Xinyue Zhang

Influence of Expendable Current Profiler Probe on Induced Electric Field of Ocean Currents

The expendable current profiler (XCP) is a new instrument that is internationally used to rapidly monitor ocean currents in marine environments. The most crucial part of this instrument is the XCP probe. Since the probe is of high electrical resistance, it acts almost like an insulator with respect to seawater. Placing it into the induced electric field (IEF) of seawater therefore yields a certain level of influence over the electric field. Therefore, in order to improve the accuracy of XCP measurements, the conditions associated with this influence can be used to guide the design of XCP probes; at the same time, these can also serve as reference points in order to provide technical support for the processing of XCP data on ocean currents. To this end, computer-based numerical simulations and laboratory-based physical simulations are used in this study. The results showed that after an XCP probe (diameter: 5 cm; length: 52 cm) was inserted into seawater, the voltage difference of ocean currents at both ends of the electric field sensor placed above the XCP probe increased by a factor of 1.85 (as compared to the case in which there is no influence from the probe).

Expendable Current Profiler for Measuring the Electric Field Induced by Ocean Currents

In this study, an expendable current profiler sensor is developed to satisfy the actual requirements of an expendable current profiler for measuring electric fields induced by ocean currents. The electric field induced by ocean currents is an important process variable for investigating the motion characteristics of ocean currents; however, accurate measurement thereof is affected by various factors. Amplitude modulation is used to modulate the measured signals into narrow-band, single-frequency signals, thereby reducing the noise level of the sensor when measuring the electric field induced by ocean currents and for extracting ocean current signals in the nanovolt range under high background noise. In this study, front-end weak signal processing circuits are designed, strong interfering signals induced by the descent of the expendable current profiler probe are partially offset by a compensation circuit for the in-phase electric field component, and useful signals are extracted using a filter circuit. System on a programmable chip technology is used for the digital processing module of the expendable current profiler probe, thereby achieving rapid development, rapid optimization, and software/hardware integration of the digital processing module, as well as enhancing the overall performance of the system. In addition, dynamic data transmission technology using an enameled wire with a diameter of 0.1 mm and a length of 2 km is developed to achieve dynamic data transmission requirements for the expendable current profiler surface float. Finally, the ocean current electric field data and ocean temperature data are acquired through experiments.

Dual-Polarized On-Chip Antenna for 300 GHz Full-Duplex Communication System

This paper presents a novel design of compact orthogonally polarized on-chip antenna to realize 300 GHz full-duplex communication system with high isolation. It consists of a dipole antenna for horizontal polarization and a disk-loaded monopole antenna for vertical polarization. They are in good cross-polarization state with more than 90 dB of self-interference suppression and then can be used to achieve good isolation between transmitting and receiving antennas. In addition, two dual-polarized antennas have been adopted in two separated transceivers to study their isolation performance. Furthermore, this compact antenna only occupies an active area of 390 μm × 300 μm × 78 μm and can be used for multiple-input multiple-output application as well.

Research and development of ADS1271 based distributed engineering seismic acquisition unit

In order to give more support to the research and development of large geophysical prospecting equipment like seismic prospecting instrument, this paper describes a design based on ADS1271 chip. The design applies to the large-scale cable digital telemetry seismograph and the development of distributed seismic acquisition unit of high precision but low power consumption, which uses high precision A/D conversion and FPGA embedded technology as well as micro-power consumption power source technology. The acquisition unit composes of data acquisition circuit board and FPGA master control circuit board. The acquisition board circuit consists of front end conditioning circuit, amplifying circuit, single-ended signal to differential signal conversion circuit, A/D switching circuit and power switching circuit; in the meanwhile a Cyclone IV E based FPGA master control board has been designed. For software, drive programs are designed for the acquisition board (including driver AD8253 and ADS1271) to achieve the function of data acquisition and the transfer of the acquisition unit.

Research on the multi-channel surface wave data acquisition for seismic exploration based on ADS1258

The technology of surface wave data acquisition acquires the surface wave data efficiently. ADS1258 serves as the AD conversion chip, Altium Designer 9.0 is used as the development tool and the hardware description language (VHDL) is applied to control the application of various hardware modules. The specific design content of the hardware is to connect the original surface wave signals acquired by 16 channels to AD8253 circuit, the software programming is used to control the amplification factor of control signal, and then input the 16-channel signals amplified to ADS1258 AD converter in order to convert the analog signals into digital signals. 3 pieces of ADS1258 are used in the detector, totally 48 channels of data are acquired. Finally, using SPI bus protocol to control the normal work, so that the hardware acquisition board can achieve its optimal working condition.