Set 2 Components

Question 1

75 MHz Filter in Marker Beacon System

Answer 1

Filter out the 75 Mhz carrier and reduce signal noise.

Question 2

What is the purpose of the Detector in the Marker Beacon System?

Answer 2

Demodulate the carrier signal and receive the audio tone, which will be sent to 3 different audio filters.

Question 3

Audio Amplifier

Answer 3

Amplify the amplitude of the audio tones filter amplifiers.

Question 4

What’s the function of a Duplexer?

Answer 4

Enables a single antenna for both transmitting and receiving. (Used in Pulse Radar Systems)

Question 5

Whats the function of a Mixer-Local Oscillator?

Answer 5

Mixer lowers frequency by shifting the high input frequency to a lower output frequency, called Intermediate Frequency (IF), for the demodulator.

Used to solve the issues of a Tuned Radio Frequency Receiver (TRF). Where the Demodulator requires a reduction in input frequency (to simplify circuit design) and bandwidth of Band Pass Filter (BPF) needs to be constant.

Question 6

What’s the function of the Filter in the VOR Airborne Loading system?

Answer 6

Filter is used to either filter out other frequency components for good carrier to noise ratio besides the 30 Hz Reference Signal or 30 Hz Variable Signal to be detected/amplified.

Question 7

What is the purpose/function of the Phase Comparator?

Answer 7

In VOR airborne loading, the Phase Comparator is used to compare the phase difference between the variable 30Hz and reference 30 Hz signals.
The detected phase difference is converted into voltage in Sync format to be indicated on Radio Magnetic Indicator (RMI)

Question 8

Function of Monitor Circuits?

Answer 8

In VOR, it is used for checking of reliability & quality.
In ATC (transponder), it is used for checking for proper operation of tuning circuits, sufficient transmit power and presence of valid interrogation. (Fault loop is turned on if signal from monitor circuit is received)

Question 9

What is the function of the 400 Hz Filter Amplifier?

Answer 9

The 3 audio filters of the Marker Beacon System discriminate audio tones received from the carrier signal. If the tone is 400 Hz, it will light up the Outer Maker and send the audio tone to audio amplifier.

Question 10

What is/are the disadvantages of A-scope over PPI?

Answer 10

A-scope is only used directionally with one angle at a time, thus making it also more suitable for tracking than searching.
PPI gives a plan view, giving 360 degrees view of area. This enables searching much easier and able to view movement of targets easier.