"Wavescan" is a weekly program for long distance radio hobbyists produced by Dr. Adrian M. Peterson, Coordinator of International Relations for Adventist World Radio. AWR carries the program over many of its stations (including shortwave). Adrian Peterson is a highly regarded DXer and radio historian, and often includes features on radio history in his program. We are reproducing those features below, with Dr. Peterson's permission and assistance.
Wavescan, April 11, 2010
The Ticking Time Clock - Chronohertz WWV
Over a period of time, everyone who tunes a shortwave radio becomes familiar with the ticking time signals that can be heard from a chronohertz station located somewhere in our world. These stations can be heard quite readily on the shortwave bands, usually on the exact frequencies such as 5 MHz, 10 MHz, 15 MHz, etc., though some are heard on alternative channels. These chronohertz stations emit very accurate time signals, as well as very accurate tone signals, on an extremely accurate frequency.
The transmissions from these stations are used for accurate time keeping, and for the purpose of checking many different forms of electronic equipment. These shortwave signals are also used in the timing of earthquake research, and by international radio monitors as a guide to propagation conditions.
Even though several chronohertz stations are still active on the shortwave bands in several different countries around the world, the oldest and the best known would have to be the twin stations WWV in the United States and WWVH out in the central Pacific in the Hawaiian Islands. On this occasion here in Wavescan, we take up the story of the grandest of all of these stations, WWV at Fort Collins in Colorado.
Interestingly, shortwave station WWV did not begin its long and illustrious history on shortwave, and neither was it broadcasting chronohertz signals during that era. Instead, WWV began its career on mediumwave, and as an entertainment radio broadcasting station. This is how it happened.
Very early, back in the year 1901, NBS, the National Bureau of Standards, was established in Washington DC and one of their very earliest assignments was to conduct research into the factors that affect radio propagation. In October 1919, the NBS was granted a license for a radio broadcasting station and they were assigned the sequential call letters WWV.
The first test broadcasts from this new radio station went on the air in May 1920 with 50 watts on the mediumwave channel 600 kHz. Programming during that era was simply a series of music concerts every Friday evening. With a beginning way back in May 1920, station WWV lays claim as the oldest continuously operating radio station in the United States.
Towards the end of the same year, station WWV began the broadcast of market reports in Morse Code, with the usage of a 2 kW spark transmitter on 750 kHz, still in the mediumwave band.
However, two years later, the NBS re-defined the purpose for the WWV broadcasts and that was as an accurate reference standard for other radio broadcasting stations. As such, WWV began its new role on January 29 1923, with the usage of tone signals at various audio frequencies on several different radio channels according to a rolling schedule.
Interestingly, in 1926 when other stations were also on the air as standard frequency stations, NBS announced that their service was no longer necessary and that they planned to close the station. However, there was such a flood of protests, that it was decided to retain the broadcasts from station WWV and to expand its coverage.
Five years later, WWV was moved from its two story location in Washington, DC to a new facility located at College Park in Maryland. During the following year, they moved again, this time to nearby Beltsville, still in Maryland. However, on November 6 1940, a fire of unknown cause almost totally destroyed the station and so they moved to an adjoining building with salvaged equipment and the usage of a temporary 1 kW transmitter.
Two years later again, station WWV moved to a new location in Beltsville and they resumed transmissions on three shortwave channels from transmitters radiating around 10 kW each. The name of this location was changed from Beltsville to Greenbelt in 1961.
However, by this time, it was evident that a large new station was needed and in order to give better coverage to the entire continental United States, station WWV was transferred to a new location and co-sited with the longwave sister station WWVB near Fort Collins in Colorado. At MN GMT on December 1, 1966, WWV in Greenbelt, MD left the air and WWV, Fort Collins, CO was activated.
These days, station WWV is on the air with a total of ten shortwave transmitters, a main transmitter and a spare for each of five shortwave channels. You can hear them in almost all countries of the world, depending on the time of day and according to the current propagation conditions. Here is a list of their on-air configurations:
|2.5 MHz||2.5 kW|
|5 MHz||10 kW|
|10 MHz||10 kW|
|15 MHz||10 kW|
|20 MHz||2.5 kW|
Radio station WWV has always been a particularly good verifier and many QSL cards have been issued, in earlier times from the Maryland locations as well as more recently from the Fort Collins location. The WWV QSL cards come as a three part folder with lots of interesting information, and these cards are numbered consecutively.
The American Chronohertz Station WWV & the Russian Satellite Sputnik
It was back on October 4, 1957, that Sputnik 1 was successfully launched into space from a location somewhere in Russia. This historic event caught the world by surprise.
Aboard this small space vehicle was a radio transmitter that gave out its pulsating beep beep as it sped around the world at eighteen thousand miles an hour. In honor of this significant occasion, Radio Moscow issued QSL cards verifying the reception of the beep beep signals from Sputnik 1. This QSL card is a highly desired item, and on the few occasions when one is offered on eBay, it commands a very high price.
Sputnik, which means traveller in the Russian language, was in orbit around the Earth for a period of just three months. By the time of its re-entry into Earth’Äôs atmosphere, the electronics on board Sputnik 1 were no longer operating, and at this stage the chronohertz station WWV played an interesting and significant part.
Dr. John Kraus, professor at the Ohio State University was tracking the deterioration of Sputnik 1 and he was aware that a meteor entering the upper atmosphere leaves in its wake a small trail of ionized air. This ionized air reflects radio signals back to Earth, strengthening the signal in the receiver on Earth for a few seconds. This enhancement of the reflected radio signal is known as meteor scatter.
Dr. Kraus figured that what was left of Sputnik 1 would exhibit the same effect of meteor scatter as it re-entered Earth’Äôs atmosphere, but on a larger scale. His prediction proved to be accurate and he was able to follow the downward pathway of the satellite on its way to destruction.
Dr. Kraus tuned a radio receiver to the 20 MHz signal from WWV, which was located at Beltsville in Maryland at the time. This channel was on the air with just 1 kW.
On that fateful day, January 4 1958, exactly three months to the very day after its launch, Sputnik 1 disintegrated as it plunged earthward. Due to the propagation enhancement caused by meteor scatter, the 1 kW 20 MHz signal from WWV was considerably strengthened for several durations lasting over one minute. This signal enhancement coincided with the known predictions concerning the timing and the pathway of Sputnik 1.
In addition to the pathway of disintegration, the various enhancements of the signal from WWV confirmed another observation which had never before been tested, and that was that a satellite does not remain in one integral piece in its downward fall to destruction. When the spacecraft reaches the atmosphere at such high speeds, it breaks up into smaller pieces.
These two facts, that is the pathway and the disintegration, were both confirmed by the enhancement of the WWV signals that were reflected from the short-lived trail of ionized air left behind as the doomed spacecraft Sputnik 1 plummeted towards planet Earth.