Ocean-bottom small aperture group OBAG-8224-RT

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

Availability on request
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