[EST] Frenzel Q&A - Chapter 2: Amplitude Modulation and Single-Sideband Modulation

Modulation

Having an information signal change some characteristic of a carrier signal is called __________.

The carrier frequency changes

Which of the following is not true about AM?

Demodulation

The opposite of modulation is __________.

Demodulator

The circuit used to produce modulation is called a __________.

Multiplication

A modulator circuit performs what mathematical operation on its two inputs?

The modulation index

The ratio of the peak modulating signal voltage to the peak carrier voltage is referred to as __________.

Information signal is distorted

If m is greater than 1, what happens?

m = 1

For ideal AM, which of the following is true?

Envelope

The outline of the peaks of a carrier has the shape of the modulating signal and is called the __________.

Vm > Vc

Overmodulation occurs when __________.

80.6 %

The values of Vmax and Vmin as read from an AM wave on an oscilloscope are 2.8 and 0.3. The percentage of modulation is __________.

Sidebands

The new signals produced by modulation are called __________.

876.5 and 883.5 kHz

A carrier of 880 kHz is modulated by a 3.5 kHz sine wave. The LSB and USB are, respectively, __________.

Frequency domain

A display of signal amplitude versus frequency is called the __________.

Carrier

Most of the power in an AM signal is the __________.

1.6 W

An AM signal has a carrier power of 5 W. The percentage of modulation is 80 percent. The total sideband power is __________.

25 percent

For 100 percent modulation, what percentage of power is in each sideband?

85 W

An AM transmitter has a percentage of modulation of 88. The carrier power is 440 W. The power in one sideband is __________.

70 percent

An AM transmiiter antenna current is measured with no modulation and found to be 2.6 A. With modulation, the current rises to 2.9 A. The percentage of modulation is __________.

507 W

What is the carrier power in the problem above if the antenna resistance is 75 ohms?

Sidebands

In an AM signal, the transmitted information is contained within the __________.

DSB

An AM signal without the carrier is called a(n) __________.

One sideband

What is the minimum AM signal needed to transmit information?

Less spectrum space is used

The main advantage of SSB over standard AM or DSB is __________.

Neither upper or lower

In SSB, which sideband is the best to use?

300 Hz to 3 kHz

The typical audio modulating frequency range used in radio and telephone communications is __________.

9 kHz

An AM signal with a maximum modulating signal frequency of 4.5 kHz has a total bandwidth of __________.

Bandwidth

Distortion of the modulating signal produces harmonics which cause an increase in the signal __________.

Frequency conversion

The process of translating a signal, with or without modulation, to a higher or lower frequency for processing is called __________.

Converter

Frequency translation is carried out by a circuit called a __________.

3.2 MHz

An input signal of 1.8 MHz is mixed with a local oscillation of 5 MHz. A filter selects the difference signal. The output is __________.

3.85, 3.8485, and 3.8515 MHz

The output of an SSB transmitter with a 3.85 MHz carrier and a 1.5 kHz sine wave modulating tone is __________.

384.5 W

Problem Solving: An SSB transmitter produces a 400 V peak-to-peak signal across a 52 ohms antenna load. The PEP output is __________.

Peak envelope power

The output power of an SSB transmitter is usually expressed in terms of __________.

250 to 333 W

Problem Solving: An SSB transmitter has a PEP rating of 1 kW. The average output power is in the range of __________.