While there are many interesting and intriguing documents in the CECOM Historical Office’s archive, we have chosen one document in particular to discuss here. It is a 1942 report titled “Screen Rooms.” The report was a product of the Coordination Group, V.I. Section, which was a part of the Signal Corps Laboratory.
This report was generated early in WWII, when the need for reliable radios in vehicles was vital to the War effort. To test vehicular radio noise suppression, it was very important that there be a convenient room that was free of RF (radio frequency) disturbances located in the radio manufacturer’s plants that would allow the testing of radios for vehicle noise in an environment free of noise sources other than the vehicle. The rooms would be used at the manufacturer’s location so as to be near the “production center” of the radio; the manufacturing facility was itself a source of radio noise of varying amplitude and character due to machinery, power stations, and electrical apparatus located within the plant.
The concept of the screen rooms was developed in 1941. The room as conceived would be 40’ long, 20’ wide, and 22’ high, surrounded by walls constructed of two sheets of copper spaced 6” apart. The doors would provide 12’ square opening. The room would also include lighting, ventilation, and testing equipment. The first room was built to design in St. Louis at an automotive plant, and proved the design satisfactory for production testing and to be less costly than standard reference screen rooms in use at the time. When a room was completed, it was necessary to determine its attenuation characteristics which could vary at each location where the screen room was used and to correlate the screen room’s readings with similar tests in noise free locations.
The report goes on to describe some of the testing that took place, including use of galvanized screen which proved to be similar in performance to copper when installed with “well made joints.” Included in the report are some photographs and inspection information for selected installation locations in Indiana, Michigan, and Missouri. There are also selected drawings and discussions for some of the rooms inspected.
A copy of this report is available from the CECOM Historical Office. The Historical Office is located at Aberdeen Proving Ground. If interested, the reader can also contact the Historical office through our “contact us” Web page at http://cecom.army.mil/historian/contactus.php.
This post was written by Floyd Hertweck