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 recommended by the Signal Corps Technical Committee at its meeting No. 152 on 9 August 1937. It was intended that they should supersede the military characteristics set forth in Appendix A.

       1. Military purposes

               a. Detect the presence in a water area of marine surface craft of types that may be employed in operations by an enemy; the apparatus to be actuated by radiated heat or radio waves projected toward and reflected from some part of the craft, or some combination of these principles.

               b. Continuously register, or indicate. the range and direction of the located craft with respect to the detector or some other designated reference point.

       2. Essential Qualities of the Device

               a. Under all atmospheric conditions, the device must indicate the direction of the target with a probable error of one degree in direction and must indicate the range of the target with a probable error not larger than one-half of one per cent of the range at ranges of 10,000 yards or more.

               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 during daylight or darkness to a maximum range of the order of 40,000 yards.

               d. The operation and functioning of the device shall not be adversely affected by the presence of smoke, fog, rain or mist between the device and the target.

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

               g. The bulk and weight or the apparatus, including power source, must be such as to permit of its ready installation in detached positions along the shore line without forming a conspicuous target.

               h. The auxiliary agencies. such as electrical current generators, required to operate the apparatus, must be such as will permit the installation and use of the device in the normal harbor defense command without the addition of complicated equipment or construction.

               i. It must not be subject to Interference known as "jamming" by other radio apparatus nor interfere with the operation of friendly communications.