扩频通信系统的中频数字化处理技术

介绍了一种应用于抗干扰综合信息系统的数字扩频通信系统 ,具体讨论了利用匹配滤波器完成PN码的快速捕获和利用谱估计完成载频的频移补偿的数字化处理技术 ,系统可以实现远距离的无线数据通信 ,文中给出了中频数字部分的实现原理以及软硬件框图。     

有关SSSA通信的相关技术

本文在加+1到M系列的正交系列集合基础上,提出一种同步多路接续频谱扩展通信方式.由于在通道之间完全同步的情况下不存在多路干扰,多路通信能力获得改善,功率控制方面的远近问题淡化了,外部干扰得到消除.通过理论分析,文中给出了通道间不同步时的平均误差概率,还讨论了在此情况下多路通信能力下降,功率控制方面的远近问题,以及通道间扩展码不能良好地同步的情况.     

一种Ka频段应答机

本文概述了上海机电产品和高新技术产品出口出现快速增长的新趋势,分 析其表现在出口产品结构、出口品种数量、出口企业类型和数量、出口贸易方式和 出口市场等方面的新特点,并从思想基础、产业基础、优化结构、基地建设、综合优 势和人才建设等方面总结其迅速发展的原因。同时,根据其在发展中存在的问题 提出相应的对策建议。     

Bancruptcy in a model of unsecured claims

Summary. We study a two periods model of incomplete markets with nominal assets unsecured by collateral, where agents can go bankrupt but there are no bankruptcy penalties entering directly in the utility function. We address two cases: first, a proportional reimbursement rule under bounded short sales and limited liability and, secondly, a nonproportional reimbursement rule, favoring smaller claims, without bounds on short-sales, but assuming that liability approaches total garnishment as debt goes to infinity. Received: September 10, 1998; revised version: August 6, 2001     

用STEL-2000A实现直接序列扩频收发系统

本文介绍了全数字式直接序列扩频芯片STEL－2000A的主要性能和用法，并以STEL－2000A为核心，辅以若干外围器件，构成了一个可用于野战信息传输的扩频收发系统。     

高速率外差式延迟锁定环及其多普勒捕获跟踪性能

分析了高速率外差式延迟锁定环的构成，环路模型、存在多普勒频移的捕获和跟踪性能，介绍了其电路设计和实验结果。     

Asymmetric structure of bid-ask spreads across the business cycle

This study argues that the structure of bid-ask spreads is asymmetric across the business cycle. During expansion, investors tend to be overconfident, leading to a higher spread component due to information asymmetry. On the other hand, during recession, the markets are more volatile, leading to a higher spread component due to order processing costs. With TAIEX futures contracts as a sample, it is found that the spread component due to information asymmetry is significantly higher in times of expansion than in times of recession, while the spread component due to order processing cost is significantly higher in times of recession than in times of expansion.     

A pairs trading strategy based on linear state space models and the Kalman filter

Among many strategies for financial trading, pairs trading has played an important role in practical and academic frameworks. Loosely speaking, it involves a statistical arbitrage tool for identifying and exploiting the inefficiencies of two long-term, related financial assets. When a significant deviation from this equilibrium is observed, a profit might result. In this paper, we propose a pairs trading strategy entirely based on linear state space models designed for modelling the spread formed with a pair of assets. Once an adequate state space model for the spread is estimated, we use the Kalman filter to calculate conditional probabilities that the spread will return to its long-term mean. The strategy is activated upon large values of these conditional probabilities: the spread is bought or sold accordingly. Two applications with real data from the US and Brazilian markets are offered, and even though they probably rely on limited evidence, they already indicate that a very basic portfolio consisting of a sole spread outperforms some of the main market benchmarks.     

直接序列扩频码分多址通信技术

本文论述了直接序列扩频码分多址通信技术(DS CDMA)。分析了系统原理、性能指标、地址码优选及生成等。从实际应用角度,对DS CDMA系统进行了较为全面的研究。文中给出了一些实验电路方框图,提供了部分实验结果。     

首要城市主导产业扩散效应研究：基于京津冀城市群的实证

为拟合京津冀城市群中核心城市的扩散与回流效应,利用2005-2019年京津冀城市群8个城市面板数据,构建以北京、天津为单核心或双核心的城市主导产业对外围城市关联产业以及高产值产业的扩散效应模型,分析得出3个结论：①首都对外围城市的回流效应导致外围城市产业发展低端化,并制约首都高端制造业发挥扩散效应;②首都与区域内中小型城市发展差距大,使第二大城市承接发展转移的中介功能得到提高,并通过与首要城市的连结促进承接发展转移的中介城市产业发展;③回流效应影响主导产业向外关联性拓展,导致外围城市产业发展仍需依托聚集经济,相同产业的大量集聚影响产业多样性,制约产业集群发展。基于此,建议通过提升外围城市公共服务与基础设施水平、加速主导产业升级以及强化第二大城市中介功能,提升城市间产业协作水平。