page_title: Geophysical MASINT
section_title: Initial WWI counterbattery acoustic systems
hierarchical_section_title: Geophysical MASINT / Acoustic MASINT / Counterbattery and countersniper location and ranging / Initial WWI counterbattery acoustic systems
caption_attribution_description: World War I Canadian artillery locating by sound-ranging
context_page_description: Geophysical MASINT is a branch of Measurement and Signature Intelligence that involves phenomena transmitted through the earth and manmade structures including emitted or reflected sounds, pressure waves, vibrations, and magnetic field or ionosphere disturbances.
  According to the United States Department of Defense, MASINT is technically derived intelligence that – when collected, processed, and analyzed by dedicated MASINT systems – results in intelligence that detects, tracks, identifies, or describes the signatures of fixed or dynamic target sources. MASINT was recognized as a formal intelligence discipline in 1986. Another way to describe MASINT is a "non-literal" discipline. It feeds on a target's unintended emissive by-products, the "trails" - the spectral, chemical or RF that an object leaves behind. These trails form distinct signatures, which can be exploited as reliable discriminators to characterize specific events or disclose hidden targets."
context_section_description: In the "Sound Ranging" graphic, the manned Listening (or Advanced) Post, is sited a few 'sound seconds (or about 2000 yards) forward of the line of the unattended microphones, it sends an electrical signal to the recording station to switch on the recording apparatus. The positions of the microphones are precisely known. The differences in sound time of arrival, taken from the recordings, were then used to plot the source of the sound by one of several techniques. See http://nigelef.tripod.com/p_artyint-cb.htm#SoundRanging
  Where sound ranging is a time-of-arrival technique not dissimilar to that of modern multistatic sensors, flash spotting used optical instruments to take bearings on the flash from accurately surveyed observation posts. The location of the gun was determined by plotting the bearings reported to the same gun flashes. See http://nigelef.tripod.com/p_artyint-cb.htm#FieldSurveyCoy  Flash ranging, today, would be called electro-optical MASINT.
  Artillery sound and flash ranging remained in use through World War II and in its latest forms until the present day, although flash spotting generally ceased in the 1950s due to the widespread adoption of flashless propellants and the increasing range of artillery. Mobile counterbattery radars able to detect guns, itself a MASINT radar sensor, became available in the late 1970s, although countermortar radars appeared in World War II. These techniques paralleled radio direction finding in SIGINT that started in World War I, using graphical bearing plotting and now, with the precision time synchronization from GPS, is often time-of-arrival.
caption: Sound Ranging
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