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We proposed a hybrid powered ankle exoskeleton. It can be able to supply positive mechanical power to the user during the swing phase of gait. The hybrid powered ankle exoskeleton was composed of a pair of compressed springs and a cable-driven actuator fasted to the shin. It was lightweight, and permitted the cable-driven actuator to provide the forces at the biological level to the ankle joint. Meanwhile...
Using commercial IEEE 802.11n/ac access points, the feasibility of 3×3 space-division-multiplexed MIMO transmission over a single OM3 multimode fiber is experimentally demonstrated. More than two-fold multiplexing gain is realized for up to 1km fiber length with a tight fiber bend radius of 2mm.
Semiconductor saturable absorber mirror (SESAM) mode-locked all-polarization maintaining (PM) fiber oscillator with a fundamental repetition rate up to 1 GHz centered around1558 nm was demonstrated. With a 450 mW incident pump power, the oscillator is operating at the soliton mode-locked regime due to intracavity anomalous dispersion. The spectral width and compressed pulse duration is 9.4 nm and...
We propose a dual-band linear frequency-modulated continuous wave (LFMCW) radar receiver based on a microwave photonic in-phase and quadrature (I/Q) mixer, able to simultaneously operate on two different bands over a very board frequency range. The sharing of hardware resources and joint processing of dual bands are implemented by applying a special dual-band sensing waveform. An unambiguous and independent...
Enlightened by photonic reservoir computing, an emerging bio-inspired approach for time-dependent information processing, we present a novel concept for realization of real-time Fourier transformation, i.e., frequency-to-time mapping (FTM), of temporal waveforms based on a coherently driven passive fiber cavity with a frequency resolution of 25 MHz and extremely simple structure.
A frequency-multiplying radio frequency (RF) source based on the optoelectronic oscillator (OEO) with low phase noise has been proposed and experimentally demonstrated. With the optical carrier suppression process, the frequency quadrupling can be achieved by biasing the intensity modulators at the minimum transmission point simultaneously inside and outside the OEO loop. In the proof-of-concept experiment,...
We proposed and demonstrated a novel photonic and digital hybrid flexible satellite payload with resources sharing for multi-channel communication payloads at L, S, Ku and Ka band. The system uses microwave photonic up/down conversion to realize receive different band microwave signals and convert to fixed IF frequency. We further show that the photonic and digital hybrid switching is used compared...
A millimeter-wave (mmW) optoelectronic oscillator employing ultra-high Q optoelectronic hybrid bandpass filter is proposed. The novel filter with Q value of 30000, bandwidth of 1 MHz and centre frequency of 29.99 GHz has been demonstrated. Based on this ultra-narrow bandpass filter, a 29.99 GHz millimetre-wave signal is successfully generated with the single-sideband phase noise about −113 dBc/Hz...
In order to settle the problem of obstacle recognition for Unmanned Surface Vessel (USV), a novel method is presented to distinguish between vessels and coastlines based on point cloud data (PCD) from ship borne laser radar. Primarily, echo data of inland river targets and noise is analyzed and filtered. Furthermore, targets are extracted from PCD based on distance. Subsequently, three robust target...
We demonstrated a fundamentally semiconductor saturable absorber mirror (SESAM) mode-locked fiber oscillator with a repetition rate up to 835 MHz at a central wavelength of 1572.3 nm. The average power of the output pulse is 6.02 mW, corresponding to a pulse energy of 7.2 pJ with an 150 mW incident pump power. Due to the intracavity anomalous dispersion, the laser is operating at soliton mode-locked...
In this paper, all-fiber based all polarization maintaining erbium-doped fiber lasers based on nonlinear amplifying loop mirror (NALM), including both figure-of-8 and figure-of-9 configurations are demonstrated. The figure-of-8 oscillator generates 1.6 ps chirped pulses at 1550 nm with a pulse energy of 0.8 nJ and a repetition rate of 12 MHz. The figure-of-9 oscillator generates 420 fs pulses at 1550...
A novel optical pulse generator with high-rate and low-jitter is proposed based on the optoelectronic oscillator using a cascaded polarization modulator and phase modulator. Optical pulses with 10 GHz repetition rate and 29 ps width are demonstrated. According to the single-sideband phase noise of the generated microwave signal, 169 fs time jitter of the generated pulses in the 100 Hz to 1 MHz frequency...
We report a broadband ytterbium-doped femtosecond fiber laser around 980nm. The cavity is based on the all-normal dispersion (ANDi) configuration, including a diffraction-grating which plays a crucial role as a narrow-band spectral filter. The spectral bandwidth of mode-locked pulse reaches 11.4 nm, which approaches the gain bandwidth (about 13nm) of the ytterbium doped fiber around 980 nm. The pulse...
A novel broadband and scalable RF switch matrix based on microwave photonics is proposed and the proof-of-concept experiments are carried out. The experiment results show that the proposed RF switch matrix is with a good linearity, link gain, port isolation and EVM performance.
The stochastic characteristics of a 3×3 MIMO RF channel enabled by two-mode graded index fiber are experimentally investigated in terms of Rice K-factor and condition number of channel matrix over different fiber reach. The results show that spatial multiplexing benefits from longer fiber reach despite of higher optical loss.
A novel photonic frequency-doubling up-converter is proposed and experimentally demonstrated with compensation of power fading after fiber transmission over 60 and 80 km and the spurious-free dynamic rang (SFDR) at 21.7GHz with 60 km fiber transmission is improved by more than 20 dB.
A novel coupled opto-electronic oscillation (COEO) employing an intracavity time lens is investigated via numerical simulation. Different from conventional COEO, this scheme can generate a high-rep-rate low-noise broadband pulse train without the participation of fiber nonlinearity. A 10-GHz pulse train with 9.65-nm 3-dB bandwidth is achieved in the simulation, which is then de-chirped and compressed...
The numerical study on microwave photonic mixers based on I/Q modulators and Mach-Zehnder modulators has been analyzed. To improve the design accuracy and efficiency of the mixing systems, some key performance indicators including best power of LO, conversion gain, noise figure, spurious performance and image rejection are simulated and discussed.
Based on the superiority of wavelet transform about frequency band division and the detection ability of wavelet entropy in disturbance signal and zero sequence voltage, this paper put forwards an algorithm that identifies fault type effectively and quickly by analyzing the relationship between standard deviation of wavelet singular entropy and wavelet energy entropy before the fault a period and...
This paper presents an algorithm of fault feature gene extraction based on time-frequency domain Statistics for the technical challenge of the fault detection radial-structured power distribution networks. By using this kind of approach, a gene bank can be obtained. Then, the typical fault type, such as short-circuit, open-circuit and single-phase grounding fault, can be detected by using this gene...
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