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have 10 equally spaced hydrophones. This VHS is not self contained and
would have to be cable-linked to the moored and stationery Salmaster,
either directly or via mooring buoys. This cable would carry the VHS
signals to its own recorder on board the Salmaster. This recorder on the
Salmaster would also be required to record accurate MSF radio time.
It is necessary to know the accurate time at which detonation occurred,
therefore the times of explosions were to be recorded on Goosander, using
hydrophone and geophone detectors, with signals going onto a recorder in
parallel with MSF radio time. In order to ensure that accurate shot
instants would be obtained, radio time from two different transmitters
(MSF and DCF), would be recorded. Additionally, near-field observations
of the shock waves were to be obtained using pressure gauges deployed by
the Goosander at its chosen stand-off position for detonating the charges.
Instrument gain and sensitivity settings depended on estimates of
pressure and impulses from the water pressure and expected seismic ground
displacements, velocities and accelerations. These estimates are
described in section 2.5.
All the sea bottom packages were to be located on
circle, the shore-shot line shown in Fig 2.2, with
distances from the 2 ton shot point as given in Table 2.1.
the same great
the spacings and
Increasing spacing with distance between the sea bottom packages was
chosen, rather than equal spacing, because of the expected 1/r n signal
decay with distance. The proposed positions for PUSSes and other offshore
equipment are given in Table 2.2. Water depths were read from Admiralty
Charts.
The exact position of each package would need to be located using
GoosanderlSalmaster navigational devices. Accuracy to better than 20 m is
desirable. Syledis and QUBIT Trac-IV navigational aids were chosen for
temporary installation on Salmaster to achieve this accuracy.
The 2 ton explosive charge would be deployed by the Goosander at about
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