The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 14, 2014
Filed:
Jun. 17, 2009
Martin Thompson, Cambridgeshire, GB;
Mark Francis Lucien Harper, Cambridgeshire, GB;
Martin Thompson, Cambridgeshire, GB;
Mark Francis Lucien Harper, Cambridgeshire, GB;
BP Exploration Operating Company Limited, Middlesex, GB;
Abstract
A low frequency sound source has a radiating piston () of the order of a few meters across backed by a gas spring () containing a fixed mass of gas. The gas pressure in the spring is kept at levels for which the natural frequency of the piston () loaded by the fluid () lies in the seismic band and may be as low as 0.5 Hz. The piston () is given an initial displacement and begins to oscillate. Its oscillations are sustained by an actuator () whose drive signal is derived from the velocity of the piston () via a velocity or displacement sensor. The sound source is caused to perform a frequency sweep by gradually compressing the gas in the gas spring () so that the spring becomes stiffer both because of the rising pressure and because of the reducing length of the gas spring spaces (). This double effect allows large changes in stiffness to be produced and hence allows the source to operate over at least three octaves of frequency.