Dynamic Range
a method of describing the extent to which a signal can vary and still be processed
Dynamic range general rule
the dynamic range of information decreases the more it is processed
transducer dynamic range
120 dB
receiver dynamic range
100 to 120 dB
scan converter dynamic range
40 to 50 dB
display dynamic range
20 to 30 dB
archive dynamic range
10 to 30 dB
How to calculate a component's dynamic range
1. divide the bigger voltage by the smaller voltage
2. count the # of zeros in the number - for each zero there is 20 dB more dynamic range
dynamic range
10:1
20 dB
dynamic range
100:1
40 dB
dynamic range
1,000:1
60 dB
dynamic range
10,000:1
80 dB
dynamic range
100,000:1
100 dB
A range from 1 volt to 100 volts can be processed accurately by the display of an ultrasound system. What is the dynamic range of the display?
40 dB
A component of an ultrasound system can properly process voltages ranging from 1 mV to 1 V. What is the dynamic range?
60 dB
A component of an ultrasound system can properly process voltages ranging from 5 V to 5000 V. What is the dynamic range?
60 dB
The same mathematics technique is used to calculate the gain of a component when the signal has units of volts.
An amplifier increases a voltage from .2 to 2000 volts. How many decibels of gain in this?
80 dB
An amplifier increases a voltage from 5 to 500 volts. How many decibels of gain is this?
40 dB
Compression
technique that reduces the dynamic range of a signal without introducing errors
requirements of compression
largest signal remains the largest
smallest signal remains the smallest
the range of signals is reduced
An uncompressed signal within the receiver of an ultrasound system has a dynamic range of 110 dB. The signal undergoes 40 dB of compression. What is the dynamic range of the compressed signal?
70 dB
110 dB - 40 dB = 70 dB
An uncompressed signal has a dynamic range of 85 dB. The signal undergoes 30 dB of compression. What is the dynamic range of the compressed signal?
55 dB
85 dB - 30 dB = 55 dB
After compression, a signal within the ultrasound system has dynamic range of 70 dB. The original signal was compressed by 40 dB. What is the dynamic tange of the original, uncompressed signal?
110 dB
70 dB + 40 dB = 110 dB
A signal within the system's receiver has a dynamic range of 60 dB after compression. The original signal was compressed by 50 dB. What is the dynamic range of the original uncompressed signal
110 dB
60 dB + 50 dB = 110 dB
number of choices
dynamic range can report the number of possible gray shades.
Narrow dynamic
fewer gray shades
few choices
black and white (bistable)
high contrast
Wide dynamic range
fewer gray shades
many choices
grayscale
low contrast