In this communication we report the design of a clock recovery circuit produced for the 20 Gbit/s demonstrator of the RACE 2011 project `TRAVEL' of the European Community. The clock recovery circuit is based on an...
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ISBN:
(纸本)0819418005
In this communication we report the design of a clock recovery circuit produced for the 20 Gbit/s demonstrator of the RACE 2011 project `TRAVEL' of the European Community. The clock recovery circuit is based on an open loop structure using a dielectric resonator narrow bandpass filter with a high quality factor. A detailed electrical characterization of the circuit and also its sensitivity to temperature and detuning variations are presented. The experimental results show that the circuit is a very attractive solution for the forthcoming STM-128 optical links.
One intermediate goal towards achieving universal secure voice interoperability in the Department of Defense (DoD) has been the development of a universal voice encoder (vocoder). This vocoder would seamlessly encode ...
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ISBN:
(纸本)9780769551241
One intermediate goal towards achieving universal secure voice interoperability in the Department of Defense (DoD) has been the development of a universal voice encoder (vocoder). This vocoder would seamlessly encode speech at a wide range of interoperable variable and fixed data rates to suit a wide range of DoD communication equipment. This paper describes the most important features of such a vocoder and recent advancements in achieving this goal. Specifically this paper will describe three main areas: 1) Summary of the variable data rate (VDR) algorithm and the most recent improvements to the vocoder. 2) Methods for transcoding between fixed rate and variable data rate vocoding modes. 3) Summary of heavily bit error protected, fixed-rate modes.
In recent years, there has been a surge of interest in using piezoelectric patches attached to optical surfaces in hope of attaining high precision of optical mirrors with minimal additional weight. Based on results f...
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ISBN:
(纸本)0819440132
In recent years, there has been a surge of interest in using piezoelectric patches attached to optical surfaces in hope of attaining high precision of optical mirrors with minimal additional weight. Based on results from preliminary investigations, the configuration of thin piezoelectric strip actuators placed in the radial and circumferential line directions of a circular plate (host structure of the mirror) is chosen to control the surface error of the mirror. The major challenges here is the two dimensional actuation effect of the actuator patches, which could induce high order modal deformations and increase the difficulty of surface errorcontrol. The purpose of this research is to investigate such effects and propose solutions. A simple model is first developed through Hamilton's principle and discretized using Galerkin's method, thus giving a set of differential equations describing the coupled mechanical and electrical systems. From the equations, the coupling between the electrical and structural systems for each mode shape can be calculated, thus giving a means to maximize the coupling between the actuator and the mode shapes of interest by changing the actuators' properties. Likewise, the properties can be tailored such that excitation of the unwanted modes can be avoided or reduced. A more comprehensive finite element model is also derived to validate the observations obtained from the simple model. From the analysis, it is found that decoupling the circumferential action from the radial action of the piezoelectric patches can dramatically improve the performance of the controller, thus achieving a greater reduction in the surface error. Methods to decouple the circumferential strain from the radial strain are then proposed.
In IoT applications with remote monitoring, the data is transferred through a wireless channel. To ensure data reliability, error control coding is essential. For the high error correcting ability, the Low density par...
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ISBN:
(纸本)9781450377515
In IoT applications with remote monitoring, the data is transferred through a wireless channel. To ensure data reliability, error control coding is essential. For the high error correcting ability, the Low density parity check (LDPC) codes are used as the most popular code for error-control in many domains like telecommunication, magnetic-recording, radio application, etc. Thus the data transmitted in IoT system may be encoded by LDPC codes. This paper presents a small length LDPC code of six-by-seven. The shifted identity matrix and a lower staircase matrix are used to construct the LDPC code. These codes have very low encoding complexity. Belief-propagation is used to decode the code. In the simulation result of the code, improved performance in bit error rate is shown. The simulation result of these codes shows a good performance in the bit-error-rate.
Permutation spreading has been proposed as an alternative technique for assigning spreading codes to the different transmit antennas of a user in a Multiple Input Multiple Output Code Division Multiple Access (MIMO-CD...
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ISBN:
(纸本)9781424429479
Permutation spreading has been proposed as an alternative technique for assigning spreading codes to the different transmit antennas of a user in a Multiple Input Multiple Output Code Division Multiple Access (MIMO-CDMA) system. In this paper, we propose the use of the permutation spreading technique using Hadamard codes for antenna separation and Gold scrambling codes for user separation. All users are assigned the same set of Hadamard sequences, thus our proposed technique reduces the overall number of spreading sequences required by the system. In the example shown in the paper, the proposed spreading combination allows both an increase in spectral effciency and a four-fold decrease in the number of spreading codes needed by the system. Moreover, permutation spreading shows more than 7dB advantage over conventional MIMO-CDMA system in a heavily loaded environment.
Reed-Solomon codes are widely used to provide reliable communication, as they are well known for their high data correction rates. However, techniques that best optimize hardware area as well as signal propagation del...
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Reed-Solomon codes are widely used to provide reliable communication, as they are well known for their high data correction rates. However, techniques that best optimize hardware area as well as signal propagation delays are needed in today's applications. In this work, two techniques are investigated and implemented using a hardware description language, synthesized to a XUPV5-LX110t development platform, and compared to commercial solutions.
This paper develops a joint coding and modulation scheme for end-to-end communication system design using an autoencoder architecture in the ultra-short blocklength regime. Unlike the classical approach of separately ...
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ISBN:
(纸本)9781509066315
This paper develops a joint coding and modulation scheme for end-to-end communication system design using an autoencoder architecture in the ultra-short blocklength regime. Unlike the classical approach of separately designing error correction codes and modulation schemes for a given channel, the approach here is to learn an optimal mapping directly from messages to channel inputs while simultaneously learning an optimal mapping directly from channel outputs to estimated messages. The block error rate (BLER) of this approach is compared against classical short blocklength linear block codes with binary phase shift keying (BPSK) modulation in additive white Gaussian noise (AWGN) and Bernoulli-Gaussian impulsive noise (BGIN) channels. For AWGN channels, numerical results show that the autoencoder can achieve better BLER performance than BPSK modulated Hamming codes with maximum likelihood decoding. For BGIN channels, numerical results show the autoencoder achieves uniformly better BLER performance than conventional block codes with BPSK modulation, even with impulsive noise mitigation techniques such as blanking and clipping. The proposed architecture is general and can be modified for comparison against other block coding schemes and higher-order modulations.
The inprocess interferometric techniques employed at British Aerospace enable diamond turning tools to be centred toaccuracies exceeding 10 microinches. In addition to Ogive error the interferograms ifiustrate higher ...
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ISBN:
(纸本)0819403814
The inprocess interferometric techniques employed at British Aerospace enable diamond turning tools to be centred to
accuracies exceeding 10 microinches. In addition to Ogive error the interferograms ifiustrate higher order effects such
as tool geometry, cuuer radius defects and wear.
A detailed analysis of diamond tool geometries was carried out and used to evaluate the resultant form defects arising
in components. This analysis was then used to develop software compensation which could eliminate the errors of
tool geometry. Simulation results showed that for the negative tool rakes used to machine infrared materials, software
compensation is essential.
A simple tool wear model was devised on the basis of wear being directly proportional to distance travelled. This
model was used to demonstrate the frequently observed phenomenon of extending a tools effective lifetime by
adjusting X-centre. Machine trials are currently underway to measure the reproducibility of wear effects .This will
determine the validity of our basic model and enable us to derive a more accurate solution.
Machine learning models can detect colorectal cancer with 93.5% sensitivity and 94.0% specificity based on diffuse reflectance spectroscopy (DRS) of superficial tissues. Extended DRS wavelength ranges improve differen...
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ISBN:
(数字)9781510647053
ISBN:
(纸本)9781510647053;9781510647046
Machine learning models can detect colorectal cancer with 93.5% sensitivity and 94.0% specificity based on diffuse reflectance spectroscopy (DRS) of superficial tissues. Extended DRS wavelength ranges improve differentiation between cancer and mucosa.
This paper shows that orthogonal coding and iterative decoding improve coding gain. The encoder maps a block of data into a block of bi-orthogonal codes. The decoder is a correlation receiver, which performs iterative...
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ISBN:
(纸本)9781424420292
This paper shows that orthogonal coding and iterative decoding improve coding gain. The encoder maps a block of data into a block of bi-orthogonal codes. The decoder is a correlation receiver, which performs iterative decoding to reduce the error and enhance the coding gain. To illustrate this concept, BER performance analysis of rate 1/2 orthogonal coding and iterative decoding is presented.
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