Silence Period
All stations using 2182 kHz were required to maintain a strictly enforced three-minute silence and listening period twice each hour, starting at h+00, h+30. This allowed any station with distress, urgent or safety traffic the best chance of being heard at that time, even if they were at some distance from other stations, operating on reduced battery power or perhaps reduced antenna efficiency, as for example from a dismasted vessel. As a visual aide-memoire, a typical clock in a ship's radio room would have these silence periods marked by shading the sectors from h+00 to h+03 and from h+30 to h+33 in green. Similar sectors were marked in red for what used to be the corresponding silence and listening period on 500 kHz between h+15 and h+18 and from h+45 to h+48. These silence periods are no longer required as the introduction of GMDSS has produced alternative automatic watchkeeping systems and the 500 kHz band is no longer in use for maritime traffic.
Read more about this topic: 2182 K Hz
Famous quotes containing the words silence and/or period:
“As the truest society approaches always nearer to solitude, so the most excellent speech finally falls into Silence. Silence is audible to all men, at all times, and in all places. She is when we hear inwardly, sound when we hear outwardly. Creation has not displaced her, but is her visible framework and foil. All sounds are her servants, and purveyors, proclaiming not only that their mistress is, but is a rare mistress, and earnestly to be sought after.”
—Henry David Thoreau (1817–1862)
“Words convey the mental treasures of one period to the generations that follow; and laden with this, their precious freight, they sail safely across gulfs of time in which empires have suffered shipwreck and the languages of common life have sunk into oblivion.”
—Anonymous. Quoted in Richard Chevenix Trench, On the Study of Words, lecture 1 (1858)