ATC equipment radar principles

Question 1

What does RADAR stand for?

Answer 1

Radio detection and ranging

Question 2

What is PSR?

Answer 2

Primary surveillance radar, returns horizontal position.

Question 3

What is SSR?

Answer 3

Secondary surveillance radar, uses a 4 digit squark code to identify a/c and sometimes shows extras like level info depending on mode.

Question 4

What will weather affect more, long wavelength or short wavelength?

Answer 4

Short

Question 5

How fast does an SMR spin?

Answer 5

45-60 RPM

Question 6

What are the 3 SSR modes?

Answer 6

A - Identity
C - Level information
S - Extra information

Question 7

What is MTI?

Answer 7

Moving target indicator, uses the Doppler effect to tell if something is moving and removes clutter.

Question 8

What is one problem with MTI?

Answer 8

If an a/c flys at a tangent to the radar it causes tangential fade and the radar may remove it as clutter.

Question 9

What is an advantage of PSR?

Answer 9

A/c do not need any equipment on board for it to work.

Question 10

What are 5 disadvantages of PSR?

Answer 10

• Requires a strong signal and correct signal therefore suffers from signal attenuation.
• Shows clutter.
• Provides limited information.
• Distance given is slant range.

Question 11

What numbers can be used for squark codes?

Answer 11

As it uses 3-bit binary only numbers 0-7 can be used.

Question 12

How many mode A squark codes are there?

Answer 12

4096

Question 13

What are the 2 types of SSR codes?

Answer 13

• Discreet codes (Assigned)

- Conspicuity code

Question 14

What are 5 advantages of SSR?

Answer 14

• Less transmitter power required for similar range.
• No ground or weather clutter.
• Provides aircraft identification.
• Level information if mode C or S.
• Provides use of conspicuity codes.

Question 15

What are 4 disadvantages of SSR?

Answer 15

• A/c requires a transponder.
• No weather or clutter displayed.
• Label garbling.
• Possible antenna shadowing will mean a/c is not displayed.

Question 16

What are 5 advantages of mode S?

Answer 16

• More accurate.
• Provides controller / pilot information via uplink and downlink capabilities.
• Allows the a/c to fly in class A and C airspace.
• Almost 17 million aircraft addresses.
• More accurate info for (STCA and TCAS 2)

Question 17

What is shown by elementary mode S?

Answer 17

• Automatic Identification
• More accurate level info (25ft)
• Flight status (On ground or in flight)

Question 18

What is shown by enhanced mode S?

Answer 18

• Magnetic heading
• Speed (IAS and Mach number)
• Roll angle
• Rate of turn
• Climb rate
• Ground speed
• Selected flight level

Question 19

What is ADS?

Answer 19

Automatic dependent surveillance is a surveillance technique where a/c automatically report Nav data via data link including a/c identification.

Question 20

What are the two ADS versions?

Answer 20

ADS-B and ADS-C

Question 21

What is ADS-B

Answer 21

Broadcast, Broadcasts data out to everyone.

Question 22

What is ADS-C

Answer 22

Contract, only ANSPs with a contract receive the data. Only used in low traffic areas.

Question 23

What is MLAT?

Answer 23

Multilateration system, a group of equipment configured to provide position derived from the SSR.