instruments Flashcards
a returning echo is what kind of wave?
mechanical wave
- at the transducer, it is converted to an electrical wave
power ratio =??
gain (dB)
gain=?
output power/ input power
input electrical power is 20 W;
output electrical power is 200 W
What is the power ratio?
10x
what is amplification the opposite of?
attenuation
If you can calculate voltage ratio, you can find out power ratio. What is the ratio?
(VOLTAGE ratio)2 = (POWER ratio)
Amplifiers allow for? (2)
- amplification (gain)
- compensation (TGC/LGC)
TGC= ?
time gain compensation
aka depth gain compensation
TGC ‘slope’ = ?
1 dB/cm∙MHz
aplification max?
100 dB
Lateral gain compensation is used for?
For adjacent structures that have different attenuation
Drawback to amplification?
- amplifies noise
Summer function?
- Signals added together as a ‘scan line’
- Also involved in reception apodization
- reducing the returning voltages on the peripheral of the transducer
If gain is 30 dB and output power is reduced by one half, the new gain is __________ dB.
27
reception channel of beam former function?
amplifies and combines the echo voltages from individual elements and sends them to signal processor
signal processor functions (3)
- filtering
- detection
- compression
pulsed wave ultrasound produces a ________ of transmitted frequencies?
bandwidth
rage of frequencies contained in a pulse?
bandwidth
signal processor- filtering?
- passes range of frequencies
- rejects those above and below the bandwidth
filtering is done with?
bandpass filters
filtering is done with?
bandpass filters
modification of the sinusoidal waveform as it propagates through the tissue is known as?
harmonics
filters in signal processor perform what function?
harmonics function
at the signal processor what is filtered out?
fundamental frequency
- happens when we press THI
