l 

i '•;-

For release Saturday 

·· 

A.M.

March 15, 1941. 

DEPARTMENT OF COMMERCE 

WASHINGTON 

NATION.AL BUREAU OF STANDA.Rl)S R:&SUMES BROADCASTING STANDARD OF MU'SIC.AL 

PI�OH 

The standard frequency radio service of the National Bureau of Standards-,

Department of Commerce, which has been conducted on a reduced basis since iast 

November when fire destroyed the Bureau broadcasting station WWV has been 

extend.ed by the resumption of the standard musical pitch and of seconds intervals. 

Barring unforeseen developments due to the current use of temporary equipment, 

it is pointed out,�� service will henceforth be on the air continuously day 

and night. The radio frequency is, as formerly, 5,000 kilocycles per second. 

The standard musical pitch carried by the broad.cast is the frequency 440 

cycles per second, corresponding to A above middle c. In addition there is a 

pulse every second; heard as a faint tick, when listening to the 440 cycles. 

The pulse lasts 0.005 second, and provides an accurate time interval for 

purposes of physical measurements. 

The 440-cycle tone is interrupted every five minutes for one minute in order 

to give the station announcement and to provide an interval for the chacking of 

radio measurements based 0n the standard radio frequency. The announcement is 

the station call letters (WWV) in telegraphic code (dots and dashes). 

The accuracy of the 5-megacycle frequency, and of the 440-cycle standard 

pitch as trausmit.ted, is better than a part in 10 000 000. Transmission effects 

in the medium (Doppler effect, etc.) may result in slight fluctuations in the 

440-cycle frequency as received at a particular place; the average frequency

received is however as accurate as that transmitted. The time interval marked by

the pulse every second is accura� to 000 01 second. The 1-minute, 4-minute,

� � 

and 5-rninute intervals marked by the beginning and ending of the announcement 

1719 
periods arc accurate to a part in 10 000 0000 The beginnings of the announcement 

periods are so synchronized with the basic time service of the u. s. Naval 

Observatory that they mark accurately the hour and the successive 5-minute 

periods; this adjustment does not l1ave the extreme accuracy of the time intervals, 

but is within a small fraction of a second. 

The broadcast is from a 1-kilowatt transmitter. It is most useful for 

moderate distances in the daytime and long distances at night. For reception in 

locations r.easonably free from interference, it is receivable in the summer at 

all distances up to about 500 miles from Washington in the middle of the day. 

The distance range increases after about 4 P.M. (EST) until at night the broadcast is receivable throughout the United States (i0e., the 5--Mc carrier frequency; 

the 440-cycle tone is sometimes not receivable at night beyond about 1300 miles). 

Sometimes at night it may be difficult to receive either the 5 Mc or the 440 

cycles at distances between about 50 and 500 miles, while it is easy to receive 

them beyond 500 milese In the autumn the daytime distance range will increase, 

rising to about 1000 miles in the winter. 

The service from the temporary transmitter will continue for some months. 

As rapidly as possible the Bureau will establish a new station to provide more 

fully than in the past, standard frequencies reliably receivable at all times 

throughout the country. These will be transmitted on more adequate power, and 

several radio carrier frequencies will be used, in order to provide more certain 

� coverage of all distances and times0

. 1719 -0-