Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
The Leading Edge Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
The Leading Edge; June 2003; v. 22; no. 6; p. 562-566; DOI: 10.1190/1.1587679
© 2003 Society of Exploration Geophysicists
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Balch, S. J.
Right arrow Articles by Paterson, N. R.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

The AeroTEM airborne electromagnetic system

S. J. Balch and W. P. Boyko

Aeroquest Limited, Milton, Ontario, Canada

N. R. Paterson

Paterson, Grant and Watson Limited, Toronto, Ontario, Canada

Corresponding author: balchsj@sympatico.ca

The first 20% of the full text of this article appears below.

Airborne electromagnetic (EM) systems have evolved into two basic platforms since their introduction in the 1950s. The helicopter-borne frequency-domain systems (HEM) use narrow-band, low-moment transmitters and closely spaced receivers with a rigid geometry between the transmitter and receiver coils. A wide range of conductance discrimination, excellent spatial resolution, and moderate depth penetration characterizes these systems. The fixed-wing time-domain systems (AEM) use wide-band, high-moment transmitters and separated receiver coils in a geometry that is not rigid. These systems have a moderate range of conductance discrimination, moderate spatial resolution, and much greater depth penetration than HEM systems. Since 1995 there have been a number of attempts at adapting the advantages of the fixed-wing time-domain systems to the helicopter platform. The AeroTEM system, the result of one such effort, is based on a rigid, concentric-loop geometry with the receiver coils placed in the center of the transmitter loop (Figure 1). The advantages of this configuration include: maximum coupling to all target geometries regardless of the depth below the surface; sharper anomalies with simpler shapes compared to fixed-wing systems; anomaly shapes independent of the flight-line direction; and coincident transmitter-receiver coils have lower sensitivity to conductive overburden than separated transmitter-receiver systems.


Figure Removed (Available Only in the Full Text)
View larger version (69K):
[in this window]
[in a new window]
  		Figure 1. The transmitter-receiver coils during a break in a diamond exploration program in Venezuela.

 
The transmitter waveform (Figure 2) is a triangular current pulse of 1.150 ms with a base frequency of 150 Hz. The transmitter loop consists of eight turns of copper wire, 5 m in diameter, with a maximum current of 250 A that produces a peak moment of 40 000 Am2. One receiver coil is oriented in a vertical plane (Z-axis) and the other in an inline horizontal plane (X-axis). The secondary field is sampled at a rate of 126 samples per half cycle, or 38 400 . . . [Full Text of this Article]






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Society of Exploration Geophysicists