63results about How to "Large dynamic measuring range" patented technology

This invention is related to an apparatus which incorporates a microfabricated silicon mass flow sensor to measure city gas flow rate in a medium pressure range for utility industry which is dominated by conventional mechanical meters such as turbine and rotary meters. The microfabricated mass flow sensor is so called micro-electro-mechanical systems (a.k.a. MEMS) device. Due to the small feature size of micro scale for MEMS mass flow sensor, the invented apparatus includes many advantages such as low power consumption, compact package, high reliability and extended dynamic measurement range. This apparatus is also provided with a stable flow conditioning to achieve a desired dynamic range capability. Furthermore, because of the high accuracy characteristic, the apparatus in this invention could be applied for custody transfer or tariff in utility industry as well.

The current measuring device comprises a first measuring resistor to receive a measurement current, and a first signal amplifier having an input connected to said first measuring resistor and an output to provide a first measurement signal. A second measuring resistor is connected in series with said first measuring resistor, and first voltage limiting means are connected in parallel on the first measuring resistor to branch a first shunt current off when a first limiting voltage is reached on said first measuring resistor. The value of the first measuring resistor is greater than the value of the second measuring resistor A processing unit comprises one such current measuring device.

The invention discloses a rubidium atomic magnetometer and a magnetic field measuring method. Based on the principle of nonlinear magneto-optic rotation, and through combination of timing control and tracking type frequency locking control, the atomic magnetometer achieves a large dynamic measurement range, high magnetic field sampling rate and high sensitivity. A DSP timing control module controls on-off of an acousto-optic modulator and a radio-frequency signal source in the physical part of the rubidium atomic magnetometer according to timing combination to adjust the magnetic field sampling rate N. The DSP timing control module further controls acquisition triggering of a data acquisition card. A calculation unit gets the Larmor precession frequency (f) through fast Fourier transform with use of a received rubidium atom Larmor precession free relaxation signal, and further calculates the value of an external magnetic field. The calculation unit selects a high magnetic field sampling rate module or a low magnetic field sampling rate module before measurement according to the pre-judged dynamic range of a to-be-measured magnetic field, and sets whether a tracking type frequency locking work mode is used when the low magnetic field sampling rate module is selected. In the working process, data is acquired and processed, and the value of the magnetic field is output.

The invention discloses a signal conversion device for an accelerometer in a strapdown inertial navigation system. An analog current signal output by the accelerometer is converted into an analog voltage signal; the analog voltage signal is subjected to integration by a voltage-to-frequency (V / F) conversion module; one path of analog voltage subjected to integration is output to a pre-amplification circuit, and the other path of analog voltage subjected to integration is converted into a pulse signal and the pulse signal is output to a field programmable gate array (FPGA) processing module; the pre-amplification circuit matches a range of the input analog voltage with an input voltage range of an analog-to-digital (A / D) conversion module; the A / D conversion module converts the analog voltage into a digital value signal and outputs the digital value signal to the FPGA processing module; the FPGA processing module acquires number of pulses output by the V / F conversion module in unit time, the number of the pulses is used as an integer part for calculating the number of pulses, the acquired number of pulses and the digital value signal input by the A / D conversion module are stored in fixed time, and a decimal value of the number of pulses in an acquisition period corresponding to the digital value signal is calculated; and a digital value corresponding to the analog current signal output by the accelerometer is determined according to the integer part and the decimal value of the number of pulses, so that the signal of the accelerometer is converted.

The invention discloses a common-light-path type multiple inclined wave surface compensation nonzero-digit interference measurement device which comprises a Fizeau interferometer, a standard optical flat, a free-form surface gradient compensation module and a free-form surface to be measured. A primary optical axis of the free-form surface gradient compensation module coincides with a primary optical axis of the interference measurement device, a parallel light beam emitted by the Fizeau interferometer passes through the standard optical flat and is divided into two light beams, one light beam is reflected by the surface of the standard optical flat back to the Fizeau interferometer to be used as reference light, the other light beam enters in the free-form surface gradient compensation module and is emitted out of the free-form surface gradient compensation module, and testing light beams with different inclined angles are formed to irradiate the free-form surface to be measured in an incident mode, are reflected by the free-form surface to be measured back to the free-form surface gradient compensation module, finally are emitted out of the free-form surface gradient compensation module and return to the Fizeau interferometer to form test light. According to the test, high-precision measurement on the optical free-form surface large in local gradient and transportability modularization on the measurement device are achieved simultaneously.

The invention discloses a variable diameter microfiber ring based optical micromechanical acceleration sensor and method thereof, which uses diameter variable ring produced by a microfiber with a diameter of 1~25 micron drawed in a standard single-mode fiber by laser heating taper-drawing technique after removing the coated layer of fiber. The microfiber connected with the standard single-mode fiber through a graded taper transition area is disposed as a diameter variable ring, and the two microfiber of microfiber ring crossing are kept axially parallel, one of which is mounted on the movable mass block of sensing acceleration, while another is mounted on the silicon substrate. The input end of the standard single-mode fiber is connected with wide-spectrum light source, the output end is connected with the fiber spectrometer, and the sensing to acceleration is realized by using diameter variable microfiber ring as high-sensitivity sensing member. The invention is capable of improving measurement precision and stability of optical micromechanical acceleration sensor and increasing dynamic measurement range.