The hydrophone string BHC4 is used to receive P-waves in water filled boreholes. The BHC4 consists of a downhole cable containing a Kevlar tension string and a number of moulded hydrophones at pre-defined intervals. Each hydrophone consists of a sensor with a pre-amplification board. The electronic boards are powered from the surface by a bank of rechargeable AA cells. The cable is terminated by a connector to the seismograph.
The standard cable length is 123 m with a hydrophone spacing of 1m (other on request).
Hydrophone sensor: SQ54 or AQ2000
Frequency response: Flat from 1 to 10.000 Hz
Pre-Amplification: 4 or 10 x
Power supply: AA cells (battery box on surface)
Operational depth: Up to 500 m
Number of hydrophones: 24 (others on request)
Hydrophone interval: 1 m (others on request)
Hydrophone diameter: 38 mm
Cable weight per metre: 200 g
Cable strength: 4700 N
Borehole diameter: Min. 50 mm
Depth indicator: Cable marking every 2 m
Connector: To any seismograph
Storage: On drum