共查询到20条相似文献,搜索用时 125 毫秒
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针对传统帧同步器只能对固定帧格式的数据进行帧同步的缺点,提出一种基于现场可编程门阵列(FPGA)的帧同步方案,用户可根据实际需求通过上位机软件配置帧长、帧同步字等参数,实现对不同帧结构的PCM遥测数据进行帧同步。该方案采用了参数可调的同步容错及前后方保护机制,提高了帧同步的可靠性和稳定性。给出了帧同步方案的工作原理,以及关键技术的实现方法,在实际应用中对其同步性能进行分析,测试结果表明该方案对不同帧结构的数据均可实现帧同步。 相似文献
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为了提高北斗接收机弱信号跟踪灵敏度,解决北斗信号中NH码跳变和比特跳变频繁限制相干积分时间加长的问题,提出一种基于相干积分的北斗弱信号优化跟踪算法.首先,利用分组比特匹配方法进行位同步/帧同步算法优化,实现全比特相干积分;然后,采用最大似然法对数据比特值进行估计和解码,实现跨比特相干积分;最后,利用卫星导航系统开发平台开展仿真验证,分别实现了20ms和40ms时间的相干积分,结果表明,采用40ms积分后信噪比提升约16dB.所提出算法能够稳定可靠地实现北斗信号位同步和帧同步功能,并快速地剥离NH码,消除数据比特跳变和NH码相位变化的影响,可实现全比特相干积分和跨比特相干积分,有效提高北斗弱信号跟踪灵敏度. 相似文献
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针对DVB-S2信号载波频率偏移较大时的帧同步问题进行了研究。为提高低信噪比下的检测概率, 通过对原算法中能量纠正项的分析和比较, 提出了一种改进的帧同步算法, 并结合帧头物理层信令部分的编码特性, 提出了一种新的DVB-S2帧同步策略。该策略将帧头物理层信令数据进行两次共轭差分, 经过相对应的累加后作为新的输入数据用于帧同步, 增加整体同步码字的长度。仿真实验表明, 与原始算法相比, 结合使用新的策略和算法能够获得更高的检测概率, 适用于大载频偏移和低信噪比条件。 相似文献
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李爽 《计算机测量与控制》2023,31(11):142-150
对于出口国际的遥感卫星移动接收站,站监控软件负责完成整站任务规划与调度、轨道预报、数据管理以及设备集中监视和控制;针对有人值守无人操作的遥感卫星移动接收站的运行特点和任务需求,制定遥感卫星数据接收优先级和任务筛选规则,按需采集地理位置信息,定时通过以太网获取最新卫星轨道数据,自动规划遥感卫星数据接收任务,利用任务节点矩阵驱动数据接收流程,自动化控制和调度移动站内各系统完成遥感卫星数据接收工作;在实际应用中提高了遥感卫星移动站的利用率,避免了人工操作降低系统运行效率,保障了遥感卫星数据接收的全覆盖,实现了有人值守无人操作的全自动化运行。 相似文献
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提出了基于特殊导频码的OFDM系统的盲帧同步算法。该算法不需要数据辅助,首先利用FFT窗跨界时产生的能量泄露实现了对符号定时参数的估计,然后对同步后的OFDM信号进行解调得到信息序列,最后利用3阶相关函数(TCF)对序列进行处理从而提取出同步码以实现帧同步。仿真结果表明,该算法在低信噪比下具有较好的同步能力和较高的同步精度。 相似文献
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飞行试验中 ,需要对地面数据采集与处理系统设备进行状态设置 ;飞行试验结束后 ,要读取已经存储的数据记录中的参数 ,这就需要设计一套数据库系统专门对上述两个问题进行管理和设置。该文对飞行试验图形监视系统数据库的结构设计进行了探讨 ,并分析了数据库管理界面开发的可行性 相似文献
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《Control Engineering Practice》2004,12(1):87-98
In this paper, two practical thrusters calibration approaches are proposed, discussed and evaluated through in-orbit flight tests. In the single thruster pulse method, one thruster is commanded to fire for a fixed period to produce a pulsed external torque disturbance. Reaction wheels are used to stabilize the satellite subject to the thruster firings. Magnetorquer coils are switched off during the experiment to reduce the external magnetic disturbances. A preliminary test without thruster firing is used to record the unmodelled external disturbances. The resulting satellite attitude responses and reaction wheel status subject to the thruster firings are recorded for calibration analyses. A batch filter algorithm is developed to estimate the thruster torque coefficients from the recorded experimental data. In the autonomous method, a repetitive torque disturbance (by using a reaction wheel) is exerted to the stabilized satellite, the cold-gas thrusters are then applied in an on-board control system to stabilize the satellite attitude. By recording the known attitude disturbances and the thruster controller outputs, a recursive least-squares algorithm is used to process the recorded data and to estimate the thruster parameters. Both simulation and in-orbit test results are presented to evaluate the performance and design objectives. The in-orbit test results converge to the same values using the two different approaches. 相似文献
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这篇文章主要介绍采用功率探测仪方式的注入式仿真系统对波束方向地面探测试验系统进行验证的系统设计和软、硬件控制与实现;通过向注入式仿真系统输入模拟目标星在不同位置发射的信号功率,以及目标星在平台坐标下的角度和位置信息,一方面确定地面探测试验系统技术方案的可行性和检测相关设备的性能,另一方面验证对目标星发射天线主波束方向的探测是否满足精度要求;通过仿真试验证明该注入式仿真系统不仅使用方便、节约成本,而且通过控制相关仪器设备能够准确记录地面探测试验系统对目标星仿真数据的计算信息,进而实现验证。 相似文献
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Jeffrey Shaman Mark Cane Alexey Kaplan 《International journal of remote sensing》2013,34(17):3735-3748
Using satellite estimates of snow depth, we examine the interannual variability of the monsoon rains of Bangladesh, an area greatly affected by land surface hydrological processes including Himalayan snowpack size, snowmelt river flooding, and Bay of Bengal storm surge. For the twentieth century, we found Bangladesh monsoon rainfall (BMR) to be uncorrelated with the All‐Indian Monsoon Index. This result is consistent with previous findings for shorter time records. We next used a short 9‐year record of satellite estimates of April snow depth for the Himalayan region and concurrent seasonal El Niño–Southern Oscillation (ENSO) conditions in the equatorial Pacific to develop an empirical model that explains a high percentage of BMR interannual variability. Inclusion of late spring river discharge levels further improves the empirical model representation of BMR for June–September. These results, though with a limited length satellite record, suggest that BMR interannual variability is constrained by concurrent ENSO conditions, spring Himalayan snowpack size and land surface flooding. The same results could not be obtained from analyses using satellite estimates of snow cover. These findings stress the need for development of a quality longer record of satellite estimated snow depth. The twentieth‐century analysis also indicates that BMR should be considered independently of Indian monsoon rainfall. 相似文献
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大型远洋捕捞船、运输船及其驻岛部队的补给船只经常航行在我国遥远的海疆,需要能够看到国内卫星电视节目并能够及时得到气象、台风等信息。若将气象、台风等数据搭载到卫星电视信号上,在船上安装一台卫星电视接收设备,在收看电视节目的同时,也能接收搭载数据信息的电视信号并能从电视信号中将所需的数据信号提取出来,通过对接收电平和信噪比的估算,判断0.7米天线是否能够接收电视信号。 相似文献
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Output-only system identification is a very attractive technique for its implementation simplicity. However, it requires long records to validate the white-noise assumption of the excitation, mainly under transient forced vibration. Alternatively, free-vibration record segments can be selected before the identification process. This improves the accuracy, even using less data, but it requires human intervention or input recording. In the present paper, an approach is proposed for accurate system identification from short output-only records of vibration induced by transient excitation, without human intervention. The approach is based on a novel heuristic search algorithm to find free-vibration record segments, which is fully automatic and it handles the possibility of free-vibration absence. Tests with real-life data from Structural Health Monitoring (SHM) of a bridge showed that the free-vibration finding improves the accuracy of the modal parameter estimates up to ten times, as compared to using record segments starting at the response peak. The proposed approach drastically reduces the need to transmit large amounts of data, which impacts on hardware requirements of SHM implementations. 相似文献
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A food recording electronic device to simplify the collection of dietary data is described. The need for a subject to maintain a quantitative account of food intake, and for a dietitian to subsequently code this record prior to computer analysis, are both eliminated using this approach. In combination with an electronic kitchen balance, the recorder, which is based upon a single-board computer (SBC) and special keyboard, enables the weight, food type and time of consumption of each food to be recorded automatically in response to simple key entry. The resident program, transparent to the user, allows data from surveys lasting up to three weeks to be stored for subsequent serial downloading to a host computer. 相似文献
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WinCC Global Script在数据存储中的应用 总被引:5,自引:0,他引:5
为了解决监控系统中过程数据的处理,通过编写WinCC的G16bal Script,提出了一种新的过程数据记录方法。将过程变量按记录时间生成日志文件和过程数据记录文件。使得对于过程数据的处理更为方便。通过自动生成的索引文件用户可以随时根据需要添加、删除记录的变量,而不需改动Global Script,使得该方法具有扩展性和可移植性。通过G1obal Script处理数据,使得数据采集周期由500ms缩短到250ms。该数据记录方法在实际工程应用中取得了良好效果.可以推广和移植到其他监控系统的数据记录中。 相似文献
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