electronic signal

analog signals

Analog signals consist of continuously changing voltage in an electric circuit. The Figure 1.1 represents analog signals. These were the first electronic signals to be invented. They were used in early computers and other early electronic devices. Analog signals are subject to distortion and noise, so they arent used as often anymore. They are used mainly in microphones and some mobile phones to encode sounds as electronic signals.

electronic messages

Electric devices, such as lights and household appliances, change electric current to other forms of energy. For example, an electric stove changes electric current to thermal energy. Other common devices, such as mobile phones and computers, use electric current for another purpose: to encode information. A message encoded this way is called an electronic signal, and the use of electric current for this purpose is called electronics. To encode a message with electric current, the voltage is changed rapidly, over and over again. Voltage is a difference in electric potential energy that is needed in order for electric current to flow. There are two different ways voltage can be changed, resulting in two different types of electronic signals, called analog signals and digital signals.

digital signals

Today, most electronic signals are digital signals. Digital signals consist of rapid pulses of voltage that repeatedly switch the current off and on. The Figure 1.2 represents digital signals. This type of signal encodes information as a string of 0s (current off) and 1s (current on). This is called a binary (two-digit) code. The majority of modern electronic devices, including computers and many mobile phones, encode data as digital signals. Compared with analog signals, digital signals are easier to transmit and more accurate.

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textbook_image

instructional diagrams

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questions

voltage is a difference in electric potential energy.

-->  a. true

b. false

an electronic signal with continuously changing voltage is a digital signal.

a. true

-->  b. false

an electronic signal with voltage that repeatedly turns on and off is an analog signal.

a. true

-->  b. false

which of the following statements about analog signals is false?

a) they were the first electronic signals invented.

b) they are subject to noise.

-->  c) they are still the most commonly used electronic signals.

d) none of the above

which of the following statements about digital signals is true?

a) they are subject to distortion.

b) they are more difficult to transmit than analog signals.

c) they are less accurate than analog signals.

-->  d) none of the above

diagram questions

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