Xem 1-20 trên 38 kết quả Digital cellular.
  • GSM

    GSM (Global System for Mobile Communications), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation digital cellular networks. Developed as a replacement for first generation analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony. The standard was expanded over time to include first circuit switched data transport, then packet data transport via GPRS (General Packet Radio Services)....

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  • The need to keep in touch—we all have it, whether for business or personal reasons. Now you can keep in touch on the way to work or the shopping center, from a construction site or the golf course, or in a rental car or on your boat. If you spend time away from your best communication tool—the telephone—a cellular phone can add several business hours to your week. Now you can stay in touch with your office, your customers, or your family, even as you inch along in a traffic jam. And cellular’s excellent audio performance ensures clear voice reception....

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  • The third generation (3G) mobile communication system is the next big thing in the world of mobile telecommunications. The first generation included analog mobile phones [e.g., Total Access Communications Systems (TACS), Nordic Mobile Telephone (NMT), and Advanced Mobile Phone Service (AMPS)], and the second generation (2G) included digital mobile phones [e.g., global system for mobile communications (GSM), personal digital cellular (PDC), and digital AMPS (D-AMPS)].

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  • The previous chapters have concentrated on the two leading second generation (2G) cellular systems: GSM and IS-95. These systems are deployed in many parts of the world and will continue to operate and evolve during the next decade as third generation (3G) systems are rolled out. We may expect that the new 3G systems will be harmonised with their evolved 2G counterparts, and that slowly 2G spectra will be refarmed to provide extra 3G spectra. No 3G systems are currently deployed, although trials are in progress. As a consequence, this chapter, which deals with systems that are about to be...

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  • GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (2G) digital cellular networks. Developed as a replacement for first generation (1G) analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony.

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  • Generation Change in Cellular Systems In Japan, mobile communications systems based on cellular technology have evolved, as illustrated in Figure 1.1. The first-generation analog car phones were first introduced in 1979, followed by the commercialization of the second-generation digital phones in 1993. Mobile phone subscribers have rapidly increased in number since then, owing to the liberation of terminal sales and continuous price reductions. In March 2000, the number of mobile phone subscribers outnumbered those of fixed telephones.

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  • The Digivance Indoor Coverage Solution (ICS) is used to extend coverage to specific areas within a building, multiple buildings, or throughout a campus environment. This digital distributed antenna system (D-DAS) solution features unique, patented technology that distributes wireless coverage digitally over optical fiber, making Digivance ICS the best choice for signal quality, flexibility, and overall performance. Its digitized optical RF transport also future-proofs in-building wireless infrastructure for higher data rate services.

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  • Mobile communication networks were commercially launched as Circuit-Switched (CS) systems centering on speech communication services. The First-Generation (1G) analog system evolved into the Second-Generation (2G) digital system, followed by the introduction of Packet-Switched (PS) communication system. These conventional mobile communication systems were realized with different technologies by country and region, and there was no internationally unified standard.

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  • Linear Prediction Modelling of Speech Linear predictive models are widely used in speech processing applications such as low–bit–rate speech coding in cellular telephony, speech enhancement and speech recognition. Speech is generated by inhaling air into the lungs, and then exhaling it through the vibrating glottis cords and the vocal tract. The random, noise-like, air flow from the lungs is spectrally shaped and amplified by the vibrations of the glottal cords and the resonance of the vocal tract.

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  • Programmable Digital Signal Processors (DSPs) are pervasive in the second generation (2G) wireless handset market for digital cellular telephony. This did not come about because everyone agreed up front to use DSPs in handset architectures. Rather, it was a result of a battle between competing designs in the market place. Indeed, the full extent of the use of programmable DSPs today was probably not appreciated, even by those who were proposing DSP use, when the 2G market began to take off.

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  • Signal processing is concerned with the modelling, detection, identification and utilisation of patterns and structures in a signal process. Applications of signal processing methods include audio hifi, digital TV and radio, cellular mobile phones, voice recognition, vision, radar, sonar, geophysical exploration, medical electronics, and in general any system that is concerned with the communication or processing of information.

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  • Wireless communications is, by any measure, the fastest growing segment of the communications industry. As such, it has captured the attention of the media and the imagination of the public. Cellular systems have experienced exponential growth over the last decade and there are currently around two billion users worldwide. Indeed, cellular phones have become a critical business tool and part of everyday life in most developed countries, and are rapidly supplanting antiquated wireline systems in many developing countries....

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  • Speech coding is at the heart of digital wireless telephony. It consists of reducing the number of bits needed to represent the speech signal while maintaining acceptable quality. Digital cellular telephony began in the late 1980s at a time when speech coding had matured enough to make it possible. Speech coding has made digital telephony an attractive proposition by compressing the speech signal, thus allowing a capacity increase over analog systems.

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  • Within the gravitational pull of the studios, independent production has been found at both the upper and lower ends of the business. Low-budget independent outfits such as Republic and Monogram, and many smaller entities, helped to serve the demand of the system for the production of ‘B’ movies, to fill the bottom half of double bills, during the 1930s.

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  • This chapter reviews the applications of antenna array signal processing to mobile networks. Cellular networks are rapidly growing around the world and a number of emerging technologies are seen to be critical

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  • In recent years, the technological trend toward high-performance mobile communications devices has caused a burgeoning interest in the field of low-power design. Indeed, with the proliferation of portable devices such as digital cellular phones, pagers and personal digital assistants, designing for low-power with high throughput is becoming increasingly necessary. It is often claimed that a full-custom ASIC will be ‘‘lower power’’ than a programmable approach.

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  • The generic cellular communication system, shown in Fig.l, is an integrated network comprising a land base wire line telephone network and a composite wired-wireless network. The land base network is the traditional telephone system in which all telephone subscribers are connected to a central switching network, commonly known as PSTN (Public Switching Telephone Network). It is a digital switching system, providing: i) Switching, ii) Billing, iii) 911 dialing, iv)l-800 and 1-900 calling features, v)...

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  • Web 2.0 is here. Internet users are not only finding information on the Internet; they are also creating and uploading content. What will be the impact on colleges and universities as more digitally savvy students, those who are accustomed to Web 2.0's two-way information exchange, enter their halls? Beginning with an exploration of the meaning and application of Web 2.0, this article considers how Net Generation students with Web 2.0 expectations will reshape institutions of higher education. Web 2.0 What is Web 2.0? If Web 1.0 was a read-only medium, Web 2.0 is a read/write medium.

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  • The Internet is arguably one of the greatest innovations of modern society—allowing for countless new businesses to thrive and dramatically altering the way society operates. The Internet has enabled a global marketplace to flourish with lightning-quick communication and an unparalleled access to information.

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  • Upon completion of this lesson, the successful participant will be able to: Identify the advantages and disadvantage of deploying cellular technology; describe how satellite technology works; explain how LBS, GPS, and GIS help to create business value; describe RFID and how it can be used to help make a supply chain more effective.

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