A small aperture seismic group consists of three-component seismic receivers which are located at a distance comparable to the wavelength of the studied signal. Such systems are successfully used in seismology to locate weak signals from remote sources.
R-sensors’ engineers have developed products providing the construction of ocean-bottom small aperture groups with high technical characteristics.
The typical structure is given at the figure.
An ocean-bottom station is the base of the group. The station consists of the CME-6011ND digital broadband seismometer and the MTAS-30 broadband hydrophone. Each station is connected to an onshore communication module through a cable.
The cable provides power supply, data transfer and synchronization of the station’s internal clocks with GNSS. RS-485 is an interface of the data exchange which ensures data transfer to a distance of up to 1,200 m. Optionally, fibre-optic lines to transfer data farther than 1,200 m can be used. The SeedLink standard protocol is used to further data transfer.
The onshore communication module consists of the NDAS-RT digital module and a power source. Extra network equipment can be set up depending on the network configuration.
Characteristics Delivery and warranty
|Frequency range||0.033 Hz (30 sec) - 50 Hz|
|Sensitivity||2000 V / (m/sec)|
|Clip level||±7.5 mm/sec|
|Self noise at 1 Hz||2.5 nm/sec|
|Dynamic range||127 dB|
|Supply voltage||5-12 V Nominal (4-17 V permissible)|
|Power consumption||300 mW|
|Temperature range||-20°C - +85°C - standard SD-card|
|ADC sampling rate||1, 10, 50, 100, 125, 250, 500, 1000 Hz|
|ADC resolution||24 bit|
|Hydrophone sensitivity||1000 µV/Pa|
|Hydrophone frequency range||0.033 Hz - 50 Hz|
|Hydrophone self-noise in the bandwidth||0.01 Pa|