Relative impact of meteor scatter and other long‐distance high‐latitude propagation modes on VHF communication systems

Abstract

We have analyzed the duty cycle, due to ionospheric propagation, of very high frequency sounding signals for both polar cap and auroral paths. We find that at 35 and 45 MHz the propagation is often sustained by sporadic E layers and other nonmeteoric modes rather than by meteor scatter. At the higher frequencies of 65 and 85 MHz we find that the path is generally dominated by meteor scatter modes. These results have important ramifications for frequency reuse and security in meteor burst communications systems and for the development of extended frequency range HF systems (above 30 MHz) with a capability to operate on any available propagation mode. The diurnal, seasonal, and geomagnetic variations of the nonmeteoric duty cycle have been examined. A polar cap path model is presented for the nonmeteoric duty cycle as a function of geomagnetic activity.

Probe experiment characterizing 30‐MHz radio wave scatter in the high‐latitude ionosphere

“…They inferred that the nonmeteoric propagation with such high probability is probably due to a sporadic E layer in the polar cap ionosphere. Cannon et al [1996] reported that a sporadic E duty cycle at midsummer and at 35 MHz, reaching a peak close to 100%, was obtained for the polar cap path. We discuss the causative characteristics of such high duty cycle signals below.…”

“…They believed this behavior to be the first quantitative demonstration of the "forward propagation characteristics" of a one-or two-hop E propagation path within and parallel to the auroral oval on a frequency at the high end of the HF band. Cannon et al [1996] analyzed the duty cycles of VHF sounding signals caused by ionospheric propagation for both the polar cap (Sondrestrom to Thule) and auroral (Sondrestrom to Narssarssuaq) paths and found that the propagation at 35 and 45 MHz is often sustained by sporadic E layers and other nonmeteoric modes rather than by meteoric scatter. Angling et al [1998] reported measurements of Doppler and multipath spread on four high-latitude, high-frequency (3-to 22-MHz) paths in Scandinavia.…”

A meteor scatter prediction model and its application to adaptive beam steering

“…The model has also been tested on a high-latitude link between SOndrestrom (66.59øN, 50.39øW) and Narsarsuaq (61.16øN, 45.45øW) in Greenland [e.g., Cannon et al, 1996] The possibility that our shower selection scheme has mitigated against winter showers has been tested by relaxing our selection criteria. Lowering the threshold to 50 has the effect of increasing the number of meteor showers in the model to 69.…”