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Adaptive HF Management, IEE Colloquium on

Date 3 Mar 1989

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Displaying Results 1 - 11 of 11
  • IEE Colloquium on `Adaptive HF Management' (Digest No.33)

    Publication Year: 1989
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (52 KB)

    The following topics were dealt with: passive monitoring of chirpsounder transmitters; automatic frequency management; HF real-time channel evaluation system; spectrum regulation and standardisation; adaptive coding; convolution coding; error control coding; HF Skywave links; adaptive chirp modem; and serial HF modem View full abstract»

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  • Automatic frequency management

    Publication Year: 1989, Page(s):211 - 214
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (212 KB)

    The author discusses the need to automate the frequency selection process of an HF chirpsounder, and considers the provision of automatic frequency management. A frequency management terminal is described which can successfully select frequencies based on quality factor data and, with additional control software, can control communications transmitters and receivers automatically View full abstract»

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  • An adaptive chirp modem for medium data rates

    Publication Year: 1989, Page(s):911 - 915
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (180 KB)

    The authors describe an experimental HF modem which uses serially transmitted chirp signals swept across a voice channel bandwidth. The modem is able to adaptively excise interference from other HF users, and has inherent tolerance to frequency selective fading and additive white Gaussian noise. A number of experimental signal formats have been incorporated so as to achieve data transmission at ra... View full abstract»

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  • Performance of a 4800 bit/s serial HF modem

    Publication Year: 1989, Page(s):10/1 - 1010
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (528 KB)

    The authors outlines, with the minimum use of mathematics, the method of operation of a 4800 bit/s serial modem designed for HF radio links, and discusses the reasons for the choice of the given design. They present the results of computer-simulation tests on the modem, for different models of the radio link, showing that the modem achieves a surprisingly good performance View full abstract»

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  • Convolutional coding for both synchronisation and protection over HF channels

    Publication Year: 1989, Page(s):711 - 712
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (52 KB)

    A new digital communication procedure is presented in which the operations of demodulation, decoding and synchronisation are combined. The modem operates in a four tone multiple frequency shift keying (MFSK) format. The system employs a new method of adaptive symbol synchronisation termed code assisted bit synchronisation (CABS), which can track variations in signal timing highly effectively View full abstract»

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  • Passive monitoring of chirpsounder transmitters as an aid to HF frequency management

    Publication Year: 1989, Page(s):111 - 115
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (204 KB)

    Chirpsounder detection methods are discussed, and a chirp-based MUF measurement system is described. Proposed enhancements to the chirp detector are discussed, including filter taps, increased receiver bandwidth, receiver characterisation, and interference effect improvement. The use of the chirp detector is an HF frequency management system is discussed View full abstract»

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  • An efficient form of error control coding applied to HF skywave links

    Publication Year: 1989, Page(s):811 - 818
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (456 KB)

    The author describes the design and performance of an efficient data transmission protocol for use on low data rate (150 baud) HF skywave links. The protocol maximises data throughput by adjusting the amount of redundancy in transmissions to suit the channel conditions, using the technique of parity re-transmission. Little redundancy is added when few errors occur during transmission, but more is ... View full abstract»

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  • Adaptive coding for HF channels

    Publication Year: 1989, Page(s):611 - 613
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (64 KB)

    The authors consider error correction codes for HF channels, explaining the advantages of adaptive coding schemes. An incremental redundancy coding scheme based on product codes is introduced. The codes described are tested by means of HF channel simulation View full abstract»

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  • Spectrum regulation and standardisation issues by the adoption of adaptive HF systems

    Publication Year: 1989, Page(s):511 - 515
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (216 KB)

    The authors propose an HF adaptive system that will cause a better utilisation of the HF spectrum, and discuss changes in frequency channel allocation. A definition of HF adaptive systems is given, and the frequency considerations of adopting adaptive systems are discussed. Standards, interference and proposed work packages are outlined View full abstract»

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  • Practical enhancements for HF systems

    Publication Year: 1989, Page(s):411 - 414
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (192 KB)

    The authors discuss the difficulties of engineering communications circuits over HF channels, considering propagation uncertainty due to the variability of the ionosopheric medium, and circuit degradation due to external noise incident on the receiving system. They describe oblique incidence ionosondes, and discuss frequency monitoring, vertical incidence sounding, backscatter sounding, the use of... View full abstract»

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  • Design & performance of AN HF real-time channel evaluation (RTCE) system

    Publication Year: 1989, Page(s):311 - 316
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (228 KB)

    The RTCE system described comprises a global network of HF (2-30 MHz) transmitters and receivers allowing users to monitor and collect a variety of real-time data on propagation and noise/interference conditions in the HF band on a worldwide basis. The system is accessible by anyone with a requirement for such data, whether they belong to professional or amateur radio communication communities. An... View full abstract»

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