title: Time-delay spectrometry measurement of magnitude and phase of hydrophone response.
abstract: A method based on time-delay spectrometry (TDS) was developed for measuring both magnitude and phase response of a hydrophone. The method was tested on several types of hydrophones used in medical ultrasound exposimetry over the range from 5 to 18 MHz. These included polyvinylidene fluoride (PVDF) spot-poled membrane, needle, and capsule designs. One needle hydrophone was designed for high-intensity focused ultrasound (HIFU) applications. The average reproducibility (after repositioning the hydrophone) of the phase measurement was 2.4°. The minimum-phase model, which implies that the phase response is equal to the inverse Hilbert transform of the natural logarithm of the magnitude response, was tested with TDS hydrophone data. Direct TDS-based measurements of hydrophone phase responses agreed well with calculations based on the minimum-phase model, with rms differences of 1.76° (PVDF spot-poled membrane hydrophone), 3.10° (PVDF capsule hydrophone), 3.43° (PVDF needle hydrophone), and 3.36° (ceramic needle hydrophone) over the range from 5 to 18 MHz. Therefore, phase responses for several types of hydrophones may be inferred from measurements of their magnitude responses. Calculation of phase response based on magnitude response using the minimumphase model is a relatively simple and practical alternative to direct measurement of phase.
authors.affiliation: US Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, MD, USA. keith.wear@fda.hhs.gov
authors.forename: Keith A
authors.initials: KA
authors.lastname: Wear
authors.forename: Paul M
authors.initials: PM
authors.lastname: Gammell
authors.forename: Subha
authors.initials: S
authors.lastname: Maruvada
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Liu
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Harris
mesh_terms: D000465:Algorithms; D019544:Equipment Failure Analysis / Q000379:methods*; D013057:Spectrum Analysis / Q000379:methods*; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods*
references.citation: Ultrason Imaging. 1984 Jan;6(1):24-36
references.pmid: 6548058
references.citation: Ultrasonics. 1989 Jan;27(1):31-8
references.pmid: 2643838
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 1988;35(2):168-74
references.pmid: 18290143
references.citation: Ultrasonics. 2004 Apr;42(1-9):349-53
references.pmid: 15047310
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 1988;35(2):185-205
references.pmid: 18290145
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 2003 Mar;50(3):344-8
references.pmid: 12699169
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 2007 May;54(5):1036-44
references.pmid: 17523568
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 2005 May;52(5):717-36
references.pmid: 16048175
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Jan;55(1):84-93
references.pmid: 18334316
references.citation: Ultrasound Med Biol. 1974 Mar;1(2):119-31
references.pmid: 4428522
references.citation: Ultrasonics. 2009 Mar;49(3):306-11
references.pmid: 19110289