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RF收发器设计 RF收发器的框图示于图2。系统的要求如下: 1.频带902~928MHz,低功率(<0dBm)传输,直接变换FM。 2.数据率 57.6kbits/S,全双工。 3.数据译码/编码-AMI。 4峰值频偏-80kHz。 5.RF带宽-330kHz。 6.信道数-5。 7.信道间隔-500kHz。 8.接收器第-IF频率-73.7MHz。 9.接收器第二 IF频率-10.7MHz。 10.基准频率一11.2MHz, ± 10ppm,100kHz内部频率。 11.收发信道δ-21.9MHz。 12.系… 相似文献
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本文阐述了一个基本的S波段锁相式频率综合器,频率范围是2.30GHz-2.70GHz,频率步进为5MHz,相位噪声指标为£(10kHz)〈-95dBc/Hz,杂散抑制优于50d,输出功率大于10dBm。 相似文献
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超高频声表面波压控振荡器 总被引:3,自引:1,他引:2
本文介绍了UHF频段声表面波压控振荡器的原理、设计与实验结果。实验制作的UHF声表面波压控振荡器的工作频率为416MHz;压控频偏>400kHz;压控线性度为±3%;输出功率为7~10dBm。 相似文献
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利用集总参数等效电路模型计算了声表面波双模耦合谐振滤波器的频响.通过改变谐振器各个参量使滤波器指标满足要求.在ST石英基片上成功研制出中心频率228MHz,△f-3dB=150kHz,插损为3dB,阻带抑制小于-50dB的铁路专用寻呼机用滤波器。理论计算与实验结果一致。 相似文献
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本文利用集总参数等效电路模型计算了声表面波波导耦合双模谐振窄带滤波器的频率响应。讨论了谐振器各设计参量对滤波器性能的影响。在X-112°YLiTaO_3基片上实验制作了中心频率114MHz左右,Δf_(-3dB)分别为70kHz和40kHz的二极和四极窄带滤波器。对二极滤波器,阻带抑制小于一30dB;对四极滤波器,阻带抑制小于一50dB;匹配后插损3dB。理论计算与实验结果一致。 相似文献
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介绍宽频偏声表面波压控振荡器的实验研究。这种声表面波压控振荡器的工作频率为18.3~19.2MHz,分四个频段进行数字信号控制,每一频段的压控频偏均大于300kHz,单边带相位噪声优于-100dBc/Hz/1kHz,平均压控灵敏度大于50kHz/V。 相似文献
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《Vehicular Technology, IEEE Transactions on》1977,26(4):358-362
The results of a measurement program that was conducted to determine the attenuation of UHF radio signals penetrating to the inside of a typical house is presented. This program is part of a study to determine the feasibility of using direct satellite communication to disseminate disaster warning messages. The measurements were made in a manner to determine the building attenuation as a function of frequency, construction type, climate, and the elevation angle to the signal source. Attenuation measurements were made in five cities: Boulder, CO, Duluth, MN, Kansas City, MO Little Rock, AR, and Houston, TX. The measurements were made at three frequencies, 860 MHz, 1550 MHz, and 2569 MHz, using the ATS-6 geosynchronous satellite as a signal source. Most measurements were made on two principal house types; wood frame with a wood outside surface, and wood-frame with a brick-veneer outside surface. The average measured building attenuation for all houses and all frequencies was 6.3 dB. 相似文献
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Birkelund Y Klemetsen Ø Jacobsen SK Arunachalam K Maccarini P Stauffer PR 《IEEE transactions on bio-medical engineering》2011,58(11):3269-3278
We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for noninvasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2-D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 s with 20 Watts power for heating, and 10?s without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder. 相似文献
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Field tests related to planned mobile satellite systems (MSS) were performed, and results that add to the existing database of propagation measurements at L -band (1.5 GHz) are described. They are considered particularly useful in that propagation effects were studied systematically with repeated and controlled runs pertaining to different path elevation angles, road types, and path geometries defining shadowing and line-of-sight modes. In addition, simultaneous L -band and UHF measurements were performed for the purpose of establishing scaling factors applicable to previous UHF (870 MHz) results. The control of the experimental parameters was made possible by using a helicopter as the source platform and a mobile van which housed the receiver 相似文献
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Wilson W.J. Yueh S.H. Dinardo S.J. Li F.K. 《Geoscience and Remote Sensing, IEEE Transactions on》2004,42(9):1829-1835
L-band radiometer brightness temperature measurements of a saltwater pond were made as a function of salinity and temperature. A precision L-band radiometer with stability better than 0.1 K per day was used for these measurements. The L-band measurements are in good agreement with three dielectric constant models over a temperature range from 8/spl deg/C to 32/spl deg/C and a salinity range from 25-40 psu. Based on this experiment, these dielectric models will provide an excellent basis for the algorithm development and design of the future National Aeronautics and Space Administration Aquarius satellite mission. 相似文献
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Fading results related to land mobile satellite communications at L -band (1502 MHz) and UHF (870 MHz) are described. These results were derived from an experiment performed in a series of canyon passes in the Boulder, Colorado region of the USA. The experimental configuration involved a helicopter as the source platform, which maintained a relatively fixed geometry with a mobile van containing the receiver and data-acquisition system. An unobstructed line of sight between the radiating sources and the receiving van was, for the most part, also maintained. In this configuration, the dominant mechanism causing signal fading (or enhancement) is a result of multipath. The resulting fade distributions demonstrated that at the 1% and 5% levels, 5.5 and 2.6 dB fades were on the average exceeded at L -band and 4.8 and 2.4 dB at UHF, respectively, for a path elevation angle of 45°. The canyon results as compared with previous roadside-tree-shadowing results demonstrate that the deciding factor dictating fade margin for future land mobile satellite systems is tree shadowing rather than fades caused by multipath 相似文献
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敦煌辐射校正场,是我国为实现对地观测卫星传感器的辐射校正于1996年确定的陆地校正场.校正场实验的目的是准确把握场地的遥感光学特性,用于校正模式模型的建立以及实施卫星传感器的校正的同步观测.校正场实验是光学遥感基础实验过程较为系统和完整的范例之一. 相似文献
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Ting Ma Yee Hui Lee Stefan Winkler Maode Ma 《International Journal of Satellite Communications and Networking》2015,33(3):259-275
Video transmissions over satellite links are sensitive to signal fades because of rain, especially in the tropics. We performed a video‐streaming experiment over a satellite link for 24 days distributed over 1 year to investigate the effects of rain fade. Based on the measurements, models for the relationships between rainfall rate, power level, packet loss, and video quality are proposed. Furthermore, for both uplink and downlink channel, an adaptive closed loop power control algorithm, with a Proportional–Integral–Derivative controller is designed. This is used for the mitigation of the rain‐induced attenuation in order to guarantee a certain level of Quality of Service and Quality of Experience. Simulation results show the effectiveness of the proposed power control solution and its ability to sustain video quality levels in spite of rain fades. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献