Communication System

What is the purpose of the communications system?

To provide the CPF with reliable and secure line of sight and over the horizon voice and data communications.

In a generic communication system, what is the Message?

The message is the information intended for transmission, which can be either voice or data.

What is the role of the Transmitter in a communication system?

The transmitter changes the input message signal to produce a modulated signal suitable for transmission.

What is the Transmission Medium/Channel in a communication system?

The medium (atmosphere, cables, water, etc.) through which the transmitted signal travels from one point to another.

How does an antenna function in the transmission medium?

It converts electrical energy into electromagnetic energy that radiates into the atmosphere.

What is the role of the Receiver in a communication system?

To capture the transmitted signal via an antenna and demodulate it to reproduce the original message signal.

What is the Output Message in communications theory?

The reproduction of the original input message after reception and demodulation.

What is fidelity in communications?

The degree to which the reproduced message matches the original input message.

What is the purpose of the HF Transmit Group?

To send communications over HF.

Where is the HF Transmit Group located?

In the HF transmitter room.

What HF transmit antennas are onboard?

18 foot whips starboard boat deck, 35 foot whips port boat deck, twin fan antennas between mast and bridge deck.

What frequency range does the HF Transmit Group operate in?

2–30 MHz.

Why do HF signals require more power than UHF signals?

Because HF signals travel longer distances and face more interference.

How many HF transmitters are in the HF Transmit Group?

Eight.

What do HF exciters do?

Generate RF signals.

What do HF power amplifiers do?

Amplify RF signals before transmission.

What does the HF Transmitter System Control Unit do?

Configures and routes signals from BPP/WADS to the proper exciter.

What does the Output Combiner Unit do?

Routes amplified signals to the proper antenna based on frequency.

What frequency range does the twin fan HF antenna cover?

2–6 MHz.

What frequency range does the 35 foot HF antenna cover?

5.5–12 MHz.

What frequency range does the 18 foot HF antenna cover?

11–30 MHz.

What is the purpose of the HF Receive Group?

To provide the ability to receive communications over HF.

Where is the HF Receive Group located?

In the Communications Equipment Room.

What HF receive antennas are used?

Three inverse conical antennas on the hangar top.

What is the HF Receive Group frequency range?

10 kHz to 30 MHz.

What is the function of HF multicouplers?

They allow multiple receivers to share a single antenna by splitting one incoming signal into several outputs.

How many HF receivers are onboard?

Eleven.

What is the HF receiving range for the HF receivers?

2–30 MHz.

How are HF receivers connected to end users?

Through BPP/WADS.

What is the frequency used for maritime distress signals?

2182 kHz.

What is the purpose of the HF Emergency Group?

To provide added HF communication capability for survivability and redundancy.

Where is the HF Emergency Group located?

In the emergency radio room.

Where is the HF emergency antenna mounted?

On the starboard side of the exhaust track.

What frequency range does the HF Emergency Group operate in?

2–30 MHz.

What type of system is the HF Emergency Group?

Half-duplex.

What components make up the HF Emergency Group?

One exciter, one power amplifier, a T/R switch, one HF receiver, and an HF emergency antenna.

What does the T/R switch do in the HF Emergency Group?

Allows the system to either transmit or receive communications.

What is the purpose of the UHF LOS Group?

To provide the CPF with the ability to send and receive communications over UHF.

Where is the UHF LOS Group located?

In the CER.

What antennas does the UHF LOS Group use?

Two hammerhead antennas forward of the hangar top.

What frequency range does the UHF LOS Group operate in?

225–400 MHz.

Why are UHF transmissions best suited for line of sight communications?

Because the higher frequency signals do not bend around the Earth’s curvature.

What type of system is the UHF LOS Group?

Half-duplex.

How many transceivers are in the UHF LOS Group?

Eight.

What do the UHF LOS transceivers do?

Act as both transmitters and receivers.

How many transmit and receive multicouplers are in UHF LOS?

Eight for transmission and eight for reception.

What is the purpose of the UHF guard coupler?

To receive signals at 243 MHz for aircraft distress.

How many hammerhead antennas normally support UHF LOS communications?

Normally only one is used.

What is the purpose of the UHF Emergency Group?

To provide the CPF with added UHF capability for survivability and redundancy.

Where is the UHF Emergency Group located?

In the ERR.

What antennas does the UHF Emergency Group use?

Two hammerhead antennas on the mast.

How does the UHF Emergency Group compare to the UHF LOS Group?

It works the same as UHF LOS but only has one coupler and one transceiver.

What is the purpose of the UHF SATCOM Group?

To send and receive communications over UHF satellite communications.

Where is the UHF SATCOM Group located?

In the CER.

Where are the UHF SATCOM antennas found?

OE-82 antennas on the port and starboard sides of the main mast.

What frequency range does UHF SATCOM operate in?

240–318 MHz.

What does DAMA stand for?

Demand Assign Multiple Access.

What is the purpose of DAMA in UHF SATCOM?

To process transmission and reception of communications so many users can share satellite channels.

What does TDMA stand for?

Time Division Multiple Access.

What is the role of TDMA in UHF SATCOM?

Assigns users time slots once demand for access has been granted.

What components make up the UHF SATCOM Group?

Two transceivers, DAMA equipment cabinet, antenna switching unit, antenna control unit, two OE-82 antennas.

What does the SATCOM antenna switching unit do?

Compares signals from port and starboard antennas and routes the selected signal for processing.

What does the SATCOM antenna control unit do?

Controls the rotation of the SATCOM antenna.

What is the purpose of the Black Patch Panel (BPP) and WADS?

To provide the ship with the ability to configure the routing of signals within the communication system.

Where are BPP and WADS located?

In the CER.

What type of device are BPP and WADS?

Passive networking devices used to organize and connect multiple cables in one place as a central hub.

What does WADS do?

Acts as the digitally controlled switch that automatically routes all communication traffic.

What does the BPP do?

Acts as the physical counterpart to WADS, allowing circuits to be generated with patch cables if WADS fails.

What is the purpose of Crypto?

To provide the ability to encrypt voice and data for secure communications.

Where are the Crypto components located?

Two crypto components are in the CCR and one is in the Ops Room.

How does Crypto secure data?

By converting data into an unreadable format using block and stream ciphers.

How do block ciphers work?

By dividing data into fixed-size blocks and encrypting each block.

How do stream ciphers work?

By encrypting data one bit at a time by mixing it with a continuously changing code.

What are block ciphers used for?

For encrypting messages.

What are stream ciphers used for?

For encrypting voice.

Where is the first crypto unit located?

Within the MHDS pathway.

Where is the second crypto unit used?

For the SHINCOM pathway.

Where is the third crypto unit used?

For the LINK system for tactical data.

What is the purpose of the Message Handling and Distribution System (MHDS)?

To provide the ship with the ability to send and receive message traffic.

Where is MHDS located?

In the CCR.

What type of messages does MHDS handle?

Radio Teletype (RATT) message traffic such as routing postings and incident reports.

How many consoles does MHDS have?

Two consoles.

What do MHDS consoles do?

Control MHDS operation and continuously check and collect information from shore units.

What components make up MHDS?

Two consoles, its own crypto part, a red patch panel (RPP), and RATT modems.

What is the role of the RPP in MHDS?

To route message traffic.

What do RATT modems do in MHDS?

Modulate message data.

What is the purpose of SHINCOM 3100?

To provide the ship with external and internal voice communications.

Where are the SHINCOM CSUs located?

Primary CSU in the CCR and secondary CSU in the SHINCOM equipment room.

What does SHINCOM unify?

Several different communication systems to provide internal and external communications.

Where are SHINCOM terminals found?

Throughout the ship.

What is the MDF in SHINCOM?

The Main Distribution Frame that connects CSUs to junction boxes.

What is the purpose of the RIU in SHINCOM?

Radio Interface Unit that interfaces with radio systems for non-secure communications.

What is the purpose of the CIU in SHINCOM?

Crypto Interface Unit that interfaces with crypto units for secure communications.

How many SHINCOM terminal types are there?

Four.

What is a Basic Rate Interface (BRI) Phone?

A single-channel SHINCOM telephone.

What is a Dual Screen Terminal (DST)?

A SHINCOM terminal that provides up to four communication channels.

What is a Console Dual Screen Terminal (CDST)?

A DST fixed to the MFW in the Ops Room.

What is an Outdoor Dual Screen Terminal (ODST)?

A DST enclosed in a ruggedized box on the upper decks.

What is the purpose of LINK?

To provide the ship with the ability to send and receive real-time tactical data.

Where are LINK components located?

In the Ops Room and in the Data Link Processing System (DLPS) within MCE 5 of CMS.