Frequency Shift Telegraphy¿Radio and Wire Applications

Davey, Jack; Matte, A. L.

doi:10.1109/t-aiee.1947.5059468

Cited by 15 publications

(1 citation statement)

References 7 publications

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“…The phase-change system is a differentially phasemodulated one, and phase multiplexing on each carrier can be used. Various analyses and comparisons of such systems have been described in existing literature, 1 "" 19 but the lack of uniformity in the methods used and the absence of test results produced under identical controlled conditions have sometimes left erroneous impressions of their relative merits. The series of tests described in this paper was made on systems of each type, which, from the results, appear to be characteristic of good practice.…”

Section: Introductionmentioning

confidence: 99%

Choice of multi-channel telegraph systems for use on H.F. radio links

Ridout

Wheeler

1963

Proc. Inst. Electr. Eng. UK

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SynopsisTelegraph systems for use over h.f. radio links are generally restricted to low modulation rates (100-200 bauds) because of the effects of multi-path propagation. The usual practice is to employ frequency-division multiplexing to exploit the bandwidth of the radio channel. Different methods of modulation in the telegraph channels may be used-frequency-shift, frequency-exchange and phase-shift. The performance of typical systems of each kind has been measured in the laboratory under similar conditions of propagation provided by a fading-circuit simulator with additive uniform spectrum random noise. The relative merits of the systems are discussed in relation to transmission accuracy and bandwidth utilization. These are found to vary according to propagation conditions and to whether automatic error correction is used or not.List of symbols P(e) = probability of element error R = normalized signal/noise ratio _ signal energy per unit element noise power per c/s of bandwidth D = demodulation factor / = specific information density /," = mean information density (practical system) B = modulation rate, bauds y = bits/unit signal element E = time-efficiency factor F = nominal channel bandwidth, c/s n = number of binary channels F s = nominal system bandwidth, c/s t g = guard period, s t s -gate period, s f s -channel separation, c/s m = number of communication carrier frequencies 1

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Section: Introductionmentioning

confidence: 99%