Data Acquisition and Auto Lab Report

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Analog Signals

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Analog Signals

• We use analog devices to measure change in physical phenomenon such as light, sound, etc.

• Even in digital systems, measurements are usually analog

• ADC converts the analog signals to digital

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Analog Signals

• Varying voltage levels

• Continuous signal

• Can be DC or AC

• Most transducers are analog

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Analog vs Digital

• Analog • Continuous

• Infinite range of values

• More accurate

• Difficult to work with

• Digital • Discrete

• Finite range of values

• Not as exact

• Easier to work with

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Examples of Analog Signals

• Time varying

• Positive or negative

• Periodic (repeating)

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Main Characteristics of Analog Signals

1. Amplitude: the difference from the peak of the signal to a reference ground. Can be referred to in Volts or Decibels.

Examples:

Sound Level (db) Sound Example

60 Normal speech

70 Students complaining about grades

120 Shotgun Blast

130 Jet Engine at take off

140+ Heavy Metal Concert

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Main Characteristics of Analog Signals 2. Frequency: the rate of change in the signal per second

• Frequency (f) is expressed in Hertz (Hz)

• Sometimes we use the period of an analog signal

• The period (τ ) is expressed in Seconds (s)

• τ = 1

𝑓

• Example: a 50 Hz signal changes 50 times every second and has a period of 0.02 s

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Main Characteristics of Analog Signals 3. Phase: the rate at which the signal changes in relation to time

• If a cycle begins at one point • It should continue until the same point is reached again • Phase shift occurs when the cycle is not completed • i.e. a new cycle begins before the old one is completed • Expressed in Degrees

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Analog Signals

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Analog C-Series Modules

NI 9263 & 9265 – Analog Output NI 9207– Analog Input NI 9923 – Terminal Block

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NI 9263 – Analog Voltage Output

• 4 Channels

• Voltage Output

• Range: ± 10 V

• 16-bit resolution

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NI 9265 – Analog Current Output

• 4 Channels

• Current Output

• Max 20 mA

• 16-bit resolution

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NI 9207 – Voltage & Current Input

• 16 Channels • 8 Voltage Input, Range: ± 10V

• 8 Current Input, Range: ± 20 mA

• 24-bit resolution

• 500 samples/second

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NI N9207 & 9923 Modules

1. Mount the NI 9923 Module onto NI 9207

2. Check the ports you need on the NI 9207

3. Check where these ports are on the NI 9923 module and connect your devices

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Piezoelectric Buzzers • Made of piezo electric element (crystal or

ceramic)

• Deforms slightly when a voltage is applied to it

• Applying an AC signal causes it to deform

• It deforms back and forth at the same frequency as the AC Signal

• This produces an audible sound

• In reverse, deforming the piezo generates a voltage

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Lab Sheet 4 – Analog I/O • What you will learn

• Using AIO modules with cDAQ • Analog signals in LabVIEW • Signal manipulation in LabVIEW • Random Numbers in LabVIEW

• You will create applications that: • Produce different kinds of AC signals • Control the sound produced by a buzzer • Alternate the buzzer output to create a Siren • Monitors a voltage level