and coming into contact with an airtight space on the other surface side is installed in a printed circuit board 4 via a base 5. A plurality of quartz sensors 3 is detachably installed respectively in a plurality of connecting terminal units provided in a horizontal arrangement on a side surface 21 of the measuring device main unit 2 via a connecting terminal unit 41 formed on an end of the printed circuit board 4 in a state that the above-described adsorbing layer faces upward.

Abstract: A digitally controlled PLL oscillation circuit has a VCO, a frequency divider, a reference oscillation circuit, an A/D converter, a phase comparator, a digital filter, a D/A converter, and an analog filter. A reference signal supplied from the reference oscillation circuit is output through a narrow-band crystal filter (MCF) to the A/D converter to cancel noise, jitter and a spurious wave included in the reference signal, making it possible to prevent the phase noise characteristic and spurious characteristic of a VCO output from being degraded.

Abstract: Disclosed is a frequency synthesizer capable of preventing occurrence of a frequency shift upon occurrence of a change in the level of an input to an A/D converter by preventing PLL control from being properly operated. The frequency synthesizer includes a carrier remove, an inverse rotational vector multiplier, a phase time difference detector, an adder, a phase difference accumulator, a loop filter, a parameter output part, an amplitude information detector, a filter, and a multiplier configured by an FPGA. Unlock detection means monitors the value of amplitude information detected by the amplitude information detector. When the value lies within a proper range, a lock (synchronization) process is performed under PLL control, whereas when the value is off the proper range, an unlock state in PLL control is detected.

Abstract: An object of the present invention is to provide a sensing instrument capable to detect a substance existing in a very small quantity, such as environmental pollutants, instantly with a high degree of precision. As a specific means for solving the problem, a frequency signal from a crystal oscillator is sampled using a frequency signal from a reference clock generating part, the sampling value is outputted in a digital signal, quadrature detection is conducted with the digital signal for a frequency signal corresponding to the output signal, the rotational vector rotating at a frequency corresponding to the difference between the frequency of the frequency signal and the frequency of a sinusoidal wave used for the quadrature detection is taken out, and the variation of the frequency is detected by detecting the velocity of the rotational vector based on the respective sampling values.