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:
Feb. 27, 2001
Filed:
Aug. 19, 1999
Daniel T. MacLauchlan, Lynchburg, VA (US);
Charles B. Overby, Campbell County, VA (US);
McDermott Technology, Inc., New Orleans, LA (US);
Abstract
A transmitting and receiving switch assembly for an electromagnetic acoustic transducer (EMAT) and a method for selectively switching an EMAT between transmit mode and receive mode both use a particular circuit. This circuit contains an EMAT coil coupled to a tuning capacitor, which allows the EMAT to be operated at a desired frequency when transmitting. A set of capacitors separates the EMAT coil from a set of diode strings (preferably containing at least one fast switching silicon diode), which are joined by a resistive connection. A transformer, which is center tapped at its primary winding, is coupled to the other end of the diode strings. Finally, a receiver input is connected to the transformer. In operation, the frequency of the EMAT is set by appropriately energizing and tuning the tuning capacitor. A voltage is then applied in the center tapped transformer and in the resistive link between the diode strings. The current automatically switches the conductivity of the diodes and permits the EMAT to switch modes as desired. Likewise, the method disclosed also utilizes this circuit, as described above, and involves several steps. First, the EMAT frequency must be selected and set, using the tuning capacitor. Then, a voltage is applied within the circuit to induce transmission by the EMAT. Next a sinusodial toneburst is given within the circuit to switch the transmit/receive capabilities of the EMAT, and then observing the input received by the EMAT-thereby permitting the alternate switching of the EMAT from receive to transmit mode in a matter of nanoseconds.