Modelling direct sequence pseudonoise(dspn) satellite reception with directional antennas in the dense scatterer mobile environment

A geometric propagation model is developed for simulating the reception of direct sequence pseudonoise (DSPN) satellite signals by a directional or omni antenna in the dense scatterer mobile environment. The model is first validated for narrowband signals by a direct comparison of both simulated cumulative signal strength statistics and simulated diffuse Doppler spectra with classical theory. The model is then used to predict fading statistics for DSPN signaling, either with omni or directional antennas. As expected, the mitigation of fading is closely related to the ratio of DSPN chip duration to delay spread of the scatterer medium for both the omni and directional antennas.     

Planar antennas for satellite reception

Direct broadcast satellite (DBS) reception requires a circularly polarized antenna with high gain and low axial ratio. Recently, various types of planar antennas have been studied and developed for DBS reception in the 12-GHz band. A summary is presented of properties and classification of planar antennas both commercialized and reported. The basic configurations, working principles, and performance of various planar antennas are described     

Effective bandwidth of DSPN signalling for mitigation of fading in dense scatterers

The use of direct sequence pseudonoise (DSPN) signalling to mitigate the fading caused by very dense scatterers in the mobile communication environment is explored for the specific case of a rectangular signal spectrum. A very simple and revealing relationship emerges between the variability of the signal strength and the signal bandwidth.<>     

Propagation measurements for satellite radio reception insidebuildings

Swept CW signals (from 700 to 1800 MHz) were received inside six buildings of brick, corrugated sheet-metal, wood-frame, mobile-home, and reinforced concrete-wall construction. A transmitter antenna was mounted outdoors on top of an 18 m tower to simulate a satellite, and a linearly scanned directional receiver antenna was used to probe the spatial, spectral, and temporal variability of the signal indoors. Levels were found to have much structure in the spatial and frequency domain, but were relatively stable in time. Typically, people moving nearby produced variations of less than 0.5 dB, whereas a person blocking the transmission path produced fades of 6 to 10 dB. Severe losses (17.5 dB) were observed in the concrete-wall building, which also exhibited the longest multipath delays (>100 ns). Losses inside a mobile home were even larger (>20 dB) and were independent of antenna orientation. The power-frequency distortion increased with the logarithm of the bandwidth, but could be reduced by moving to a position of higher power. Only the losses showed a clear frequency dependence, but they could be mitigated by moving the antenna     

2.6 GHz band satellite ISDB system for mobile reception

At the World Administrative Radio Conference (WARC)-92, the 2.6 GHz frequency band was allocated to a group of East Asian countries including Japan. This band is being studied for use in mobile multimedia broadcasting. This paper describes the outline of a system for 2.6 GHz band mobile multimedia broadcasting services, together with its requirements. In particular, the effects of the broadcasting signals attenuation due to shadowing by buildings and foliage, and the signals deterioration due to multipath propagation and fading, must be taken into account in order to realize the 2.6 GHz band system. This study considers the economic and technical constraints related to the modulation schemes, transmitting power, satellite antenna reflector aperture, the gain of the receiving antennas and the scale of the satellites. The configuration of satellite hardware systems based on the channel plan, channel bandwidth, and other specifications is investigated taking into account of these constraints. For example, a bit-rate of 4.8 Mbps can be provided when a 2-ton class satellite bus is utilized. This indicates that 2.6 GHz band services are technically feasible     

Investigation of signal variance,bit error rates and pulse dispersion for DSPN signalling in A mobile dense scatterer ray tracing model

The canonical ray tracing model of R. H. Clarke is used to validate the concept of mitigation bandwidth as used to predict DSPN spread spectrum signal variability at a mobile receiving antenna in dense scatterers. Illustrative examples of chip pulse dispersion are presented, and bit error rate performance is explored under the assumption of slow fading. The pulse dispersion is seen to pose potential obstacles to any eventual chip timing extraction and radio-location ranging functions. Serendipitously, the performance of a DSPN embodiment of a 180° DPSK data link is seen to approximate closely that of a corresponding narrowband Rician fading link, even though no specular signal component is available to the DSPN link. The parameters of the equivalent Rician link are easily predicted from those of the DSPN link.     

Bit error outage for diversity reception in shadowing environment

This letter addresses the problem of evaluating the bit error outage (BEO), i.e., the outage probability defined in terms of bit error probability, in a Rayleigh fading and shadowing environment. We consider coherent detection of binary phase-shift keying with maximal ratio combining (MRC). As an example application, the BEO in a log-normal shadowing environment is analyzed and the improvement in terms of BEO due to MRC is quantified in different shadowing environments.     

一种可用于北斗卫星信号接收的微带天线设计

基于微带天线技术提出一种应用于北斗导航系统的新型天线设计。该天线采用FR-4衬底上的弯曲微带和含有通孔的微带贴片实现。天线的小型化设计可使其更好地应用于北斗导航之中。与此同时,与常规的天线相比,该天线拥有更好的反射系数。实验结果表明,这里设计的天线非常适用于北斗导航系统,进而可应用于车辆导航系统之中。     

Impact of spreading bandwidth on RAKE reception in dense multipathchannels

Spread spectrum (SS) multiple access techniques have been proposed for third generation broadband wireless access. We develop an analytical framework to quantify the effects of spreading bandwidth on SS systems operating in dense multipath environments in terms of the receiver performance, receiver complexity, and multipath channel parameters. In particular, we consider wide-sense stationary uncorrelated scattering (WSSUS) Gaussian channels with frequency-selective fading. The focus of the paper is to characterize the combined signal of the RAKE receiver fingers tracking the strongest multipath components. Closed form expressions for the mean and the variance of the total RAKE receiver output signal-to-noise ratio (SNR) are derived in terms of the number of RAKE fingers, spreading bandwidth, and multipath spread of the channel. The proposed problem is made analytically tractable by transforming the physical RAKE paths into the virtual path domain. A representative result indicates that for SS systems with 5 MHz signal bandwidth operating in a channel with constant power delay profile having 5 μs spread, the average SNR gain from increasing the number of RAKE fingers from one to three is 3.8 dB and from three to five is 1.5 dB. Furthermore, the reduction in the variation of SNR is 1.1 dB and 0.4 dB for the same increments in the number of fingers     

Increasing the up-link CW interference immunity of non-coherent direct sequence pseudonoise (DSPN) reception with on-board processing

The adaptive threshold A/D converter is by now a familiar technique for increasing the CW interference immunity of coherently detected direct sequence pseudonoise (DSPN) spread-spectrum signals, especially where the frequency of the CW interferer may be changing so rapidly and over such a large portion of the signalling bandwidth that well known spectrum excision techniques prove ineffective. The present paper extends the theory to the case of non-coherent reception of direct sequence pseudonoise (DSPN) signals. The A/D converter is found to perform well in both CW and Gaussian interference. Conversion gain is seen to persist even if the interference is intentionally pulsed at an optimally reduced duty factor (from the interferer's point of view) in the attempt to confuse the adaptive threshold. The specific case of 32-chip data symbols is treated, wherein the adaptation is applied strictly to individual symbols. In some cases these restrictions will actually improve performance.     

Study of the diversity reception in a forested environment

The feasibility of using spatial diversity within a foliage environment is examined in this letter. It is found that the presence of lateral waves in the forested environment is the main reason for the highly dependent multi-propagation paths. These highly dependent multipaths produce a high spatial correlation between diverse receptors when used in a forested environment. The mutual coupling effects between the receptors are analyzed through the study of the antennas? mutual impedance and angular pattern of the receiving array. It is founded that, in the forested environment where there is a large angular spread of multipaths, when spatial diversity is used, the coupling induced change in the antenna pattern becomes a dominant factor. This lowers the correlation property between the multiple receptors.     

A metal plate Fresnel lens for 4 GHz satellite TV reception

A metal plate Fresnel lens antenna with aperture dimensions12 ft times 12 ft, and fed by a pyramidal horn has been built for satellite TV reception at 4 GHz. When used with a commercial receiver equipped with a 120K LNA it produced good video pictures from the geostationary satellite Satcom F3. We believe this to be the first application of a Fresnel lens antenna for ground-based satellite TV reception.     

SJ／T11387-2008《直播卫星电视广播接收系统及设备通用规范》概要

本规范依据GD/JN 01-2007<先进卫星广播系统一一帧结构、信道编码与调制>并参考国家广播电影电视总局科技司2008年4月份发布的<中国广播电视直播卫星村村通系统技术体制白皮书>(2008)相关要求制定,适用于中国广播电视直播一期工程.     

网络存储器在卫星小站数据接收上的应用

文章对网络存储器在卫星小站数据接收上的应用进行了论述,对网络存储器在数据存储上的优点进行了相关介绍,并描述了架设FTP服务器的方式方法和卫星小站软件的相关设置,以此来实现对卫星小站数据接收存储起到降低存储设备成本的目的。     

Geometric correction algorithms for satellite imagery using abi-directional scanning sensor

High-precision geometric correction algorithms for a bidirectionally scanned image that are based on separate geometric models according to the distortion characteristics are described. The modeling accuracy is evaluated through the use of simulated and observed Landsat Thematic Mapper (TM) images. TM images include a discontinuous distortion and a high-frequency distortion due to attitude fluctuations and bidirectional scans. A geometric model consisting of a single-valued-function is used to correct these distortions. The iteration calculation of the mapping cannot be converged, resulting in an enormous amount of calculation and data. Therefore, geometric models consisting of separate geometric models of the bidirectional scans and frequency components are proposed     

CATV中卫星电视接收匹配问题的理论分析与计算

在ＣＡＴＶ中卫星电视接收匹配是实际工作中的技术问题,特别是在接收ＳＣＰＣ方式下行的数字压缩节目时,由于其下行信号比模型拟信号低１０ｄＢ左右,直接影响接收信号的质量,所以有必要在对此理论上进行详细尽的分析与匹配计算。     

Low-cost approach for steerable flat-plate antenna design withapplication to reception of broadcasting from satellite

A novel design approach for circularly polarised flat-plate antennas has been developed. The proposed antenna is of multilayer construction, rotatable about its normal axis, and comprises a polarisation convertor, an array of elements and a beamforming network. In one potentially large application, the reception of satellite broadcast signals in the 12 GHz band, it can be mounted flat on the most suitable wall of an arbitrarily orientated house and be readily aligned     

Symbol-aided plus decision-directed reception for PSK/TCMmodulation on shadowed mobile satellite fading channels

The symbol-aided (SA) synchronization concept developed by Moher and Lodge (1989) is applied to the MSAT channel modeled with a shadowed Rician process. Simulation data demonstrate that it can track the severe phase jitter encountered on the fading channel free of the false lock which plagues conventional techniques. The algorithm multiplexes known symbols into the data stream, establishing an absolute reference free of decision errors that is used to estimate the fading phase. An improvement to the SA algorithm which extracts phase information from the data-bearing symbols is proposed. It is found that the new technique is more effective for larger K. The improved algorithm is referred to as symbol-aided plus decision-directed (SADD) phase estimation. A system employing SADD phase estimation, trellis-coded modulation, interleaving, and amplitude weighting within the Viterbi decoder yielded the best BER performance on the shadowed MSAT channel considered     

Air interfaces for satellite based digital TV broadcasting in the railway environment

This paper deals with the analysis of possible air interfaces to be employed in order to provide digital TV services to high speed trains via satellite. This turns out to be an extremely challenging issue, since in addition to traditional impairments characterizing the land mobile satellite channel, one has to face the presence of frequent tunnels, whose duration can easily reach several kilometers, and the presence of a variety of peculiar obstacles, such as electrical trellises and posts with and without brackets, which may result in frequent and deep fades. A large variety of possible solutions, based on standardized air interfaces with proper modifications, are analyzed by means of extensive software simulations, showing that effective solutions can be devised. Some consideration concerning the deployment of terrestrial gap-fillers to bridge the satellite connectivity inside long railway tunnels, large train station and within dense urban areas are also briefly addressed.