THE SIGNAL CORPS DEVELOPMENT of U.S. ARMY RADAR EQUIPMENT PART 1 Early Research and Development - 1918 - 1937 by H. M. DAVIS, 1st Lt., Signal Corps March 1943 CONFIDENTIAL DECLASSIFIED DOD DIR5200.9 1972 Control Approval Symbol SPSEO-100 Project "A-1"

NOTICE: This document contains information affecting the  national defense of the United states within the meaning of the  Espionage Act, 50 17. S. C. , 31 and 32. as amended.  The transmission or the revelation of its contents in any manner to an unauthorized person is prohibited by law. Copy No. 27of35copies made xiv plus 69pages and  31 illustrations Historical Section Field office Special Activities Branch Office Service Division Office of the Chief Signal officer Army Service Forces

       The following military characteristics were set up by the Chief of Coast Artillery in 18th Ind. dated 1 February 1936, file 413.684/AF and forwarded to the Chief Signal officer with approval of The Adjutant General on 29 February 1936.

1. Military purposes.
 

 a. Detect the presence of aircraft in a sector of approximately 120 degrees in azimuth, elevation limits 0 to 90 degrees. This sector represents the zone which the device must be able to cover by rapid sweeping in azimuth and elevation; the apparatus to be actuated by the heat radiation or radio waves set up by the airplane.

b. Register, or indicate, in proper units of measure the position of the located airplane with respect to the detector or some other designated reference point; this indication of data to be continuous so that the aircraft while in motion may be followed by a searchlight or observing instrument laid on such data.

2. Essential qualities of the device.
 

a. Under all atmospheric conditions, the accuracy of the indicated data must be such as to permit laying the searchlight, or observing instrument, with a maximum deviation of one degree in azimuth and in elevation from the actual position of the aircraft.

b. It must begin to furnish data of the above specified accuracy immediately after the device begins to operate.

c. Under average atmospheric conditions it must function at ranges up to 20,000 yards.

d. Under conditions of rain, mist, smoke, or fog, during day light or darkness, it must function at ranges up to 10,000 yards.

e. The design of the apparatus and the material employed must be such as to permit of operation by the average skilled enlisted personnel.

 f. The material employed must be of such nature as to withstand the conditions of climate and service, including shock from gun fire, which ordinarily obtain in localities where the apparatus would be employed.

g. The bulk and weight of the apparatus must be such as to permit of its being readily moved from one position to another in a permanent antiaircraft defense installation. Consideration should also be given to ultimate development of a type suitable for use with a mobile organization.

h. The requirements of agencies, such as electric current, to operate the apparatus must be such as to permit of its installation and use in the average antiaircraft defense system of an area.

i. In case of the radio detector, it must not be subject to interference known as "jamming" by other radio apparatus nor interfere with the operation of friendly communications.