The "brain".

Organizes and times the functions of the individual components in order to operate as a single intergrated system.

Output gain

Acoustic power

Pulser power

Energy output

Transmitter Output

Power or Gain

1. Functions during transmission.
2. Creates electrical signals to stimulate the PZT.
3. Determines PRF, PRP, & Amplitude.
4. Can adjust power, amplitude, & intensity.
5. Creates firing pattern for phased array systems (beamformer).

1. Only in phased arrays due to multiple crystals.
2. Determines firing pattern of the crystals.
3. Apodization during transmission & Dynamic Aperture during receiving.

Transmit/Receive Switch

(Beam Former Switch)

"Surge Protector"

Switches back and forth during transmission and receiving to protect the system.

High voltage = transmit

Low voltage = receive

Channels

(Most systems have 32-356 channels)

Transmission: changes voltage to sound.

Reception: changes sound to voltage.

Made up of several crystals, the beam former/pulser, and the wires that connect them.

# of crystals = # of wires

1. Amplification
2. Compensation
3. Compression
4. Demodulation
5. Rejection

Amplification _(dB)

(Receiver Gain)

1. Increases the entire screen equally.
2. Entire image is made brighter or darker by the sonographer.
3. No bioeffects because it's receiving.
4. 2-D button on machine.

Compensation _(dB)

(TGCs, DGCs, Swept Gain)

The sonographer can create an image that is uniformly bright from top to bottom.

Compensates for attenuation.

1. Near Gain: superficial depth, little compensation
2. Delay: variable amount of compensation
3. Slope: region of increasing compensation
4. Knee: depth of maximum compensation
5. Far Gain: maximum compensation the receiver can provide
   

Compression _(dB)

(Dynamic Range or Log Compression)

• Keeps the gray scale image within the range of view for the human eye.
• Keeps the signal levels in the accuracy range of the system.

A 2 part process that changes return signals to signals more appropriate for the CRT.

Rectification:  eleminates or converts all negative volts to positive volts.

Smoothing or Enveloping:  sends individual signals in one package. Smoothes the "bumps" of multiple volts.

Reject

(Threshold or Suppression)

Controls the number of low level echoes.

Reject = Internal

Threshold/Suppression = External

Output Power: Modifies the brightness.  Bioeffects concern.

Receiver Gain (Amplification):  Alters the strength of the returning echoes in the receiver.

Both sonographer controlled.

1. Transducer
2. Pulser/Beam Former
3. Receiver
4. Display
5. Storage
6. Master Synchronizer

An error in imaging.

A misrepresentation of data on the display.