Geometric considerations in the design of communications circuits using field‐aligned ionospheric scatter

Stathacopoulos, A. D.; Barry, G. H.

doi:10.1029/rs009i011p01021

Cited by 11 publications

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“…The geometry of the experiment was designed to take full advantage of the aspect sensitivity of the reflecting cloud in accordance with the principles described by Stathacopoulos and Barry [1974]. Design of the circuit was the reverse of that which would normally be encountered by the communications engineer.…”

Section: Introductionmentioning

confidence: 99%

HF‐VHF communications experiment using man‐made field‐aligned ionospheric scatterers

Barry¹

1974

Radio Science

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Scatter from man‐made, field‐aligned, F‐layer irregularities offers a means of over‐the‐horizon communication at VHF frequencies. Experimental data collected in 44 days of field operation in the autumns of 1972 and 1973 defines representative characteristics of signals transmitted over such a scatter circuit. A cloud of field‐aligned scatterers was created by the Platteville, Colorado, ionospheric modification facility; test transmitting sites were established in Texas and receiving sites in California. The data describe mean and peak cloud radar cross section, the dependence of cross section on heater power, heater modulation, time of day, and signal frequency, the circuit coherent and incoherent bandwidths, the signal amplitude statistics and spatial correlation, and the signal spectral spreading. The experiment also included the transmission of representative types of modulated signals including SSB voice, 100‐word/min FSK teleprinter data, 2400‐bit/sec data, 30‐kHz FM voice, and 3‐kHz FSK facsimile.

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Section: Introductionmentioning

confidence: 99%

HF‐VHF communications experiment using man‐made field‐aligned ionospheric scatterers

Barry¹

1974

Radio Science

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“…This distribution also rules out the possibility of scatter from FAIs because the angle of scatter from FAIs must be equal to the angle of incidence with respect to the geomagnetic field. The scattered rays form a cone that contains the extension of the incident ray beyond the FAIs and with the geomagnetic field at the scatter point forming the axis of symmetry, similar to how light scatters from a reflective rod (Barry, 1974; Stathacopoulos & Barry, 1974). This can be expressed analytically by the expression

{\overset{boldk}{true}}_{i} \cdot \overset{false^}{B} = {\overset{boldk}{true}}_{r} \cdot \overset{false^}{B}

where

{\overset{boldk}{true}}_{i}

and

{\overset{boldk}{true}}_{r}

are unit vectors in the direction of the incident and scattered rays, respectively, and

\overset{false^}{B}

is the unit vector in the direction of the geomagnetic field at the scatter point (D. L. Hysell & Chau, 2001).…”

Section: Discussionmentioning

confidence: 99%

Using Broadband Radio Noise From Power‐Lines to Map and Track Dense E_s Structures

et al. 2021

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We present passive observations of midlatitude sporadic E (Es) structures in the 30–50 MHz range using the long wavelength array telescopes in New Mexico. Spectral and temporal analysis of the structures reveals that some of the emissions can be characterized by broadband, spark‐like radiation occurring at a repetition frequency of 60 Hz. The azimuthal distribution indicates that the brightest emissions come from the directions of several large metropolitan centers with distances ranging from 700 to 1,250 km from the telescopes. This implies that the source is unintended human‐made noise, originating from devices connected to 60 Hz alternating current power. The geometry of our observations rule out coherent scatter from field‐aligned irregularities, and indicate that the unintended noise must undergo a specular reflection off of over‐dense plasma distributed approximately parallel to Earth's surface. On certain occasions the reflections are seen at such high frequencies and high elevation angles that the local plasma frequency must be above 30 MHz. During both day and night Es conditions, the dense structures are observed to be arranged in propagating fronts, and travel at speeds of 70–100 m/s. We also present observations that reveal quasi‐periodic amplitude oscillations with frequencies consistent with atmospheric gravity waves and acoustic waves.

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“…In order to examine that the radio wave reception is due to EPBs, we have determined ray paths of radio waves by a ray‐tracing calculation combined with a model of scattering by field‐aligned irregularities [ Nakata et al , 2004]. It is expected that a fairly high degree of aspect sensitivity is associated with the scattering by field‐aligned irregularities [e.g., Stathacopoulos and Barry , 1974; Rao and Thome , 1974]. Since the high aspect sensitivity means that angles of incidence and reflection are the same, we can accurately estimate the position of scattering by field‐aligned irregularity.…”

Section: Comparison With All‐sky Airglow Imager Observationsmentioning

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Observations of equatorial plasma bubbles using broadcast VHF radio waves

Nakata

Nagashima

Sakata

et al. 2005

Geophysical Research Letters

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The propagation of VHF radio waves affected by field‐aligned irregularities within equatorial plasma bubbles is examined. Continuous observation of VHF radio waves at Tateyama, Japan, shows that broadcast radio waves transmitted from Southeast Asia propagate to Japan. Using a ray‐tracing calculation combined with a model of scattering by field‐aligned irregularities, we determined scatter points suitable for the reception of these radio waves. The results of the calculation show that radio waves transmitted from the Philippines can propagate to Japan owing to field‐aligned irregularities within equatorial plasma bubbles located west of Japan. Comparing with all‐sky imager data observed at Sata, Japan, we found that the radio waves are received at Tateyama when the plasma bubbles are observed at Sata. The results of this study show that the reception of these radio waves is closely correlated with the equatorial plasma bubbles.

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Geometric considerations in the design of communications circuits using field‐aligned ionospheric scatter

Cited by 11 publications

References 0 publications

HF‐VHF communications experiment using man‐made field‐aligned ionospheric scatterers

HF‐VHF communications experiment using man‐made field‐aligned ionospheric scatterers

Using Broadband Radio Noise From Power‐Lines to Map and Track Dense E_s Structures

Observations of equatorial plasma bubbles using broadcast VHF radio waves

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Geometric considerations in the design of communications circuits using field‐aligned ionospheric scatter

Cited by 11 publications

References 0 publications

HF‐VHF communications experiment using man‐made field‐aligned ionospheric scatterers

HF‐VHF communications experiment using man‐made field‐aligned ionospheric scatterers

Using Broadband Radio Noise From Power‐Lines to Map and Track Dense Es Structures

Observations of equatorial plasma bubbles using broadcast VHF radio waves

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Using Broadband Radio Noise From Power‐Lines to Map and Track Dense E_s Structures