Evening star., 1924-05-04
Fog Signals by Radio.

Eventually a system of forty seven
radio fog signal stations, each with a
tube transmitter, will be operated by
the United States lighthouse service.
There are now ten spark stations and
the one new tube set, which was in
stalled last week on the Ambrose
Channel lightship, off New York,
Commissioner of Lighthouses George
r. Putnam stated yesterday.
Speaking before the National Acad
emy of Sciences, Commissioner Put
nam reviewed the development of the
radio fog signals for the protection
lighthouse service three years ago
with three spark stations near New
York. Recent tests, using 250-watt
transmitting tubes, with view of
tuned more sharply to the proper
wave. thus 1essening interference.
and a more powerful and economic
signal, have proven successful, he
was practically no difference in the
direction of radio bearings taken
from tube or spark transmitting sig
nails, but that far greater interference
was caused by the latter.
A temporary sending station was
established on a lightship in lower
New York Bay, where both spark and
tube transmitters were installed and
arranged to send signals alternately.
The tests were made from the light
straight east from New York a dis
tance of 115 nautical miles. On board
the Tulip several observers took fre-
Quent bearings en- route on both sets
of signals with the ships radio COM
pass, and found no practical differ
ence. Out of ninety-three radio bear
ings taken, March 13 only seyen"r read
ings showed an apparent error of
over two degrees when compared with
the Tulips course, plotted from Wis
al
Radio signals transmitted in an ear
lier test were received successfully
by the Nantucket Shoal lightship. 202
miles distant from the tranSmitter.
Tube radio fog signal experiments
conducted from Cape Henry. Va, de-
veloped the fact that, although spark
signals from that station had previ
cusly been complained of, the tube
set was operated for four hours daily
for eight days during which time a
shore radio compass station. five
miles distant, reported no interfer-
ence. Operators of local military
station close by, reported that they
did not know the radio fog signals
were being sent. Transmissions of
fog signals on 1,000-meter wave by
tube sets, it was pointed out, were
equally effective compared with spark
sets and with one-third less power.
The radio fog signal, in conjunc-
tion with the radio compass, is likely
to prove one of the greatest advances
yet made in providing aids for the
guidance of Mariners" Mr.. Putnam
declared, adding that they give the
navigator d means of taking accurate
bearings on fixed points or other YES
sells, regardless of fog or weather, and
at greater distances than are possi-
BILE for sight bearings, even in clear
weather.
Preliminary tests made between
stations at Cape Henry and Wolf
Trap, thirty miles distant in Chesa-
peake Bay. for nine days, to study the
so-called night effects on radio bear
ings at sunrise and sunset, showed
that such disturbances do not seri-
ously affect radio bearings. They did
demonstrate, however, that it was
difficult to be accurate during these
hours, and shall serve as a warning
for greater care in taking bearings
around sunrise and sunset.
Out of $50 bearings taken on a
single-coil compass at Wolf Trap,
only two showed a discrepancy from
the mean of three degrees, and only
three reached two degrees. These
discrepancies were during static and
when the receiving set was not oper
ating properly, it was said.
Concluding, Mr.. Putnam pointed out
that the utilization of radio as an
aid to navigation is in an early stage,
and that there is strong probability
of further important progress.