MF-HF Equip. and Comms:
MF-HF Propagation-1; Day-Night-Winter-Summer:
The "short rules" of propagation necessary to select the appropriate frequency band are:
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Shorter distance = Higher Frequency, Daytime = Higher Frequency.
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Correct AnswerShorter distance = Lower Frequency, Daytime = Higher Frequency.
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Shorter distance = Higher Frequency, Daytime = Lower Frequency.
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Shorter distance = Lower Frequency, Daytime = Lower Frequency.
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GMDSS operators should learn which of the following propagation "rules of thumb"?
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Longer distance = lower frequency, Shorter distance = higher frequency; Daytime = higher frequency, nighttime = lower frequency.
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Longer distance = lower frequency, Shorter distance = lower frequency, Daytime = lower frequency, nighttime = higher frequency.
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Correct AnswerLonger distance = higher frequency, Shorter distance = lower frequency, Daytime = higher frequency, nighttime = lower frequency.
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Longer distance = higher frequency, Shorter distance = higher frequency, Daytime = lower frequency, nighttime = higher frequency.
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What would be the most appropriate HF bands for communicating from San Francisco to Taiwan or the Philippines?
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12 MHz during daylight at each end and 2 MHz when dark at each end.
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8 MHz during daylight hours and 16 MHz during darkness.
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6 MHz during daylight hours and 8 MHz during darkness.
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Correct Answer16 or 22 MHz when daylight at each end and 8 MHz when dark at each end.
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GMDSS operators should routinely focus on the factors affecting propagation in what priority?
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Correct AnswerDistance & time of day, seasonal variations, sunspot cycle, solar flare alerts.
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Sunspot cycle, distance & time of day, seasonal variations, solar flare alerts.
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Solar flare alerts, distance & time of day, sunspot cycle, seasonal variations.
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Solar flare alerts, sunspot cycle, seasonal variations, distance & time of day.
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Which statement concerning frequency band selection and propagation most corresponds with standard practice.
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Maximum Usable Frequency (MUF) and Optimum Usable Frequency (OUF) should be calculated prior to setting up the transceiver.
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Propagation rules, Sunspot cycle status and seasonal variations (winter & summer) must always be employed to calculate the proper band selection.
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Propagation "rules of thumb" should be combined with Solar flare alerts to determine band selection.
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Correct AnswerPropagation "rules of thumb" are usually sufficient for routine operations.
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To ensure effective HF communications, GMDSS operators should:
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Correct AnswerEmploy the short rules of propagation selection or rely on previous successful communications as a guide.
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Disregard the short rules of propagation selection and try different bands until one works.
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Do not rely on previous successful communications on the selected frequency band - the ionosphere changes too rapidly and inconsistently.
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Rely on the equipment calculations of Optimum Usable Frequency.
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