The Promis device is a multi-frequency, multi-spacing 3 component slingram type EM System for sounding and profiling surveysl. This system features a transmitter loop to produce a primary magnetic field that will induce eddy current in conductive materials. These eddy currents will generate a secondary magnetic field that will be measured with the receiver loop. This system measures the in-phase and the out-of-phase components of the secondary magnetic field.
The length between receiver and transmitter loops range between 20 m and 400 m for standard applications. This system allows to work with 10 frequency ranging from 110 Hz to 56 kHz. The depth of penetration depends on the spacing and on the frequency. It is usually considered as of the order of half the spacing. Profiling can be performed by moving both the transmitter and the receiver to the next station.
Traditional HLEM slingram systems only measure the vertical component of the magnetic field (Hz). The Secondary/Primary magnetic field ratio, being linked to the soil conductivity, allows to locate conductive structures intersecting a profile. The 3 components measured by the PROMIS system permits to give an information on the direction (strike) of the structure (because the magnetic field remains perpendicular to the eddy current directions).
With the Promis system, the productivity is increased by an automatic processing (measurement automatically carried out for the set of frequencies, without required communication between the two operators). Two leds indicate when the transmitter has to move to the next station. Two inclinometers correct for deviations from horizontal position and a GPS unit can be connected. The selection of the frequencies and the stacking parameters is made at the beginning of the survey for optimizing the field work.
The data can be transferred, edited, filtered, plotted and exported with the EMSYS software provided with the instrument.
|Magnetic moment:Loop 75cm/130cm||
360/720 Am2 @ 110 Hz
320/740 Am2 @ 220 Hz
280/560 Am2 @ 440 Hz
235/470 Am2 @ 880 Hz
220/440 Am2 @ 1 760 Hz
160/320 Am2 @ 3 520 Hz
110/220 Am2 @ 7 040 Hz
60/120 Am2 @ 14 080 Hz
30/60 Am2 @ 28 160 Hz
15/30 Am2 @ 56 320 Hz
|Loop diameter||75 cm. Optional loop 130 cm for doubling the magnetic moment.|
|Inclination||2 inclinometers for horizontal position|
|Indicators||Two LEDs (green and red) indicating start/end of reading|
|Dynamic range||24 bits|
|Channels||3 (Hx,Hy,Hz) channels (on demand)|
|Resolution||0.01% of the primary field.|
|GPS||GPS for location (coordinates)|
|Readings||in-phase and out-of-phase parts of the three magnetic components Hx, Hy,Hz, standard deviation, tilt angles of transmitter & receiver, battery levels, temperature, GPS data|
|Noise Reduction||50/60 Hz notch filters and overload detection|
|Weight||Transmitter: 9.8 Kg (5.8 Kg in backpack)Receiver: 5.0 Kg|
|Operating T||-20 to +70°C|
|General||Transmitter: 30 cm x 20 cm x 20 cmReceiver: 30 cm x 15 cm x 20 cm|