Communications System

Question 1

What is the purpose of the MH-60S communications system?

Answer 1

Provides internal communications among crew members and external communication functions that handles the transferring of sensor and tactical data between the aircraft and ship/shore

Question 2

What are the major functions of the communication system?

Answer 2

1. Communication control and status
2. Voice communications
3. Intercommunications
4. Auotmatic Direction Finding (ADF)
5. Identification Friend or Foe (IFF)

Question 3

What are the capabilities of the communication system?

Answer 3

1. Line of Sight (LOS) UHF/VHF communications
2. UHF Satellite Communications (SATCOM) Over-the-Horizon (OTH)
3. Link-16 subsystem

Question 4

What radio is used for UHF/VHF communications?

Answer 4

The ARC-120 radio

It is a Line-of-Sight transmitter and reciever.

Question 5

Where are the two MFRs located in the aircraft?

Answer 5

In the transition section

Question 6

Each ARC-120 MFR has a separate gaurd reciever that recieves voice transmissions on what frequency?

Answer 6

Each MFR has a separate gaurd reciever for transmissions for each standard emergency frequency (121.5 and 243.0)

Question 7

What are the different AM/FM Electronic Counter-Countermeasure Modes (ECCM) for the ARC-120?

Answer 7

1. HAVEQUICK
2. HAVEQUICK II
3. SATURN
4. SINCGARS V (Single Channel Ground and Airborne Radio System)

Question 8

What are the embedded capabilities of the MFRs?

Answer 8

1. Clear & secure LOS transmit/recieve
2. Clear & secure LOS ECCM via HAVEQUICK, HAVEQUICK II, and SINCGARS
3. OTH capability via SATCOM/DAMA SATCOM
4. Automatic Direction Finding (ADF)
5. Variable Message Format (VMF) Not installed

Question 9

When using the U/VHF radios to relay U/VHF communications, what should we avoid?

Answer 9

Avoid the following:
1. UHF-to-UHF frequency separations of less than 10 MHz
2. UHF-to-UHF relays to frequencies below 265 MHz
3. VHF-to-VHF relays where possible

Question 10

What are the two kinds of Build-In Tests that the UHF/VHF radios perform?

Answer 10

• Operator-Initiated BIT (IBIT): an auto-test that is initiated by the operator
• Continous BIT (CBIT): runs in the background during normal radio operations and requires no operator intervention

Question 11

What kind of Maritime frequencies does the MFRs support?

Answer 11

Supports only International Duplex Maritime preset channels (Maritime presets 1-28 & 60-88)

Maritime radio freqs can be found in the SAR TACAID

Question 12

What are the backup/failure modes for the communications system?

Answer 12

1. Single-FMC Failure (AMC operational, AC pwr available)
2. FMC Back-up Mode (AMC operational, AC pwr available)
3. AMC Backup Mode (FMCs operational, AC pwr available)
4. Battery mode (electrical problem or prior to APU start, DC Battery pwr available)

Question 13

Single-FMC Failure Mode

Answer 13

No impact on ICS/radio communications

Question 14

FMC Backup Mode

Answer 14

• The MFRs function normally but can only be selected via the OCP/RCU and tuned via the RCU
• No impact on ICS

Question 15

AMC Backup Mode

Answer 15

• Radio #1 is hardwired to the pilot station (right seat)
• Radio #2 is hardwired to the co-pilot station (left seat)

(Both radios are controlled by the RCU and is PTT only)

• ICS Call is available to all stations

Question 16

Battery Mode

Answer 16

• Only Radio #1 is available and is hardwired to the pilot station (controlled by the RCU and is PTT only)
• ICS is not available to the aft stations

Question 17

What does the APX-123 IFF transponder do?

Answer 17

Responds to interrogations from other friendly units

Consists of an upper and lower antennae

Question 18

What is Transponder Mode 1?

Answer 18

A non-secure mehtod used by ships to track aircraft and other ships

Question 19

What is Transponder Mode 2?

Answer 19

Used by aircraft to make carrier controlled approaches to ships during inclement weather

Question 20

What is Transponder Mode 3/A?

Answer 20

The standard system also used by commercial aircraft to relay their position to ground controllers for ATC

Question 21

What is Transponder Mode C?

Answer 21

Turns altitude transmissions ON/OFF for all currently enabled transponder modes

Question 22

What is Transponder Mode 4?

Answer 22

An obsolete secure encrypted IFF

Is no longer used

Question 23

What is Transponder Mode S?

Answer 23

Is a civil ATC Surveillance System that can respond to selective interrogations and provide air-to-air and air-to-ground data link of aircraft identification and flight parameters

Question 24

What does the interference blanker do?

Answer 24

Prevents interference due to simultaneous transmissions on the following transmitters:
* IFF transponder
* TACAN set
* Link 16 (transmit only)

Question 25

Where is the interference blanker located?

Answer 25

It is located in the transition avionics rack