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time-frequency

  • 無線技術指南

    Radio frequency (RF) can be a complex subject to navigate, but it does not have to be. If you are just getting started with radios or maybe you cannot find that old reference book about antenna aperture, this guide can help. It is intended to provide a basic understanding of RF technology, as well act as a quick reference for those who “know their stuff” but may be looking to brush up on that one niche term that they never quite understood. This document is also a useful reference for Maxim’s products and data sheets, an index to deeper analysis found in our application notes, and a general reference for all things RF.

    標簽: 無線技術

    上傳時間: 2013-10-08

    上傳用戶:kinochen

  • MAX7060的ASK_FSK的ISM射頻發射機

    Abstract: This application note illustrates the flexibility of the MAX7060 ASK/FSK transmitter. While the currently available evaluationkit (EV kit) has been optimized for the device's use in a specific frequency band (i.e., 288MHz to 390MHz), this document addresseshow the EV kit circuitry can be modified for improved operation at 433.92MHz, a frequency commonly used in Europe. Twoalternative match and filter configurations are presented: one for optimizing drain efficiency, the other for achieving higher transmitpower. Features and capabilities of earlier Maxim industrial, scientific, and medical radio-frequency (ISM-RF) transmitters areprovided, allowing comparison of the MAX7060 to its predecessors. Several design guidelines and cautions for using the MAX7060are discussed.

    標簽: ASK_FSK 7060 MAX ISM

    上傳時間: 2013-11-14

    上傳用戶:swaylong

  • 有源RFID局域定位系統設計

    提出了一種基于PIC16F877A微控制器和CC2500射頻收發器芯片的低功耗、低成本RFID(Radio Frequency Identification, 無線射頻識別)局域定位系統設計方法,介紹了系統的定位工作原理、主要硬件電路模塊及定位算法的設計和實現。采用基于序列號對時隙數運算的排序算法有效解決了多標簽識別碰撞的問題,基于射頻輻射強度(Received Signal Strength Indication, RSSI)和圓周定位算法實現了基于RFID多標簽系統的平面定位。實驗測試表明,這種射頻定位方法能夠實現一定精度下的無線局域定位的功能。

    標簽: RFID 有源 局域 定位

    上傳時間: 2013-11-06

    上傳用戶:weareno2

  • 降低OFDM信號PAPR的方法研究

    正交頻分復用 (Orthogonal Frequency Division Multiplexing,OFDM)是一種多載波調制技術,由于具有良好的抗多徑干擾性能,適用于高速數據傳輸,OFDM成為近年來人們研究的熱點。但是其峰均比較高,應用受到了限制,因此有必要研究降低PAPR的方法。本文首先介紹了OFDM的基本原理和PAPR的基本概念,然后討論了目前常用的降低PAPR的方法,最后對SLM和PTS方法進行了MATLAB仿真。

    標簽: OFDM PAPR 信號 方法研究

    上傳時間: 2013-11-19

    上傳用戶:moshushi0009

  • DN381 RFID接收器的基帶電路

      Radio Frequency Identifi cation (RFID) technology usesradiated and refl ected RF power to identify and track avariety of objects. A typical RFID system consists of areader and a transponder (or tag). An RFID reader containsan RF transmitter, one or more antennas and an RFreceiver. An RFID tag is simply an uniquely identifi ed ICwith an antenna.

    標簽: RFID 381 DN 接收器

    上傳時間: 2013-10-17

    上傳用戶:lepoke

  • 無線電干擾 Radio Susceptibility

      Abstract: Engineers often wish that radio susceptibility (RS) or radio immunity could be cured with an antibiotic, a vaccine, or someform of cure-all. Unfortunately, solving the RS problem is not that easy. Indeed, the laws of physics apply. In this article we discusssources of RS. We also offer tips and hints to protect systems, power supplies, printed circuit boards (PCBs), and electroniccomponents from radio frequency interference.

    標簽: Susceptibility Radio 無線電干擾

    上傳時間: 2014-12-30

    上傳用戶:旗魚旗魚

  • MAX16948雙遙控天線LDO開關

      Abstract: This application note helps system designers choose the correct external components for use with the MAX16948 dualremote antenna LDO/switch, thus ensuring that automobile-regulated phantom antenna supply and output-current-monitoring circuitrymeet performance objectives. An electronic calculator is provided that helps specify the critical external components for theMAX16948, thus reducing design time. The calculator also determines the device's analog output voltage, output current-limitthreshold, and output current-sensing accuracies. The calculator includes new automatic Step By Step feature that assists designerswith component choice. To use the new automatic feature, click on the Step By Step button relative to the desired section.

    標簽: 16948 MAX LDO 遙控天線

    上傳時間: 2013-11-04

    上傳用戶:lhll918

  • 基于ZigBee技術的無線智能家用燃氣報警系統

    在研究傳統家用燃氣報警器的基礎上,以ZigBee協議為平臺,構建mesh網狀網絡實現網絡化的智能語音報警系統。由于傳感器本身的溫度和實際環境溫度的影響,傳感器標定后采用軟件補償方法。為了減少系統費用,前端節點采用半功能節點設備,路由器和協調器采用全功能節點設備,構建mesh網絡所形成的家庭內部報警系統,通過通用的電話接口連接到外部的公用電話網絡,啟動語音模塊進行報警。實驗結果表明,在2.4 GHz頻率下傳輸,有墻等障礙物的情況下,節點的傳輸距離大約為35 m,能夠滿足家庭需要,且系統工作穩定,但在功耗方面仍需進一步改善。 Abstract:  On the basis of studying traditional household gas alarm system, this paper proposed the platform for the ZigBee protocol,and constructed mesh network to achieve network-based intelligent voice alarm system. Because of the sensor temperature and the actual environment temperature, this system design used software compensation after calibrating sensor. In order to reduce system cost, semi-functional node devices were used as front-end node, however, full-function devices were used as routers and coordinator,constructed alarm system within the family by building mesh network,connected to the external public telephone network through the common telephone interface, started the voice alarm module. The results indicate that nodes transmit about 35m in the distance in case of walls and other obstacles by 2.4GHz frequency transmission, this is able to meet family needs and work steadily, but still needs further improvement in power consumption.

    標簽: ZigBee 無線智能 報警系統

    上傳時間: 2013-10-30

    上傳用戶:swaylong

  • UHF讀寫器設計中的FM0解碼技術

       針對UHF讀寫器設計中,在符合EPC Gen2標準的情況下,對標簽返回的高速數據進行正確解碼以達到正確讀取標簽的要求,提出了一種新的在ARM平臺下采用邊沿捕獲統計定時器數判斷數據的方法,并對FM0編碼進行解碼。與傳統的使用定時器定時采樣高低電平的FM0解碼方法相比,該解碼方法可以減少定時器定時誤差累積的影響;可以將捕獲定時器數中斷與數據判斷解碼相對分隔開,使得中斷對解碼影響很小,實現捕獲與解碼的同步。通過實驗表明,這種方法提高了解碼的效率,在160 Kb/s的接收速度下,讀取一張標簽的時間約為30次/s。 Abstract:  Aiming at the requirement of receiving correctly decoded data from the tag under high-speed communication which complied with EPC Gen2 standard in the design of UHF interrogator, the article introduced a new technology for FM0 decoding which counted the timer counter to judge data by using the edge interval of signal capture based on the ARM7 platform. Compared with the traditional FM0 decoding method which used the timer timed to sample the high and low level, the method could reduce the accumulation of timing error and could relatively separate capture timer interrupt and the data judgment for decoding, so that the disruption effect on the decoding was small and realizd synchronization of capture and decoding. Testing result shows that the method improves the efficiency of decoding, at 160 Kb/s receiving speed, the time of the interrogator to read a tag is about 30 times/s.

    標簽: UHF FM0 讀寫器 解碼技術

    上傳時間: 2013-11-10

    上傳用戶:liufei

  • 基于塑料光纖的高壓隔離通信接口設計

     通過比較各種隔離數字通信的特點和應用范圍,指出塑料光纖在隔離數字通信中的優勢。使用已經標準化的TOSLINK接口,有利于節省硬件開發成本和簡化設計難度。給出了塑料光纖的硬件驅動電路,說明設計過程中的注意事項,對光收發模塊的電壓特性和頻率特性進行全面試驗,并給出SPI口使用塑料光纖隔離通信的典型應用電路圖。試驗結果表明,該設計可為電力現場、電力電子及儀器儀表的設計提供參考。 Abstract:  y comparing characteristics and applications area of various isolated digital communications, this article indicates advantages of plastic optical fiber in isolated digital communications. Using the standardized TOSLINK interface, it helps to control costs and difficulty in hardware development and design. Then it gives the hardware driver circuit of plastic optical fiber module, explains the noticed details in design process, gives results on the basis of the optical transceiver module voltage characteristics and frequency characteristics tests. Finally,it gives typical application circuit of the SPI communication port by using plastic optical fiber isolation .The results show that this design can be referenced for the power field, power electronics and instrumentation design.

    標簽: 塑料光纖 高壓隔離 通信 接口設計

    上傳時間: 2014-01-10

    上傳用戶:gundan

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