Study on the Multi-Sensing System Based on the Tin Oxide pH Electrode

In this study,the multi-sensing system based on the tin oxide pH electrode for the ion-determination was presented. With the advantages of the real-time supervisory control apparatus,the measured values could be displayed on the liquid crystal display (LCD) immediately.In this study,the basic sensor was the tin oxide pH electrode,which was fabricated by radio frequency (r.f.) sputtering system on the indium tin oxide (ITO)/glass substrate.Moreover,the major blocks of the system consist of the tin oxide electrode-based ion selective electrodes (ISEs),an analog front-ended readout circuit,a microcontroller with built-in analog to digital (A/D) converter.In addition,by the embedded system design,the measurement results can be transmitted to a portable system or computer through the Universal Serial Bus (USB) and Universal Asynchronous Receiver Transmitter (UART) interface immediately.According to the experimental results,the multi-sensing system has high performance and reliability for pH,K^+,and Na^+ detection.

Active anti-noise transmitters and receivers

In general, the low-frequency capability of noise reduction of conventional anti-noise transmitters and receivers is not encouraging, but more and more sound energy of the modern high-intensity noise environments concentrates in that frequency range. Active anti-noise transmitters and receivers, which are developed from active ear defenders, supply the devices not only the benefit of advanced low-frequency anti-noise capability, but also a selectivity in sound reduction. The latter virtue ensures a high intelligibility of speech when the low-frequency noise is highly attenuated. On the basis of ref. [1], a thorough discussion on the principles, structures and experimental results of active anti-noise transmitters and receivers are given in this paper.

1.5μm, 8×12.5Gb/s of hybrid-integrated TOSA with isolators and ROSA for 100GbE application

Compact transmitter and receiver optical sub-assemblies（TOSA and ROSA） are fabricated in our laboratory and have an aggregated capacity of 100 Gb/s. Specially, directly modulated laser（DML） drivers with two layers of electrical circuit boards are designed to inject RF signals and bias currents separately. For all the lanes, the3 dB bandwidth of the cascade of the TOSA and ROSA exceeds 9 GHz, which allows the 12.5 Gb/s operation.With the 12.5 Gb/s × 8-lane operation, clear eye diagrams for back-to-back and 30-km amplified transmission with a dispersion compensation fiber are achieved. Low cost and simple processing technology make it possible to realize commercial production.

Design and analysis of an energy-efficient O-QPSK coherent IR-UWB transceiver with a 0.52° RMS phase-noise fractional synthesizer

This paper explores an energy-efficient pulsed ultra-wideband（UWB） radio-frequency（RF） front-end chip fabricated in 0.18-μm CMOS technology, including a transmitter, receiver, and fractional synthesizer. The transmitter adopts a digital offset quadrature phase-shift keying（O-QPSK） modulator and passive direct-phase multiplexing technology, which are energy-and hardware-efficient, to enhance the data rate for a given spectrum.A passive mixer and a capacitor cross-coupled（CCC） source-follower driving amplifier（DA） are also designed for the transmitter to further reduce the low power consumption. For the receiver, a power-aware low-noise amplifier（LNA） and a quadrature mixer are applied. The LNA adopts a CCC boost common-gate amplifier as the input stage, and its current is reused for the second stage to save power. The mixer uses a shared amplification stage for the following passive IQ mixer. Phase noise suppression of the phase-locked loop（PLL） is achieved by utilizing an even-harmonics-nulled series-coupled quadrature oscillator（QVCO） and an in-band noise-aware charge pump（CP） design. The transceiver achieves a measured data rate of 0.8 Gbps with power consumption of 16 m W and31.5 m W for the transmitter and the receiver, respectively. The optimized integrated phase noise of the PLL is0.52° at 4.025 GHz.

Demonstration of a 400 kbps real-time non-line-of-sight laser-based ultraviolet communication system over 500 m

We extend the transmission range of non-line-of-sight ultraviolet communication to 500 m in a real-time system experiment using a 200 mW solid-state 266 nm laser,where the data rate can reach 400 kbps at a frame error rate lower than 10-5 in the real-time system test.The results can beat the best record so far,in terms of both the data rate and transmission distance.

DFT-spread combined with clipping method to reduce the PAPR in VLC-OFDM system

Orthogonal frequency division multiplexing(OFDM) is an attractive technique to realize high data rate in light emitting diodes(LEDs)-based visible light communication(VLC). However, high peak-to-average power ratio(PAPR) of OFDM makes VLC-OFDM very sensitive to the nonlinearity of LEDs. In this paper, the discrete Fourier transform-spread(DFT-spread) combined with clipping method is proposed to reduce the PAPR of OFDM signal in VLC system. Combining simulation with experiment, a performance comparison is made among conventional OFDM, DFT-spread-OFDM, and clipped DFT-spread-OFDM with different clipping ratios(CRs) in a single LED-based VLC system. The experimental results show that the proposed clipped DFT-spread-OFDM method can effectively improve the system performance compared with the other two methods. At the optimum signal peak-to-peak(PTP) value, by using the clipped DFT-spread-OFDM scheme with CR at 8 dB, the bit error rate(BER) of the system can be reduced from 0.003 7 to 0.000 287.

Realization of OFDM modulation and demodulation for visible light communication based on FPGA

In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) are studied in this paper. The time-domain synchronization,frequency synchronization and channel equalization of receiver are analyzed and optimized by utilizing short and long training preamble. Moreover,field programmable gate array(FPGA) development board(Xilinx Kintex-7) and Verilog hardware description language are used to realize the design of proposed OFDM-VLC system. Simulation and experiment both verify the feasibility of the hardware designs of this system. The proposed OFDM-based VLC system can process signal in real-time,which can be used in actual VLC application systems.