Cordless Telephone Research Articles

Cordless loud speaking telephone

A cordless loud-speaking telephone of the present invention is shaped to be placed on a table or desk or to be suspended from a ceiling. Unlike cordless portable telephones of the handy transceiver type, it enables hands-free talking or communication through a receiving speaker and a transmitting microphone located outside a casing. An antenna conductor and counterpoises are projected from the casing, and a microphone is attached to the counterpoises or the antenna conductor such that the microphone is separated as remotely as possible from the speaker in the casing. As a result, howling and echo which disturb talking or communication via the telephone can be suppressed. Further, plural microphones are attached to plural antenna conductors or counterpoises to cancel the sound of the receiving speaker to prevent the voice from again entering the microphones, or the microphones are attached to the counterpoises or the antenna conductors in such a manner that they effectively receive the voice from the mouth of a talking person from a certain direction. This enables hands-free talking or communication to be more effectively and reliably achieved.

Digital voice-band spectrum inversion apparatus

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Wireless personal communications: what is it?

This article attempts to identify different issues and to put many of the activities in wireless into a framework that can provide perspective on what is driving them, and perhaps even yield some indication of where they appear to be going in the future. The technologies and systems that are currently providing, or are proposed to provide, wireless communications services can be grouped into about seven relatively distinct groups. All of the technologies and systems are evolving as technology advances and perceived needs change. Some trends are becoming evident in the evolutions. The different groups and evolutionary trends are explored along with factors that influence the characteristics of members of the groups. The grouping is generally with respect to scale of mobility and communications applications or modes. Different design compromises are evident in the different technologies and systems. The evidence suggests that the evolutionary trajectories are aimed toward at least three large groups of applications or services, namely, high-tier PCS (current cellular radio), high-speed wireless local-area networks (WLANS), and low-tier PCS (an evolution from several of the current groups). It is not clear to what extent several groups, e.g., cordless telephones, paging, and wide area data, will remain after some merging with the three large groups. >

Overview of wireless personal communications

This article presents an overview of the current state of wireless communications, including relevant ongoing activities in technology development, standards, and spectrum allocation. The authors discuss cellular radio, cordless telephony, and wireless data systems. Ongoing and planned future developments are summarized. The presentation is oriented toward broad coverage rather than technical depth. However, brief discussions of the air interfaces for existing digital cellular and digital cordless systems are provided, because the air interface bears heavily on system capacity and the environments in which the system can be used, as well as on the cost and complexity of the equipment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new radio receiver system for personal communications

A new radio receiver system for personal communications is described. This technology incorporates direct conversion into an integrated circuit in such a way that the need for discrete IF filters is avoided. It also employs a second IF functional circuit that contains a carrier leak detector and an adjustment-free system. The carrier leak detector suppresses the level of unwanted carrier leak and the adjustment-free system automatically compensates for any variation in circuit response that corrupts the performance of the receiver. The resulting design is particularly suitable for use in wireless devices such as pagers and cordless telephones. >

Advances in Electrode Materials Research

The technologies of primary (non-rechargeable) and secondary (rechargeable) lithium batteries have been developed in parallel to the developments in the microelectronics industry for about 20 years. The lithium batteries can be the lightest and most compact power sources when they are intended for portable equipment such as watches, calculators, cameras, cordless telephones, computers, and so on. During the past 10 years, the worldwide green revolution has requested a new, clear, and noiseless system of energy storage for replacing petrol. Rechargeable lithium batteries as high power and high energy density devices can also meet the requirements of clear and noiseless energy source, especially in the development of electric vehicles. Consequently, rechargeable lithium batteries with high power and long-life cycles have been very attractive to research groups all over the world. Thermodynamically, an electrochemical e.m.f, system is generated if an dectrolyte is sandwiched between two electrode materials with different chemical potentials. Electrodynamically, if a constant supply of ions can be maintained and transported through the electrolyte, this system will deliver current when connected across a load circuit. In the beginning of the research on rechargeable lithium batteries, a simple effect system has been studied. As a Li intercalation compound consists of a host (H) matrix into/from which x guest ions Li + may be inserted/extracted reversibly without a rearrangement of the host structure, a simple lithium battery may be represented as:

Calculation of the electromagnetic fields induced in the head of an operator of a cordless telephone

This paper shows the capability of the finite difference time domain (FDTD) method to predict the interaction between the human body and the electromagnetic field generated by a cordless telephone. Both the influence of the human head on the performance of the cordless telephone and the energy deposited in the human head have been determined. The interaction has been evaluated for a simple dipole model and for an accurate “box” model of the telephone. The FDTD method is a versatile method for refining the antenna model. The results show that the use of the accurate box model in combination with a realistic model of the head derived from a nuclear magnetic resonance image is a prerequisite for accurate determination of the near fields induced in the head. The total amount of power absorbed in the head has been compared to the radiated power. From our calculations we found that about 15% of the antenna input power at 900 MHz is absorbed in the head.

Mangoes on Azalea

Mrs. Shozz is a God-fearing woman with a bad haircut. She didn't hire me for my inner beauty. think she felt sorry for me, for my type, my caste. She has lived here for twenty years, yet all the old-world moral eyebrows still twitch for her. Brahmins stocking cosmetics at Kmart doesn't faze her. only when the lesser of us manage to prosper as cardiologists or own strip malls, and have modem houses in the suburbs, that Mrs. Shozz mutters about a return to tradition; but it's too late. She and her husband have managed to dig themselves deep into this continent. was born here a matter of days before her plane touched the ground at La Guardia. Now work for her in the video store on Fifth and Azalea. The front half of the store is a meticulous display of kindly rewound American videos. Fifty-cent late charge per day past 5 P.M. The store opens at 10 A.M. Mr. Shozz does this since most people work nine to five. There's no off-hours drop box. considers himself a clever entrepreneur. Mrs. Shozz works in the back with the Indian movies. Never rewound. No late fees enforced. No bookkeeping, save a shoddy spiral notebook. Just Mrs. Shozz and her cordless telephone. call her Auntie out of respect, but we speak in English. am what they call a modern girl, something tantamount to a lost soul. Auntie, think want to go to Bombay next Oh God, Bombay in the summer will broil You want to be a film star? Find a husband? is so hot in the summer. Power outs all the time, no air conditioning, mosquitoes, beggars, useless fans - are you kidding? Papa says it will be good for me. haven't been in over ten years. He dreams. Why waste a summer when you can make money for your college? My God, what will you eat there? Mangoes. Mangoes? In India, one person doesn't get one mango! how many? More? Nonono, only a couple slices, and rarely expect the seed to yourself. They are expensive there, too. But they grow on trees There are more mouths to feed sympathize with Mrs. Shozz. can't be easy managing the store seven days a week. Her husband plays bridge with his friends when he isn't working, and even when he works he is distant. They have only one son, Dev, who is a year older than I. They consider me his friend. am technically his lover. If you can call it love. certainly kills time. Dev is through working at the video store. spent a semester in London under the pretense of studying architecture. wants to be a poet. The only thing he said to me when he first got back was that there were a lot of Indian restaurants over there. The other night he called to talk. Usually he invites me over for a game of pool. I can't be with you right now. Five months in London and lose my luster? It's not you. Then you met someone. No. No? Yes. Great. Blonde? It was nothing. Just an experiment. glad it's costing me some dignity then. Listen, this is just too much, okay, I'm young, need space. let Dev touch me the first time we met. trusted him completely. After all, he couldn't see me as exotic, he understood the same languages, and he had some interest in intellectualizing about the diaspora. We had even joked about how it sounded like a personal hygiene product. Or a parasite. At the time, locking up the store and crossing a quiet Azalea, it seemed safe to kiss him. We're both good Indian kids; we can keep anything from our parents. Everything a secret, everything very discreet. not even a conspiracy. We're just being used. And so you've replaced me working as a peon in the Shozz video empire. It'll help with my tuition costs. Who do these city colleges give their money to anyway? I'll have nothing left for grad school, Dev. Bureaucracy. …

Portable communications: trends in systems and component technology

Journal of Electronics ManufacturingVol. 04, No. 04, pp. 203-209 (1994) PAPERSNo AccessPortable communications: trends in systems and component technologyDENIS GROSSDENIS GROSSBPA (Technology & Management) Ltd, Dorking, Surrey RH4 1QT, UK Search for more papers by this author https://doi.org/10.1142/S0960313194000213Cited by:4 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractImmense progress in mobile communications technology has made wireless, mobile and personal communications one of the fastest-growing markets worldwide. The new wireless age centres on ‘globalization and personalization’, and employs technologies like cellular telephones, radio pagers, digital cordless telephones and mobile data systems in the integration of voice, data, image and communications. Developments are very rapid across all mobile communications sectors, especially as digital technology has been successfully introduced into all major categories. While cellular markets will remain dominated by analogue systems well into the middle of the decade, digital technology, high frequencies, small, light and low-cost handheld units are the major driving factor behind the forthcoming communications boom. Digital cellular telephones, for example, involve high frequencies (1.8 GHz), built-in high-performance computing power (30–40 MIPs), and can be built in 12 minutes, compared to the 8 hours it took in the late 1980s. Within this dramatic growth market, there are clearly significant opportunities for the manufacturers of the equipment, for the network and service providers, and also for the electronic components materials, interconnection, packaging and assembly industries.Keywords:Mobile communicationswireless communicationscellular telephonescordless telephonesdigital cellular telephonypersonal communication systems FiguresReferencesRelatedDetailsCited By 4A new under bump metallurgy for solder bump flip chip applicationsKari Kulojärvi and Jorma Kivilahti1 Aug 1998 | Microelectronics International, Vol. 15, No. 2A low temperature interconnection method for electronics assemblyK. Kulojarvi and J.K. Kivilahti1 Jun 1998 | IEEE Transactions on Components, Packaging, and Manufacturing Technology: Part A, Vol. 21, No. 2Effects of chip scale package and flip‐chip on the design and manufacturing of electronic productsPetri Savolainen1 Apr 1998 | Microelectronics International, Vol. 15, No. 1A low temperature interconnection method for electronics assemblyK. Kulojarvi and J.K. Kivilahti Recommended Vol. 04, No. 04 Metrics History KeywordsMobile communicationswireless communicationscellular telephonescordless telephonesdigital cellular telephonypersonal communication systemsPDF download

A common air interface between wide‐area cordless telephone and urban cellular radio: Frequency channel doubly‐reused cellular systems

AbstractThis paper proposes a new system [1] in which the frequency channel of the wide‐area cordless telephone is reused doubly by the frequency channel employed in the urban cellular mobile telephone with a weak power. A condition is imposed whereby the two systems can operate with equal telephone qualities when cochannel interferences exist between two systems.The radius of the microcell and the weak power are analyzed and completed. According to the analysis, the theoretical limit of the spectrum efficiency of the new system is doubled compared to the system where the frequency bands of the two systems are placed independently in adjacent bands (AB) [2, 3]. To realize the cooperation between the wide‐area cordless telephone and the urban cellular mobile telephone on the equally coexistent condition, an autonomous spectrum distributed management system is proposed in principle [3] which can maintain in a simple way the cochannel interference sharing.

Sound quality evaluation of cordless telephones by the three-way scaling method, and the correlation analysis between psychological measure and physical measure

Sound quality evaluation of cordless telephones by the three-way scaling method, and the correlation analysis between psychological measure and physical measure

Toward the personal communication era—A proposal of the “radio access” concept from Japan

This paper presents our insights into so-called “personal communication” and describes a conceptual proposal of “radio access,” which connects terminals with network services. Firstly, personal communication services are classified into basic (personal connection) services and advanced (personalized) services. Based on this categorization, features of the Japanese Personal Handy Phone (PHP) system, which offers services in homes, offices, and outdoor environments using a small cordless telephone terminal, are presented. The PHP system is defined here as a combination of three functional elements: a digital cordless terminal, radio access, and intelligent network. Secondly, the PHP system is described in detail including service definition, system design, network configuration, and evolutional scenario. Thirdly, we present standardization activities for the PHP-common air interface (CAI). The results of a three-month series of verification experiments, which have been successfully completed in 1992, are also explained. Based on the results, the specifications of PHP CAI were fixed at the end of 1992 through the cooperation of MPT, industries, and network operators. Technical items, mainly the 1.9-GHz 4-channel TDMA-TDD technology, are presented. Concerning R&D activities, the structure of frame synchronization for improving frequency utilization efficiency is described as one example of the many technical breakthroughs made in developing the PHP system. Finally, general considerations on service aspects of the PHP system are presented. This section includes comparisons between PHP and cellular systems from service viewpoints, such as charging, terminal performance, and service coverage area. The important results demonstrate the possibility of the coexistence of and the prosperity of both systems, due to the spread of the outdoor communication market caused by the introduction of the economical PHP system. In addition, our view on the phased approach for future service integration is given.

Frequency mixer with a frequency doubler for integrated circuits

We have developed a bipolar LSI, including a frequency mixer and a local oscillator frequency doubler. The local oscillator frequency doubler consists of two identical unbalanced emitter-coupled pairs with a different emitter area ratio, whose input terminals are connected cross-coupled and whose output terminals are connected in parallel, and is coupled with the frequency mixer directly in the LSI. The fabricated LSI operates on supply voltage as low as 2.7, and has been put into practical use for a cordless telephone system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Development of WaveLAN®, an ISM Band Wireless LAN

Wireless voice communications has seen a great many changes in the last few years, including the evolution of cordless telephones, cellular systems, and the development of standards for personal communications services (PCS). Recently, high-speed wireless local area networks (WLANs) have been getting more attention, both in marketing and research. This paper discusses the design philosophy in the development of NCR's WaveLAN®, and the technical tradeoffs.

Energy storage and the environment: the role of battery technology

Batteries can store energy in a clean, convenient and efficient manner. Battery-powered electric vehicles are expected to contribute to a cleaner environment. In today's world, batteries are used everywhere: in electronic watches, pocket calculators, flashlights, toys, radios, tape recorders, cameras, camcorders, laptop computers, cordless telephones, paging devices, hearing aids, heart pacers, instruments, detectors, sensors, memory back-up devices, drug dispensing, wireless tools, toothbrushes, razors, stationary emergency power equipment, automobile starters, electric vehicles, boats, submarines, airplanes and satellites. Worldwide, about 15 billion primary batteries, and well over 200 million starter batteries are produced per year. What is the impact of this widespread use of batteries on the environment? What role can battery technology play in order to reduce undue effects on the environment? Since this paper is presented at a lead/acid battery conference, the discussion refers, in particular, to this system. The following aspects are covered: (i) the three “E” criteria that are applicable to batteries: Energy, Economics, Environment; (ii) service life and environment; (iii) judicious use and service life; (iv) recycling.

Regulators Markets And Standards Coordination: Policy Lessons From Telepoint

A central problem in setting standards is finding a balance between the use of government standards bodies and market forces. Telepoint, a UK public cordless telephone system, provides a valuable example of an attempt to use market forces within a regulated framework. The exercise has to date had an unhappy history. A problem has been that despite intentions the regulator effectively defined the system, pursuing its own broad policy agenda. The initial configuration did not appeal to users and attempts to redefine it took too long. Meanwhile, thc service providers scemed to lack commitment. As a result initial services were withdrawn within two years of the launch, though a subsequent re-launch by a single operator has taken place. Hopes that the system could become a de facto European standard have been set back. Neither policy nor commercial aims have been achieved. The result, including the commitment and credibility problems, may be traced to contradictions in policy. If hybrid policies are to work the framework may need to be more market responsive, and the private agenda of the regulator less evident than here.

Wireless network access for personal communications

An explanation of the widely different technological approaches and technologies being proposed for different interpretations of wireless personal communications services (PCS) is presented. Different wireless communications applications and issues surrounding the applications are discussed. Descriptions of the compromises that have been made in developing specific technologies optimized to serve the cordless telephone and the vehicular mobile radio applications are presented. Characteristics of a technology that is aimed at the widespread pedestrian PCS application and environment are outlined. Different wireless technologies that have been aimed at different applications and environments are compared.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Cordless telephone headset

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Cordless pen telephone handset

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Acoustic trauma in a telephone operator

This case report describes an incident where a telephone operator suffered acoustic trauma from a subscriber blowing a whistle down a telephone mouthpiece, the sound being transmitted into the ear of the operator. Evidence of hearing loss persisted for several months before complete recovery was achieved. Comparison is made with hearing loss associated with the use of cordless telephones.