week 5 Flashcards
how do you convert decimal no. (base 10) to binary no (base 2)?
Decimal numbers (base 10) can be converted to Binary numbers (base 2) by simply dividing the decimal number successively by 2
What happens if there is a remainder for decimal to binary conversion?
If there is a remainder, the digit is 1 and no remainder the division result is 0
How do you convert binary to decimal?
Binary numbers are converted to decimal by multiplying each bit (0 or 1) by the
corresponding power of 2 and then adding the results together
What is the low state of logic gates?
the low state is approximately zero volts (0 V)
What is the high state of logic gates?
high state is approximately five volts positive (+5V)
What is a NOT gate?
• NOT gate will make the output LOW if the input is HIGH or vice versa and
hence called an Inverter
For a NOT gate when the input is high the output is??
Low
What is an AND gate
AND gate will make the output HIGH ONLY if all inputs are HIGH. All
other input combinations will make the output LOW
What is an OR gate?
OR gate will make the output HIGH if any of the inputs is HIGH
What is an NAND gate?
NAND gate is the reverse of an AND gate. It will make the output LOW ONLY if
all inputs are HIGH. All other input combinations will make the output HIGH
What is a NOR gate?
NOR gate is the reverse of an OR gate. It will make the output high ONLY if all
inputs are LOW.
What is the EX-OR gate?
EX-OR gate will make the output HIGH if ONLY ONE of the inputs is
HIGH.
What are physical quantities?
Physical quantities such as temperature, pressure, stress, flow and displacement can be
measured using sensors. The sensors convert the change in the physical quantity into a
corresponding change in an electrical quantity
What is signal conditioning?
Signal conditioning transforms the sensor output to an appropriate form
What is the data acquisition system?
The conditioned signals are sent to the data acquisition system that periodically samples the
signal and converts to digital using an analog to digital converter (ADC)
What is the process of the computer-based instrumentation system (CBIS)?
Physical system
CBIS
(
Sensor
Signal conditioning
Data acquistion
{
Sampling
A/D conversion
}
)
General purpose computingWhat are sensors?
Sensor, also called a transducer, converts the physical variable to an
electrical variable
What is an 2 examples for physical sensor?
Pressure sensor
Temperature sensor
Acoustic sensor
What are some applications of pressure sensors? (4)
measure the fuel pressure during fuel pumping
measure the tire pressure in vehicle tires
measure the air pressure outside an aircraft (using an aneroid barometer)
measure blood pressure using a small sensor penetrated into blood vessels
What is a pressure sensor
responds to the pressure applied to its sensing surface and
converts to an electrical signal
What is a temperature sensor?
responds to the temperature and converts to an electrical
signal
What are applications of temperature sensors? (3)
measure the air temperature to control the air conditioning and heating systems
measure the temperature inside the case of an computer to turn on the fan
measure the food temperature in transport and storage in order to minimise the harmful bacterial growth
What is an acoustic sensor?
converts to the sound energy into electrical energy
What are applications of acoustic sensors? (2)
These sensors help offshore exploration, reduce the impact of tsunami, aid in
navigation etc.
Used in avalanche warning and research
What are two most important signal conditioning functions?
amplification and filtering
What is signal amplification?
Signal amplification increases the power of the signal received from the
sensor
What is filtering?
Sensor signals may consist of interference from noise or undesired output.
Filtering of the output signal from the sensor is carried out to eliminate such
noise effects
What is data acquisition?
Data acquisition is the process that converts the conditioned signals in to
digital numeric values that can be manipulated by a computer
What does a data acquisition system consist of?
Data acquisition systems consist of an analog multiplexer (MUX), a buffer, a
sample/hold amplifier and an ADC
What is a multiplexer (MUX)?
The channel to be monitored is selected and applied to a sampler
What does the multiplexer do in the data acquisition system? (3)
The operational amplifier reduces the impact that two parts of a system may have on
each other
The sampled output is converted to digital using the multiplexer that is controlled by
the control circuit, which simultaneously triggers the sampling circuit and the ADC
The multiplexer then selects the next channel after the ADC completes the conversion
and sends an appropriate signal to the control circuit
What are the two main steps in ADC (analog to digital conversion)?
(2)
Sampling – sampled at regular time intervals to generate a discrete-time
signal
Quantisation – the sampled signal is quantised and encoded in to a
binary signal
What is the Nyquist rate?
Sampling must be conducted at a rate higher than the
twice the highest frequency,
fH of the analog signal and
this rate is called the Nyquist rate, Fs greater than or equal to 2fH
If
Fs greater than 2fH, the reconstruction of the sample values
cannot match the original analog signal and aliasing will occur
As the number of quantisation levels increases…
the number of bits required to
represent those levels too increases
What is Resolution?
Resolution is defined as the maximum analog voltage range divided by the number of
quantisation intervals, (2n - 1) = (L-1)
