Monthly Archives: March 2021

1921 Creed Automatic Radiotelegraphy System

No. 7W/3 Reperforator, manufactured by Creed and Company Limited, Croydon, London, England, 1925

Creed No. 7W/3 Reperforator (1925). Image courtesy of Science Museum Group Collection, © The Board of Trustees of the Science Museum, U.K. released under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence.

No. I.T. Morse Tape Printer (1925).

No. I.T. Morse Tape Printer (1925). Image courtesy of Science Museum Group Collection, © The Board of Trustees of the Science Museum, U.K., released under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence.

The two devices shown above represent a hundred year old method of automatically decoding International Morse Code. They, along with the sending device, are described in the March 1921 issue of Radio News.

1921MarRadioNews3At the sending end, the message is typed on a typewriter-like keyboard and punched onto a paper tape. An example of the tape is shown below. It’s not immediately obvious that the tape contains Morse code, but upon closer observation, it is. A “dot” is indicated by one hole directly above another hole. A “dash” is indicated by two holes that are slanted. Once you see this, the Morse code is obvious. The first word shown here is “the.” The first two holes are slanted. This is a single dash for the letter T. This is followed by four sets of holes, one directly above the other–four dots, for the letter H. Next, there is a single set of vertical holes, another dot for the letter E.

Once this tape is produced, it is sent through another machine which keys the transmitter and sends the Morse signal over the air.

At the receiving station, the two machines shown above are used to receive and print the message. The reperforator (top) connects to the receiver and produces an exact duplicate of the paper tape. Then, the paper tape is fed into the Morse Tape Printer, which prints the message on a paper tape.

The process was known as the Creed Automatic System, named after inventor Frederick G. Creed, an important figure in the development of the teleprinter. At the beginning of the 20th Century, Creed was told my none less than Lord Kelvin  that “there is no future in that idea.” Undaunted, he managed to sell twelve machines to the British post office in 1902.  The 1921 machine described for use with wireless telegraphy appears to be a variation of that device.

By the late 1920s, the company was producing teleprinter equipment using a variant of the five-bit Baudot code.  The company became part of IT&T, and Creed retired from the company in 1930. Among his later projects was the “Seadrome,” a floating airport which could be placed along international air routes. The project is described in a March 1939 article in the Glascow Herald, and was undoubtedly a casualty of both the War and increased aircraft range. The Seadrome is the subject of US Patent 2238974, applied for in February 1939 and granted in April 1941.

The images above are copyrighted and provided courtesy of the Science Museum Group, U.K., where they are on display, and released under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence.

Santa Catalina Radiotelephone, 1921

1921MarRadioNews1A hundred years ago, if you were located 26 miles across the sea (40 kilometers, for those in leaky old boats) at Avalon, Santa Catalina Island, California, you could enjoy the luxury of telephone service with any telephone in the United States, thanks to the radiotelephone service operated by Pacific Telefone and Telegraph Co., as described in the March 1921 issue of Radio News.

The system consisted of stations KUVX at Avalon and KUXT at Long Beach. A complicating factor was the presence of naval station NZL, also located at Avalon. To avoid interference, the radiotelephone receiving station employed a wave trap to null out NZL’s frequency. The article gives the radiotelephone wavelength of 425 meters (706 kHz). The system was full duplex, meaning that there would be different transmitting and receiving frequencies. Since the 425 meter wavelength is discussed in conjunction with the wave trap on the receiving antenna, it appears that the Long Beach station transmitted on 425 meters, and Avalon transmitted on a different frequency.

The author described an interesting catch for an SWL as part of a test conducted by the Avalon station. He listened in on a conversation from Avalon to the mainland, which was carried by the transcontinental telephone lines to New York, where the call was carried by another radiotelephone station to a ship in the Atlantic. The author reported that the voice was a little distorted, but could be clearly heard throughout the ten minute test.

The Avalon station was powered by a motor generator, and to avoid having to restart the power, the carrier was left on 14 hours a day, with calls to and from local hotels, stores, and residents carried as needed. A licensed radio operator oversaw the transmitter, connected to an eight-wire antenna, and receiver, connected to a loop antenna. A telephone operator put through the calls, presumably with another operator at the Long Beach side of the circuit doing the same.

The system was able to transmit telegraph signals simultaneously with telephone conversations without interference. This was accomplished by “superimposing a high pitched harmonic on the carrier wave.”

A more detailed technical description of the system can be found in the December 1921 Proceedings of the IEEE.  You can also find additional references at Wikipedia, which notes that the system was replaced by a submarine cable in 1923, ending the possibility of radio listeners being able to tune in to telephone conversations.

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Icebox Experiment: 1941

1941MarPSEighty years ago, this young woman was conducting a scientific experiment to determine the best way to maintain ice in an icebox. In 1941, not everyone had a refrigerator. The icebox was still common. It was nothing more than in insulated box in which ice, usually delivered by the iceman, was placed to keep the food cold.

You had to pay for the ice, so the natural tendency of the frugal housewife would be to wrap up the ice in a towel to make it last longer. This experiment showed that this was false economy. As Popular Science, March 1941, puts it, by saving the ice, you’re spoiling the food.

To prove this, she made prepared two identical cans, making one hole at the top and one hold at the bottom of each. The bottom hole was for drainage, and the top hole was for a thermometer. Into each can was placed an ice cube. One was wrapped in paper and the other was bare.

When a thermometer was placed in each, the one with the unwrapped ice would be colder, although the ice would last longer.

The modern student could replicate this experiment quite nicely. Even though we no longer use ice boxes in the home, the experiment demonstrates the best procedure for use in a travel cooler.  In addition to measuring the temperature inside the can, the student could compare the length of time the ice lasted.



Radio Hams Practice for War: 1941

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In 1941, the ham radio operator shown here was asked how long he would need to get his portable station into operation in the field. “Six minutes is the average time,” he replied. The officers asking the question were skeptical, but they watched as he opened his suitcase, hooked up a car battery, hammered in a ground stake and slung the antenna into a tree. He then tapped out a message to the control station fifteen miles away.

This was but one of the tales recounted eighty years ago this month, in the March 1941 issue of Popular Mechanics, in an article entitled “Radio Hams Practice for War.” It detailed the work of the 1800 member Army Amateur Radio System and pointed out that in time of war, thousands of trained hams would go into the military for active duty, and others would take on civilian duties such as listening for clandestine stations.

In another exercise, hams were asked, “your radio transmitter is completely smashed by a falling chimney. How long will it take to borrow an old broadcast receiver from a neighbor and build a new transmitter from its parts?” Another ham was ordered, “simulate destruction of your main transmitter. Rig up your emergency equipment and report back on the air as soon as you can.”

The article detailed a number of ways in which hams were “preparing themselves against a possible ‘M’ day.”