The ASM V instrument is an upgrade of the ASM-IV which was primarily developed for high resolution measurements at the bottom of the seabed (ocean/river locations). It records the suspended particle matter. It provides an independent contribution to the complex questions which arise from the context of transport of solids.


The instrument operates with backscatter infrared sensors (850 nm) embedded in a stainless steel rod. The sensors are placed on an active board at a distance of 10 mm. This means that 100 sensor pairs (emitter and receiver) are mounted per meter.


Each sensor pair consists of an infrared high power led transmitter and a photo detector. The detection angle is between 10 and 180°. A light stop will reduce ambient light impacts. The volume depends on the density of the suspension. The measuring distance range is 0…100 mm in front of each individual sensor..


Optical day light filters prevent interference by other light sources. This makes the instrument suitable for locations like tidal areas with dry periods.


As the ASM-IV, ASM-V consists of an inclinometer for two directions. It will give the actual angle between ground and instrument. The maximum range is 60° in all directions. The calculation is processed on board by the internal processor.


A pressure gauge senses the actual depth of the location of the instrument and it gives information about sedimentation’s during the turn of the tide.


A on board temperature sensor detects the temperature of the steel housing which is related to the water temperature.


Activation and power supply of the sensors as well as the transmission of the signals are controlled by a battery powered central unit in the head of the instrument. The sealed in unit consists of a microprocessor, a data memory, the additional sensors and the energy supply. The energy consumption is only < 6mAs. That means one 9V block alkaline battery (lithium will double the duration time) will provide the necessary energy for 2 months, assuming a sample rate of 10 measurements every 5 minutes, or the energy for a standby status of approx. 6 months at the sample rates stated above.


A microprocessor carries out all of the tasks necessary for control. Incoming data is processed by the microprocessor and stored in memory. The capacity of 8 MB will provide a measuring time of approx. 4 weeks in total, without weakening the battery (10min sampling time). The ASM-V is a Stand Alone unit.




To communicate with the instrument an optical IRDA- USB port and a hard wire RS485 connector (subconn) is integrated in the housing head. All communications can be done without opening the instrument.


For communication, a standard PC or laptop with USB ports and ASMA4.XX© software must be installed. Once the communication unit is plugged into the USB port of the computer and is placed on top of the instrument, or connected hard wired a communication table appears on the screen.


The Controller section


The titanium stainless (stainless steel) head contains the inclinometer, the temperature sensor and the pressure sensor as well as the microcontroller, the memory and the energy supply. On the top end of the housing the optical communication window is visible. The diameter of the head is 60 mm. The rod part with the embedded sensor electronics is 30 mm in diameter. These dimensions make the instrument suitable for the most measuring sites specially in fast running rivers.


The Sensor array


The sensor electronic board is only mm wide and 9 mm high and is fitted in the titanium rod (stainless steel on request). The optical sensors are covered by a black ABS optic filled with daylight epoxy filters. The back of one pcb element carries control circuits and a 16 channel analog multiplexer. The channel multiply with no. elements connected to each other. One board measures 160mm in length. The boards will be stacked together and embedded in a flexible polyurethane casting resin. This prevents the board from breaking, if the rod gets bent e.g. fast running rivers



  • Measuring section: 0.96 m (Type S), 1.44 m (Type N), 1.92 m (Type L)
  • Measuring intervals: 1 sec. ….no limit
  • Sampling rate: 1 … 255 samples per burst
  • Memory capacity: 8 MB standard
  • Energy supply:
    • Main supply: one alkaline 9V block battery minimum, two lithium 9 V block battery for maximum energy source
    • Memory backup: gold cap rechargeable battery
  • Standard lengths of the instrument: 1.9 m (Type S), 2.4 m (Type N), 2.9 m (Type L)
  • Dimension of the instrument:
    • Sensor area: 30 mm (Type –S, -N), 35mm (Type –L) diameter
    • Head: 60mm (diameter)
  • Weight: 4.5 kg (Type -S), 5.5 kg (Type -N), 7.5 kg (Type –L)
  • Ambient temperature: -15…+45°C
  • Installation depth: 40 m water depth max.
  • Distances: First OBS sensor up => Pressure sensor : 190 mm


  • Measuring method: optical
  • Sensors: high power ir-emitter (850nm), Ir-photo diode 850nm optimal sensitivity
  • Sensor distance: 10 mm
  • Number of sensors: 100 per meter
  • Measuring range:
    • 50..10,000 mg/l sand (d50=250µm)
    • 5…3,000 mg/l mud (d50=20µm)
    • 0…1000 FTU (standard formazin)
  • Resolution: 1FTU
  • Accuracy: +/-10%


  • Measuring method: gravimetric
  • Sensors: 2-D integrated circuit
  • Measuring range: 0…60° all directions
  • Resolution:
  • Accuracy: +/- 1°

Water depth

  • Measuring method: piezoelectric
  • Sensor: stainless steel pressure housing & membrane
  • Measuring range: 0…5,000 hPa abs. other ranges on request
  • Resolution: 0.5%
  • Accuracy: +/- 0.3% (full range)


  • Measuring method: resitive
  • Sensor: silicon integrated circuit
  • Measuring range: -10…45 °C
  • Resolution: 0.5°C
  • Accuracy: +/- 0.5°C

Related Projects

Sorry, no posts matched your criteria.