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A compact optical-microwave phase detector is proposed and its performance is evaluated by synchronizing an 8-GHz oscillator to a 250-MHz mode-locked laser. The residual out-of-loop phase noise at 1 Hz and 100 kHz offset are −115 dBc/Hz and −146 dBc/Hz respectively. And the RMS timing jitter is 600 as when integrated from 100 kHz to 1 Hz. The proposed phase detector has a compact structure and is...
The helical antennas (HAs) work as three different types with respect to various revolution length, which are the normal-direction helical antenna (NHA), the axial-direction helical antenna (AHA) and the conical-direction antenna (CHA). In this letter, the vortical radio waves carrying the multiple orbital angular momentum (OAM) modes generated by the NHAs and CHAs is proposed. The results of the...
This paper reports on the design, fabrication and performance of a third-harmonic fixed-tuned frequency mixer, working at W-band frequencies. The mixing circuit consists of a variation of crossbar structure, a combination of the suspended stripline circuit and the microstrip matching circuit. The mixing diodes are arranged as a single balanced configuration near the end of the RF waveguide. The precise...
A phase stable radio frequency (RF) distribution technique is proposed and experimentally demonstrated. The system transmits optical frequency comb lines through an optic cable with multiple fibers. At the receiver, RF phase variation is removed by frequency mixing based on phase conjugation. In the proposed system, round-trip transmission is implemented through different fibers, thus the signal degradation...
A compact scheme for stable frequency dissemination over optical fiber is proposed and demonstrated. A standard signal in the center station is delivered to the remote end without any assistant signal source. The frequency of the received signal is the same as the signal source in the center station. A proof-of-concept experiment is performed. A 6-GHz standard signal is transmitted in a 20-km fiber...
In this paper, maximum rate interference alignment (MR-IA) algorithm is proposed for multi-cell downlink interference systems. Based on the researches on distributed interference alignment (IA) algorithms, the proposed algorithm can further enhance the sum rate. In this scheme, the precoding matrices are optimized by searching precoding alone the gradient ascent direction of throughput. In this process,...
Recent work has demonstrated the superiority of compressive sensing (CS) for the sound source localization. Using the microphone array, the direction-of-arrival (DOA) estimation is obtained by using the wideband extensions of CS technique. For tracking moving wideband sound sources, a method combined CS with particle filter (PF) algorithm is proposed. Each source is approximated by a set of particles...
Wherein the framework of block compressive sensing sampling of images, an l_p norm minimization algorithm is proposed. The proposed algorithm is memory efficient as we just need to store a block diagonal sensing matrix for sampling the small blocks divided from an original image. The whole image is reconstructed with an l_p norm minimization. To improve the quality of the reconstructed images and...
A compact scheme for stable frequency dissemination over optical fiber is proposed and demonstrated. A standard signal in the center station is delivered to the remote end without any assistant signal source. The frequency of the received signal is the same as the signal source in the center station. A proof-of-concept experiment is performed. A 6-GHz standard signal is transmitted in a 20-km fiber...
The transfer of radio frequency (RF) signal via optical fiber is widely used in distributed antenna systems. To compensate the phase variation caused by fiber length fluctuation, passive phase correction technique is proposed with obvious advantages over the traditional active phase correction method. This paper reviews the recent developments of the stable RF transfer based on passive phase correction...
A novel passive phase error correction technique for stable radio transfer via an optic cable with three fibers is proposed. The single-tone radio (at f0) to be transmitted is first frequency-divided by 2. The half-frequency signal is transmitted to the receiver through one fiber of the cable and then frequency-tripled. The obtained signal is mixed with another half-frequency signal that passes the...
A simple, compact, cost-effective post-phase correction method for stable fiber transfer of RF signal is proposed and demonstrated. By employing only one LO source and two frequency mixers, a RF signal is transmitted to the local station with very small phase jitter. An experiment is performed. When a 6-GHz RF signal is delivered through a 20-km SMF, effective cancellation of the phase jitter induced...
According to the existing drawbacks of SC algorithm with a peak plateau and Minn and Park algorithms with side peaks, an improved OFDM synchronization algorithm is proposed based on training symbol. On the basis of the defect analysis of traditional methods, a new sequence is presented with conjugate symmetric structure and a new timing metric function is adopted with multiplication two correlation...
Amide proton transfer (APT) imaging offers a novel and powerful MRI contrast mechanism for quantitative molecular imaging based on the principle of chemical exchange saturation transfer (CEST). Asymmetric magnetization transfer ratio (MTRasym) quantification is crucial for Z-spectrum analysis of APT imaging, but is still challenging, particularly at clinical field strength. This paper studies the...
The repeater is a bi-directional duplex amplifier working between base station and mobile station. Based on adaptive interference cancellation technology, the scheme and algorithm of adaptive interference cancellation are studied in this paper. The comprehensive structure of adaptive interference cancellation is implemented on FPGA. The simulation and test results show that the interference problem...
A novel blind digital image watermarking scheme based on Schur factorization in contourlet domain is proposed in this paper. Firstly, the original cover image is decomposed by contourlet domain, then Schur factorization is adopted to the selected symmetric blocks determined by the lowpass subband where watermark information is embedded. Additionally, the watermark image is encrypted by a pseudorandom...
The information is often uncertain, incomplete, and ignorant and the weights of attributes are not equal to each other in multi-attribute decision-making (MADM). The evidence theory is a method for MADM under uncertainties, but focal element increases rapidly. A feature reduction algorithm based on rough set is used when classification result is almost invariable, on the one hand, adopts a little...
Based on electrical Map and measured elevation data, noise mapping of South Second Ring in Xi'an City is attained based on GIS and CadnaA software. In the Noise mapping, sound pressure level isn't consistent with measured data. The main reason is that foreign noise prediction model does not apply in China. According to some kinds of feature, such as concentrated viaduct and intersection, host and...
Deterministic design optimization (DO) may lead to unreliable designs due to not taking into consideration uncertainties. In recent years, DO under uncertainty has attracted more and more attention. In DO practice, both aleatory and epistemic uncertainties may exist, furthermore, the two types of uncertainties may affect both the objective function and the constrains of the optimization problem. In...
With the techniques of mechantronics and pneumatics, this paper has developed the automatic conveying system for dangerous goods that consists of a vehicle and a manipulator. The vehicle transports the barrels with dangerous goods to the designated place; the manipulation pours out the dangerous goods from the barrel and puts back the barrel on the vehicle. The control subsystem is master-slave mode...
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