Method for adaptively filtering doppler signals using a complex time domain filter

US5445156A · kind A · utility

Assignee

• General Electric Company · US

Inventors

• Christopher DAFT · Pleasanton, US
• Anne Lindsay Hall · New Berlin, US
• Sharbel E. Noujaim · Clifton Park, US
• Lewis J. Thomas, III · Palo Alto, US
• Kenneth Brakeley Welles, II · Scotia, US

Key dates

• Filing date: Nov 2, 1994
• Grant date: Aug 29, 1995
• Expiry date: Nov 2, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S7/52033
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A time domain technique for implementing an adaptive wall filter improves imaging of low-velocity blood flow by removing signals associated with slowly moving tissue. Adaptive wall filtering is performed by estimating wall velocity and bandwidth, and then filtering the basebanded data with a complex time domain notch filter. The wall velocity estimate determines the center frequency of a wall signal while the wall variance estimate determines the wall signal bandwidth. The complex filter coefficients selected are those which will center the complex notch filter on the wall center frequency, and which will set the filter cutoff frequencies (measured from this center frequency) to match the wall signal bandwidth.