20.4 INTERCOMMUNICATION SYSTEM

Question 1

How many MAPs are there?

Answer 1

Eleven

Question 2

How many speakers and jack boxes are there?

Answer 2

Eleven

Question 3

What does MMAP stand for?

Answer 3

Maintenance Mission Audio Panels

Question 4

How many FDMCPs and FDACPs are there?

Answer 4

Three

Question 5

What does FDIU stand for?

Answer 5

Flight Deck Interface Unit

Question 6

What is the purpose of the FDIU?

Answer 6

Interface to VHF radios and navigation audio

Question 7

The FDIU provides access to which radios?

Answer 7

VHF and one of the mission V/UFH radios (used as a UHF) for emergency operation

Question 8

T/F The FDIU can mute speakers

Answer 8

The FDIU also provides speaker muting for the PA system so that when a crewmember keys the PA
system, PA speakers in the vicinity of that crewmember are muted so that there is no feedback

Question 9

Where are the CSUs located?

Answer 9

Forward Comm Rack-E810

Question 10

Briefly explain how the ICS works?

Answer 10

Analog voice enters the mic where it is digitized by the Crewmember Position Equipment (CPE) and sent via the T-1 Ethernet line to the CSU. From there it is sent to the Time-Division Multiplex (TDM) where it is made available to all the interfaces in the system.

Audio in the ICS is handled as digital information. Audio coming into the system from the crewmember microphone is digitized at the Crewmember Position Equipment (CPE). The PTT signal travels along with the audio information as a digital “flag.” The digitized audio is sent to the CSUs over a T-1 Ethernet line. The digitized voice is received by interface cards in the CSU and routed to a Time-Division Multiplex (TDM) bus that makes the digitized voice available to all the interfaces in the system. A fiber-optic digital network interconnects the two CSUs to make digitized audio generated in one of the CSUs available in the other CSU.

Question 11

What are the functions of the CSUs?

Answer 11

Routes digitized voice for ICS communication

Crypto
Link 11
Sonobuoy command switching functionality

Located in Rack-E-810

Question 12

What is the function of the MAP?

Answer 12

Primary Crewmember interface with ICS

Analog-to-digital and digital-to analog audio conversion

Question 13

Where are the MAPs located?

Answer 13

Five MCWs
Port and Starboard Observer
Crew rest seats
Mission Planning station
Starboard sonobuoy rack
Galley

Question 14

What is the function of the junction box?

Answer 14

Primary interface between the Crewmember headsets and the ICS (through the MAP)

Also has speaker switch

Question 15

Where is the speaker switch located?

Answer 15

On the junction box

Question 16

Is there a functional difference between the OPERATOR and OBSERVER jacks on the junction box?

Answer 16

No

Both allow for communication via the MAP

Question 17

T/F You can hear classified comms over the speaker?

Answer 17

False
Speaker switch. Allows user to listen to unclassified voice communications over external speaker. Volume is controlled by respective MAP location.

Question 18

What is the function of the MMAP?

Answer 18

Tie headsets at the key fill panel (E-810 rack) to ALL CALL
Emergency intercom when aircraft is on battery power

The Mission Maintenance Audio Panel (MMAP) (Figure 20-28) enables crewmembers working at the keyfill panel (Forward Comm Rack-E810) to tie headsets into the ALL CALL net for communications at the position with either mission crewmembers or flight crewmembers. The MMAP is also a tie point for the emergency intercom that connects all users in the event the aircraft is operating on battery power (loss of all TRU power).

Question 19

How many CSUs are there?

Answer 19

Two