Lesson 3 (Part 1) Flashcards
What does the T/R switch involve? (2)
- Transmission channel
2. Reception channel
What does the T/R switch do? (2)
- Directs the returning echo voltage from the transducer to the amplifiers during reception
- Protects the sensitive inputs from the larger voltages
What does T/R prevent?
Incorrect direction of a signal
- acts as a traffic cop
Which is stronger, the beam going out or coming back?
The beam going out
What do amplifiers normally receive?
A weaker signal
- attenuated
What happens if the amplifier receives a stronger voltage from the pulser/pulse delay?
The amplifier gets overloaded
What does the T/R switch protect?
The amplifiers from the outgoing voltage
What happens to the voltage at the transducer?
The pulse is converted to an electrical signal
What gets sent to the amplifier?
The electrical signal that was converted from the pulse
What does an amplifier do?
It increases voltage amplitude
Amplification
Is the conversion of the smaller voltages received from the transducer elements to larger ones for storage
Gain
Is the ratio of the output of the amplifier to the electric power input
How is power ratio expressed?
In decibles
- dB
What is the formula for gain?
Gain = output power/inputpower
What is another term for gain?
Power ratio
What is power ratio equal to?
Power ratio = voltage ratio^2
What is amplification the opposite of?
Attenuation
- attenuation = -10
- amplification = +10
What is 3dB equal to in intensity?
2x
What is 10dB equal to in intensity?
10x
What is used to counteract attenuation?
Amplifiers
What are amplifiers involved with?
Gain/TGC
What does gain control determine?
How much amplification is accomplished by the amplifier
What happens if you have too little gain?
Weak echos are not expressed
What happens if you have too much gain?
Saturation occurs
- cant get proper readings
Why is the gain set?
So that echos appear with an appropriate brightness
What does each channel have?
An amp that amplifies the voltages
What can you figure out once you have voltage?
Power
- power ratio = voltage ratio^2
What do amplifiers allow for? (2)
- Amplification
2. Compensation
TGC
Time gain compensation
Time gain compensation
Equalizes the differences in the received echo amplitude arriving at the transducer if their travel distances are different
What is another word for time gain compensation?
Depth gain compensation
What happens to sound as you travel?
It gets weaker
What does TGC produce?
Uniform brightness throughout the image
How is TGC set?
By the operator
Compensation
Amplification at specific depths
