Linjie Chen

A Field Programmable Analogue ASIC towards Low Power Processing-on-Node BSNs

Modern microelectronics technologies play important roles in body sensor networks (BSN). In this paper a field programmable analogue ASIC working on the discrete-time mode for biomedical signal filtering was presented. The ASIC we have developed incorporates a switched-capacitor based analogue module, a current source, a voltage source, an oscillator, and a double-phase non-overlapping clock source offering different clock rates. By alternating the circuit topologies and the clock frequencies for the on-chip switched-capacitors the ASIC could be dynamically configured as a high-pass filter or a low-pass filter with adjustable cut-off frequencies and pass-band gains. The ASIC was fabricated using the SMIC 0.18um CMOS technology with a die size of 1.0mm×1.2mm and the power consumption of approximately 1.1 mW. The ASIC was fully tested and the results indicated that the ASIC performed as desired. In the future an autonomous Field Programmable Analogue Array ASIC will be developed towards intelligent processing-on-node BSNs.

Broadband radio spectral observations of the solar eclipse on 2008-08-01 and its implications on the quiet Sun atmospheric model

Based on the joint-observations of the radio broadband spectral emissions of the solar eclipse on August 1, 2008 at Jiuquan (total eclipse) and Huairou (partial eclipse) at the frequencies of 2.00–5.60 GHz (Jiuquan), 2.60–3.80 GHZ (Chinese solar broadband radiospectrometer, SBRS/Huairou), and 5.20–7.60 GHz (SBRS/Huairou), the authors assemble a successive series of broadband spectra with a frequency of 2.60–7.60 GHz to observe the solar eclipse synchronously. This is the first attempt to analyze the solar eclipse radio emission under the two telescopes located at different places with broadband frequencies in the periods of total and partial eclipses. With these analyses, the authorsmade a semiempirical model of the coronal plasma density of the quiet Sun, which can be expressed as ne ≃ 1.42×109(r−2+1.93r−5) (cm−3), in the space range of r=1.039–1.212 R⊙, and made a comparison with the classic model.

The concept of space ultra long wavelength array

Due to the absorption and scattering in the Earths ionosphere, sky radio emission at very long wavelength (ULW) region is inaccessible from the Earth ground. However, the potential scientific discoveries make it greatly attractive to open up this virgin spectral region. In this paper, we propose a space ultra long wavelength pathfinder mission to answer some of the key science questions and open ways to future comprehensive ULW study.

GPU-Based High-performance Imaging for Mingantu Spectral RadioHeliograph

As a dedicated solar radio interferometer, the MingantU SpEctral RadioHeliograph (MUSER) generates massive observational data in the frequency range of 400 MHz -- 15 GHz. High-performance imaging forms a significantly important aspect of MUSERs massive data processing requirements. In this study, we implement a practical high-performance imaging pipeline for MUSER data processing. At first, the specifications of the MUSER are introduced and its imaging requirements are analyzed. Referring to the most commonly used radio astronomy software such as CASA and MIRIAD, we then implement a high-performance imaging pipeline based on the Graphics Processing Unit (GPU) technology with respect to the current operational status of the MUSER. A series of critical algorithms and their pseudo codes, i.e., detection of the solar disk and sky brightness, automatic centering of the solar disk and estimation of the number of iterations for clean algorithms, are proposed in detail. The preliminary experimental results indicate that the proposed imaging approach significantly increases the processing performance of MUSER and generates images with high-quality, which can meet the requirements of the MUSER data processing.

A plan for two-element solar radio spectra-interferemeter

Solar radio observation is still an important, in some situation the unique tool to obtain the solar emission details for solar radio physics study as well as for space weather forecaster. In this paper, based on the existing 2-20m diameter parabolic antenna in Ming-An-Tu Observing Station in Inner Mongolia, a new plan for a meter spectra interferometer is introduced, which will have good performance with high frequency resolution and high dynamic range and sensitivity, and will be working in the frequency band from long meter to decimeter wavelength.

First bust event from CSRH-I

Radio imaging spectroscopy over wide range wavelength in dm/cm-bands will open new windows on solar flares and coronal mass ejections by tracing the radio emissions from accelerated electrons. The Chinese Spectral Radioheliograph (CSRH) with two arrays in 400MHz–2GHz /2–15GHz ranges with 64/532 frequency channels have just been established. We will introduce the progress and current status of CSRH. Some preliminary results of CSRH will be presented.

Calibration and data processing Chinese Spectral Radioheliograph

Radio imaging spectroscopy is in its infancy and will open new observational windows on flares and CMEs, it will also provide coronal magnetograms. It is important to have imaging - spectroscopy over centimetric - decimetric wave range to address fundamental processes in the solar eruptive phenomena. To reach this goal, The Chinese Spectral Radioheliograph (CSRH) project has been funded and construction was completed by the end of 2013. CSRH is a solar-dedicated interferometric array with frequency from 0.4GHz to 15 GHz. There are 40 4.5m antennas with 400MHz to 2 GHz, and 60 2m antennas with 2 GHz to 15 GHz in this telescope. CSRH located at Mingantu station, which is about 400 km away from Beijing in China. CSRH-I and CSRH-II, which include antennas, receivers, and correlators have already been established. Some measurements and experiments have been carried out to test and calibrate the whole system. During the period of test observation, some radio sources were observed including stationary satellite, GPS satellites, Cygnus A, quiet sun and burst and some good images were obtained but still for further calibration and verification. This paper introduces the whole system of CSRH-I briefly, and presents delay measurements, polarization calibration, and some other results of calibration, and data processing for CSRH-I and CSRH -II

Solar physics with Chinese Spectral Radioheliograph

It is important to have imaging - spectroscopy over centimetric-decimetric wave range to address fundamental processes in the solar eruptive phenomena. The Chinese Spectral Radioheliograph (CSRH) is a solar-dedicated interferometric array with frequency from 0.4GHz to 15 GHz. There are 40 antennas with 400MHz to 2 GHz, and 60 antennas with 2 GHz to 15 GHz in this array. CSRH-I and CSRH-II, which include antennas, receivers, and correlators have already been established. This paper introduced the system, progress and current status of CSRH.

CSRH-II analog receiver system stability designing and testing

Analog receiver is one of the key parts of the Chinese Spectral Radioheliograph (CSRH). Analog receiver CSRH-II is used to amplify, transmitting and down converting the solar emission signal from 2GHz to 15GHz. Its system stability is much important for achieving the best quality solar images. CSRH-II system specifications set high requirements for the analog receiver systems stability designing and testing. In this paper, CSRH-II analog receiver system specification requirement, designing and testing will be discussed and presented.

Five-element Digital Corrector Receiver for the Chinese Spectral Radioheliograph

The design of five-element digital receiver system is decribed. At first, we analyzed the process of data processing in the receiver system. Then we wrote programs to implement the FIR parallel filter and showed its simulation results. Finally the testing result of the correlation receiver system is demonstrated.