查询词典 radio frequency

In order to realize the compatible communications system between digital TETRA and analogy MPT1327. Communications protocol between digital radio and control center is defined. Emergency call software flow for TETRA and MPT module is designed, and also state information sending and receiving for TETRA and MPT module is designed in this communication system. By comparing several solutions, switch methods between analogy TETRA communications and digital TETRA communications are designed including manual-switch and soft-switch. In the article, coding module of receiving and sending equipments in TATT analogy TETRA communications is described, so that it can be compatible with NOKIA network equipments and it also can improve the availability rate of the trunk system. In order to realize the integration of digital TETRA communication and analogy MPT1327 communications, double- frequency antenna system is researched.

通过几种车载电台解决方案比较，设计了相应的模拟集群通信系统与数字集群通信系统的切换方法，其中包括人工切换和软切换，实现了模拟与数字集群兼容的一体化移动列车调度电台解决方案；为了实现数字集群通信系统与模拟集群通信系统以及NOKIA与TAIT模拟集群通信系统之间的相互兼容，设计了新的数字车载电台与控制中心之间的通信协议；系统设计了用于数字集群通信模块的紧急呼叫通讯流程，以及设计了用于模拟集群通信模块状态信息发送与接收流程，以满足列车无线调度的运营要求；论文还论述了对TAIT模拟集群收发设备编码模块的改造，使之能与NOKIA的集群设备相兼容，提高了集群设备的利用率，为在NOKIA模拟集群通讯模块停产后寻找了一种可替代的兼容解决方案；为了实现数字集群通信系统与模拟集群通信系统设备的综合，论文还探讨了本工作所需专用的双频段的天线系统。

A method of keying a radio carrier for transmitting binary data or teletypewriter signals, which consists of shifting the carrier frequency in one direction for a marking signal and in the opposite direction for a spacing signal.

对无线载波频率进行键控用于传输二进制数据或电传打字机信号的一种方法。这种方法是在某一方向上对载波频率进行漂移用于传输标记信号，而在相反方向上对载波频率进行漂移用于传输空格信号。

Communications functions range from basic ultrahigh/very high frequency to single channel ground and airborne radio system and Have Quick. The aircraft also supports several datalinks for communications and situational awareness such as Link 16 and a specialized multi-array datalink for stealthy communications between aircraft.

通信系统功能有甚高频/超高频频段通信，单通道空地无线电系统以及"Have Quick"跳频通信。F-35还支持多种通信和战场感知数据链，例如16号链以及一条用于战机间保密通信的多阵列数据链。

Frost turned on the radio controls and tuned them to a very high frequency.

霜冻打开无线电操纵和调谐的他们对非常高的频率。

Because light has a very high frequency, it can carry a lot more data than microwaves or radio waves, which have much lower frequencies.

由于光的频率非常高，可以比频率低很多的微波或无线电波承载更多的数据。

Because light has a very high frequency, it can carry a lot moredata than microwaves or radio waves, which have much lowerfrequencies.

由于光的频率非常高，可以比频率低很多的微波或无线电波承载更多的数据。

By time-varying filtering, we realize the signal selectivity and interference suppression, especially for the signals with time-varying power spectrum. It is shown herein that conventional eigenstructure based methods are lower dimensional special case of the time-frequency subspace fitting method. The closed-form array response estimation algorithms for blind source separation in wireless communication is also developed in the dissertation by exploiting the data structure of second-order statistics of the array output in the presence of multipath. The proposed method achieves array response estimation with little constraint on signal property and propagation environment such as scatters or angular spread. Moreover, the array utilized here can be of arbitrary geometry and even uncalibrated. Since the closed-form solution is obtained, no misconvergency may occur and large amount of computation can be saved. The equivalent feed model and corresponding optimization designation are proposed to realize the downlink multi-user selective transmission. By coherent and non-coherent superposition of the electromagnetical field, multiple beams can be formed using a single array, so that each co-channel user signal is transmitted in each beam and will not interfered with each other. The proposed system scheme implements the digital beamforming and the channel allocation in the base band, therefore is suitable for the utilization of the radio software technology. The feasibility and effectiveness of the proposed model are proved by the RF experiment.

在窄带条件下，GSC－SSF方法还可以提高阵列的虚拟孔径，从而提高估计的性能；可以证明，Cyclic DOA 和SC-SSF方法可看作该方法的特例或近似； 3、提出了二维GSC－SSF方法和宽带谱相关DOA矩阵方法，利用信号的循环平稳特性解决了宽带条件下二维 DOA 估计问题，并具有阵元数少、计算量较小的特点； 4、提出了时频子空间拟合和宽带时频DOA估计算法，将联合时频分析的理论和方法引入到阵列信号的空间谱估计研究中，利用时变滤波实现信号选择性测向和干扰抑制，特别适合于谱时变信号；可以证明传统特征结构法可看作是时频子空间拟合方法的特例； 5、提出了多用户环境下阵列响应的估计方法——CARE方法，该方法对信号结构和传播参数（主要是散射源分布与角度散布）的约束较少，适用于各种几何结构的阵列甚至未校准的阵列，能够直接得到阵列响应的闭式解，因此计算量小、稳健性好，不存在收敛问题； 6、提出了针对多用户下行选择性发送的阵列等效激励模型、优化设计方法及其系统实现方案，通过空间场的相干叠加与非相干叠加使得单一阵列能够形成多个波束，并保证各波束内的用户信号各不相同且相互干扰最小；其系统方案具有在基带实现数字波束成形、信道分配并便于软件无线电实现的特点，其有效性已得到外场实测数据的证实。

On the silicon substrate an epitomical layer is made,where IC components are formed subsequently.In an CVDprocess,the silicon substrates places in a vacuum crystal tube are first heated to 1,600°C by high-frequency radio power and then H⒉Cl⒉Si and certain gaseous compounds of As or P is injected into the tube to make a deposit of several um on their surface.Ions of As or P are impurity deliberately added to the singl-crystalline silicon structure to supply electrons that transmit "negative"current in the silicon crystals,which is called n-type silicon.Bcan be added as impurity to produce p-type silicon that supplies holes for transmitting "positive"current.Whether a p--type of an n-type silicon substrate is needed depends on what type of transistors is expected to be manufactured on it:n-p-n type of p-n-p type

对硅衬底上的一个epitomical层了，而IC零件形成subsequently.in一个CVD法（化学气相depsition ）过程中，硅衬底的地方在真空晶体管均先加热至1600 ° C时，由高频率的无线电功率，并然后h ⒉氯⒉硅和某些气态的化合物，砷或P ，是注入试管，使存款的几位嗯对他们surface.ions的作为或P是杂质刻意添加到单结晶硅的结构，以供应电子传递的&负面&目前，在硅晶体，即所谓N型silicon.b ，可以增加一条，作为杂质产生的p型硅供应孔转递&积极& current.whether一个P -类型的一个n型硅衬底，是需要靠哪些类型的晶体管预计将在制造上它： NPN型的PNP型

The radio channel is time-variant, frequency-selective and noisy, so the received OFDM signals are corrupted by intercarrier interference.

但是由于无线信道的多径性和时变性，造成了接收端 OFDM 符号子载波间的干扰，为了能够准确地解调 OFDM 信号，就必须对接收到的信号进行信道估计。

In anFDD wireless system, the duplex spacing between uplink and downlink islarger than the coherence bandwidth of the mobile radio channel, thus theuplink and the downlink small-scale fading is uncorrelated. Moreover, thearray response is correlated with the frequency of the signal carrier. So it isimpossible to resue the uplink weights for downlink beamforming. As aresult, the application of smart antenna for the downlink is a difficult problem.

在频分双工系统中，由于上、下行载波的频率差大于相干频带，上、下行信道衰落是不相关的，而且阵列响应也与信号的载波频率有关，因此，上行信道不能直接用来估计下行信道，故智能天线应用于下行链路是一个难点。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。