Book 3 Flashcards
List the advantages of SSB compared to AM
Fades less
Less bandwidth
Less noise
Saves power
Why use a single side band system
Power saving by not transmitting the carrier and one of the side bands.
Describe pilot carrier SSB
Small pilot carrier wave and the sideband
Suppressed Carrier
No carrier is transmitted and only one side band
Describe Controlled carrier SSB
Sideband is transmitted and the carrier when there are gaps in speech
Disadvantages of SSB
The receiver has to generate the carrier signal accurately to prevent distortion of the audio
Crystal filter
Gets rid of one of the side bands (Mainly LSB)
HF oscillator (SSB)
Generates final carrier signal at required transmission frequency
Balanced modulator (SSB)
Creates the USB and LSB
Master oscillator (SSB)
Generates low frequency carrier signal
Balanced mixer (SSB)
Mixes USB with output of a high frequency oscillator to produce the desired output frequency
C.I.O
Reinserts the master oscillator signal for the SSB detector so that it removes it to leave the audio signal left
List the advantages of FM compared to AM
Capture effect
Better quality audio
Sate the disadvantage of FM compared to AM
Wide bandwidth (typically 200KHz)
For a frequency modulated signal define deviation
How much the frequency changes proportional to the audio amplitude
For a frequency modulated signal define “rate of deviation”
How fast the frequency changes proportional to the audio frequency
VCO (FM Transmitter)
Makes carrier change in terms of deviation and rate of deviation
Identify the purpose of the IF, limiter and frequency stages of a FM receiver (IF AMP)
FM signals require a wide bandwidth to ensure that the maximum deviation is passed through the receiver.
Identify the purpose of the IF, Limiter and Frequency stages of a FM receiver (Limiter)
Frequency discriminators are susceptible to amplitude and frequency variation. The Limiter ensures a constant level of signal and removes any noise.
Identify the purpose of the IF, Limiter and Frequency stages of a FM receiver (Discriminator)
converts the Deviation into Amplitude and Rate of Deviation into Frequency.
