New Location for WWV
April 1967 Radio-Electronics

April 1967 Radio-Electronics [Table of Contents] Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

Greenbelt, Maryland, is not very far from where I grew up just outside of Annapolis. One of the most recognizable technology facilities residing there is NASA's Goddard Space Flight Center. A guy, Mr. Dick Webber, in the Prince Georges Radio Control (PGRC) club to which I belonged captured the FAI Closed Course Record with 225 miles flown in 5 hours and 38 minutes. My friend, Jerry Flynn, and I served as distance marker flagmen for the feat (no skill involved on our part). Being close to both Washington, D.C., and the University of Maryland, there were many high tech operations in the area. Since that time, new ones have come and others have gone. The National Bureau of Standards' (NBS), now called the National Institute of Standards and Technology (NIST), primary timekeeping facility, WWV, was located in Greenbelt until its move to Fort Collins, Colorado, as reported in this 1967 issue of Radio-Electronics magazine. BTW, I have also lived in Loveland, CO, just south of Ft. Collins. Maybe I'm naturally drawn to WWV ;-)

New Location for WWV

At 7:00 PM EST on Dec. 1, 1966, National Bureau of Standards radio station WWV terminated forever standard time and frequency transmissions from the Greenbelt, Md., site which it had occupied since 1923. At the same instant, the station began transmitting from its new site at Fort Collins, Colo. The central location of Fort Collins provides better signal coverage throughout the US.

There are eight transmitters as in the Greenbelt installation. Each is operated at half its maximum power rating. Three transmitters radiate 10 kW on 5, 10 and 15 MHz. The fourth 10-kW rig is kept on standby, ready to operate on any of these three frequencies. Three 5-kW transmitters radiate 2.5 kW on 2.5, 20 and 25 MHz. The fourth 5-kW unit is on standby, ready for emergency use on these frequencies. The transmitter drivers are bandswitching types built to NBS specifications. The power amplifiers are commercial units.

Six of the antennas are modified sleeve vertical dipoles; each tuned to one of the transmitting frequencies and permanently connected to one of the transmitters. The towers are 200, 100, 50, 33, 25 and 20 feet high. The 200-footer operates on 2.5 MHz, the 100-footer on 5 MHz and so on in inverse order of frequency. The other two antennas, on the standby transmitters, are 88-foot Collins monopoles which can be tuned to any of the WWV frequencies.

The NBS radio stations provide standard radio frequencies, standard audio frequencies, musical pitch, time intervals (1 second, 1 minute, 1 hour, etc), time signals indicating Universal Time, Universal Time corrections (UT2), propagation forecasts and geophysical alerts. The hourly broadcast schedules of WWV and WWVH are shown.

Radio broadcasts from WWV on 2.5, 5, 10, 15, 20 and 25 MHz are continuous night and day except for silent periods of approximately 4 minutes beginning 45 minutes after each hour. Broadcast frequencies are held constant to within 5 parts in 1011. WWVH transmits on the four lower frequencies with 4-minute silent periods beginning 15 minutes after each hour. WWVB and WWVL broadcast continuously on 60 and 20 kHz, respectively, with normal stability of 2 parts in 1011.

Standard audio frequencies of 440 and 600 Hz are broadcast on all WWV and WWVH frequencies. The tones are transmitted alternately in 5-minute intervals beginning with 600 Hz on the hour. The first tone transmission from WWV is 3 minutes long, all others are 2 minutes long. At WWVH, all tone transmissions are of 3-minute duration. WWVB and WWVL do not transmit standard audio tones.

For time signals, the audio frequencies are interrupted precisely 3 minutes before each hour at WWV and 2 minutes before each hour at WWVH. The tones are restored on the hour and at 5-minute intervals throughout the hour.

Universal Time (referenced to the zero meridian at Greenwich, England) is announced in International Morse Code each 5 minutes from WWV and WWVH. At WWV, a voice announcement in Mountain Standard Time is made during the last half of each fifth minute during the hour. At WWVH, a similar voice announcement of Hawaiian Standard Time is made during the first half of each fifth minute. WWVB transmits a special time code. WWVL does not transmit time signals.

Corrections to be applied to Universal Time signals are given in International Morse Code during the last half of the 19th minute from WWV and during the last half of the 49th minute from WWVH. The correction symbols consist of UT2 followed by AD (for add) or SU (for subtract) followed by a 3-digit number indicating the correction in milliseconds.

Propagation forecast announcements in Morse Code indicating ionospheric conditions and the quality of radio reception that can be expected within the next 6 hours are made from WWV at 0500, 1200 (1100 in summer), 1700 and 2300 UT. The forecast consists of a letter and a number. The letters N, U and W indicate normal, unsettled and disturbed conditions, respectively. Numbers 1 to 4 (disturbed) indicate useless, very poor, poor and poor-to-fair; 5 (unsettled) is fair; 6 to 9 (normal) indicate fair-to-good, good, very good and excellent, respectively.

A letter symbol indicating the current geophysical alert is broadcast in slow Morse from WWV during the first half of the 19th minute of each hour and from WWVH during the first half of each 49th minute. The geophysical alert identifies days in which outstanding solar or geophysical events are expected or have occurred during the preceding 24 -hour period.

The announcement is identified by the letters GEO followed by the letter symbol repeated five times. The letter M means magnetic storm, and .N is magnetic quiet. C is cosmic-ray event. E means no geoalert issued. S indicates the presence of solar activity, and Q is solar quiet. W is stratospheric warning.

More complete information on the services of NBS stations WWV, WWVH, WWVB and WWVL will be found in NBS Standard Frequency and Time Services (Miscellaneous Publication 236) available from Superintendent of Documents, US Government Printing Office, Washington, D.C. 20402, for 15 cents per copy.

Posted March 26, 2024