a Se er mam otek, ae e . . DC trigger Gevice located in the primary cathode fellever and ea nette! directly to the recsiving antenna. The 2 microsecond delay Line vas added to permit the leading sige of the waveform to be re- corded, In onder to establish a definite time relationship between the reception of the signal ani the triggering of a given device such as @ counter or transmitter, « time marker pip, gererated by the delay trigger from one of the oncilloscopes, is fel “hrough the 2 nicreeovend delay line ani superimpose! an the initial pertion of the reselved wavefora, T20GE All cecilloscopes are enlilrute? against a know frequenay standard for sveep lisearity. The cathode follower triggering aystem is eet to trigger appron- imately db. above the ncise lewel. The vertical deflector of the Seellloscopes are get to receive the predicted field strength. SMES Perry Ho data obtained for this shot since cecilloscopes hed already been triggered ty signal from FLATFRAD. Since there arc two traces present in the photo it fe assumed that both FLATHEAD and BLACKFOOT traces are present, Since the oscilloscope sensi-ivities hai been set for FLATHPAD, the trace of BLACKFOOT is of eucd @ smal: amplitude that it is of questionable walus. trigger. me scope iid not BEST AVAILABLE COPY 7 on . ye € nals “Me