Lecture 3 Flashcards
Transmit/recieve switch
Involve transmission channel and reception channel
Prevents incorrect direction of signal
Acts as a traffic cop
Which beam is stronger, the beam sent out or the echo that comes back
The beam sent out
Are the amplifiers normally receiving a strong signal or a weak one
Weak one
Why is it importnatnt that the reciever recieves a weak signal
A stronger voltafe from the pulser/ pulse delays results in overload of the amplifier
Transmit/recieve switch thus protects
The amplifiers from the outgoing voltage
Returning echo is a ____ wave
Mechanical
At the transducer the mechanical wave is converted to
Electrical signal
The electrical signal converted in th e transducer travels to
The amplifiers
Amplifiers (power) ratio
Amplified output power/ input electrical power
Power ratio =
GAIN (dB)
Or
Output/input = gain
Applification is opposite of
Attenuation
What are amplifiers used for
To counteract our attenuation
What setting on our machine are amplifiers involved with
Gain/TGC
Each channel has
An amp that amplifies the voltage
Voltage ratio
(Output/input)^2 = Power ratio
what do amplifiers do
Amplify the signal that returns from the tissue
Amplifiers allow for (2)
Amplification (GAIN)
Compensation (TGC/LGC)
What does compensation mean
Simply amplification at specific depths
TGC slope
1 dB/cm MHz
Max amplifier dB
100dB
What is lateral gain compensation for
Adjacent structures that have different attenuation
What is the drawback to amplification
Amplify noise
Weaker echoes from the electric current
Results in grainer signal
Analog-digital converters aka
Digitizers
Analog-digital converters do what
Converts to binary
Interrogates voltages and gives a digital value
What are echo delays the same as, and whats the difference
Same as pulse delays
These are digital delay lines now
WHAT DO ECHO DELAYS Allow for
Reception focus and steering
Listen from a certain depth/direction
Summer aka
Adder
What does the summe do
Signals added together as a scan line
Summer also involved in
Reception apodization
Which means it is reducing the returning voltages on the peripheral of the transducer
