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ASA Radio Direction Finding Standard Operating Procedures


6-1. Methods of Communications Within DF Nets.

The methods of communications used by DF nets are landline teletypewriter, radio teletypewriter, CW, and radiotelephone. All of these methods of communications must be secured with cryptosystems. A prime consideration of a DF net is the security and speed with which its users may effectively, communicate.

a. The primary method of communications for strategic DF is secure, online teletypewriter using the Defense Special Security Communication System (DSSCS).

DF Net SOP Operations Schematic

b. Methods of communications for tactical DF are CW, secured radio teletypewriter, and radiotelephone.

6-2. Problems of Control.

From the simplest to the most complex DF nets, there are certain functions which must be performed from the time a bearing is requested until the resultant bearings are obtained and the estimated target location is reported. These functions, in a reasonably chronological sequence, are:

a. The bearing to or position of a target station is required for intelligence purposes(mission authorized action). Sufficient information concerning callsigns, frequency, and type of traffic passed must be furnished to permit identification of the target signal. This information is usually obtained from an intercept-search mission which identities new stations of interest or substantiates the continuance of old stations with an interest in determining possible displacement. The completeness of this information is not always predictable. Generally, however, the DF operator does not spend his time searching the frequency bands for targets.

b. The mission, with all available information on the operation of the target station or net, is given to the radio intercept operator who searches for the desired signal and copies it to obtain traffic and keep the DF controller informed of the station's or net's activities.

c. As soon as the desired station or net is active, the radio intercept operator notifies the DF controller. He also provides the controller with any identifying details not already known.

d. The DF controller notifies all DF operators of the station's or net's activities, callsigns, frequencies, and other identifying information. This takes place over the flash net.

e. Bearings obtained by the DF operator are reported to net control. The reported bearings are plotted and the probable target location given to the commander who authorized or requested the mission. The assignment of the mission to the DF operator and the reporting of the results is accomplished by any of the means of communications mentioned above. If a DF station happens to be colocated with the intercept facility, communication between the DF controller and the operator is within the confines of the facility, and requires none of the above. When only one DF set is used, only a line bearing can be obtained. In this situation, the commander desiring the bearing is usually in close proximity to the supporting DF site, and requests are made in person, with the results rendered in the same way. This single site DF effort is usually for close tactical support when a ground commander wishes to confirm his contacts or suspicions about the enemy's location. After the inital mission has been assigned to the operator, the controller can employ certain codes (if equipped with online cipher devices) or speak directly to the operator (if speech privacy equipment is available) to keep him informed as to exactly what the target station is doing. This is called "tracking" the station, and is used to ensure positive identification by the operator. Various DF missions will be assigned priorities depending upon the urgency of the tactical situation or the overall intelligence effort. When the missions terminate, the results are forwarded to control over a second net, called the reporting net.


6-3. General.

Tasking, or mission assigmnent, is extremely complex, ranging from the tactical commander's request to requirements generated at the national level. A discussion of the detailed generation of missions is not within the scope of this manual. Such information may be obtained, if required, from the liaison officer assigned at each level of command who acts as a resources manager for the units providing DF support.

6-4. Basic Net Requirements for DF Support.

Without regard for the means of communications employed, a DF net requires communications circuits as shown in figure 6-1. The flash net, over which missions are assigned, is indicated by the solid lines, while the reporting net over which mission results are passed, is indicated by the broken lines. This is the basic communications requirement for any DF net. Tracking is conducted over the flash net after the missions are assigned. All bearings are returned over the reporting net.

Note: Above extracted/edited from: DA Field Manual FM 30-476 Radio Direction Finding April 1977 version.