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Communications, Radar and Signal Processing, IEE Proceedings F

Issue 4 • Date July 1984

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Displaying Results 1 - 15 of 15
  • Performance comparison of two suboptimum detection procedures in real environment

    Publication Year: 1984 , Page(s): 341 - 344
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    Two suboptimum detection procedures, one based on the binary matched filtering and the other based on the weighting of partial decisions, were introduced earlier into the literature as very suitable for the cost-effective microprocessor-based implementation of the medium-speed voice-band data modems. Previous analysis of these two detection procedures was limited to the case when only Gaussian noise is present in the communications system. Here, both procedures are treated comparatively under conditions typical of realistic applications. These conditions refer to the cases when Gaussian noise is combined with intersymbol interference or timing jitter. To provide a reference against which the new detection procedures can be evaluated, results known from the literature for the optimal detector are here utilised and are comparatively presented. View full abstract»

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  • Minimum bandwidth signals with various combinations of specified waveform parameters

    Publication Year: 1984 , Page(s): 345 - 348
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    For each of four separate conditions placed on a waveform (amplitudes at certain epochs and slopes at those epochs), constraints on the corresponding spectra are obtained for a system of any bandwidth. Waveforms which satisfy certain combinations of amplitude and slope constraints, within a minimum bandwidth, are shown to have unique spectra. The method confirms that Nyquist's first and second conditions are satisfied by the raised-cosine frequency spectrum, and spectra are obtained for other waveform conditions. The results are of interest in practical systems where constraints are placed on intersymbol interference and telegraph distortion, or as design targets in theoretical systems. View full abstract»

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  • Generating analogue FM pulses using a 1 bit digital technique

    Publication Year: 1984 , Page(s): 349 - 356
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (848 KB)  

    A method of generating sinusoidal frequency-modulated pulses using a 1 bit digital technique is developed. The method utilises the information in the zero crossings of the signal, rather than sampling and voltage quantisation, to reconstruct the signal. An intuitive view of the spectrum of a frequency-modulated square wave (FMSW) is derived, and confirmed by mathematical analysis. The spectrum consists of a series of harmonics of the form associated with the modulation law used. The bandwidth and TB product of the harmonics increase in direct proportion to the order of the harmonic. The effect of the time quantisation of the zero crossings necessary to generate a FMSW using digital logic is analysed. The relationship between the time quantisation, signal bandwidth and clock frequency is discussed. The generation of nonlinear FM pulses is illustrated using a truncated Gaussian 15 dB spectrum, and the effect of the time quantisation on the compressed pulse sidelobe levels is computed. The effect of Doppler shift on the sidelobe levels is also illustrated. Hardware for generating FMSWs is described, and the effect of the logic risetime on the spectrum is analysed. The concept of the FMSW is verified using a simple TTL circuit to generate a LFM pulse. View full abstract»

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  • Combined mobile telephone and dispatch services in a cellular land-mobile radio system

    Publication Year: 1984 , Page(s): 357 - 363
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (851 KB)  

    In this paper a cellular land-mobile radio system with combined mobile telephone and dispatch services is considered. A hybrid scheme for channel assignment is considered. Two flow control levels for dispatch users are introduced to preserve the quality of mobile telephone service. Results are obtained by computer simulation of the system. View full abstract»

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  • Data transmission over UHF fading mobile radio channels

    Publication Year: 1984 , Page(s): 364 - 374
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1470 KB)  

    A combination of transparent tone-in-band (TTIB) and feedforward signal regeneration (FFSR) audio signal-processing techniques enable the efficient transmission of speech and data communications over mobile radio links, and amplitude companded pilot tone single sideband (SSB) in particular. The contribution is concerned primarily with data communications, coherent and noncoherent, over such networks in the presence of multipath induced amplitude and phase distortion. A detailed consideration of the properties of the combined TTIB/FFSR system show it to have several significant advantages over data-derived reference schemes. View full abstract»

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  • Fast start-up channel estimation

    Publication Year: 1984 , Page(s): 375 - 382
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (989 KB)  

    The paper considers the receiver of a digital data-transmission system which is fed from a number of different transmitters in an arrangement where separate short messages are transmitted, in turn, from the different transmitters, with arbitrary time gaps between adjacent messages when no signal is transmitted. The signals received from the different transmitters may be subjected to widely different levels of amplitude and phase distortions, so that a training or synchronising signal must be transmitted at the start of each message, during which the receiver must obtain a reasonably accurate estimate of the sampled impulse response of the channel. The latter may then be used for the initial adjustment of an adaptive equaliser, but this or any other application of the channel estimate is not studied here. Since a satisfactory estimate of the sampled impulse response of the channel is needed in the shortest possible time, in order to maximise the transmission rate of useful data over the duration of the message, an optimum, estimation process must be used together with the training signal that enables the best estimate of the channel response to be obtained. The paper derives the maximum-likelihood estimation process for the sampled impulse response of the channel, which, under the assumed conditions, gives the unbiased estimate with the minimum mean-square error. The paper then determines the conditions that must be satisfied by the training signal to minimise the mean-square error in the channel estimate, and lists a number of such optimised training signals using two-, three-and four-level symbols. Finally, the new systems are compared with the more promising of the techniques previously described. View full abstract»

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  • IEE Colloquium on Electronic Support Measures

    Publication Year: 1984
    Save to Project icon | PDF file iconPDF (117 KB)  
    Freely Available from IEEE
  • Multinotch logic-product polarisation suppression filters: a typical design example and its performance in a rain clutter environment

    Publication Year: 1984 , Page(s): 383 - 396
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1662 KB)  

    Polarisation filtering is applied in radar systems to improve target detection in adverse environments. Fluctuations of the polarisation states of unwanted incident signals dictate the need for filters that suppress such signals in the polarisation domain and cover a controllable area of polarisation space. This has led to the concept of the multinotch logic-product (MLP)polarisation filter which attempts to meet the above need. The paper describes the parameters that affect the general characteristics of the MLP filter, gives a typical design example and uses a representative set of experimentally derived rain clutter data to evaluate the performance of this MLP filter. View full abstract»

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  • Threshold detection of CPFSK in non-Gaussian noise

    Publication Year: 1984 , Page(s): 397 - 402
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (490 KB)  

    A locally optimum receiver structure is derived for the coherent detection of continuous phase frequency shift keying in non-Gaussian noise. Performance of the receiver, which consists of a zero-memory nonlinearity followed by a correlator, is evaluated for a number of important noise models. The effects of varying the observation interval and modulation index on receiver error probability are determined. View full abstract»

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  • Performance analysis of 16-ary QAM signalling through two-link nonlinear channels in additive Gaussian noise

    Publication Year: 1984 , Page(s): 403 - 406
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    This paper considers the problem of evaluating the performance of a 16-ary quadrature amplitude modulation (QAM) signal transmitted through a bandpass nonlinearity (BPNL), exhibiting AM-AM and AM-PM conversions, and in the presence of additive gaussian noise (AGN) both preceding and following the nonlinearity. An expression for the error probability is derived and computed. Also, the effect of TWT back-off from saturation on 16-ary QAM system performance is studied. Finally, as an example, a comparative study of 16-ary CPSK and 16-ary QAM transmissions is undertaken with the BPNL operated at various levels of back-off from saturation. View full abstract»

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  • New direct regenerator for 16-ary QAM signalling

    Publication Year: 1984 , Page(s): 407 - 411
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (569 KB)  

    This paper proposes a new 16-ary quadrature amplitude modulation (QAM) direct regenerator to be used in digital communications systems. Theoretical analysis follows to evaluate the performance of a two-link system in additive Gaussian noise (AGN) incorporating a practical 16-ary QAM direct regenerator and an ideal coherent receiver. In addition to nonlinearities and circuit limitations in the regenerator, optimum detection in the receiver is also taken into account. View full abstract»

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  • New syndrome decoding techniques for the (n,k) convolutional codes

    Publication Year: 1984 , Page(s): 412 - 416
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    This paper presents a new syndrome decoding algorithm for the (n,k) convolutional codes (CCs). The construction of the trellis diagram of this algorithm is simpler than the syndrome decoding algorithms of Schalkwijk, Vinck and De Paepe. The new algorithm is based on the general solution of the syndrome equation, a linear diophantine equation for the error polynomial vector E(D). The set of diophantine solutions is a coset of the CC. In this error coset a recursive, Viterbi-like, algorithm is developed to find the minimum weight error vector ¿¿(D). An example, illustrating the new decoding algorithm is given for the binary nonsystematic (3,1) CC. View full abstract»

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  • Formulas for measuring radar ECCM capability

    Publication Year: 1984 , Page(s): 417 - 423
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (830 KB)  

    In view of the lack of a simple and generalised method for measuring radar ECCM capability, a set of formulas are derived for calculation of radar anticlutter, antijamming and generalised ECCM capability. The fundamental part of these formulas consists of the technical parameters of the radar and represents the radar potential ECCM capability. The supplementary part of these formulas, expressed in terms of characteristic specifications of the radar ECCM devices, represents the quality levels of these devices. Examples are given and the applications of the calculated results to radar system analysis and system design are discussed. View full abstract»

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  • Comments on ¿Effectiveness of a ground jammer¿

    Publication Year: 1984
    Save to Project icon | PDF file iconPDF (141 KB)  
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  • Comments on ¿Bit synchronisation method based on sensitivity function¿

    Publication Year: 1984
    Save to Project icon | PDF file iconPDF (106 KB)  
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Aims & Scope

The latest version of this title is Radar, Sonar & Navigation, IET.

Full Aims & Scope