SiSMoS-4: Site Survey Monitoring System
The SiSMoS-4 provides a PC-based, fast, four-channel, 24-bit data acquisition system with data-logger and spectrum analyzer for Bartington Instruments fluxgate sensors and industry standard ICP accelerometers. Applications include environmental monitoring (of EMI and vibration) for pre-installation surveys for MRI systems, electron microscopes and similar sensitive equipments. The SiSMoS-4 performs data acquisition in three channels for a triaxial sensor fluxgate or a one channel for a uniaxial accelerometers and produces both time domain and frequency domain plots showing either slow or fast trends for magnetic and vibration data in three axes.
The conversion of time-varying information into a frequency spectrum is accomplished using Fast Fourier Transforms referred to as FFT in the text. When used as a data-logger, time-stamped data can be logged (for extended periods) then retrieved and post-processed in both time and frequency domain. The system is software controlled and connection to the user’s PC is via a USB interface. Prior to data acquisition, system configuration is accomplished using the SiSMoS-4 software (Device configurationDevice configurationDevice configuration). Additional functions provided by the SiSMoS-4 system include:
- Selectable plot of time or frequency data
- Data post-processing (selectable filtering and averaging)
- Availability of cursors and markers for effective measurements
- Exports the graph data to excel file or to the clipboard in a tab-delimited format, which is accepted by most spreadsheet applications
- Saving of plots (images) in .bmp, .eps and .emf formats for use in reports
- Up to 10 hours operation powered by a rechargeable battery
- 51,2 kS/s sampling rate giving a spectral plot up to 25,6 kHz (-3dB point)
The SiSMoS-4 software records time and frequency domain data over a wide frequency range – from DC to 3.5kHz (-3dB point) for all input channels. Data logging with time-stamping is also provided hence the system functions as a high resolution data logger for magnetic and vibration measurements. The SiSMoS-4 software is compatible with Windows XP or later.
The SiSMoS-4 hardware unit contains a rechargeable battery for up to 10 hours operation under typical conditions to allow field-work with a laptop computer. In order to extend battery operation, magnetometer power is applied only when the user must use. The system is ideal for magnetic, vibration measurements and is also suited for recording the magnetic fields due to 50/60Hz mains supplies and associated harmonics.
Specification
| Number of input channels | 3 for magnetic field sensors
1 for accelerometers or acoustic sensors |
| Voltage input range | ±10 V |
| Resolution | 24 bit A to D converter |
| ADC Resolution | 24 bits |
| Type of ADC | Delta–Sigma (with analog prefiltering) |
| Sampling mode | Simultaneous |
| Frequency domain display options | Amplitude spectrum (RMS, peak-to-peak)
Amplitude spectral density (RMS/√Hz, p-p/√Hz) |
| Internal master timebase (f M)
Frequency Accuracy |
13.1072 MHz
±50 ppm max |
| Data rate range (f S) using internal master timebase
Minimum Maximum |
1.652 kS/s
51.2 kS/s |
| Input coupling | AC/DC (software-selectable) |
| AC cutoff frequency
– 3dB – 0.1 dB |
0.5 Hz
4.6 Hz max |
| IEPE excitation current (software-selectable on/off)
Minimum Typical |
2.0 mA
2.1 mA |
| Power on glitch | 90 mA for 10 ms |
| IEPE compliance voltage | 19 V max |
| Overvoltage protection (with respect to chassis ground)
For a signal source connected to AI+ and AI For a low-impedance source connected to AI+ and AI– |
±30 V
-6 to 30 V |
| Gain drift
Typical Maximum |
0.14 mdB/°C (16 ppm/°C)
0.45 mdB/°C (52 ppm/°C) |
| Accuracy | |
| Offset drift
Typical Maximum |
19.2 mV/°C
118 mV/°C |
| Gain
Typical Maximum |
0.01 dB
0.04 dB |
| Phase (fin in kHz) | fin ? 0.045° + 0.04 max |
| Passband
Frequency Flatness (fs = 51.2 kS/s) |
0.45 ? fs
±40 mdB (pk-to-pk max) |
| Phase nonlinearity (fs = 51.2 kS/s) | ±0.45° max |
| Stopband
Frequency Rejection |
0.55 ? fs
100 dB |
| Alias-free bandwidth | 0.45 ? fs |
| Crosstalk (1 kHz) | -110 dB |
| Spectrum range | Software selected as sample rate or maximum frequency |
| Output interface | USB2 |
| Software | Windows® 98/2000/XP/Seven compatible |
| Operating temperature range | -10°C to +50°C (0°C to +45°C for charging) |
| Storage temperature range | -20°C to +70°C |
| Humidity | 0 – 50% (non condensing) |
| Enclosure | Aluminium |
| Dimensions | 250 x 190 x 80 mm |
| Weight | 3.5 kg |
| Connectors | 1 x DB9 plug to magnetic field sensors
1 x BNC sockets for ICP® piezoelectric vibration sensors/microphone preamplifiers 1 x USB to PC 1 x IEC socket for 110-220V input from mains adaptor for recharging |
| Power output to sensor | ±15 V, ±75mA |
| Sensor input (magnetic field sensor) | Unbalanced |
| Suitable ICP® vibration sensor | PCB Piezoelectronics |
| Battery | Internal rechargeable Ni-Mh 7.2V battery with universal mains adaptor for charging |
| Battery life | 10 hours (typical) |
| Battery charging time | 15 hours for full charge |
| Power consumption from chassis
Active mode Sleep mode |
900 mW max
25 mW max |
| Thermal dissipation (at 70°C)
Active mode Sleep mode |
930 mW max
25 mW max |
| Channel-to-earth ground | ±30 V max, Measurement Category I |
| Input impedance (magnetic field sensor inputs) | 1 MΩ |
| ICP® constant current | 4mA ±20% for cables up to 1km in length |
| Optional accessories | Tripod and adaptor for Mag-03 sensors
Rugged carrying case |
| Carrying case dimensions | 616 x 493 x 220 mm |
| Total weight with carrying case | 12kg with SiSMoS–4, Mag-03 sensor, 5m cable and tripod |
| CE Compliance | 2006/95/EC; Low-Voltage Directive (safety)
2004/108/EC; Electromagnetic Compatibility Directive (EMC) |