Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-07-04
RADIO DETERMINES |
DISTANCES At SEA.
Lighthouse Service Replaces
Fog Siren With 0scilIator .
Off Cape Henry.
nv MARTIN conEL.

Maritime navigators are finding radio
increasingly useful. Not only does 1t
serve to maintain regular and emer-
gency communication with land, but .
new application has been found to en-
able them to determine exact distances
at sea. First experiments In this coun.
try with the new distance finding APP
paratus have been carried out with sue
cess at the United States Lighthouse
Services radio-beacon station at Cape
Henry, Va. -.-
The new method involves the syn
chronization of radio and sound signals.
The navigator measures the difference
in the transmission time Of the respec.
tive signals and can compute his actua!
distance from their source. The method
Is particularly valuable In onshore nav
igation or In plying dangerous waters
Radio signals travel at the speed Of
light, or about 10000 miles per second.
Sound-in-air signals, such as q fog
horn, travel approximately 1000 feet per
second. When the two signals are
transmitted simultaneously, simple
synchronizing device on the vessel makes
It possible to calibrate the difference
and then to compute the exact distance.
Oscillator Replaces Siren.
The Lighthouse Service installed an
electrically operated oscillator In place
of the old fog siren at the Cape Henry
beacon station. This made 1t possible
to synchron1ze the radio and sound sig
mails so they could be sent at the same
instant.
Last May this synchronized distance
finding signal was placed In commits
sion, and the Lighthouse Service re-
ports that 1t is now In regular opera
ton.
While necessarily Of limited and va
riable range" said George r. Putnam,
commissioner of lighthouses, ut Is likely
TO prove useful to vessels In fog and
haze In getting their distances on I'M
portant points. The system requires nc
| special receiving equipment on q vessel
equipped with radio and no additional
apparatus at station equipped with
oscillator ana radio beacon other than
a simple synchronizing device. A vessel
! equipped with radio compass can at the
same time readily obtain the direction
of the signal"
william Terrell, supervisor of radio
Of the Department of Commerce and the
American radio delegate to the recent
| London Conference on Safety Of Life
at Sea, reports that q recommendation
is included in the proposed convention
drawn up by maritime nations for the
| inclusion Of either radio or underwater
sonic distance finding and position-find-
! ing apparatus aboard ships.
BeacOns All Along Coasts.
Tests similar TO those conducted al
Cape Henry have been carried out BY
the Clyde lighthouses on the British
Isles, using the radio telephone instead
of radio beacon code signals.
The American service employs bea.
cons all along the coasts These trans.
NIT at regular intervals, enabling navi.
gators to employ radio compass TO take
bearings ana keep true direction. The
same system is rapidly being extended
to provide the same service for aeria
navigation.
Another recent radio development o!
importance to ocean travel Is the pro.
posed installation Of the radio telephone
aboard the steamship LeviathAn to fur.
nish a means for carrying on two-way
conversations between ship and shore
This is expected to become o genera
service on all large passenger liners ir
| due time.
| Copyright, 1929. by North American News.
| RApsE- Allaneel