FGS-04e
Product Description
The FGS-04e is a low noise 3-axis fluxgate sensor. It extends the frequency range for MT measurements down to DC. The sensor core unit is a Bartington Mag-13 MCL (MC = cylindrical core, L = low noise).
For lower frequencies all transfer functions are linear. This sensor is designed for crustal studies where periods of 10,000 seconds and more are needed. Recording time for those periods are three to eight weeks depending on the data quality (magnetic activity and external interferences by man made noise).
The fluxgate is measuring the total magnetic field (B). A induction coil is measuring dB/dt.
A good coincidence can be seen for periods greater than 100s. For higher frequencies (smaller periods) a fluxgate can not be used for MT.
If the sample rate is too high, the data looks strange:
Coming to lower sampling rates, you start to see the fluxgate data:
The fluxgate has constant transfer function: divide the spectra by 10E-4. Phase shift is zero for f < 1Hz.
Data from Bartington
| Performance | |||
|---|---|---|---|
| Number of axes | Three | ||
| Polarity | +ve when pointing North | ||
| Full Scale Measuring Ranges | ±70 000 nT | ±100 000 nT | ±250 000 nT |
| Scaling | 0.143 mV/nT | 0.1 mV/nT | 0.04 mV/nT |
| Scaling error | ±0.5% | ||
| Scaling Temperature Coefficient | <±60ppm | ||
| Linearity error | 0.0015% (least squares fit) | ||
| Frequency response at 50µT peak | DC to 1kHz (±5%) | ||
| Max Bandwidth at 50µT peak | 3400 Hz | 3100 Hz | 3000 Hz |
| Max Bandwidth at full scale | 3000 Hz | 2500 Hz | 1100 Hz |
| Primary Resistance | 10Ω ±1.5Ω | ||
| Primary Inductance | 1000µH typical | ||
| Secondary Resistance | 36Ω ±4Ω | ||
| Secondary Inductance | 5600µH typical | ||
| Noise: | |||
| Standard | ≤10 pT rms / √Hz @1Hz | ||
| Low noise (L) | <6 pT rms / √Hz @1Hz (70 and 100 µT range only) | ||
| Very low noise (Q) | <5 pT rms / √Hz at 1Hz (70 and 100 μT range only) | ||
| Zero Field Offset | ≤±30 nT | ||
| Offset Temperature Coefficient | ≤±0.6 nT/°C | ||
| Perming (Magnetisation Hysteresis) | <2nT (at 1 x Full-scale, when powered) | ||
| Orthogonality error between axes | <±0.1° (<±0.2° for MCD and MCDFL) | ||
| Alignment to datum face/s | <±0.1° (Mag-13MS only) | ||
| Excitation Breakthrough | <5mV pk-pk 15.625kHz typical | ||
| Start-up/Settling time | <100ms | ||
| Warm-up drift time | 15 minutes to meet specifications for scaling | ||
| <60 minutes to meet specifications for noise | |||
| Mag-13® Three-Axis Magnetic Field Sensors |
| Electrical Specification | Value |
|---|---|
| Supply Voltage | ±12 to 17V |
| Current Consumption – Positive | 35 to 41mA in zero-field |
| Current Consumption – Negative | 13 to 17mA in zero-field |
| Power Supply Rejection Ratio | 120dB |
| Power-on Surge | +90mA, -25mA, 20ms |
| Analogue Output | ±10V |
| Output Impedance | 10Ω |
| Test function field in each axis | -1µT ±10% |
| Maximum cable length @ 12V supply | 70 000 nT = 1000m |
| 100 000 nT = 1000m | |
| 250 000 nT = 800m | |
| 500 000 nT = 650m | |
| 1 000 000 nT = 500m | |
| Maximum cable length @ 14V supply | 70 000 nT to 500 000 nT = 1500m |
| 1 000 000 nT = 1100m | |
| Cable Length Note | Higher supply voltages will allow longer cable lengths to be used, dependent on cable resistance and magnetometer range. |
| Environmental | |
|---|---|
| Operating temperature range | -40 to +70°C |
| Storage temperature range | -40 to +70°C |
| Compliance (CE, etc.) | EMC BS EN 61326 & RoHS |
| Additional environmental qualifications | Mag-13MCD 550bar hydrostatic pressure test |
| Environmental protection / sealing | |
| MC | IP67, metronix uses IP68 enclosure |
| MS | IP67 |
| MCD | IP68 (5000m) |
| MCDFL | IP68 (500m) |
| U | N/A (unpackaged) |
| U-TPU | N/A (unpackaged) |
| MSS | IP68 (200m) |
| Environmental | |
|---|---|
| Operating temperature range | -40 to +70°C |
| Storage temperature range | -40 to +70°C |
| Compliance (CE, etc.) | EMC BS EN 61326 & RoHS |
| Additional environmental qualifications | Mag-13MCD 550bar hydrostatic pressure test |
| Environmental protection / sealing | |
| MC | IP67 |
| MS | IP67 |
| MCD | IP68 (5000m) |
| MCDFL | IP68 (500m) |
| U | N/A (unpackaged) |
| U-TPU | N/A (unpackaged) |
| MSS | IP68 (200m) |