Appendix
11-27
Selecting communication frequencies in the MF/HF band (reference)
When communicating with the MF/HF radio equipment, select frequencies referring to the
frequency transition table and the radio wave propagation images (excluding the polar
latitudes) shown below
9
.
Example: When communicating with a station approximately 5000 km away at
around 12 pm in the winter with a sunspot number of 100, select
frequencies in the 18, 22, or 25 MHz bands for the best results.
Frequency transition table
日中
夜間
冬
夏
冬
夏
遠距離
（例 ：5000km）
近距離
（例 ：1000km）
距離 季節と時刻 2M 4M 6M 8M 12M 16M 18M 22M 25M
周波数選択の目安 （太陽の黒点数 = 100の場合）通信条件
日中
夜間
日中
夜間
日中
夜間
Transmissions conditions
Distance Season & time
Day
Winter
Night
Day
Long distances
(e.g. 5000 km)
Summer
Night
Day
Winter
Night
Day
Short distances
(e.g. 1000 km)
Summer
Night
Guideline for selecting frequency (for a sunspot count of 100)
Radio wave propagation images
9
These are based on the prediction of HF radio wave propagations. Communication is not
guaranteed.
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