gsm

无线相关术语

由 半世苍凉 提交于 2020-01-10 10:42:56
802.11 802.11是IEEE最初制定的一个无线局域网标准，主要用于解决办公室局域网和校园网中用户与用户终端的无线接入，业务主要限于数据存取，速率最高只能达到2Mbps。由于它在速率和传输距离上都不能满足人们的需要，因此，IEEE小组又相继推出了802.11b和802.11a两个新标准，前者已经成为目前的主流标准，而后者也被很多厂商看好。 802.11b 802.11b采用2.4GHz直接序列扩频，最大数据传输速率为11Mb/s，无须直线传播。动态速率转换当射频情况变差时，可将数据传输速率降低为5.5Mb/s、2Mb/s和1Mb/s。使用范围 支持的范围是在室外为300米，在办公环境中最长为100米。802.11b使用与以太网类似的连接协议和数据包确认，来提供可靠的数据传送和网络带宽的有效使用。 802.11a 802.11a标准是已在办公室、家庭、宾馆、机场等众多场合得到广泛应用的802.11b无线联网标准的后续标准。它工作在5GHzU-NII频带，物理层速率可达54Mb/s，传输层可达25Mbps。可提供25Mbps的无线ATM接口和10Mbps的以太网无线帧结构接口，以及TDD/TDMA的空中接口；支持语音、数据、图像业务；一个扇区可接入多个用户，每个用户可带多个用户终端。 现在一些厂商对于该标准的计划已提到议事日程。例如

MapXtreme2010开发车辆监控系统

由 杀马特。学长 韩版系。学妹 提交于 2020-01-10 05:46:54
在过去10 年中,车辆定位和导航以及与智能交通系统有关的技术在世界范围内取得迅猛发展,而如何实现各类车辆的有效指挥、MapXtreme2010电子地图协调控制和管理、防止车辆犯罪以及减少环境污染已经成为交通运输和安全管理部门面临的一个重要问题。针对这一热点问题,本文设计了一个能实现车辆定位和监控的可行方案。 首先,通过对国内外GPS 车载系统现状的认真研究,设计了一套基于GPS、GSM、GIS 三大技术的车载定位监控系统的实现方案,并对该方案的重要组成部分:GPS 卫星系统、车载台、无线传输网络和监控中心的作用和功能进行了简单地分析。其次,在理论方面对GPS、GSM、GIS 进行了深入地研究:对GPS 卫星系统的组成、信号构成、导航电文、定位误差等进行了分析,并着重对GPS 的基本定位原理和差分GPS 的定位原理进行了研究;对车载定位监控系统的各种无线通信网络进行了分析比较,确定了以GSM 数字蜂窝移动通信技术的短消息业务(SMS)作为本系统的无线通信方式;对GIS 地理信息系统进行了深入研究,确定了以MapX 组件式开发作为电子地图的开发平台。通过理论上的准备,为项目的顺利开展奠定了基础,缩短了系统的开发周期。最后,本文从实践的角度论述了车载台和监控中心的设计方案。对车辆定位监控系统的系统构成、系统功能和系统原理进行了深入研究。在介绍GPS 车载台模块组成的基础上,对GPS 模块

GSM AT COMMAND | How to upload .amr audio file

由 若如初见. 提交于 2020-01-06 14:57:29
问题 I can list the directory using below command. AT+FSLS=\ i found AT+FSCREATE="1.amr",3 command to crate files in directory but the problem is, how to upload the file from my local drive. 回答1: I don't have any modem that supports AT+FSWRITE command. But based on SIMcom AT-command manual, AT+FSWRITE= command responds with prompt: > . Manual does not clearly tell how to use the command. But it might work similar way than AT+CMGS= command: Send AT+FSWRITE=1.arm,0,512,10 command to modem. Wait >

Compress WAV PCM to Microsoft GSM 6.10 Audio Codec using C#

由 和自甴很熟 提交于 2020-01-06 04:32:47
问题 Does any one know how to convert a uncompressed wave file in PCM format to a wav file compressed in GSM 6.10 Audio Codec? 回答1: Try How to convert to Gsm Wav file static void ToWavWithGsm() { string fileName = @"e:\Down\male.wav"; WaveReader wr = new WaveReader(File.OpenRead(fileName)); IntPtr format = wr.ReadFormat(); IntPtr formatGsm = AudioCompressionManager.GetCompatibleFormat(format, AudioCompressionManager.Gsm610FormatTag); byte[] dataGsm = AudioCompressionManager.ToFormat(wr, formatGsm)

How to create a GSM-7 encoding in Python?

由 前提是你 提交于 2020-01-06 03:18:29
问题 The GSM-7 character set is defined as a basic mapping table + an extension character mapping table (https://en.wikipedia.org/wiki/GSM_03.38#GSM_7-bit_default_alphabet_and_extension_table_of_3GPP_TS_23.038_.2F_GSM_03.38). Meaning that u'@' should be mapped to b'\x00' (a byte string of length 1), but u'[' should be mapped to b'\x1b<' or b'\x1b\x3c' (a byte string of length 2). I've managed to get the encoding part to work by extending the encoding_table , but I'm not sure what to do that with

How to create a GSM-7 encoding in Python?

由 巧了我就是萌 提交于 2020-01-06 03:18:07
问题 The GSM-7 character set is defined as a basic mapping table + an extension character mapping table (https://en.wikipedia.org/wiki/GSM_03.38#GSM_7-bit_default_alphabet_and_extension_table_of_3GPP_TS_23.038_.2F_GSM_03.38). Meaning that u'@' should be mapped to b'\x00' (a byte string of length 1), but u'[' should be mapped to b'\x1b<' or b'\x1b\x3c' (a byte string of length 2). I've managed to get the encoding part to work by extending the encoding_table , but I'm not sure what to do that with

How to play GSM 6.10 compressed files in Java

由 丶灬走出姿态 提交于 2020-01-06 03:06:13
问题 Can you please tell me how these lines of code can be modified to be able to play some GSM files. File audioFile = new File(audioFilePath); AudioInputStream audioStream = AudioSystem.getAudioInputStream(audioFile); AudioFormat format = audioStream.getFormat(); AudioFormat format = audioStream.getFormat(); DataLine.Info info = new DataLine.Info(Clip.class, format); Clip audioClip = (Clip) AudioSystem.getLine(info); audioClip.open(audioStream); audioClip.start(); audioClip.close(); audioStream

How to send SMS with GSM Click Modem?

由 别说谁变了你拦得住时间么 提交于 2020-01-05 09:38:02
问题 I can finally make a phone call, receive, and answer it. But if I try to send an SMS I receive CMS ERROR: 500 . The GSM modem I am using is Telit GL865-Quad module. Since the Call function is working, what's preventing the SMS to work? please enlightenment me. The Sim Card works fine on my phone to rule out some of the problems. I am using a hyperterminal to type the commands at 19200 speed. This is the user guide with commands for your own convenience. To send an SMS: AT+CMGF=1 // Select

Huawei Mobile Connect E170

由 旧时模样 提交于 2020-01-03 04:47:07
问题 I am trying to receive SMS messages with a Huawei Mobile Connect, Model: E170 device through hyper terminal but can't. I used the below commands to initialize the modem: AT+CMGF=1 AT+CNMI=2,2,0,0,0 (But this gives me this error: +CMS ERROR: 303) This same commands working on my nokia N70, 6630 and many other nokia models i can't remember. I know the modem can receive and send SMS messages, but how do i do it? 回答1: Below worked for me in Huawe E153. at+cmgf=1 //Set text format at+csmp=49,167 /

Receiving SMS with GSM modem

由 我只是一个虾纸丫 提交于 2020-01-01 18:58:50
问题 I read that a GSM modem can only receive up to 30 SMS per minute. What would you do if you need to receive more than that? Is there another technology? 回答1: I think you might want something different to those answers listed at What are the best practices for building an SMS server If you just have one service that is running where you want to receive many SMS then it would be most cost effective (and simplest) to avoid integrating with a mobile network operator and instead use a SMS
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