MFS-12e

Chopper Free Coil

The MFS-12e is a super broadband coil, allowing to record LF (MT) and HF (AMT) at the same time.
This allows to collect a complete station within 8 hours, reaching depth of 1000 m and more, depending on your surface resistivity.

Product Description

The MFS-12e magnetometer is the successor of the most famous coil MFS-06e. The preamplifier has been newly designed which offer a broad band mode ranging from 0.0001 Hz (10,000 s) to 20 kHz. This allows you to make a ‘single shot’ for AMT and MT. Additionally, compared to the MFS-6e preamplifier, it requires less power.

In spite of its broad bandwidth, the MFS-12e shows outstanding low-noise characteristics, extremely low temperature drift, very stable transfer function over time.

The MFS-12e acts as an “intelligent plug and play” sensor. Thus, once connected to the ADU systems, it will send its type and serial number as well as its calibration function automatically. The user does not have to care about any further sensor parameter setup.

Technical Specifications:

Parameter	Specification
Frequency range	0.0001 Hz … 20 kHz
Sensor noise	\(5 \cdot 10^{-2} nT / {\sqrt{Hz}} @ 0.01Hz\)
	\(4.5 \cdot 10^{-4} nT / {\sqrt{Hz}} @ 1Hz\)
	\(3 \cdot 10^{-6} nT / {\sqrt{Hz}} @ 1000Hz\)
Output sensitivity	0.05 V/(nT*Hz) f << 16 Hz, for exact values refer to individual calibration file
Output voltage range	+/- 10V
Function	induction coil with magnetic field feedback
Connector	10 pole ODU Series K
Calibration coil sensitivity	4 nT / V
Feedback cut-off frequency	16 Hz
Supply voltage	+/- 12V to +/-15V stabilized and filtered
Supply current	+/- 25mA
Case	ruggedized, waterproof case
Weight	ca. 5.8 kg
External dimensions	length 980 mm, diameter 75 mm
Operating temperature range	-25° C … +70° C

Features

Wide frequency range from 0.0001 Hz to 20 kHz covered by only one sensor
High linearity
Ultra low noise
low power consumption
High accuracy calibration with built-in precision calibration facility
high permeable ferrite cores
Wide operating temperature range from -25° C to +70° C
high stability of the sensor´s transfer function due to magnetic field feedback coil
dual path amplifier
metronix “smart sensor” technology – sensor parameters incl. transfer function can be read out by ADU systems automatically
light and easy field handling: one person can carry two magnetometers all at once
ruggedized, waterproof case

Preamplifier

The preamplifier has two signal amplification paths. The LF path is chopper stabilized to achieve excellent low-noise and drift characteristics, with a chopper frequency above 100 kHz. The HF path runs independently.
The signals of both paths are seamlessly mixed in the output stage, and appear as one signal for all frequencies.

Calibration

\[F_{Sensor}=\frac{V_{output}}{H}= 0.8 \frac{V}{nT}\cdot\frac{ P_1}{(1+P_1)}\cdot \frac{1}{(1+P_2)} \cdot \frac{1}{(1+P_4)}\]

with

\[ P_1 = i \cdot \frac{f}{16Hz} , P_2=i \cdot \frac{f}{9645Hz} P4=i \cdot \frac{f}{50048Hz} \]

(old \(P_3\) is skipped); in the old calibration the amplitude is divided by f, so the unit is \(V/(nT*Hz)\); this gives a flat response for frequencies < 0.1 Hz.
Whereas the MFS-06e converges to \(0.2 V/(nT * Hz)\) for f << 0.1 Hz, the MFS-12e converges to \(0.05 V/(nT*Hz)\).
The phase converges to 90 degrees for f << 0.1 Hz.

In the new metronix json format it would be simply multiplied by 1000 to get mV/nT:

\[F(f) = \frac{ mV}{nT} = 800 \enspace \frac{mV}{nT} \cdot \frac{P_1}{1+P_1} \cdot \frac{1}{1+P_2} \cdot \frac{1}{1+P_4} \]

(this format is never normalized by f)

In addition to the delivered calibration file the sensor is equipped with the calibration data stored on a chip inside the sensor. This information will be read by the ADU. Each time a data recording is done this calibration data is stored along with the recording data.

The calibration is valid for more than 10 years, if the sensor is handled with care. You can check anytime the validity of the calibration by a simple field test with the built-in calibration coil (Insitu Coil Calibration Tool).

Initial Calibration

metronix takes special care of the initial calibration of all MFS-12e magnetometers as part of the ISO 9001 certified production process. Tests have demonstrated an excellent long time stability of the transfer function. The calibration is performed in the “Magnetsrode” geomagnetic laboratory which is operated by the Institute of Geophysics at the Technical University of Braunschweig, mostly to calibrate space flight magnetometers. It offers special environmental circumstances and has an extremely low distortion level. A large solenoid (l = 3.6 m; d = 30 cm) has been calibrated by a reference sensor with an accuracy of better than ±0.2%. It is used to generate a homogeneous magnetic field of known strength as input signal. The input signal for the solenoid. Unlike others, we tune the coil to reach the theoretical calibration function as described above, and therewith the 0.1 Hz entry in the calibration must show values close to 0.05 V/(nT*Hz), like 5.0104E-02 and +8.9563E+01.

Sensor noise

For a basic introduction to sensor noise please refer to the MFS-06e documentation.

Environmental

In case the item is no longer needed, please dispose it according to the local regulations for electronic waste.
Dispose items only at qualified places, not in your household waste.