This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feed...This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feedback loop and to solve the problem of phase ambiguity,the tracking performance of the algorithm has been improved greatly. Only a few preambles are needed in the al-gorithm since the preambles are not used to estimate the frequency offset but used to provide the variation information of the phase due to the presence of frequency offset. Simulations verify that the algorithm has low SNR bound for tracking as well as high tracking accuracy and the tracking range is expanded to 30% of one subcarrier spacing.展开更多
We proposed an optical 4-ary frequency shift keying （FSK） modulation scheme applying dual-parallel Mach-Zehnder （MZ） modulator. The 4-ary FSK based on the single-side-band modulation scheme can greatly lower the t...We proposed an optical 4-ary frequency shift keying （FSK） modulation scheme applying dual-parallel Mach-Zehnder （MZ） modulator. The 4-ary FSK based on the single-side-band modulation scheme can greatly lower the transmission speed in each sub-carriers and increase the transmission performance, comparing with the 2-FSK signal. The transmission performance of the 4-ary FSK was demonstrated after a 50 km single mode fiber. The results showed that the 4-ary FSK can realize error-free transmission. Moreover, we analyzed the influence of factors （such as disperse compensation and demodulation bandwidth） on the transmission performance in this paper. The analysis of the influenced factors can provide a theoretical basic for experiment.展开更多
Based on the principle of information theory, a novel scheme of unequal-interval frequency-hopping (FH) systems was proposed. For cases of spectrum overlapping systems and non-overlapping systems, the implementation m...Based on the principle of information theory, a novel scheme of unequal-interval frequency-hopping (FH) systems was proposed. For cases of spectrum overlapping systems and non-overlapping systems, the implementation methods were presented and the security performances were discussed theoretically. Firstly, the definitions of absolute and relative key amounts of FH systems, equal-interval and unequal-interval FH systems were given. Then, the absolute key amount and relative key amount were analyzed for equal-interval and unequal-interval FH systems. The results indicated that the absolute key amount had become the key point in improving the security and secrecy of FH systems, especially in today's epoch of highly developed computer science and IC design technology. Theoretical analysis and practical examples showed that the absolute key amount of unequal-interval FH systems was generally over two orders larger than that of equal-interval ones when spectrum overlapping was allowable. Therefore, there was great superiority in enhancing the security and secrecy for the scheme mentioned.展开更多
A new optical method based on frequency-shift feedback and laser confocal microscopy is presented to noninvasively measure a microstructure inside a sample. Due to the limit of axial resolution caused by poor signal d...A new optical method based on frequency-shift feedback and laser confocal microscopy is presented to noninvasively measure a microstructure inside a sample. Due to the limit of axial resolution caused by poor signal detection ability, conventional laser feedback cannot precisely measure the microstructure. In this Letter, the light scattered by the sample is frequency shifted before feedback to the laser to obtain a magnification. Weak signals that change with the microstructure can be detected. Together with the tomography ability of laser confocal microscopy, the inner microstructure can be measured with high axial resolution. ＆展开更多
Power&signal multiplex transmission(P&SMT)is a technique that uses power electronic circuits for communication signal transmission.In this paper,a three-phase cascaded multilevel inverter-based P&S MT syst...Power&signal multiplex transmission(P&SMT)is a technique that uses power electronic circuits for communication signal transmission.In this paper,a three-phase cascaded multilevel inverter-based P&S MT system is proposed.The proposed method can transmit communication signals without using a Controller Area Network bus,thereby reducing the wiring cost of the conventional electric vehicle(EV)communication system.The designed system can achieve motor speed regulation and battery balance discharging for EVs.With the combined pulse width modulation scheme and frequency shift keying method,both power and communication signals are transmitted successfully in a simulation model implemented in Matlab/Simulink.By evaluating the bit error rate of the transmitted signal,the maximum signal rate of the proposed system is determined as 600 bit/s.展开更多
In this paper, we describe the generation, detection, and performance of frequency-shift keying （FSK） for high-speed optical transmission and label switching. A non-return-to-zero （NRZ） FSK signal is generated by ...In this paper, we describe the generation, detection, and performance of frequency-shift keying （FSK） for high-speed optical transmission and label switching. A non-return-to-zero （NRZ） FSK signal is generated by using two continuous-wave （CW） lasers, one Mach-Zehnder modulator （MZM）, and one Mach-Zehnder delay interferometer （MZDI）. An RZ-FSK signal is generated by cascading a dual-arm MZM, which is driven by a sinusoidal voltage at half the bit rate. Demodulation can be achieved on 1 bit rate through one MZDI or an array waveguide grating （AWG） demultiplexer with balanced detection. We perform numerical simulation on two types of frequency modulation schemes using MZM or PM, and we determine the effect of frequency tone spacing （FTS） on the generated FSK signal. In the proposed scheme, a novel frequency modulation format has transmission advantages compared with traditional modulation formats such as RZ and differential phase-shift keying （DPSK）, under varying dispersion management. The performance of an RZ-FSK signal in a 4 x 40 Gb/s WDM transmission system is discussed. We experiment on transparent wavelength conversion based on four-wave mixing （FWM） in a semiconductor optical amplifier （SOA） and in a highly nonlinear dispersion shifted fiber （HNDSF） for a 40 Gb/s RZ-FSK signal. The feasibility of all-optical signal processing of a high-speed RZ-FSK signal is confirmed. We also determine the receiver power penalty for the RZ-FSK signal after a 100 km standard single-mode fiber （SMF） transmission link with matching dispersion compensating fiber （DCF）, under the post-compensation management scheme. Because the frequency modulation format is orthogonal to intensity modulation and vector modulation （polarization shift keying）, it can be used in the context of the combined modulation format to decrease the data rate or enhance the symbol rate. It can also be used in orthogonal label-switching as the modulation format for the payload or the label. As an example, we propose a simple orthogonal optical label switching technique based on 40 Gb/s FSK payload and 2.5 Gb/s intensity modulated （IM） label.展开更多
The effect of hydrostatic pressure （up to 28 MPa） on Brillouin frequency shift （BFS） within two types of bare, single-mode fibers is studied via Brillouin optical time domain analysis technique. Experimental resul...The effect of hydrostatic pressure （up to 28 MPa） on Brillouin frequency shift （BFS） within two types of bare, single-mode fibers is studied via Brillouin optical time domain analysis technique. Experimental results show a negative linear relation between pressure and BFS, with almost the same sensitivity in both types of fibers. The average value of experimental slopes is –0.742 MHz/MPa. This value is found to be well suited to theoretical analysis on the basis of data on bulk silica glass in previous reports. This preliminary evaluation may result in a new method for distributed pressure sensing along silica optical fiber.展开更多
This paper presents a human body communication(HBC)transceiver for wireless body network applications.The transceiver employs on frequency shift keying(FSK)modulation and op-erates in 40 MHz-60 MHz which is the resona...This paper presents a human body communication(HBC)transceiver for wireless body network applications.The transceiver employs on frequency shift keying(FSK)modulation and op-erates in 40 MHz-60 MHz which is the resonant frequency of the human body as an antenna.It achieves high performance and stability through establish passive microstrip line and via models and active device-models.The proposed transceiver is designed and fabricated by FR4 printed cir-cuit board(PCB)process,the transceiver has the ability of configurable data rate up to 2 Mbps and it achieves-86 dBm receiving sensitivity at 2 Mbps data rate.Meanwhile,the transceiver out-put power dynamics range is 34 dB.Furthermore,with a visual interaction interface,the transceiv-er can be agility use in a variety of scenarios.Its measurements are verified on human body.The result shows that the transceiver has ability to send data from person to person by relying on hu-man body antenna radiation.The transceiver shows great prospect in wireless body area networks(WBAN)for telemedicine and emergency communication.展开更多
The transmission characteristics of the optical label switching system based on the FSK/ASK orthogonal modulation format is investigated. The factors that affect the transmission performance, such as the FSK tone spac...The transmission characteristics of the optical label switching system based on the FSK/ASK orthogonal modulation format is investigated. The factors that affect the transmission performance, such as the FSK tone space, dispersion compensation and coupler split ratio, are studied by numerical simulation. The proposed scheme is also experimentally demonstrated with a transmission of 155 Mbit/s FSK label combined with 10 Gbit/s ASK payload.展开更多
This paper describes the design of modulation, compression coding and transmission control in underwater acoustic color image transmission system. This design adapts a special system of modulation and transmission con...This paper describes the design of modulation, compression coding and transmission control in underwater acoustic color image transmission system. This design adapts a special system of modulation and transmission control based on a DSP(Digital Signal Processing) chip, to cope with the complex underwater acoustic channel. The hardware block diagram and software flow chart are presented.展开更多
An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme...An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme is a pair of cascaded polarization-sensitive LiNbO_(3) Mach–Zehnder modulators and phase modulators,whose polarization directions of the principal axes are mutually orthogonal to each other.A proof-of-concept experiment is carried out,where a 0.5 Gb/s FSK signal with the carrier frequencies of 4 and 8 GHz and a 1 Gb/s FSK signal with the carrier frequencies of 8 and 16 GHz are generated successfully.展开更多
In order to realize homodyne reception and Doppler frequency shift tracking in ground-to-satellite coherent laser communication, a local laser is experimentally demonstrated in this Letter. It is realized based on mod...In order to realize homodyne reception and Doppler frequency shift tracking in ground-to-satellite coherent laser communication, a local laser is experimentally demonstrated in this Letter. It is realized based on modulation- sideband injection locking, and has a 10 OHz tuning range, a 1 THz/s tuning rate, a 5 kHz linewidth, and 16 mW of output power. When applied to a Costas loop in a coherent laser communication system, the local laser can achieve ±5 GItz Doppler frequency shift tracking with a 20 MHz/s frequency shift rate, which is sufficient for the ground-to-satellite coherent laser conmmnication.展开更多
In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler(PAD) frequency shift is calculated based on a series of individual ...In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler(PAD) frequency shift is calculated based on a series of individual A scans using an autocorrelation method. A 532 nm pulsed laser with repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused piezoelectric(PZT) ultrasound transducer with central frequency of 5 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by the Hilbert transformation from time-domain photoacoustic signal, and then it is autocorrelated to calculate the Doppler frequency shift. The photoacoustic Doppler frequency shift is calculated by averaging the autocorrelation results of some individual A scans. The advantage of the autocorrelation method is that the time delay in autocorrelation can be defined by user, and the requirement of high pulse repetition rate is avoided. The feasibility of the proposed autocorrelation method is preliminarily demonstrated by quantifying the motion of a carbon particle suspension with flow velocity from 5 mm/s to 60 mm/s. The experimental results show that there is an approximately linear relation between the autocorrelation result and the setting velocity.展开更多
A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks（WBANs）in medical applications is presented.The RF transceiver with an asymmetric architecture is propose...A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks（WBANs）in medical applications is presented.The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs.The transceiver consists of a main receiver（RX）with an ultra-low-power free-running ring oscillator and a high speed main transmitter（TX）with fast lock-in PLL.A passive wake-up receiver（WuRx）for wake-up function with a high power conversion efficiency（PCE）CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power.The chip is implemented in a 0.18μm CMOS process.Its core area is 1.6 mm^2. The main RX achieves a sensitivity of-55 dBm at a 100 kbps OOK data rate while consuming just 210μA current from the 1 V power supply.The main TX achieves ＋3 dBm output power with a 4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates 3.25 mA/6.5 mA/6.5 mA current from a 1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is-15 dBm and the PCE is more than 25%.展开更多
For differential phase shift keying （DPSK） and noncoherent frequency shift keying （NFSK） systems over fading channels, the post-detection combining method is a popular means for improving the bit error performance...For differential phase shift keying （DPSK） and noncoherent frequency shift keying （NFSK） systems over fading channels, the post-detection combining method is a popular means for improving the bit error performance. However, the bit error performance of such systems over Nakagami channels with an arbitrary covariance matrix and real distinct fading parameters has been seldom described in the literature. This paper studies the problem using a generic correlated Nakagami fading model and presents a closed form solution which is used to study the influence of the fading parameters and the signal-to-noise ratio （SNR） distribution ratios among all the branches on the bit error performance. Moreover, the average SNRs of each branch are not restricted to one value in the analysis. The closed form solution developed for the problem can be used to study the influence of the fading parameters and the SNR distribution ratios on the error performance.展开更多
We discuss the feasibility of realizing a cold atom space clock with counter-propagating cold atoms in microgravity. The design of the space clock is based on an atomic beam clock with Ramsey cavity, except that magne...We discuss the feasibility of realizing a cold atom space clock with counter-propagating cold atoms in microgravity. The design of the space clock is based on an atomic beam clock with Ramsey cavity, except that magneto-optical trap （MOT） is placed at each side. Cold atoms are launched simultaneously from the MOTs at both sides of the clock and they move at the counter-direction towards each other. The velocity of the launched atoms is precisely controlled to Ramsauer-Townsend resonance so that no additional collision frequency shift takes place. Such configuration can efficiently cancel the frequency shift resulting from cavitv phase shift and increase the signal-to-noise ratio （SNR）.展开更多
Optical frequency shift keying （FSK） homodyne detection utilizing image rejection in FSK/amplitude shift keying （ASK） re-modulation wavelength-division-multiplexed passive optical network （WDM-PON） is proposed a...Optical frequency shift keying （FSK） homodyne detection utilizing image rejection in FSK/amplitude shift keying （ASK） re-modulation wavelength-division-multiplexed passive optical network （WDM-PON） is proposed and demonstrated. Image rejection is adopted to achieve better performance. We show the result in back-to-back and 40-km distance respectively and apparent improvement is obtained in the latter situation by using image rejection. Several factors which affect the image rejection receiver are analyzed in order to find out the optimum parameters. Result shows that the presented scheme is suitable for super long reach access network, especially for future metro access network.展开更多
In this paper, a technique was numerically implemented to generate a frequency shift keying （FSK） radio-over-fiber （RoF） signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme i...In this paper, a technique was numerically implemented to generate a frequency shift keying （FSK） radio-over-fiber （RoF） signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme is highly stable with reduced complexity and extremely cost effective. The remote heterodyne detection method was used to detect the signal, where beating occurs to detect the FSK signal. With this scheme, it is able to efficiently generate FSK signal in the range of 60 and 75 GHz at 8 Gbit/s and effectively transmit it over 80 km link without degrading the signal shape and quality. The nonlinear threshold （NLT） point of the system has also been numerically analyzed to estimate the nonlinear tolerance of the system. Besides, the impact of transmission distance and polarization mode dispersion （PMD） was evaluated. Furthermore, the wavelength reuse for the uplink was implemented in the scheme by reusing the same wave- length for uplink that was used for signal generation at downlink. The whole process was performed in optical domain. Thus this scheme is very cost effective as the overall architecture of RoF system is simplified.展开更多
基金the Natural Science Foundation of Jiangsu Province (BK2006701)the National Natural Science Foundation of China (No.60672079).
文摘This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feedback loop and to solve the problem of phase ambiguity,the tracking performance of the algorithm has been improved greatly. Only a few preambles are needed in the al-gorithm since the preambles are not used to estimate the frequency offset but used to provide the variation information of the phase due to the presence of frequency offset. Simulations verify that the algorithm has low SNR bound for tracking as well as high tracking accuracy and the tracking range is expanded to 30% of one subcarrier spacing.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61471179 and 61301226）, and the High Technology Research and Development Program of China （No. 2015AA016904）.
文摘We proposed an optical 4-ary frequency shift keying （FSK） modulation scheme applying dual-parallel Mach-Zehnder （MZ） modulator. The 4-ary FSK based on the single-side-band modulation scheme can greatly lower the transmission speed in each sub-carriers and increase the transmission performance, comparing with the 2-FSK signal. The transmission performance of the 4-ary FSK was demonstrated after a 50 km single mode fiber. The results showed that the 4-ary FSK can realize error-free transmission. Moreover, we analyzed the influence of factors （such as disperse compensation and demodulation bandwidth） on the transmission performance in this paper. The analysis of the influenced factors can provide a theoretical basic for experiment.
文摘Based on the principle of information theory, a novel scheme of unequal-interval frequency-hopping (FH) systems was proposed. For cases of spectrum overlapping systems and non-overlapping systems, the implementation methods were presented and the security performances were discussed theoretically. Firstly, the definitions of absolute and relative key amounts of FH systems, equal-interval and unequal-interval FH systems were given. Then, the absolute key amount and relative key amount were analyzed for equal-interval and unequal-interval FH systems. The results indicated that the absolute key amount had become the key point in improving the security and secrecy of FH systems, especially in today's epoch of highly developed computer science and IC design technology. Theoretical analysis and practical examples showed that the absolute key amount of unequal-interval FH systems was generally over two orders larger than that of equal-interval ones when spectrum overlapping was allowable. Therefore, there was great superiority in enhancing the security and secrecy for the scheme mentioned.
基金supported by the National Natural Science Foundation of China(No.51375262)the Natural Science Foundation of Beijing(No.4152024)
文摘A new optical method based on frequency-shift feedback and laser confocal microscopy is presented to noninvasively measure a microstructure inside a sample. Due to the limit of axial resolution caused by poor signal detection ability, conventional laser feedback cannot precisely measure the microstructure. In this Letter, the light scattered by the sample is frequency shifted before feedback to the laser to obtain a magnification. Weak signals that change with the microstructure can be detected. Together with the tomography ability of laser confocal microscopy, the inner microstructure can be measured with high axial resolution. ＆
文摘Power&signal multiplex transmission(P&SMT)is a technique that uses power electronic circuits for communication signal transmission.In this paper,a three-phase cascaded multilevel inverter-based P&S MT system is proposed.The proposed method can transmit communication signals without using a Controller Area Network bus,thereby reducing the wiring cost of the conventional electric vehicle(EV)communication system.The designed system can achieve motor speed regulation and battery balance discharging for EVs.With the combined pulse width modulation scheme and frequency shift keying method,both power and communication signals are transmitted successfully in a simulation model implemented in Matlab/Simulink.By evaluating the bit error rate of the transmitted signal,the maximum signal rate of the proposed system is determined as 600 bit/s.
基金supported by the National High Technology Research and Development Program(973)of China(Grant No.2010CB328300)National Natural Science Foundation of China(No.61107064,No.61177071,No.600837004,No.60777010)+1 种基金Doctoral Fund of Ministry of Education,Open Fund of State Key Lab of ASIC&System(No.11MS009)Pujiang Fund and Shuguang fund
文摘In this paper, we describe the generation, detection, and performance of frequency-shift keying （FSK） for high-speed optical transmission and label switching. A non-return-to-zero （NRZ） FSK signal is generated by using two continuous-wave （CW） lasers, one Mach-Zehnder modulator （MZM）, and one Mach-Zehnder delay interferometer （MZDI）. An RZ-FSK signal is generated by cascading a dual-arm MZM, which is driven by a sinusoidal voltage at half the bit rate. Demodulation can be achieved on 1 bit rate through one MZDI or an array waveguide grating （AWG） demultiplexer with balanced detection. We perform numerical simulation on two types of frequency modulation schemes using MZM or PM, and we determine the effect of frequency tone spacing （FTS） on the generated FSK signal. In the proposed scheme, a novel frequency modulation format has transmission advantages compared with traditional modulation formats such as RZ and differential phase-shift keying （DPSK）, under varying dispersion management. The performance of an RZ-FSK signal in a 4 x 40 Gb/s WDM transmission system is discussed. We experiment on transparent wavelength conversion based on four-wave mixing （FWM） in a semiconductor optical amplifier （SOA） and in a highly nonlinear dispersion shifted fiber （HNDSF） for a 40 Gb/s RZ-FSK signal. The feasibility of all-optical signal processing of a high-speed RZ-FSK signal is confirmed. We also determine the receiver power penalty for the RZ-FSK signal after a 100 km standard single-mode fiber （SMF） transmission link with matching dispersion compensating fiber （DCF）, under the post-compensation management scheme. Because the frequency modulation format is orthogonal to intensity modulation and vector modulation （polarization shift keying）, it can be used in the context of the combined modulation format to decrease the data rate or enhance the symbol rate. It can also be used in orthogonal label-switching as the modulation format for the payload or the label. As an example, we propose a simple orthogonal optical label switching technique based on 40 Gb/s FSK payload and 2.5 Gb/s intensity modulated （IM） label.
基金supported by the National Natural Science Foundation of China under Grant No. 51074059
文摘The effect of hydrostatic pressure （up to 28 MPa） on Brillouin frequency shift （BFS） within two types of bare, single-mode fibers is studied via Brillouin optical time domain analysis technique. Experimental results show a negative linear relation between pressure and BFS, with almost the same sensitivity in both types of fibers. The average value of experimental slopes is –0.742 MHz/MPa. This value is found to be well suited to theoretical analysis on the basis of data on bulk silica glass in previous reports. This preliminary evaluation may result in a new method for distributed pressure sensing along silica optical fiber.
基金the National Key R&D Program of China(No.2018YFC2001002)the National Natural Sci-ence Foundation of China(No.62173318)+1 种基金Shenzhen Basic Research Project(No.JCYJ20180507182231907,PIFI 2020 FYB0001)CAS Key Lab of Health Informatics.
文摘This paper presents a human body communication(HBC)transceiver for wireless body network applications.The transceiver employs on frequency shift keying(FSK)modulation and op-erates in 40 MHz-60 MHz which is the resonant frequency of the human body as an antenna.It achieves high performance and stability through establish passive microstrip line and via models and active device-models.The proposed transceiver is designed and fabricated by FR4 printed cir-cuit board(PCB)process,the transceiver has the ability of configurable data rate up to 2 Mbps and it achieves-86 dBm receiving sensitivity at 2 Mbps data rate.Meanwhile,the transceiver out-put power dynamics range is 34 dB.Furthermore,with a visual interaction interface,the transceiv-er can be agility use in a variety of scenarios.Its measurements are verified on human body.The result shows that the transceiver has ability to send data from person to person by relying on hu-man body antenna radiation.The transceiver shows great prospect in wireless body area networks(WBAN)for telemedicine and emergency communication.
基金supported by the National Natural Science Foundation of China(Grant No 60677004)the National High Technology Research and Development Program of China(Grant No 2007AA01Z260)+4 种基金The project is also supported by the Key Project of Chinese Ministry of Education(Grant No 107011)the Key Laboratory of Broadband Optical Fiber Transmission and Communication Networks(UESTC)(Ministry of Education of China)Teaching and Scientific Research Foundation for the Returned Overseas Chinese Scholars(State Education Ministry of China)the Corporative Building Project of Beijing Educational Committee(Grant No XK100130737)the Program for New Century Excellent Talents in University of China(Grant No NECT-07-0111)
文摘The transmission characteristics of the optical label switching system based on the FSK/ASK orthogonal modulation format is investigated. The factors that affect the transmission performance, such as the FSK tone space, dispersion compensation and coupler split ratio, are studied by numerical simulation. The proposed scheme is also experimentally demonstrated with a transmission of 155 Mbit/s FSK label combined with 10 Gbit/s ASK payload.
文摘This paper describes the design of modulation, compression coding and transmission control in underwater acoustic color image transmission system. This design adapts a special system of modulation and transmission control based on a DSP(Digital Signal Processing) chip, to cope with the complex underwater acoustic channel. The hardware block diagram and software flow chart are presented.
基金supported by the National Natural Science Foundation of China(Nos.U2006217,61775015,61801017,and 61827818)。
文摘An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme is a pair of cascaded polarization-sensitive LiNbO_(3) Mach–Zehnder modulators and phase modulators,whose polarization directions of the principal axes are mutually orthogonal to each other.A proof-of-concept experiment is carried out,where a 0.5 Gb/s FSK signal with the carrier frequencies of 4 and 8 GHz and a 1 Gb/s FSK signal with the carrier frequencies of 8 and 16 GHz are generated successfully.
基金supported by the National Natural Science Foundation of China(No.61405218)the Shanghai Natural Science Foundation(No.14ZR1445100)
文摘In order to realize homodyne reception and Doppler frequency shift tracking in ground-to-satellite coherent laser communication, a local laser is experimentally demonstrated in this Letter. It is realized based on modulation- sideband injection locking, and has a 10 OHz tuning range, a 1 THz/s tuning rate, a 5 kHz linewidth, and 16 mW of output power. When applied to a Costas loop in a coherent laser communication system, the local laser can achieve ±5 GItz Doppler frequency shift tracking with a 20 MHz/s frequency shift rate, which is sufficient for the ground-to-satellite coherent laser conmmnication.
基金supported by the Joint Funds of the National Natural Science Foundation of China(No.U1204612)Natural Science Foundation of He’nan Educational Committee(No.13A416180)
文摘In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler(PAD) frequency shift is calculated based on a series of individual A scans using an autocorrelation method. A 532 nm pulsed laser with repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused piezoelectric(PZT) ultrasound transducer with central frequency of 5 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by the Hilbert transformation from time-domain photoacoustic signal, and then it is autocorrelated to calculate the Doppler frequency shift. The photoacoustic Doppler frequency shift is calculated by averaging the autocorrelation results of some individual A scans. The advantage of the autocorrelation method is that the time delay in autocorrelation can be defined by user, and the requirement of high pulse repetition rate is avoided. The feasibility of the proposed autocorrelation method is preliminarily demonstrated by quantifying the motion of a carbon particle suspension with flow velocity from 5 mm/s to 60 mm/s. The experimental results show that there is an approximately linear relation between the autocorrelation result and the setting velocity.
基金Project supported by the National High-Tech Research and Development Program of China(Nos2008AA010703,2009AA011606)the National Natural Science Foundation of China(No60976023)
文摘A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks（WBANs）in medical applications is presented.The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs.The transceiver consists of a main receiver（RX）with an ultra-low-power free-running ring oscillator and a high speed main transmitter（TX）with fast lock-in PLL.A passive wake-up receiver（WuRx）for wake-up function with a high power conversion efficiency（PCE）CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power.The chip is implemented in a 0.18μm CMOS process.Its core area is 1.6 mm^2. The main RX achieves a sensitivity of-55 dBm at a 100 kbps OOK data rate while consuming just 210μA current from the 1 V power supply.The main TX achieves ＋3 dBm output power with a 4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates 3.25 mA/6.5 mA/6.5 mA current from a 1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is-15 dBm and the PCE is more than 25%.
文摘For differential phase shift keying （DPSK） and noncoherent frequency shift keying （NFSK） systems over fading channels, the post-detection combining method is a popular means for improving the bit error performance. However, the bit error performance of such systems over Nakagami channels with an arbitrary covariance matrix and real distinct fading parameters has been seldom described in the literature. This paper studies the problem using a generic correlated Nakagami fading model and presents a closed form solution which is used to study the influence of the fading parameters and the signal-to-noise ratio （SNR） distribution ratios among all the branches on the bit error performance. Moreover, the average SNRs of each branch are not restricted to one value in the analysis. The closed form solution developed for the problem can be used to study the influence of the fading parameters and the SNR distribution ratios on the error performance.
基金supported by the National"863"Program of China(No.2006AA12Z311)the National"973"Program of China(No.2005CB724506)
文摘We discuss the feasibility of realizing a cold atom space clock with counter-propagating cold atoms in microgravity. The design of the space clock is based on an atomic beam clock with Ramsey cavity, except that magneto-optical trap （MOT） is placed at each side. Cold atoms are launched simultaneously from the MOTs at both sides of the clock and they move at the counter-direction towards each other. The velocity of the launched atoms is precisely controlled to Ramsauer-Townsend resonance so that no additional collision frequency shift takes place. Such configuration can efficiently cancel the frequency shift resulting from cavitv phase shift and increase the signal-to-noise ratio （SNR）.
基金supported by the National "973" Project of China (No. 2010CB328300)the National Natural Science Foundation of China (No. 60777010)+3 种基金the National "863" Project of China (No. 2009AA01Z253)the Shuguang Found (No. 08SG05)the China Postdoctoral Science Foundation (No. 20090460593)the Shang-hai Postdoctoral Science Foundation (No. 10R21411600)
文摘Optical frequency shift keying （FSK） homodyne detection utilizing image rejection in FSK/amplitude shift keying （ASK） re-modulation wavelength-division-multiplexed passive optical network （WDM-PON） is proposed and demonstrated. Image rejection is adopted to achieve better performance. We show the result in back-to-back and 40-km distance respectively and apparent improvement is obtained in the latter situation by using image rejection. Several factors which affect the image rejection receiver are analyzed in order to find out the optimum parameters. Result shows that the presented scheme is suitable for super long reach access network, especially for future metro access network.
文摘In this paper, a technique was numerically implemented to generate a frequency shift keying （FSK） radio-over-fiber （RoF） signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme is highly stable with reduced complexity and extremely cost effective. The remote heterodyne detection method was used to detect the signal, where beating occurs to detect the FSK signal. With this scheme, it is able to efficiently generate FSK signal in the range of 60 and 75 GHz at 8 Gbit/s and effectively transmit it over 80 km link without degrading the signal shape and quality. The nonlinear threshold （NLT） point of the system has also been numerically analyzed to estimate the nonlinear tolerance of the system. Besides, the impact of transmission distance and polarization mode dispersion （PMD） was evaluated. Furthermore, the wavelength reuse for the uplink was implemented in the scheme by reusing the same wave- length for uplink that was used for signal generation at downlink. The whole process was performed in optical domain. Thus this scheme is very cost effective as the overall architecture of RoF system is simplified.
