闡述了軌道交通列車定位技術(shù)。介紹了在軌道交通系統(tǒng)中列車定位技術(shù)的功能，國內(nèi)外軌道交通中主要采用的列車定位方法，重點論述了幾種主要定位技術(shù)，并從定位精度、閉塞制式、維護投資成本、抗干擾等方面進行分析比較。提出目前軌道交通定位技術(shù)應(yīng)綜合運用，取長補短，多種方法相互融合，才能滿足軌道交通中對安全可靠性的要求。
Abstract:
Rail train positioning technology is described. The paper introduces the funetions of the train positioning technology in the rail transit system， the main methods of train positioning do mestic and international rail， and focuses on several key methods， analyzes and compares from the positioning accuracy， block system, maintenance and investment cost， interference and so on， suggested that the current rail positioning technology should be integrated use of positioning method of meriging， learn from each other， to meet the reliability requirements of rail safety.
In this project we analyze and design the minimum mean-square error (MMSE) multiuser receiver for uniformly quantized synchronous code division multiple access (CDMA) signals in additive white Gaussian noise (AWGN) channels.This project is mainly based on the representation of uniform quantizer by gain plus additive noise model. Based on this model, we derive the weight vector and the output signal-to-interference ratio (SIR) of the MMSE receiver. The effects of quantization on the MMSE receiver performance is characterized in a single parameter named 鈥漞quivalent noise variance鈥? The optimal quantizer stepsize which maximizes the MMSE receiver output SNR is also determined.
The most straightforward approximation is the standard Gaussian approximation, where the MAI is approximated by a Gaussian random variable. This approximation is simple, however it is not accurate in general. In situations where the number of users is not large, the Gaussian approximation is not appropriate. In-depth analysis of must be applied. The Holtzman?s improved Gaussian approximation provides a better approximation to the MAI term. The approximation conditions the interference term on the operation condition of each user.
Spread-spectrum techniques are methods by which electromagnetic energy generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure communications, increasing resistance to natural interference and jamming, and to prevent detec
problem of blind demodulation of multiuser
information symbols in a high-rate code-division multiple-access
(CDMA) network in the presence of both multiple-access interference
(MAI) and intersymbol interference (ISI) is considered.
In 揚erformance of multi-carrier DS CDMA Systems?we apply a multi-carrier signaling technique to a direct-sequence CDMA system, where a data sequence multiplied by a spreading sequence modulates multiple carriers, rather than a single carrier. The receiver provides a correlator for each carrier, and the outputs of the correlators are combined with a maximal-ratio combiner. This type of signaling has the desirable properties of exhibiting a narrowband interference suppression effect, along with robustness to fading, without requiring the use of either an explicit RAKE structure or an interference suppression filter.
The TAS3204 is a highly-integrated audio system-on-chip (SOC) consisting of a fully-programmable, 48-bit digital audio processor, a 3:1 stereo analog input MUX, four ADCs, four DACs, and other analog functionality. The TAS3204 is programmable with the graphical PurePath Studio? suite of DSP code development software. PurePath Studio is a highly intuitive, drag-and-drop environment that minimizes software development effort while allowing the end user to utilize the power and flexibility of the TAS3204’s digital audio processing core.
TAS3204 processing capability includes speaker equalization and crossover, volume/bass/treble control, signal mixing/MUXing/splitting, delay compensation, dynamic range compression, and many other basic audio functions. Audio functions such as matrix decoding, stereo widening, surround sound virtualization and psychoacoustic bass boost are also available with either third-party or TI royalty-free algorithms.
The TAS3204 contains a custom-designed, fully-programmable 135-MHz, 48-bit digital audio processor. A 76-bit accumulator ensures that the high precision necessary for quality digital audio is maintained during arithmetic operations.
Four differential 102 dB DNR ADCs and four differential 105 dB DNR DACs ensure that high quality audio is maintained through the whole signal chain as well as increasing robustness against noise sources such as TDMA interference.
The TAS3204 is composed of eight functional blocks:
Clocking System
Digital Audio Interface
Analog Audio Interface
Power supply
Clocks, digital PLL
I2C control interface
8051 MCUcontroller
Audio DSP – digital audio processing
特性
Digital Audio Processor
Fully Programmable With the Graphical, Drag-and-Drop PurePath Studio? Software Development Environment
135-MHz Operation
48-Bit Data Path With 76-Bit Accumulator
Hardware Single-Cycle Multiplier (28 × 48)
Device-to-device(D2D) communications are now considered as an integral part of future 5G networks
which will enable direct communication between user equipment (UE) without unnecessary routing via
the network infrastructure. This architecture will result in higher throughputs than conventional cellular
networks, but with the increased potential for co-channel interference induced by randomly located
cellular and D2D UEs.
Communication today is not as easy as it was in the past. Protecting numerous com-
munication services, which are operating in the same or adjacent communication
channels, has become increasingly challenging. Communication systems have to be
protected from both natural and manmade interference. Electromagnetic interfer-
ence can be radiated or conducted, intentional or unintentional.
