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A brief review of the history of radio communications, which were used before the advent of humanity tubes, in the context of the essays in the series "At the root of media", published in the "History of Technical Progress" section of the supplement to our journal "Science and Education". The review covers the main stages of the development of spark radio-telegraph systems, the creation of the first powerful arc and electric machine generators of non-stopping oscillations of the carrier frequency for radiotelephony and the detection features. The first experiments of Mahlon Loomis, scientific and technical achievements of James Maxwell, Henry Hertz, Eduard Branly, Alexander Popov, Oliver Lodge, Jagadish Bosch, Karl Brown, Lee de Forest, Louis Austin, Herman Simon, William Duddel, Valdemar Paulsen, Ernst Alexander, Valentin Vologdin, Semyon Eisenstein and other creators of the nascent radio engineering. Particular attention is paid to the intersections of their work with the work of Thomas Edison, Nikola Tesla, Guglielmo Marconi, Reginald Fessenden and other heroes of our essays.

This study considers the feasibility of using 100% recycled Acrylonitrile Butadiene Styrene (rABS) in the caseworks of small consumer electronic products as a step towards more circular design and manufacturing. A Digitally Enhanced Cordless Telephone (DECT) handset was chosen as a representative example of such a product. Materials testing on the rABS demonstrated that 100% recycled ABS has similar properties to virgin ABS and can be substituted for virgin ABS as long as the product design allows for the slightly stiffer nature of the rABS and addresses issues of surface finish and ability to colour. By clearly understanding these issues at the outset of the design process, and by adapting the designs appropriately at the outset, it was possible to produce an rABS handset which was as robust and as cosmetically acceptable as one made of virgin ABS. This suggests that the recycled material could be used widely in this type of product and also at reduced cost to using virgin ABS. Furthermore, an abridged Life Cycle Analysis of the existing handset suggested that other issues associated with the environmental impact of the product could be relatively easily addressed at the design stage by considering energy use and end of life issues.

Gaussian Minimum Shift keying is used in GSM (Global system Mobile communication). It is also used in Cellular Digital Packet Data (CDPD), Digital European Cordless Telephone (DECT). GMSK supports better spectral efficiency the use of this is to have less sidebands as par with other technologies. After filtering the signal it is given to the MSK modulator. The major purpose in GMSK is it doesn’t consider amplitude variations hence there will not be much noise getting effected with the signal also this consumes low battery usage in accordance with other technologies so this is a pivotal parameter we consider in cell phones. GMSK modulator and demodulator is present in either ends i.e. at Cell Phone side and at BTS station. Inter-symbol Interference will diminish the usage of GMSK there by introducing Bit errors so these need to be considered and they are removed by using suitable decoding techniques generally Viterbi algorithm was used for efficient output or demodulation of the signal.

Background To assess a possible signal drift, noise and influences of electromagnetic radiation on the measurement behaviour of the Triggerfish® contact lens sensor, which might be mistaken as IOP fluctuations. Methods Contact lens sensors (Triggerfish®, SENSIMED AG, Lausanne, Switzerland) were fixed in a water bath. To reduce any external electromagnetic impulses, all plugs were removed from the sockets, no lights were switched on and no electronic devices, except a temperature logger were left in the test room. For 24 h signal drift, noise and the influences of a cordless telephone (Ascom d43 DECT Handset, EU DECT 1880–1900 MHz, Ascom Wireless, Baar, Switzerland), a smartphone (Sony Xperia Go ST27i, Sony Corporation, Tokyo, Japan) and a computer (Hewlett-Packard ProBook 650 15,6″ - D9S33AV, Hewlett-Packard Inc., Palo Alto, USA) on the measuring profile were analysed. Results Twenty-four-hour measurements without provoked external electromagnetic impulses yielded a profile without any signal drift and 8.2 mV eq noise. During the activation of the cordless telephone a maximum measurement variation of 3.2 mV eq. (4.1–7.3), smartphone 1.8 mV eq. (4.7–6.5) and computer 1.4 mV eq. (6.3–7.7) were observed. Conclusions During 24-h measurements there was no signal drift and a very low noise. Patients concerned about electronic devices possibly interfering with the measurements of the contact lens sensor, can be informed, that the use of their cordless telephone, smartphone or computer does not cause any problems. The amount of the signal noise might help to define actual IOP fluctuations. Temperature fluctuations might influence the measuring profile.

Technology development and its future trends are essential for decision making consideration to decide on the appropriate technology investment. Constructing Technology Life Cycle (TLC) allows stakeholders to identify technology trends in the future. Therefore, the forecasting approaches play a key role to obtain right decision making since there is need forecasting result with high accuracy and less computational time required. This study aims to construct TLC approach based on artificial intelligence to overcome these problems. This approach was developed through Artificial Neural Network (ANN) that has intelligent capability to define the technology performance towards patent analysis for forecasting and fitting the TLC phases. This study also employed the analysis of numerical gradient to strengthen the forecasting result. The potential of the proposed approach has been demonstrated by cordless telephone patent data as the worldwide tools to obtain up-to-date technology information. The findings can contribute to a better understanding of constructing TLC through intelligence approach that supported by numerical gradient analysis. The implication of this study is possibility that the model can be applied to the diverse technologies for facilitating to make proper technology investment decision.

In this work, a microwave tunable filter of inverted microstrip with dual-mode resonator using liquid crystal (LC) technology has been designed, manufactured, and characterized. It comprises a thin LC layer between a ground plane and a directly coupled and inverted microstrip line. Central frequency tunability was realised by applying low ac voltages, thus involving low power consumption. The transmission characters of the filter were specifically designed for working at C-band microwave frequency range, which are allocated for many communication applications such as satellite, cordless telephone or weather radar systems. Additionally, its compact structure allows the device to be integrated on circuit board to adapt with other MW components for expanded applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1626–1628, 2016

It has been suggested that the low frequency modulations of the radiofrequency (RF) signal from a wireless phone could be demodulated by human tissue. If this occurred it could lead to interactions with ions in the tissue, with possible biological consequences. In recent experiments it has been shown that biological cells do not exhibit significant electrical nonlinearity to be able to demodulate low frequency signals present as modulations of a RF carrier. This makes irrelevant any hypothetical interactions between RF electromagnetic waves and biological systems involving such demodulation mechanisms. Your wireless phone is not an athermal hazard to your brain.

The use of personal exposure meters (exposimeters) has been recommended for measuring personal exposure to radio frequency electromagnetic fields (RF-EMF) from environmental far-field sources in everyday life. However, it is unclear to what extent exposimeter readings are affected by measurements taken when personal mobile and cordless phones are used. In addition, the use of exposimeters in large epidemiological studies is limited due to high costs and large effort for study participants. In the current analysis we aimed to investigate the impact of personal phone use on exposimeter readings and to evaluate different exposure assessment methods potentially useful in epidemiological studies. We collected personal exposimeter measurements during one week and diary data from 166 study participants. Moreover, we collected spot measurements in the participants' bedrooms and data on self-estimated exposure, assessed residential exposure to fixed site transmitters by calculating the geo-coded distance and mean RF-EMF from a geospatial propagation model, and developed an exposure prediction model based on the propagation model and exposure relevant behavior. The mean personal exposure was 0.13 mW/m2, when measurements during personal phone calls were excluded and 0.15 mW/m2, when such measurements were included. The Spearman correlation with personal exposure (without personal phone calls) was 0.42 (95%-CI: 0.29 to 0.55) for the spot measurements, −0.03 (95%-CI: −0.18 to 0.12) for the geo-coded distance, 0.28 (95%-CI: 0.14 to 0.42) for the geospatial propagation model, 0.50 (95%-CI: 0.37 to 0.61) for the full exposure prediction model and 0.06 (95%-CI: −0.10 to 0.21) for self-estimated exposure. In conclusion, personal exposure measured with exposimeters correlated best with the full exposure prediction model and spot measurements. Self-estimated exposure and geo-coded distance turned out to be poor surrogates for personal exposure. Keywords: Radio frequency electromagnetic field (RF-EMF), Exposure assessment method, Mobile phone base station, Wireless LAN (W-LAN), DECT cordless phone, Radio and television broadcast

In this paper a new electromagnetic (EM) interference analysis is proposed using the total harmonic distortion (THD) measurement of the audio signal by the 900MHz cordless telephones. The cordless telephone network in 900MHz was built up to be weak in EM interference. 400 and 800Hz of the sine-wave signal were used in transmitter (TX) system, and the receiver (RX) system was exposed to the EM interference. The THD value varies as the level of the exposed EM interference changes. The model of the cordless telephone also affects the THD value. By using fluctuation of the THD value depending on the amount of the exposure, the threshold value of the interference electric field strength was derived. Based on the derived threshold value of the electric field strength, validity of the regulation value for low power radio devices by CISPR 22 [CLASS B] and FCC is discussed.

Assistive mobile robots that autonomously manipulate objects within everyday settings have the potential to improve the lives of the elderly, injured, and disabled. Within this paper, we present the most recent version of the assistive mobile manipulator EL-E with a focus on the subsystem that enables the robot to retrieve objects from and deliver objects to flat surfaces. Once provided with a 3D location via brief illumination with a laser pointer, the robot autonomously approaches the location and then either grasps the nearest object or places an object. We describe our implementation in detail, while highlighting design principles and themes, including the use of specialized behaviors, task-relevant features, and low-dimensional representations. We also present evaluations of EL-E's performance relative to common forms of variation. We tested EL-E's ability to approach and grasp objects from the 25 object categories that were ranked most important for robotic retrieval by motor-impaired patients from the Emory ALS Center. Although reliability varied, EL-E succeeded at least once with objects from 21 out of 25 of these categories. EL-E also approached and grasped a cordless telephone on 12 different surfaces including floors, tables, and counter tops with 100% success. The same test using a vitamin pill (ca. 15 mm × 5 mm × 5 mm) resulted in 58% success.

In thinking about convergent media and new digital technologies, the place of mobile services and technologies in the broader media policy field has not been addressed satisfactorily. This article reviews the beginnings of cellular mobiles in Australia to see what this piece of history can tell us about today's policy challenges. My case study revolves around the technology choices made by the federal government in the 1980s, especially the decision to essentially mandate the second-generation Global Standard for Mobiles (GSM) digital standard. I examine the structuring of the mobiles market with three initial licence-holders, and look at the implications of this as mobiles developed through the 1990s. The article offers a brief comparison with the New Zealand mobiles market, and also the promising yet ultimately ‘failed’ technology of the public-access cordless telephone. I conclude with some observations about how such critical examination of history can help to open up policy vistas about mobile media.

This paper presents a low-cost fully-integrated 2.4 GHz ZigBee transceiver in 180 nm CMOS. Optimized from architecture to circuitry design, it is able to coexist with Wi-Fi/BT/Cordless Telephone, Microwave Oven, and Air Conditioning systems in the absence of external filtering components. The transceiver employs an on-chip Balun to realize simultaneous impedance matching for the TX and RX, which share one RF port for single-antenna configuration. IIP2 self-calibration is integrated in the inductor-less RX to avoid sensitivity degradation due to intermodulation. The RX achieves ?97 dBm sensitivity, 75 dB DR, and 50 dBm calibrated IIP2 while dissipating 23.5 mA DC current. The TX features +3 dBm output power

A novel scheme to access the basic rate service of the Integrated Service Digital Network (ISDN) using the Digital Enhanced Cordless Telephone (DECT) radio interface standard is presented. The S-interface in the ISDN reference configuration has been used for the ISDN interface and the unprotected class 0 transmissions are used for the DECT interface. The design of a state of the art interworking unit is described which endeavors to make the use of DECT transparent to the ISDN equipment. The complete design has been simulated and the results presented quantify the overall quality of the link for varying qualities of the radio channel. The simulation results show that DECT radio link can actually replace the fixed S-bus hence locating and relocating of terminal equipment is achieved and this can form the stepping stone for user locating in the 3G (third generation) Universal Mobile Telecommunications System (UMTS). Furthermore, the study also shows that this technique saves on the spectrum usage as it gives 20% spectrum efficiency improvement.

Integrated 900-MHz ISM band transceiver LSI for analog cordless telephone has been realized by cost-effective process technology with sufficient performance. This LSI consisted of fully integrated transceiver, from RF-LNA to audio amplifier for RX chain, from microphone's amplifier to RF-PA for TX chain, and integrated RX- and TX-LO consisting of PLLs and VCOs. In view of narrow signal bandwidth with analog modulation, extremely low phase noise at low offset frequency from carrier was required for integrated VCO. Also, in view of fully duplex operations, signal isolation between TX and RX was required. Despite such a high integration and high performance, chip cost had to be minimized for low-cost applications. The 12-dB SINAD RX sensitivity was -111.2 dBm, the output power of TX was +3 dBm, and the phase noise of integrated VCO was -77 dBc/Hz at 3 kHz offset away from carrier. The current consumption at fully duplex operation was 76 mA at 3.6 V power supply. The chip was realized by 0.8 μm standard silicon BiCMOS process.

Power management is a low-power design technique applicable in almost all design levels. Here, the idea of exploiting events to trigger the shut-down of hardware resources is applied at the behavioral-level of a DECT digital receiver design. Power management involves a trade-off between the power savings arising from the power-down (or shut-down) parts of the system and the power increase due to the additional logic for the generation of the shutdown signals. For that purpose, taking into account the digital receiver's characteristics, a behavioral-level power management technique is introduced. The efficiency of the proposed technique is proven by its application on an industrial DECT receiver, where a power saving of 50% in terms of the dynamic power consumption is achieved.

The authors' case-control study on the possible association between brain tumors and mobile and cordless telephone use included 1,617 patients and 1,617 controls. A questionnaire was answered by 1,429 (88%) cases and 1,470 (91%) controls. Use of analog cellular telephones yielded an odds ratio (OR) for brain tumors of 1.31, 95% confidence interval (CI) equals; 1.04-1.64, increasing for ipsilateral use to OR equals; 1.65, 95% CI equals; 1.19-2.30. The authors found the highest risk for the 20-29-yr age group, with OR equals; 5.91, 95% CI equals; 0.63-55 for ipsilateral use of analog phones. The highest risks were associated with >5-year latency period in the 20-29-yr age group for analog phones (OR equals; 8.17, 95% CI equals; 0.94-71), and cordless phones (OR equals; 4.30, 95% CI equals; 1.22-15).

In mobile communications, such as the cordless telephone, it is important to identify the service area for situations where a base station is installed indoors. However, the mix of walls, columns, and partitions in the typical indoor environment makes it difficult to develop a precise signal propagation estimation formula. The ray-tracing method provides a precise method for the estimation of electric field strengths. Although this method provides a relatively facile way of estimating the electric field strength by simply determining the geometric tracing between sender and receiver, an increase in the number of structural components, such as walls, columns, and partitions, results in a rapid increase in the required processing time. Therefore, the practical utilization of an area prediction system requires an increase in processing speed. This paper proposes a ray-trace-based algorithm that permits high-speed processing. It also describes an indoor area prediction system, IMAP, that has been developed based on the proposed algorithm, and discusses its prediction accuracy. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(10): 60–72, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10189

This study was conducted to assess the quality of interview-based exposure estimates obtained in a large epidemiologic case-control study: The Northern Germany Leukemia and Lymphoma Study (1997-2002) (NLL). The NLL used standardized, face-to-face, computer-assisted interviews to record subjects' lifetime use of radiofrequency (RF)-emitting appliances such as cellular telephones, cordless telephones, baby monitors, and television headphones. Exposure assessment comprised 3 levels of precision: ever use, gross vs. net appliance-years, and lifetime cumulative exposure hours. In the current study, the authors analyzed data from 3041 interviews of NLL controls, representing an age-stratified random sample of the general populations of 6 counties in Northern Germany. Weighted kappa coefficients for gross vs. net appliance-years for men were 0.59 (95% confidence interval [CI] = 0.46, 0.71) for baby monitors and 0.98 (95% CI = 0.97, 0.99) for cordless phones; for women, the coefficients were 0.68 (95% CI = 0.56, 0.79) and 0.97 (95% CI = 0.94, 0.98), respectively. Weighted kappa values were considerably lower when net appliance-years and lifetime cumulative exposure hours were compared. Study results demonstrated that interview information on use of RF-emitting appliances, when measured at different levels of precision, can result in misclassification and biased risk estimates.

The usage of object-oriented methodologies in conjunction with formal description techniques has arisen as a promising way of dealing with the increasing complexity of embedded real-time systems. These methodologies are currently well supported by a set of tools that allow the specification, simulation and validation of the functional aspects of these systems. However, most of these methodologies do not take into account non-functional aspects such as hardware interaction and real-time constraints, which are especially important in the context of this kind of system. Based on our experiences in developing embedded real-time systems, we present a new methodology to design them. This methodology is based on a combination of ideas from different existing methodologies (UML, OCTOPUS, etc.) together with the integration of rate-monotonic analysis in the context of the SDL formal description technique development cycle. Additionally, in order to get this integration, a real-time execution model for SDL is presented to allow us to express hard real-time constraints. The methodology pays special attention to the transition from the object model to the task model, taking into account real-time and hardware integration issues. We also illustrate our proposal by applying it to the development of a multi-handset cordless telephone.

During the 1990s, we witnessed a string of advances in silicon RF integration: from the introduction of the first integrated silicon bipolar radios for groupe special mobile (GSM) and digital European cordless telephone in the late 1980s toward full single-chip integration capabilities based on silicon-germanium BiCMOS technologies. Where RF design used to be a black art, it is becoming a "normal practice" today. In this paper, the authors look back on the past ten years of circuits, silicon technology, and system research with roots in standardization and a scope reaching from the early ideas to the final product success on the market and some perspective toward new concepts and systems.

Recently, we have developed a synchronous SR beam position diagnostic system. In this system, more than one X-ray beam position monitor is used synchronously and an oscillation of the SR beam position all through the storage ring can be detected. For an example, during the high speed driving of the insertion device, beam oscillation and shift can be simultaneously observed at different beamlines. To start the measurements simultaneously at the different beamlines, a trigger signal was conveyed by a cordless telephone. This paper describes the system and performance tests of it.

Future high-performance wireless communication applications such as wireless local area networks (WLANs) around 5 GHz require low-power and highly integrated transceiver solutions. The integration of the RF front end especially poses a great challenge in these applications, as traditional front-end implementations require a large number of external passive components. In this paper, we present the single-package integration of complete transceivers based on a thin-film multichip module (MCM) technology with integrated passives. The MCM substrate is a a common carrier onto which different ICs are mounted. passive components such as RF bandpass filters, inductors, capacitors, and resistors are directly integrated into the MCM substrate with the use of the multilayer structure of the MCM technology. The "system-on-a-package" approach is illustrated with a voltage-controlled oscillator for Digital European Cordless Telephone (DECT) applications and a 5-GHz WLAN front end. These examples indicate that this approach yields a compact low-power implementation of complete transceivers for high-performance wireless applications.

Previous research that has measured brainwaves using electroencephalograph (EEG) equipment consistently show that electromagnetic fields (EMF's) of various ranges can alter the neuro-electrical system of the human brain. The results of brainwave research indicate that different levels or ranges of EMF exposure (e.g., 8Hz, 50Hz and 1200MHz) produce different types of corresponding EEG brainwave patterns. The cordless telephone emits an EMF of around 900-1200MHz and no previous research involving cordless telephones or EMF exposure at similar ranges could be found. This study was an empirical investigation of EEG characteristics resulting from 10 minutes of cordless phone (EMF of 900 MHz) exposure. The 10 minutes of exposure to the 900MHz cordless phone resulted in significant magnitude and power changes in the slow wave (Delta2) and the higher (SMR, Alpha, Beta1) frequency bands; However, slow wave theta was unaffected by the EMF exposure of the cordless phone. Overall total EEG power increased and magnitude reflected more instability.

A 13-bit, 1.4-MS/s, sixth-order cascaded sigma-delta modulator oversampling at 16 X is implemented in a 0.72 /spl mu/m complementary metal-oxide-semiconductor process for use in the baseband path of a radio-frequency receiver. The modulator achieves 77 dB of dynamic range and dissipates 81 mW from a 3.3 V supply. It is characterized for the blocking and intermodulation requirements of a cordless telephone application.

Expectations are that by the end of the first quarter of the next century, accessibility to the telephone will be universal. Virtually, the entire population will be free of the telephone cord and the home or office connection. To meet these expectations, more effective utilization of available cellular bandwidth is needed. As demand for higher performance and increased bandwidth grows, the need for compound semiconductors, which are already used in cordless telephone sets and in some networks, will also grow. This article presents an overview of wireless systems, and methods used for signal modulation coding and decoding, flexible satellites, and handset and hardware requirements will be discussed. Laced with the hardware discussion will be the uses of compound semiconductor devices and circuits.

Background: The exposure of young people to radiofrequency electromagnetic fields (RF-EMFs) has increased rapidly in recent years with their increased use of cellphones and use of cordless phones and WiFi. We sought to ascertain associations between New Zealand early-adolescents’ subjective well-being and self-reported use of, or exposure to, wireless telephone and internet technology. Methods: In this cross-sectional survey, participants completed questionnaires in class about their cellphone and cordless phone use, their self-reported well-being, and possible confounding information such as whether they had had influenza recently or had a television in the bedroom. Parental questionnaires provided data on whether they had WiFi at home and cordless phone ownership and model. Data were analysed with Ordinal Logistic Regression adjusting for common confounders. Odds ratios (OR) and 95% confidence intervals were calculated. Results: The number and duration of cellphone and cordless phone calls were associated with increased risk of headaches (>6 cellphone calls over 10 minutes weekly, adjusted OR 2.4, CI 1.2-4.8; >15 minutes cordless use daily adjusted OR 1.74, CI 1.1-2.9)). Texting and extended use of wireless phones was related to having a painful ‘texting’ thumb). Using a wired cellphone headset was associated with tinnitus (adjusted OR 1.8, CI 1.0-3.3), while wireless headsets were associated with headache (adjusted OR 2.2, CI 1.1-4.5), feeling down/depressed (adjusted OR 2.0, CI 1.1-3.8), and waking in the night (adjusted OR 2.4, CI 1.2-4.8). Several cordless phone frequencies bands were related to tinnitus, feeling down/depressed and sleepiness at school, while the last of these was also related to modulation. Waking nightly was less likely for those with WiFi at home (adjusted OR 0.7, CI 0.4-0.99). Being woken at night by a cellphone was strongly related to tiredness at school (OR 3.49, CI 1.97-6.2). Conclusions: There were more statistically significant associations (36%) than could be expected by chance (5%). Several were dose-dependent relationships. To safeguard young people’s well-being, we suggest limiting their use of cellphones and cordless phones to less than 15 minutes daily, and employing a speaker-phone device for longer daily use. We recommend parental measures are taken to prevent young people being woken by their cellphones.

Society is confronted with an increasing number of applications making use of wireless communication. We also notice an increasing awareness about potentially harmful effects of the related electromagnetic fields on living organisms. At present, it is not realistic to expect that wireless communication will decrease or disappear within the near future. That is why we currently are investigating the mechanisms behind these effects and the effectiveness of possible solutions. In order to be efficient and effective, we designed and validated a fast and easy test on ants - these insects being used as a biological model - for revealing the effect of wireless equipments like mobile phones, smartphones, digital enhanced cordless telephone (DECT) phones, WiFi routers and so on. This test includes quantification of ants' locomotion under natural conditions, then in the vicinity of such wireless equipments. Observations, numerical results and statistical results allow detecting any effect of a radiating source on these living organisms.

To verify that the electromagnetic analysis system NEC2 is effective for the development and design of the second generation digital cordless telephone investigated for use in the frequency band of 1.9 GHz. Two types of personal handy phone models with metal housing and plastic housing were fabricated and measurement and analysis by NEC2 were carried out for radiation patterns. The analysis results were found to agree with the measured results in regard to the absolute gain and shape. For the metal housing model, examples of the procedures were presented for modeling the housing by wire grids or surface patch elements. It was shown that the analysis results agree well with the measured results. It was also found that the radiation pattern of the plastic housing model is only slightly affected by the housing material. By realizing the installed circuit as an analytical model, estimations and evaluations of the radiation pattern are possible by means of NEC2. As a result, NEC2 is effective for the analysis of the radiation pattern of personal handy phone systems at 1.9 GHz.

An efficient implementation of GMSK modulators achieved by taking advantage of symmetry properties of the premodulation filter is described. The design bypasses typical processing steps such as modulating waveform ROM lookup, integration, and sine/cosine ROM lookup, and therefore does not introduce the related errors. A design for a cordless telephony IC with a bit rate of 72 kbps and 64 samples per symbol was implemented using only simple logic and 128/spl times/6 bits of ROM plus 2 simple 6b+sign DACs.

The United States industrial, scientific, and medical (ISM) band has been released for spread spectrum communication, and various applications for it are being proposed. A spread spectrum cordless telephone set has been developed for domestic use as one of its applications. In this paper, the design outline and its characteristics are explained. the direct sequence spread spectrum technique with spreading ratio of 16 in the 902- to 928- MHz ISM band is used. to solve the near-far problem in the mobile radio communication channel, the frequency division multiple access-time division duplex (FDMA TDD) technique is adopted where different frequencies can be assigned to each channel. Compact size and low power consumption is achieved by developing a chip in which spread spectrum processing and transceiver multi plexing can be handled on a single ASIC chip. The voice codec uses ADPCM and provides better voice quality compared to the conventional analog cordless phones. Wider talking range compared to the conventional 46/49 MHz cordless phone is obtained by increasing the amount of transmitted power. Moreover, since the ISM band is used, interference from other sources can be avoided by changing the channel frequencies.

A low-power consumption variable-gain low-noise amplifier (LNA) is demonstrated. To achieve low noise, low distortion, and low power consumption simultaneously, a cascode connection between an enhancement-mode GaAs MESFET (EFET) and a depletion-mode GaAs MESFET (DFET) is employed. The EFET is superior to the DFET in its gain and noise figure performance while the DFET offers good intermodulation distortion performance. The advantages of both types of FET's are combined in the developed LNA. It shows excellent performance with an NF of 2.0 dB, a gain of 12.2 dB, and an IP/sub 3/ of 5.1 dBm at 1.9 GHz. The demonstrated performance satisfies the specifications of the Japanese Personal Handyphone System even at the ultra-low power consumption of 2.0 mW. >

This paper describes a mixed-signal ASIC for dual-mode (analog/digital) cellular telephony applications. It consists of two transmit and two receive channels corresponding to the I and Q channels of a quadrature phase-shift keying (QPSK) modulation system. It also includes three 8 b DAC's for control purposes, as well as a bandgap voltage reference and bus interface circuitry. The chip is part of a four-chip implementation of an IS-54 dual mode telephone. The chip was implemented in a 0.8 /spl mu/m n-well double-metal CMOS process and uses a 5 V power supply. The die area of the chip was 23 mm/sup 2/ and the average power consumption was 125 mW. >

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.

This 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.

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. >

Background: During the revision of the American National Standards Institute (ANSI) C63.19 and the development of the ANSI/Telecommunications Industry Association–1083 hearing aid compatibility standards, it became evident that additional data concerning user acceptance of interfering magnetic noises generated by wireless and cordless telephones were needed in order to determine the requirements for telecoil-coupling compatibility. Purpose: Further insight was needed into the magnetic signal-to-noise (S/N) ratios required to achieve specific levels of telephone usability by hearing aid wearers. (A companion article addresses magnetic signal level requirements.) Research Design: Test subjects used their own hearing aids. The magnetic signals were applied through large magnetic head-worn coils, selected for the field orientation appropriate for each hearing aid. After adjusting their aid's volume control to an acoustic speech reference, the subjects adjusted the applied magnetic signal level to find their Most Comfortable Level (MCL). Each subject then adjusted the levels of six of eight different representative interfering noises to three levels of subjective telephone usability: “usable for a brief call,” “acceptable for normal use,” and “excellent performance.” Each subject's objective noise audibility threshold in the presence of speech was also obtained for the various noise types. Study Sample: The 57 test subjects covered an age range of 22 to 79 yr, with a self-reported hearing loss duration of 12 to 72 yr. All had telecoils that they used for at least some telecommunications needs. The self-reported degree of hearing loss ranged from moderate to profound. Data Collection and Analysis: A guided intake questionnaire yielded general background information for each subject. A test control box fed by prepared speech and noise recordings from computer files enabled the subject or the tester, depending on the portion of the test, to select A-weighting-normalized noise interference levels in 1.25 dB steps relative to the selected MCL. For each subject for each tested noise type, the values for the selected S/N ratios were recorded for the three categories of subjective usability and the objective noise threshold. Results: About half of the test subjects needed a minimum 21 dB S/N ratio for them to consider their listening experience “acceptable for normal use” of a telephone. With a 30 dB S/N ratio, about 85% of the subjects reported normal use acceptability. Significant differences were apparent in the measured S/N user requirements among the noise types, though, indicating a deficiency in an A-weighted level measurement's ability to consistently predict the subjective acceptability of the various noises. An improved weighting function having both spectral and temporal components was developed to substantially eliminate these predictive inconsistencies. Conclusions: The interfering noise level that subjects chose for a telephone usability rating of “excellent performance” matched closely their objectively measured noise audibility threshold. A rating of “acceptable for normal use” was typically achieved at a 4 dB higher noise level, and a rating of “usable for a brief call,” at a 10.4 dB higher noise level. These results did not relate significantly to noise type or to the subject's aided noise-in-speech hearing acuity.

Radiocommunication in terms of wireless devices is a part of daily activity and includes the garage door opener, remote control, toys, navigation system (land, air and sea), radio and TV broadcasting (terrestrial and satellite), earphone, cordless telephone, card reader and internet connection (Wi-Fi) in smart phone devices. To manage the use of radiocommunication is the duty of the national regulatory authority (NRA), which has established rules. In Thailand, spectrum management has developed in several phases, from the establishment of an authority without a radiocommunication act to the implementation of that act, the establishment of the national frequency management board, and the establishment of an independent regulator. This paper provides a chronological account of how the spectrum assignment, especially spectrum commons, developed in Thailand. Access to the archive of the post and telegraph department, Thailand, including the minutes of the national frequency management board, and interviewing the relevant persons have provided the rationale for spectrum assignment, how it has been developed and why this concept is essential for the regulator and society.

Cordless and mobile (cellular) telephone use has increased substantially in recent years causing concerns about possible health effects. This has led to much epidemiological research, but the usual focus is on mobile telephone radiofrequency (RF) exposure only despite cordless RF being very similar. Access to and use of cordless phones were included in the Mobile Radiofrequency Phone Exposed Users Study (MoRPhEUS) of 317 Year 7 students recruited from Melbourne, Australia. Participants completed an exposure questionnaire—87% had a cordless phone at home and 77% owned a mobile phone. There was a statistically significant positive relationship (r = 0.38, p < 0.01) between cordless and mobile phone use. Taken together, this increases total RF exposure and its ratio in high-to-low mobile users. Therefore, the design and analysis of future epidemiological telecommunication studies need to assess cordless phone exposure to accurately evaluate total RF telephone exposure effects.

The authors describe the Si ECL (emitter coupled logic) 3-mW, 1.0 GHz dual-modulus prescaler (64/65,/128/129) for a 3-V PLL (phase-locked loop) synthesizer system. This prescaler has low power dissipation suitable for automobile telephone, cordless telephone, and cellular radios. To achieve high speed with low power, circuits are fabricated with a 0.2- mu m emitter-based self-aligned with polysilicon electrodes and resistors (ESPER) process. This process features a shallow junction profile, small self-aligned emitter, a walled base, selectively ion-implanted collector, and polysilicon electrodes. The minimum device used for circuits has a 0.2*1.0 mu m/sup 2/ emitter area. These features enable the transistor to attain a maximum cut-off frequency of 28 GHz, 1.7 fF collector-base capacitance, and 2.4 fF emitter-base capacitance. >

A single-chip 2.7-V voltage-controlled oscillator (VCO) with an integrated-bias network has been implemented in an Si-bipolar process with an f/sub T/ of 25 GHz. With an on-chip resonator consisting of vertically coupled inductors and varactor diodes, an oscillation frequency of 1.56 GHz was measured. A careful design of the oscillator and bias network was necessary to achieve a phase noise performance of -139 dBc/Hz at 4.7 h MHz off carrier. The tuning sensitivity was 100 MHz/V, which is sufficient to compensate for production tolerances. The VCO can be used as a building block for single-chip transceivers in digital European cordless telephone or global system for mobile communication systems.

Information on the exposure of individual persons to radiofrequency (RF) fields is scarce, although such data are crucial in order to develop a suitable exposure assessment method, and frame the hypothesis and design of future epidemiological studies. The main goal of this survey is to assess individual RF exposure on a population basis, while clarifying the relative contribution of different sources to the total exposure. A total of 377 randomly selected people were analyzed. Each participant was supplied with a personal exposure meter for 24-hour measurements (weekday), and kept a time–location–activity diary. Electric field strengths were recorded in 12 different RF bands every 13s. Summary statistics were calculated with the robust regression on order statistics method. Most of the time, recorded field strengths were not detectable with the exposure meter. Total field, cordless phones, WiFi-microwave, and FM transmitters stood apart with a proportion above the detection threshold of 46.6%, 17.2%, 14.1%, and 11.0%, respectively. The total field mean value was 0.201 V/m, higher in urban areas, during daytime, among adults, and when moving. When focusing on specific channels, the highest mean exposure resulted from FM sources (0.044 V/m), followed by WiFi-microwaves (0.038 V/m), cordless phones (0.037 V/m), and mobile phones (UMTS: 0.036 V/m, UMTS: 0.037 V/m). Various factors, however, contributed to a high variability in RF exposure assessment. These population-based estimates should therefore be confirmed by further surveys to better characterize the exposure situation in different microenvironments. Keywords: Base station, Cellular phone, Cordless phone, Exposure assessment, FM, Radiofrequency, TV, WiFi

The IEEE 802.15.4 as one of the facto low layer communication standards for PANs and WSNs may be interfered by other wireless devices in the ISM frequency bands, especially at home, such as devices of IEEE 802.11b, Bluetooth, Cordless telephone, and microwave oven. This paper examines the mutual interference effects of 2.4 GHz devices which are widely deployed at home, via both theoretical analysis and real-life experiment. In the paper an analytical model is proposed to estimate the Packet Error Rate (PER), the collision probability and the active-rate of the interference networks. The model is verified through a series of experiments. The Experimental results also show that Bluetooth has little impact of interference on 802.15.4 networks, whereas microwave oven and 802.11b wireless networks can cause problems to 802.15.4; however the effects can be significantly reduced by a proper channel selection.

This chapter contains sections titled: An Integrated Si Bipolar RF Transceiver for a Zero IF 900 MHz GSM Digital Mobile Radio Frontend of a Hand Portable Phone BBTRX: A Baseband Transceiver for a Zero IF G5M Hand Portable Station A2.7V 800MHz-2.1GHz Transceiver Chipset for Mobile Radio Applications in 25 GHz ff Si-Bipolar An Analog Radio Front-end Chip Set for a 1.9GHz Mobile Radio Telephone Application A 900MHz Transceiver Chip Set for Dual-Mode Cellular Mobil Terminals A 2.7V to 4.5V Single-Chip GSM Transceiver RF Integrated Circuit A2.7V GSM Transceiver ICs with On-Chip Filtering A 2.4 GHz Single Chip Transceiver The Future of CMOS Wireless Transceivers A 1.9G Hz Wide-Band IF Double Conversion CMOS Integrated Receiver for Cordless Telephone Telephone Applications A 2.5GHz BiCMOS Transceiver for Wireless LAN A 2.7V DECT RF Transceiver with Integrated VCO A 2.7V 2.5GHz Bipolar Chipset for Digital Wireless Communications A 2.7V GSM RF Transceiver IC

In January 1988, The European Conference of Postal and Telecommunication administrations (CEPT) decided to base the standard for medium and long-term applications of advanced digital European cordless telecommunications (DECT) on a multicarrier/time-division-multiple-access/time-division-duplex (MC/TDMA/TDD) approach. The Ericsson DCT 900 MC/TDMA/TDD pico cellular cordless telephone system concept is presented. It is a DECT-like system with limited data services operating up to 8 MHz in the 860 to 870 MHz frequency band, but it can be implemented anywhere in the 800 to 900 MHz bands. A description of the DCT 900 system and the cordless radio subsystem is included. >