Home
Glossary
Pre-radio technologies and early radio development
Fill in all the gaps, then press "Check" to check your answers.
Prior to the introduction of radio, maritime communication was generally limited to line-of-sight visual signaling during clear weather, plus noise-makers
as
between
for
grouped
such as
to qualify
units
visual
when
bells and foghorns with only limited ranges. Beginning in the mid-1800s, an international convention was developed using special semaphore flags to exchange messages
as
between
for
grouped
such as
to qualify
units
visual
when
merchant ships. In the same book, Examination Paper on the use of the International Code of 1901 it provided an overview of signaling proficiency that a candidate needed to master in order
as
between
for
grouped
such as
to qualify
units
visual
when
for a Certificate of Competency issued by the British Board of Trade Examinations. Over time an extensive vocabulary of signals was created, even as the expansion of radio was beginning to make
as
between
for
grouped
such as
to qualify
units
visual
when
signaling obsolete. The Urgent and Important Signals: Two Flag Signals section of Brown's Signaling reviewed over 600 basic signals,
as
between
for
grouped
such as
to qualify
units
visual
when
by category, with meanings as diverse
as
between
for
grouped
such as
to qualify
units
visual
when
"Where are you bound?" (SH), "In distress; want immediate assistance" (NC), and "Heave to or I will fire into you" (ID). And in addition to the two-flag signals, there were thousands of three- and four- flag groupings, for communicating a huge variety of messages, including ship identifiers, geographical names, temperature and barometer readings, compass points, and
as
between
for
grouped
such as
to qualify
units
visual
when
of measurement. The development of radio resulted, by 1911, in the addition of two more visual signals -- ZMX
as
between
for
grouped
such as
to qualify
units
visual
when
"Wireless telegraph apparatus" and ZMY for "Report me by wireless telegraphy" -- which heralded the beginning of a major decline in the use of seaboard visual signals. However, to this day NC continues to be an international distress signal
as
between
for
grouped
such as
to qualify
units
visual
when
using flag signaling.
Check
OK
