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"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, February 7, 2010

Eclipse Radio in the Pacific: Monitoring Observations When Radio Was Very Young

It was back in the year 1930, on October 21, that a major solar eclipse passed over the Pacific Ocean. Special teams from the United States and New Zealand co-operated in the scientific research associated with this astronomical event.

The island of Niu'afoou was chosen as the most suitable ground location from which to make observations of the total eclipse. This small island is the most northerly island in the kingdom of Tonga and it is in reality the top of a volcano that has erupted on numerous occasions.

The whole island is formed in the shape of a doughnut, with large twin lakes in the center surrounded by a wide circle of steep land. There are two islands in the lakes; and the total land area of the entire surrounding island is just six square miles.

This island has been populated by Polynesian peoples for many hundreds of years and their language is described as a dialect of the Tongan form of Polynesian. The population on the island is plus or minus one thousand, depending on the era involved. After the disastrous volcanic eruption in 1946 all of the islanders were evacuated and re-settled on distant Eua Island. They began to return to their home island twelve years later.

The island of Niu'afoou was first visited by European explorers in the year 1616 during the circumnavigation of the globe by Dutchman Willem Schouten. In 1845, the many widespread islands were united into a Tongan confederacy; and thirty years later again, the nation was integrated as a constitutional monarchy. All of the Tongan islands were placed under a British protectorate in the year 1900, and Tonga finally attained independence in the year 1970.

The main village on Niu'afoou island today is Hihifo, though at the time of the eclipse, the main village was Angaha. Today in Hihifo, you would find a police station, the post office, one shop, and the communication building.

These days, there are three radio stations on the island, all on FM, as well as the radio communication station in use for inter-island and international contact. The main government radio broadcasting station takes a relay from Radio Tonga 1 in the national capital.

One of the other stations, licensed under the callsign A3V, operates on 101.1 MHz under the slogan Radio Vava'u. The third FM station is affiliated with the Christian organization UCB, United Christian Broadcasters in New Zealand and it operates on 89 MHz.

Over the years, this island has been known under two other names. The Dutch called it Good Hope Island, as we would say in English; and it was known more famously as Tin Can Mail Island.

Back in 1882, plantation manager William Travers wrote a letter to the Tongan postal authorities asking that they seal mail addressed to him in a ship's biscuit tin and solder it closed. This Tin Can filled with postal mail was then taken by the next passing ship and thrown overboard at Niu'afoou Island where swimmers came out and brought the container ashore. In 1928, the resident postman on Tin Can Island made a rubber stamp with the slogan, Tin Can Mail, and thus began a tradition that caught the attention of stamp collectors throughout the world.

Mail was delivered to this island in this way for a hundred years, until the year 1983 when a small airport on the island enabled delivery of mail by plane.

Anyway, back to the story of the 1930 eclipse. The US navy built up a large expedition and they sent out a team of scientists and tons of equipment. The entire expedition arrived at Niu'afoou Island two months in advance so that they could construct housing, establish themselves on the island, and set up all of the apparatus, including the astronomical and radio equipment.

A temporary radio station was installed on the island for the purpose of general communications as well as for sending out news items. They received time signals from the navy wireless station NAA in Arlington Virginia, and press news from a shortwave station in San Francisco, probably the RCA communication station at Bolinas, KPH.

On Eclipse Day, the temporary American radio station broadcast a live description of the events associated with the eclipse, using the temporary radio station that was housed in a series of tents. A photograph of the occasion shows at least three tents and a dwelling on level ground surrounded by tropical palm trees.

During the eclipse events on Niu'afoou, a government radio station was officially opened for communication with the national capital of Tonga, and Her Majesty, Queen Salota, sent the first official message, wishing the expedition every success.

In order to study radio propagation conditions during the eclipse, arrangements were made in advance for special transmissions from the communication stations located on widely separated islands throughout the Pacific. These plans were co-ordinated in New Zealand and each station was on the air for ten minutes at a time followed by five minutes silence, in a rolling schedule. It would be presumed that all of the transmissions for this propagation research were made in Morse Code.

The stations involved in this scientific research were as follows:

Samoa Apia ZMA 100 watts 353 kHz LW
500 watts 5770 kHz SW
1500 watts 15790 kHz SW
Fiji Suva VRP 5 kW 375 kHz LW
New Zealand Wellington ZLW 5 kW 5885 kHz SW
500 watts 15790 kHz SW
New Caledonia Papeete FBP 200 watts 7500 kHz SW
200 watts 12400 kHz SW
Hawaii Navy Ruby 26 kHz LW
Tonga Niu'afou Island

Throughout the Pacific and all across New Zealand, numerous listening stations participated in the monitoring of these special radio transmissions for several days; before the time of the eclipse, during the eclipse, and also after the event was concluded.

A summary of the monitoring results indicated that the reception of the transmissions was very similar to the observations made at the time of previous solar eclipses, though with a couple of interesting and unexpected outcomes. This is what they observed:

These radio monitoring observations made throughout the Pacific during the October 1930 eclipse were the most comprehensive that had been made, up to that time. Subsequent studies in radio propagation during an eclipse have been made on many occasions and in many countries. However, these Pacific studies in 1930 have established a pattern of expectation that has never been superseded even to this day.