基于FPGA的S模式应答机设计

针对现有S模式应答机体积、重量过大,不适用于小型通用航空飞机尤其是无人机的现状,设计了一种用于通用航空的新型S模式应答机。系统采用全FPGA设计,用状态机的方法实现编码、解码功能,使用脉冲宽度滤波的方法对通讯信号进行了数字滤波。实验结果表明：该系统工作稳定,实现了对询问信号的应答,符合RTCA的DO-181D及DO-260B标准;并且具有体积小,重量轻,成本低等特点,适用于内部空间有限的各种小型通用航空飞行器。     

一种新型的海上遇险报警和搜索营救系统

本文介绍了一种由现有舰载或机载导航雷达和安装在救生艇(筏)上的搜索营救应答机组成的一种新型的海上遇险报警和搜索营救系统。阐述了系统的工作原理及信号编码格式,着重讨论了搜索营救应答机的指标论证、精度分析及其设计要点和实现方案。最后指出了该系统的应用前景。     

基于ISO 15693的RFID中间件反冲突算法设计与实现

反冲突作为射频识别(radio frequency identification,RFID)技术的基础,引起了各种相关机构的重视,各种读写器与标签之间的反冲突算法层出不穷,但由于算法的复杂性,许多读写器往往只具有冲突探测功能,而没有实现完全的反冲突。利用ISO15693—3协议中关于冲突探测机制和反冲突算法描述,设计并实现了对读写器进行反冲突控制的算法。实验表明：该反冲突控制算法达到了高效反冲突的目的。     

光通信用10Gbit/s Transponder的设计

本文分析了在高速光模块设计中介质损耗和微带结构对信号的影响,并对PCB中信号串扰模型的参数进行了计算.解决了高速光模块设计的一些关键问题,设计出满足MSA的300-pin transponder,并对模块进行了一系列性能和指标测试.测试结果表明,该模块完全满足SDH/SONET(STM-64/OC-192)以及10G Ethernet应用要求.     

无源UHF RFID电子标签模拟前端设计

提出了一种符合ISO/IEC 18000-6B标准的高性能无源UHF RFID电子标签模拟前端,在915MHz ISM频带下工作时其电流小于8μA.该模拟前端除天线外无外接元器件,通过肖特基二极管整流器从射频电磁场接收能量.该RFID模拟前端包括本地振荡器、时钟产生电路、复位电路、匹配网络和反向散射电路、整流器、稳压器以及AM解调器等.该芯片采用支持肖特基二极管和EEPROM的Chartered 0.35μm 2P4M CMOS工艺进行流片,读取距离大于3m,芯片面积为300μm×720μm.     

Modeling the retention of rumen boluses for the electronic identification of goats

We constructed a regression model to estimate the retention of electronic boluses in goats. With this aim, 2,482 boluses were administered to goats from dairy (Murciano-Granadina, n = 1,326; French Alpine, n = 381) and meat (Blanca de Rasquera, n = 532) breeds. A total of 19 bolus types made of materials (ceramic, plastic tubes filled with concrete or silicone, and ballasts) differing in their specific gravity (SG) were used, thereby obtaining a wide variation in bolus features: diameter (9 to 22 mm), length (37 to 84 mm), weight (5 to 111 g), volume (2.6 to 26 mL), and SG (1.0 to 5.5). Each bolus contained a half-duplex glass encapsulated transponder (32 × 3.8 mm) and was administered using adapted balling guns. Murciano-Granadina and Blanca de Rasquera goats also wore 2 visual plastic ear tags: V1 (double flag, 5.1 g) and V2 (flag-button, 4.2 g). No data on ear tags in French Alpine goats was available. Bolus and ear tag retention [(retained/monitored) × 100] was recorded for at least 1 yr. Dynamic reading efficiency [(dynamic reading/static reading) × 100] was also evaluated from 1,496 bolus readings. No administration incidences or apparent negative behavior or performance effects were observed for any bolus type. Static reading efficiency of retained boluses was 100%, except for the prototypes with metal ballasts, which yielded a 93.3% reading efficiency. Retention of metal-ballasted boluses was confirmed using x-ray equipment. Excluding ballasted boluses, a 99.5% dynamic reading efficiency was obtained. Ear tag losses were 6.5% for V1 and 3.7% for V2, ranging from 3.2 to 7.8% depending on ear tag type and goat breed. Bolus retention varied (0 to 100%) according to their physical features. Obtained data allowed the fitting of a logistic model of bolus retention rate according to bolus volume and weight (R² = 0.98); the SG was implicitly considered. Estimated weight and SG to produce medium- (15 mL) and standard-sized (22 mL) boluses for 99.95% retention rate in goats were 73.0 and 94.1 g, and 4.87 and 4.28, respectively. Mini-boluses are not recommended, as none of the available radio translucent materials reach the required SG. In conclusion, increase of SG was fundamental to optimize bolus retention. Medium-sized boluses (10 to 15 mL; SG 5.8 to 4.9) for early administration and efficient retention in adult goats could be produced, thereby addressing the problem of using proper boluses for goat identification.     

多用途射频IC卡应用系统的设计

射频识别是最近几年兴起的一门新的自动识别技术,它利用无线射频方式在读写基站和应答器之间进行非接触双向通信,以达到目标识别和数据交换的目的.文中介绍了由一种典型的射频识别IC卡-TEMIC公司的TK5550卡组成的多用途应用系统的设计方案.     

ATC A/C模式应答机编码电路设计

本设计实现ATC A/C模式应答机编码电路的设计。通过控制面板可以控制系统的工作状态,当接收到的询问信号与控制面板上所置定的模式相符时,应答机产生相应的应答信号。如果是A或B模式询问,则将控制面板上输入的飞机识别代码进行编码后输出;如果是C模式询问,则将来自大气数据计算机的飞机气压高度进行编码后输出。编码电路还具有自测试功能,由自身内部产生模拟询问信号,以使译码和编码电路工作,从而可以检测系统是否可以正常工作。     

数字应答机相参转发的实现

针对数字应答机中相参转发的技术问题,提出了改变直接数字频率合成(DDS)频率控制字或相位累加器溢出值实现相参转发的方法,并对转发性能、资源需求进行了分析比较,结果表明,在同等条件下改变相位累加器溢出值的方法性能稍优,但消耗的逻辑资源显著减少.该方法将DDS溢出值设置为与转发比相关的常数,避免了利用乘法器进行实时运算的过程,能有效实现高精度转发,且消耗资源少,转发比可任意设置.该方法已成功在多个工程中应用,满足测量系统精度的要求.     

航管应答机中多模式大功率开关设计

根据航管应答机的应用需求,基于PIN 二极管设计了一款低插损、高隔离度、多模式的国产大功率开 关;理论分析了电路结构,介绍了器件选型以及锡金焊料烧结和金丝键合工艺设计;通过在设计中切换不同通道,实 现了不同功率模式的输出,利用ADS 软件对电路进行仿真和优化,进行了小信号和大信号下的测试。实物测试表 明,在1~2 GHz 频带内,开关插损<0. 5 dB,隔离度>60 dB,切换时间<500 ns,功率容量可达1000 W(峰值,占空比 4%),指标优异,可靠性高,具有很高的实用价值。