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| SediMeter™ Model 2 specifications
| |
| SM2 versions | SM2A - stand-alone and cable operation SM2N - cable operation only |
| Physical | |
| Dimensions | 700 mm x 51 mm (27.6" x 2" - excluding finger screw) |
| Mass | 0.5 kg (1 lb.) |
| Buoyancy in sea water | Will lay down on the bottom |
| Depth rating | 45 m (150') - higher on request |
| Sedimeter sensor | |
| Active sensor length | 350 mm (13.8") |
| Detectors per sensor | 36 optical backscatter detectors (OBS) |
| Detector zoning | 6 zones times 6 detectors (this increases the signal-to-noise ratio) |
| Detector spacing | 10 mm |
| Turbidity resolution | 0.3 FBU (formazin backscatter units, aka FTU) |
| Turbidity accuracy | 6 FBU |
| Turbidity accuracy in holder | 100 FBU |
| LED wavelength | 945 nm |
| Visual indicator | A white LED at the top of the sensor blinks once per measurement |
| PCODE | 63682 (turbidity sensor classification in NWIS of USGS) |
| Other sensors | |
| Built-in channels | Temperature (cK, ±0.3 K), battery voltage (mV, ±0.1 V) |
| Optional sensors | 2 channels with signal conditioning (e.g., light, pressure) |
| Logger | |
| Model | LogDator™ LM-01-00/D |
| A/D converter | 12-bit resolution in hardware, 16-bit after anti-aliasing |
| Sedimeter channels | 6 analog channels, one for each phototransistor zone |
| Sedimeter sampling | Each LED lits up individually, measures background light and signal |
| Optional sensor sampling | Bursts of 0 to 84 samples at 0.5 Hz to 50 Hz |
| Measurement interval | User selectable from 1 second to 24 hours |
| Real-time clock | UTC (GMT) by default, can be set to within 0.02 s |
| Data records | 512-byte records that include metadata and 16-bit analog data |
| Analog data | Stored as voltage, not in physical units (with the exception of temperature) |
| Conversion and calibration | Performed in software, see below |
| Internal memory | 2 MB (4096 records) |
| Memory cards | SD and MMC cards up to 2 GB* |
| User interface | NavPin control stick and 2 x 8 char LCD display* |
| Diver interface | Magnetic switch for mode change |
| Computer interface | USB* and RS-485 (EIA-485, TIA-485) |
| Network | Up to 255 units per RS-485 cable |
| Network protocol | LogDator Communication Protocol ver. 1.0 |
| Power supply options | 2 size AA Li batteries 2.1 Ah*, RS-485 cable, USB* (only for set-up and download) |
| Power backup | Keeps settings for several minutes without power connected, if in idle |
| Power demand | |
| Input voltage range | 5.5 V < Usupply < 9 V during measurements, 3.5 V < Usupply < 9 V during communication |
| Minimum RAM retention voltage | 1.8 V (lower voltages lead to a Reset) |
| Current use in idle, no card | 0.83 mA in RS485 mode; 32 μA in Log or Sleep mode |
| Current use of memory card | MMC and SD cards typically use 0.1 mA to 0.25 mA in idle |
| Current drain from supply | Ipeak < 27 mA, Iaverage < 1 mA |
| Multiple power sources at once | The one with the highest voltage is used (battery, USB, or RS-485 cable) |
| Version specific: Model SM2A | |
| Supported features | All those mentioned above |
| Version specific: Model SM2N | |
| Supported features | RS-485, 2 MB memory, logging mode, real-time mode, cable power |
| Unsupported features | USB, user interface, memory cards, battery-powered stand-alone operation |
| Underwater RS-485 connector | 1 included, a second one optional (required for networking in a daisy-chain) |
| Power | Supplied via the underwater RS-485 connector |
| Software "sedimeter.exe" | |
| Functions | Set-up, download, real-time monitoring, data analysis, data export, edit calibrations, etc. |
| Analysis functions | Analyze sedimeter-sensor turbidity, convert to sediment level, analyze optional data |
| Turbidity intensity plots | Background, signal, signal minus background, calibrated signal, converted signal in FBU, ppm |
| Sediment level | Resolution 0.1 mm, linearity without level calibration typically better than 1 mm |
| Optional data analysis | Average, frequency, and amplitude measure of burst samples from one measurement |
| Water turbidity estimate | Based on 6 OBS highest from the bottom, estimated accuracy 3 FBU (40 FBU with holder) |
| Communication methods | USB and RS-485 (EIA-485, TIA-485) |
| Simultaneous capacity | 255 instruments via RS-485, 1 via USB |
| File import | .ld2 files written by the LogDator™ on memory cards |
| Conversion to physical units | Fixed equation for sedimeter sensor, selectable equation for optional sensors |
| Conversion coefficients | User-editable calibration file allows any number of calibration sets per instrument |
| Network definition file | Lists the instruments to be monitored, and optionally their coordinates, in plain text |
| Functions, logging | Instrument setup; data download, presentation, analysis, export |
| Functions, real-time | Control 1 to 255 networked SediMeters; data presentation locally and on web server |
| *Features marked with an asterisk only apply to certain models | |
More Information
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We reserve the right to change specifications and prices without notice, and do not assumte responsibility for typos or other inadvertet errors. Accuracy values refer to one standard deviation and are estimates unless otherwise noted.
