title: A Sub-Nyquist, Variable Sampling, High-Frequency Phased Array Beamformer.
abstract: A digital receive beamformer implementing a "one sample per pixel" variable sampling technique is described. The sampling method reduces the required sampling rates by a factor of 3, and reduces the data capture rate by a factor of 2, in comparison with the previous systems based on variable sampling. The sampling method is capable of estimating broadband pulse envelopes accurate for bandwidths up to 83.0%. This beamforming method has been implemented on a field-programmable gate array with maximum transmit and receive delay errors measured to be less than ±1.0 ns. The beamformer was tested and verified on a previously described 45-MHz 64-element phased array. The system generates images with 128 lines, 512 pixels per RF line, and 2 transmit focal zones. The system generates images with approximately 55 dB of dynamic range and was tested by imaging wire targets submersed in a water bath, wire targets embedded in a tissue phantom, and real-time in vivo imaging of a human wrist.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Samson
authors.forename: Andre
authors.initials: A
authors.lastname: Bezanson
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Brown
mesh_terms: D000818:Animals; D007758:Ear, Inner / Q000000981:diagnostic imaging; D006168:Guinea Pigs; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted; D014463:Ultrasonography / Q000379:methods*; D014953:Wrist / Q000000981:diagnostic imaging