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Radio Receivers and Associated Systems, 1995., Sixth International Conference on

Date 26-27 Sep 1995

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Displaying Results 1 - 25 of 45
  • An integrated active transponder for ISM-band applications

    Page(s): 172 - 175
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    The paper describes a multifunction GaAs MMIC dedicated to ISM-band short range microwave link application. The chip was designed to satisfy the typical transponder system specifications and to be easily adaptable to different transponder architectures. Experimental results are reported and discussed View full abstract»

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  • A low power consumption receiver at LF using frequency shift keying technique

    Page(s): 67 - 70
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    A low cost, compact, low power receiver has been designed and implemented. The frequency of operation was chosen to be 176 kHz. The modulation method was frequency shift keying. In the design, no bulky inductor was employed View full abstract»

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  • A high-performance 1 GHz surface transverse wave based receiver for hand-held personal communications

    Page(s): 76 - 80
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    This paper describes a compact, efficient and highly sensitive 1 GHz superheterodyne receiver which can track, receive and detect frequency modulation (FM), and frequency shift keying (FSK) signals with a modulation bandwidth of 200 kHz and a sensitivity threshold of 500 nV. The tracking bandwidth of 500 kHz allows reliable operation over the temperature range of (-30...+60) deg. C. The receiver can process FSK signals with a data rate in excess of 200 kbit/s, draws a current of 12 mA from a 3.5 V direct current (DC) source and has the dimensions of 100×50×12 mm with batteries included. The key to achieving this receiver performance in such a small volume is the utilization of novel surface transverse wave (STW) technology which allows the design of compact and temperature stable local oscillators (LO) featuring excellent tunability and superior phase noise performance View full abstract»

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  • HF radar receiving system image rejection requirements

    Page(s): 128 - 132
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    The sensitivity and consequent detection capability of an HF radar employing a superheterodyne receiving system may be compromised by spurious signals arising from inadequate receiver image rejection characteristics. The image rejection phenomenon arises due to the fact that in addition to the intended action of a mixer in translating a wanted signal from its input frequency to an intermediate frequency, the mixer will also be susceptible to mixing an unwanted signal (the image), displaced from the wanted signal by twice the intermediate frequency, to the same intermediate frequency. Unless the amplitude of the image signal is contained by an appropriate degree (the image rejection), the image signal will be processed along with valid radar returns, and constitute a source of spurious signals with the potential to degrade radar detection performance. In order to estimate a measure of adequate receiver image rejection, it was first necessary to establish a theoretical basis on which the estimation could be based. The theoretical analysis revealed that, in addition to several radar specific parameters, adequate image rejection was critically dependent on the ratio of the power at the receiver image frequency to that of the background noise spectral density at the intended radar operational frequency. The article includes a theoretical analysis and the extraction of relevant data from a synoptic data base of the HF environment. Based on a statistical analysis of the data base, it has been possible to deduce the impact on radar performance as a function of the receiver image rejection performance, and hence ascertain a measure of adequate image rejection View full abstract»

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  • Repeaters in PCN and mobile cellular networks

    Page(s): 154 - 157
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Repeater implementations need to be tailored to the environment in which they are deployed. The operation of two types of repeater, indoor and outdoor, is illustrated through the use of operating scenarios in order to define performance limits and equipment requirements. The results of trials of such repeaters in Mercury One-2-One network is then provided View full abstract»

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  • Application of zero-IF radio architecture to multistandard compatible radio systems

    Page(s): 81 - 85
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    This paper covers the results of the radio architecture studies towards common multistandard compatible radio front-ends carried out within the RACE Project 2123 GIRAFE (Gigahertz Radio Front Ends) which is a research project in the area of mobile telecommunications focused on the application of advanced microelectronics integration and packaging techniques for RF components to be used in terminals of future mobile communications systems. These terminals will be based on combinations of available second generation systems in Europe (GSM, DCS1800, DECT and INMARSAT). The objective is to create a set of RF building blocks (RX and TX mixers, 90° phase shifters, VCO and prescaler) and develop multistandard RF front-ends in high frequency bipolar process, complemented by the investigation and adaptation of novel packaging techniques which have a major low cost, high volume RF components View full abstract»

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  • Where is the thrust in the cellular telephony?

    Page(s): 158 - 162
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    This paper presents an overview of wireless telephony. The key points relating to different markets are analyzed: their size, customer needs, coming changes etc. Next the evolution of analogue and digital cellular systems is described and also the different skills that are needed to create a multinational cellular service are listed. The conclusion is that while wireless telephony is becoming a real consumer market, the emphasis in this business is changing from complex technical issues to issues more closely related to quality and versatility of services View full abstract»

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  • Performance of a multi-carrier code division multiple access frequency domain RAKE receiver

    Page(s): 86 - 90
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    A multi-carrier code division multiple access system with a frequency domain RAKE receiver is described. We compare multi-carrier and direct sequence CDMA systems using frequency and time domain RAKE receivers in the downlink of a mobile cellular system. No guard interval or interleaving is used in our multi-carrier system and in this way the multi-carrier and direct sequence systems occupy the same bandwidth. The modulation scheme is differential phase shift keying. The results are presented as received bit error rates from Monte Carlo simulations. The simulations are conducted in a multipath channel with Rayleigh fading characterised by a 300 Hz classical Doppler spectrum with additive white Gaussian noise. In the multipath fading channel the performance of the direct sequence CDMA system is superior to the multi-carrier CDMA RAKE receiver for multiple users using the architectures described View full abstract»

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  • Detecting and identifying spurious signals generated in radar receivers

    Page(s): 119 - 122
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    HF radar receivers require the suppression of inherent spurious signals (spurii) far below the IEC specified level. Measurements of the appropriate sensitivity are often thwarted by spurii originating in test equipment, making it difficult to identify those spurii which originate in the receiver. A technique is proposed which allows spurii generated from harmonics of the tuned local oscillator to be differentiated from those originating from sources external to the receiver. The method involves stepping the tuned frequency of the receiver through its range with the receiver input terminated in a dummy load and examining the receiver output. The tuning frequency steps of the receiver are made much smaller than the output bandwidth so that spurious signals generated due to harmonics of the local oscillator are not missed in the scan of the receiver's RF range. The method requires the search to be automated with the receiver local oscillator and the spectrum analyser at the receiver output under computer control. Spurii detected by the spectrum analyser may be analysed immediately by the computer. Signals which are detected on successive scans of the baseband may have their origins identified, at least in part, by noting their shift in frequency across the output band from one scan to the next. A shift of N times the tuned frequency increment indicates that the Nth harmonic of the tuning local oscillator is responsible. A shift equal to the increment indicates that the fundamental of the LO is involved or alternatively that the spur source is external to the receiver View full abstract»

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  • Evolution of radio systems into the 21st century

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    Progress in the development and application of radio communications over the past century, from initial discoveries to mass markets has been both rapid and profound. As we approach the second century of radio this paper explores the possible evolution of radio systems in the coming years. In considering future evolution of radio systems we should recognise the enormous potential of radio systems to develop and proliferate as have computers, in a variety of forms, large powerful systems, small portable systems and embedded technology in a multitude of different products in diverse markets. Such proliferation will have far reaching consequences. In considering evolution paths we must identify and evaluate potential new applications and markets, and consider the wider environment in which the technology will be applied. This paper has sought to begin to do this, albeit to a very limited degree, giving examples of such applications and markets and some of the relevant issues that will drive them View full abstract»

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  • An Omega radio-navigation receiver for animal tracking

    Page(s): 163 - 167
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    By taking a fundamental look at the way animal-tracking systems work, suggestions are made for alternative systems of improved performance. The feasibility of an animal-tracking `tag', based on an Omega radio-navigation receiver is explored, and the design and performance of a prototype receiver described. The paper demonstrates that such an Omega tag is more than competitive with the use of the widely-used Argos satellite tracking system because of the substantial cost and power savings it offers View full abstract»

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  • Channel-adaptive modulation

    Page(s): 144 - 147
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    Packet reservation multiple access (PRMA) assisted adaptive modulation using 1, 2 and 4 bit/symbol transmissions is proposed as an alternative to dynamic channel allocation (DCA) in order to maximise the number of users supported in a traffic cell. The cell is divided in three concentric rings and in the central high signal-to-noise ratio (SNR) region 16-level star quadrature amplitude modulation (16-StQAM) is used, in the first ring differential quaternary phase shift keying (DQPSK) is invoked, while in the outer ring differential phase shift keying (DPSK) is utilised. A channel SNR of about 7, 10 and 20 dB, respectively, was required in order to maintain a bit error ratio (BER) of about 1%, which can then be rendered error-free by the binary BCH error correction codes used. A 4.7 kbps algebraic code excited linear predictive (ACELP) speech codec is favoured, which is protected by a quad-class source-sensitivity matched BCH coding scheme, yielding a total bit rate of 8.4 kbps. A GSM-like voice activity detector (VAD) controls the PRMA-assisted adaptive system, which ensures a capacity improvement of a factor of 1.78 over PRMA-aided binary schemes View full abstract»

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  • A modular testbed for automatic channel selection, link establishment and maintenance

    Page(s): 105 - 108
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The paper describes the development of a testbed radio system for automatic channel selection (ACS), automatic link establishment (ALE) and automatic link maintenance (ALM) techniques. As HF radio systems become more automated, the concept of ALE has evolved to describe the start-up phase of communications. ALE involves the co-ordination of channel encoding and decoding, encryption and decryption, frequency management and system control in order to meet specified user requirements. The most common requirement is a reduction in the level of operator expertise necessary to operate the radio system successfully. The purpose of ACS is to provide a quality analysis of the available channels, to enable the most suitable to be used for communications. Once a radio link has been established it is sensible for the system to employ ALM techniques to maintain the link in the event of interference or channel degradation View full abstract»

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  • Digital HF receiver

    Page(s): 47 - 51
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    The paper describes an experimental digital receiver (tuner) for wideband applications in the HF-band. The output from the receiver is an undemodulated digitised signal with 750 kHz of useful bandwidth. The 5 MHz sampling frequency is generous compared to the bandwidth. This relaxes the demands on the analogue components and gives us the possibility of using baseband sampling without introducing aliasing distortion from the harmonic signals. Measurement shows a spurious free dynamic range of 80 dB. The low baseband sampling frequency enables us also to make use of an operational amplifier as the final drive amplifier for the A/D converter View full abstract»

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  • Performance assessment of receivers used in HF radar

    Page(s): 133 - 138
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    The High Frequency Radar Division of the Australian Defence Science and Technology Organisation has developed an automated HF receiver testing station which can perform exhaustive testing and assessment of multiple performance modes of radio and radar receivers as well as other HF and VHF components and systems. The system developed has the capability of performing detailed examination of a receiver's (or other component's) attributes in an unattended mode with virtually no requirement for user intervention. This has been achieved using graphical user interface based software controlling dedicated interface equipment. Particular attention has been given to make the automated testing exhaustive with the user selecting both the types and extents of testing but the actual user operation easy to set up and perform. External parameters such as power supplies, signal and noise sources, filters etc. are all under user set up and control via a dedicated computer interface. Assessment of parameters may range from simpler functional and operational checks to more stringent checks for linearity, distortion, noise and more. All results are processed and presented to the user in a number of novel and unique ways in order for the user to be able to make a judgement based on all the information available. A description of the hardware architecture is given. The control and processing software is also described as well as some sample results for various receiver characterisations performed to date View full abstract»

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  • An HF DSP based frequency management system

    Page(s): 123 - 127
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    The requirement to optimise the operation of a high frequency (HF is 2 to 30 MHz) communication link is primarily a function of two main factors; (i) the varying nature of the HF medium causes the need to regularly monitor the operation of high performance links, and (ii) the allocated available spectrum to be utilised with greater efficiency. In response to this challenge, adaptive HF systems have been developed. The definition of an adaptive system provided by Penningtion and Wilkson (1985) is “when path data is in real time or near real time and is used to optimise some parameter of the communications equipment, the overall system can be defined to be adaptive”. Path data is usually generated by real time channel evaluation (RTCE) tools. Frequency management routines then assess this information to determine how the system can adapt to counter propagation effects. To ensure that adequately modelled trends are followed, a short term forecast is required in addition to long term prediction. This enhancement is obtained by taking data from long term prediction models and extrapolating the real time data View full abstract»

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  • Linearised transceivers for mobile communications base stations using adaptive array antennas

    Page(s): 208 - 211
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    With the increased demand on higher capacity and better services from mobile communications networks, the rise of an adaptive antenna in mobile communications base stations is seen as inevitable. This technique has the potential of increased spectrum efficiency, extended range of coverage and higher data throughput. It has presented an incentive to further investigate hardware aspects in the realisation of these systems. One of the key components in an adaptive antenna system is the transceiver subsystem. This contribution investigates linearity aspects of the up- and down-conversion chain on the performance of adaptive antennas and suggests solutions to the non-linearity problems within an adaptive antenna system View full abstract»

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  • A new method for multipath channel characterisation for terrestrial transmitted video

    Page(s): 22 - 25
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    Under the multipath conditions of terrestrial television transmission, ghost carriers cause additive information to be generated by the VSB filter within the television receiver. By analysis of this a priori effect of the VSB filter under a ghosted condition the inphase and phase quadrature detected video signals are defined. Derived from these results, a new algorithm based upon correlation techniques is presented which finds the characteristics of the amplitude and delay of individual ghosts. These characteristics are then passed to a deterministic deghoster to minimise ghost effects View full abstract»

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  • Identification of PSK signals

    Page(s): 95 - 99
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    PSK signals may be identified using decision theoretic techniques. The paper compares the performance of the optimum, the statistical moments, the DFT and the maximum likelihood DFT classifiers. The robustness of each classifier is examined for the effects of symbol imbalance due to a finite signal time frame, error in the SNR estimate, channel filtering and phase error. Simulation results are presented in terms of the SNR at which 1% misclassification probability occurs, in order to provide a comparison between the techniques View full abstract»

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  • In-band channel sounding in operative cells for mobile and wireless communications

    Page(s): 31 - 35
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    This paper presents an analysis of the swept time delay crosscorrelator, as used in wideband, RF, channel sounding systems, with a view to examining its use in already occupied channels. It is shown that the probe signal can be selectively filtered at the transmitter and receiver to minimise interference to users within the band. This filtering degrades the dynamic range of the sounder and hence the dynamic range can be traded against the spatial resolution performance in a given scenario. An analysis of the various factors is presented and some sample results are discussed View full abstract»

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  • An antenna correlation measuring receiver

    Page(s): 91 - 94
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    The paper presents a simple antenna correlation measuring receiver that is capable of measuring the complex cross-correlation of the signals produced by two receiving antennas connected to it. To measure complex correlation, information about the amplitude and phase of each signal is required. Synchronous phase measurement dictates that highly phase-stable oscillators and signal generators are used in both the transmitter and the receiver. The design presented however, employs common first and second oscillators in a two-branch measuring receiver. This method removes the necessity for expensive signal generators, as phase fluctuations (produced by either the transmitter or the shared receiver oscillators) are common to both branches and do not effect the complex correlation calculated between them View full abstract»

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  • A 5 kHz channelling VHF linear modulation receiver for volume production

    Page(s): 6 - 10
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Increased demand for spectrum has led the regulatory authorities to encourage the adoption of voice and data systems using 5 kHz channelling. In the USA, 200 duplex channels in the 220 to 222 MHz band released by the FCC are now in use. In the UK, a regulatory specification is published by the Radiocommunications Agency and trials have been carried out in the 70 MHz, 160 MHz and 220 MHz bands. Manufacturers are now using digital signal processing (DSP) in low-cost, flexible mobile transceivers. DSP is applicable both for linear receivers and for transmitters such as those using a Cartesian loop. Private Mobile Radio (PMR) equipment operating with 5 kHz channelling is now manufactured in volume and provides both excellent analogue voice quality and 14.4 kb/s digital capability for data or digital voice applications in both static and fading environments View full abstract»

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  • Using method of slowly changing amplitudes for analysing oscillations in phase-locked loops

    Page(s): 181 - 184
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The phase-locked loop has been found to be a very useful element in many types of communication systems. It is used in two fundamentally different ways [Gardner (1981), Encinas (1993)]: (1) For demodulation, where it is used to follow phase or frequency modulation of the input signal. (2) For tracking a carrier or synchronizing signal which may vary in frequency with time. The authors discuss stability loss criteria, loop oscillations and stationary loop oscillations View full abstract»

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  • A novel data-rate adaptation approach for meteor burst communications: direct-sequence spread-spectrum modulation

    Page(s): 148 - 153
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    There are a number of basic approaches to implementing a variable data-rate modem. A meteor burst communication channel can be fully exploited during an adaptive data-rate operation. In adaptive data-rate operation, the actual data-rate is matched to the instantaneous power received from a meteor trail. This paper theoretically investigates the benefit of such an operation and introduces a new method which has some advantages over conventional approaches such as better adaptation and lower complexity View full abstract»

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  • RF transformers considered as transmission line devices

    Page(s): 109 - 113
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    The lumped element circuit model for broad-band transformers has been in use for at least 50 years. It was developed for audio frequency transformers. Unfortunately, it ceases to give accurate results when the length of the windings becomes significant with respect to the signal wavelength. This is the case in RF broad-band transformers. For these, a model based on transmission lines is proposed. This model will help the designer to visualise how the device works, enable him to set achievable design goals, and allow him to perform more accurate computer simulations of his RF circuits View full abstract»

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