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PROTEM Digital TEM
Receiver
Features
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Provides 24 bit resolution, a
system bandwidth of 500kHz, microsecond sampling
gates, and simultaneous XYZ component measurements.
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When used with a 3-component
coil mineral surveys are greatly accelerated.
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Quick and accurate checks on
geoelectric sounding data for lateral variations in
conductivity.
General
It is well known that there is a
tradeoff between depth of exploration and target
definition in terms of conductivity, extent and
orientation. Greatest depth is obtained with large fixed
loop Turam-type systems that generate large half space
responses. This fact, along with current gathering,
makes target detection difficult. Better spatial
resolution is obtained with a moving transmitter
configured with short intercoil spacing, but this
configuration is limited to shallower exploration
depths. These variations in survey requirements make
system flexibility an important design consideration.
Time Domain systems are routinely
employed for general geological exploration such as
searching for freshwater aquifers in bedrock fractures,
and mapping gro.undwater contaminant plumes. Mapping
shallow depths requires a very wide bandwidth and many
narrow sampling gates.
Recognition of these diverse
requirements led to the development of the extremely
flexible Protem time domain system. The digital,
3-channel receiver is used with any of the three TEM
transmitters and choice of receiver coils to cover all
applications. With its 23 bit resolution, system
bandwidth of 500kHz, microsecond sampling gates and
simultaneous XYZ component measurements, the Protem
receiver provides the ultimate in time domain
capability. Used with a 3-component coil, mineral
surveys are greatly accelerated with more data in either
the fixed loop or slingram mode. Three component
measurements make possible quick and accurate checks on
geoelectric sounding data for lateral variations in
conductivity. This could invalidate a layered-earth
interpretation.
The latest addition to the PROTEM
receiver enables the selection of either 20 gates per
base frequency covering 2 decades of time, or 30 gates
for a 3 decade range. If 3 decades of time are required
to cover the decay then this selection saves switching
frequencies and repeating the measurement; or if only 2
decades are required, using the 20 gate range reduces
the measurement time by a factor of 10. A further
receiver improvement enables automatic measurements
during the on-time in addition to the standard off-time
measurements.
Specifications
Measured Quantity: Rate of decay of
induced magnetic field along 3 axes, in nV/mē
EM Sensor: Air-cored coils
Channels: 1 channel used sequential
for 3 components or 3 channels for 3 components
simultaneous operation
Time Gates: 20 gates covering 2
time decades 30 gates covering 3 time decades
Dynamic Range: 23 bits (132 dB)
Frequency: 0.3, 0.75, 3, 7.5, 30,
75 and 285 Hz or 0.25, 0.625, 2.5, 6.25, 25, 62.5 and
237.5Hz
Integration Time 2,4,8,15,30,60,120
or 240s
Display: 240 x 64 dot graphic LCD
Data Handling: Solid-state memory
for 3300 data-sets. RS-232 output
Synchronization: Reference cable or
optionally, highly stable quartz crystal
Power Supply: 12V rechargeable
battery for 8 hrs continuous operation
Dimensions: 34 x 38 x 27cm
Weight: 15 kg
Standard Components
Instrument console, shipping case
and instruction manual.
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