The Calculation of Ionospheric Doppler Spread on HF Communication Channels

Pickering, L.

doi:10.1109/tcom.1975.1092843

Cited by 8 publications

(5 citation statements)

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“…In this paper we use a simple parabolic model of the ionosphere which restricts changes in phase path to three variables. As developed by Pickering [1975], the phase path for a parabolic layer model of the ionosphere is given by where x = , and f is the operating frequency, f c is the critical frequency of the parabolic layer (foF2), y m is the half width of the parabolic layer, and h m is the height of the parabolic layer peak.…”

Section: Theorysupporting

confidence: 84%

A technique for calculating ionospheric Doppler shifts from standard ionograms suitable for scientific, HF communication, and OTH radar applications

Lynn

2009

Radio Science

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[1] High-resolution Doppler ionograms taken at 5 min intervals were obtained from a KEL IPS 71 ionosonde operating over a full ionosonde sweep range. The ionograms were converted into true height profiles using the program POLAN. POLAN also produced an equivalent parabolic layer model of best fit to the true height profile. A parabolic layer model of the ionosphere is defined by three parameters, namely, peak height, maximum electron density/critical frequency, and parabolic thickness. Equations for calculating Doppler shift from a time-varying parabolic layer model have long been known but have seen remarkably little use in the absence of suitable input data and a means of verifying the results. This paper shows that these equations can provide an accurate means of calculating ionospheric Doppler shift based on standard ionospheric ionograms taken at a 5 min rate over a 24 h period when compared with actual Doppler measurements. Apart from its scientific interest, the demonstrated technique will prove particularly valuable in deriving Doppler shift and associated signal fading for the real-time control of over-the-horizon radar and HF communication links.

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Section: Theorysupporting

confidence: 84%

A technique for calculating ionospheric Doppler shifts from standard ionograms suitable for scientific, HF communication, and OTH radar applications

Lynn

2009

Radio Science

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“…The width of the spectrum about a subchannel peak is given in this case by 1/-rr(i ) where 'rr(i ) is the correlation time of the tropospheric irregularities (see (64)). When the ratio of the velocity of the ionospheric irregularities to the correlation length is much greater than the corresponding ratio for the troposphere, the contribution to the Doppler spectrum by scattering of the high wave off the F layer is found to be negligible in 20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1 [Pickering, 1975], the Doppler spread is greatest at sunrise and sunset. In addition, B z, decreases as the carrier frequency approaches the MUF because the ray paths tend to merge at that frequency.…”

Section: Ionospheric Modelsupporting

confidence: 74%

Delay and Doppler power spectra of a fading ionospheric reflection channel

Malaga¹,

McIntosh²

1978

Radio Science

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The time and frequency selective behavior of a fading HF ionospheric reflection channel is considered in this paper. Both deterministic and random spatial and temporal variations of the ionosphere and the troposphere are included in determining the multipath delay and Doppler frequency spreading of a channel in which the signals are reflected off of a multilayered ionosphere. An example which illustrates the diffuseness of the multipath and Doppler spectra under typical propagation conditions is given.

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“…The conventional HF bandwidth has been designed based on the factor that the frequency selective channel can be regarded as “ flat ” or readable content when the symbol duration of the signal is designed larger than that of the delay spread. The theoretical calculations and the experimental measurements agree well with each other at the “ flat ” bandwidth in range of hundreds hertz to a few kilohertz for the HF channel 6, 7.…”

Section: Introductionsupporting

confidence: 72%

Studies on the coherence bandwidth of high‐frequency vehicular communication system with antenna array

Li¹,

Duan²,

Ma³

et al. 2011

Wireless Communications

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High-frequency (HF) vehicular communication system works with the frequency-selective fading channel, thereby the coherence bandwidth is limited due to the multipath time dispersive effect, which imposes the difficulty for achieving the high-data rate transmission. The present paper investigates the antenna array technique for its ability in reducing the multipath delay spread of the ionosphere channel and, thus, increasing possibly the bandwidth of the HF system. To enable fast moving speed of the vehicular receiver, we propose to use single antenna at the receiver and the adaptive array at the transmitter. The adaptive beamforming is driven based on the protocol design and reciprocity principle of channel. In order to evaluate the performance of array system, a statistical HF double-directional channel model, which includes angular information at both the transmitter and receiver, is presented. The explicit expressions are obtained for calculating the coherence bandwidth. The numerical results show the efficiency of this approach for mid-latitude mid-range channel.

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The Calculation of Ionospheric Doppler Spread on HF Communication Channels

Cited by 8 publications

References 0 publications

A technique for calculating ionospheric Doppler shifts from standard ionograms suitable for scientific, HF communication, and OTH radar applications

A technique for calculating ionospheric Doppler shifts from standard ionograms suitable for scientific, HF communication, and OTH radar applications

Delay and Doppler power spectra of a fading ionospheric reflection channel

Studies on the coherence bandwidth of high‐frequency vehicular communication system with antenna array

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