Unit 4

• What is operating principle one composed of 


  Beam former
• What is operating principle one composed of

  Beam former

  Signal processor

  image processor

  display
• What is the beam former 


  Where action begins
• what is the beam former made of 


  pulser

  pulse delays

  transmit/receive switch

  amplifiers

  analog-to-digital converter

  echo delays

  summer
• What is the pulser


  Produces electrical voltages that excite the transducers PZT
• what does the frequency of the voltage pulse determine 


  the frequency of the resulting ultrasound pulse
• what does voltage equal 


  amplitude and intensity of ultrasound pulse
• how does the pulser avoid misplacement 


  the echoes from one pulse must be received before the next pulse is emitted
• what tasks do the pulser and pulse delays carry out 


  sequencing

  phase delays

  variations in pulse amplitudes
• what is a channel 


  independent signal path made up of a transducer element, delay and other electronic components
• what is apodization 


  reduces side lobes of an image
• how is apodization accomplished 


  with pulser and pulse delays
• what reduces the appearance of grating lobes 


  pulse delays
• what is transmit/receive switch 


  protects the input components of the amplifiers format he large driving voltages from the pulser
• what does the T/R switch do during transmission 


  opens the path from the pulser to the transducer elements
• what does the T/R switch during reception 


  opens the path from the elements to the reception amplifiers
• What does an increased number of channels allow 


  More precise control of beam characteristics
• what do the modern sonography systems consists of 


  64

  128

  192
• what does the amplifier do 


  increase voltage amplitude
• how many amplifiers does a beam former have 


  one for each channel
• what does the amplifier function with 


  reception
• what is gain 


  ration of amplifier output to electric power input
• What are two useful decibel values 


  3dB

  10dB
• what is output 


  how much energy is put out
• What is time gain compensation 


  Compensates for the effect of attenuation on an image
• What does attenuation and maximum amplifier gain determine 


  Maximum imaging depth
• what is maximum amplifier gain determined by 


  noise
• what is another name for analog to digital converters 


  digitizers
• what does the analog to digital converters do 


  convert the analog voltages representing echoes to numbers for digital signal processing and storage
• when echo voltages are digitized what are they replaced with 


  numbers
• what is echo delays 


  echoes pass through delays to accomplish reception dynamic focus and steering
• what is summer

  after delays

  they are added together to produce the resulting scan line and send it to signal processor
• what does the signal processor receive from the beam former 


  digital signals
• where does the signal processor send the digital signal after it’s done processing 


  image processor
• what are the functions of the signal processor 


  filter

  amplitude detection

  compression
• What does filtering do during signal processing 


  Reduces noise
• what does amplitude detection do 


  converts echo voltages to video form

  retains amplitude data
• what does compression do during signal processing 


  controls dynamic range
• what is dynamic range 


  number of shades of gray
• what does a smaller dynamic range equal 


  more contrast on the image