Login or Register for FREE!
Subelement H

Modulation

Section 58

SSB Modulation

In Figure 3H17, the block labeled 4 would indicate that this schematic is most likely a/an:

  • Audio amplifier.
  • Shipboard RADAR.
  • Correct Answer
    SSB radio transmitter.
  • Wireless LAN (local area network) computer.

In Figure 3H17, the block labeled 4 would indicate that this schematic is most likely a/an:

SSB radio transmitter.

The IF amplifier points to another mixer (Symbol 4). The 4 figure is another mixer, removing LSB and the carrier.

Symbol 1 is a local oscillator that controls the mixer (Symbol 3).

For more information, please see Electronics Notes for the article on RF Mixing / Multiplication: Frequency Mixers

Last edited by markadlerdallas. Register to edit

Tags: none

In Figure 3H17, which block diagram symbol (labeled 1 through 4) represents where audio intelligence is inserted?

  • 1
  • Correct Answer
    2
  • 3
  • 4

In Figure 3H17, which block diagram symbol (labeled 1 through 4) represents where audio intelligence is inserted?

2

The Symbol 2 adds audio to the oscillator waves in the Symbol 3 mixer.

Symbol 1 is a local oscillator that controls the mixer (Symbol 3).

The IF amplifier points to another mixer (Symbol 4).

Last edited by markadlerdallas. Register to edit

Tags: none

What kind of input signal could be used to test the amplitude linearity of a single-sideband phone transmitter while viewing the output on an oscilloscope?

  • Whistling in the microphone.
  • An audio frequency sine wave.
  • Correct Answer
    A two-tone audio-frequency sine wave.
  • An audio frequency square wave.

What kind of input signal could be used to test the amplitude linearity of a single-sideband phone transmitter while viewing the output on an oscilloscope?

A two-tone audio-frequency sine wave.

Two-tone tests can help determine whether the radio is able to pick up on each frequency. For full discussion of two-tone testing, please see Wikipedia's article on Two-tone testing


From kj6prf:

When testing for linearity in a radio system, we're making sure that our two signals are being added kind of like the first example, except with sines and cosines instead of a simple scalar value.

If our system is nonlinear, this will cause distortion and the resulting output will sound strange or behave unpredictably.

When you test for linearity, you are testing how two inputs are being added together and checking that the output is what you would expect it to be.

If a system is linear, it shouldn't matter if two inputs are scaled or added together before you input them into the system or after, the resulting output should be the same regardless. In nonlinear systems, things don't necessarily add together as you might expect.

EXAMPLE 1: As an example, the function y = 2x is linear. It doesn't matter if we take two inputs, say x=3 and x=4, and add first add them together and then perform the operation, or perform the operation twice and then add them together.

Symbolically, y = 2∗(3+4) = 2∗(7) = 14 as opposed to y = 2∗(3) + 2∗(4) = 6+8 = 14.

The order doesn't matter because this is a linear system.

EXAMPLE 2: Take as a counterexample, y = x2. In this case it matters whether the inputs are added before or after the operation because y = (3+4)2 = 49 but y = 32+42 = 25. This is a nonlinear relationship.

Last edited by markadlerdallas. Register to edit

Tags: none

What does a two-tone test illustrate on an oscilloscope?

  • Correct Answer
    Linearity of a SSB transmitter.
  • Frequency of the carrier phase shift.
  • Percentage of frequency modulation.
  • Sideband suppression.

What does a two-tone test illustrate on an oscilloscope?

Linearity of a SSB transmitter.

Two-tone tests can help determine whether the radio is able to pick up on each frequency. For full discussion of two-tone testing, please see Wikipedia's article on Two-tone testing


From kj6prf:

When testing for linearity in a radio system, we're making sure that our two signals are being added kind of like the first example, except with sines and cosines instead of a simple scalar value.

If our system is nonlinear, this will cause distortion and the resulting output will sound strange or behave unpredictably.

When you test for linearity, you are testing how two inputs are being added together and checking that the output is what you would expect it to be.

If a system is linear, it shouldn't matter if two inputs are scaled or added together before you input them into the system or after, the resulting output should be the same regardless. In nonlinear systems, things don't necessarily add together as you might expect.

EXAMPLE 1: As an example, the function y = 2x is linear. It doesn't matter if we take two inputs, say x=3 and x=4, and add first add them together and then perform the operation, or perform the operation twice and then add them together. Symbolically, y = 2*(3+4) = 2*(7) = 14 as opposed to y = 2*(3) + 2*(4) = 6+8 = 14. The order doesn't matter because this is a linear system.

EXAMPLE 2: Take as a counterexample, y = x^2. In this case it matters whether the inputs are added before or after the operation because y = (3+4)^2 = 49 but y = 3^2+4^2 = 25. This is a nonlinear relationship.

Last edited by markadlerdallas. Register to edit

Tags: none

How can a double-sideband phone signal be produced?

  • By using a reactance modulator.
  • By varying the voltage to the varactor in an oscillator circuit.
  • By using a phase detector, oscillator, and filter in a feedback loop.
  • Correct Answer
    By modulating the supply voltage to a class C amplifier.

How can a double-sideband phone signal be produced?

By modulating the supply voltage to a class C amplifier.

For more information, please see Wikipedia's article on Power amplifier classes

Also, see Electronics Tutorials site for article on Amplifier Classes

And, see Ham Radio Stack Exchange site for the article on Why does a Class-C non-linear power amp distort SSB but does not distort AM?

Last edited by markadlerdallas. Register to edit

Tags: none

What type of signals are used to conduct an SSB two-tone test?

  • Two audio signals of the same frequency, but shifted 90 degrees in phase.
  • Correct Answer
    Two non-harmonically related audio signals that are within the modulation band pass of the transmitter.
  • Two different audio frequency square wave signals of equal amplitude.
  • Any two audio frequencies as long as they are harmonically related.

What type of signals are used to conduct an SSB two-tone test?

Two non-harmonically related audio signals that are within the modulation bandpass of the transmitter.

Two-tone tests can help determine whether the radio is able to pick up on each frequency. For full discussion of two-tone testing, please see Wikipedia's article on Two-tone testing


From kj6prf:

When testing for linearity in a radio system, we're making sure that our two signals are being added kind of like the first example, except with sines and cosines instead of a simple scalar value.

If our system is nonlinear, this will cause distortion and the resulting output will sound strange or behave unpredictably.

When you test for linearity, you are testing how two inputs are being added together and checking that the output is what you would expect it to be.

If a system is linear, it shouldn't matter if two inputs are scaled or added together before you input them into the system or after, the resulting output should be the same regardless. In nonlinear systems, things don't necessarily add together as you might expect.

EXAMPLE 1: As an example, the function y = 2x is linear. It doesn't matter if we take two inputs, say x=3 and x=4, and add first add them together and then perform the operation, or perform the operation twice and then add them together.

Symbolically, y = 2x(3+4) = 2x(7) = 14 as opposed to

y = 2x(3) + 2x(4) = 6+8 = 14. The order doesn't matter because this is a linear system.

EXAMPLE 2: Take as a counterexample, y = x². In this case it matters whether the inputs are added before or after the operation because

y = (3+4)² = 49 but y = 3²+4² = 25.

This is a nonlinear relationship.

Last edited by markadlerdallas. Register to edit

Tags: none

Go to 57 Go to 59