HF communications В 737 и А 320.

Подробно рассматривается соответственно в [3] и [5] рекомендуемой литературы.

General

The high frequency (HF) communication system supplies voice communication over long distances. It gives communication between airplanes or between ground stations and airplanes.

The HF system operates in the aeronautical frequency range of 2 MHz to 29.999 MHz. The system uses the surface of the earth and an ionized layer to cause a reflection (skip) of the communication signal. The distance between skips changes due to the time of day, radio frequency, and airplane altitude.

 

 

Abbreviations and Acronyms

· ACARS - aircraft communications addressing and reporting system

· ACP - audio control panel

· AM - amplitude modulated

· AME - amplitude modulation equivalent

· ARINC - Aeronautical Radio Incorporated

· BITE - built-in test equipment

· comm - communication

· EE - electronic equipment

· EEC - electronic equipment compartment

· FDR - flight data recorder

· FDRS - flight data recorder system

· freq - frequency

· HF - high frequency

· I/C - interphone communication

· LCD - liquid crystal display

· LED - light emitting diode

· LRU - line replaceable unit

· mic - microphone

· PSEU - proximity switch electronics unit

· PTT - push-to-talk

· RCP - radio communication panel

· REU - remote electronics unit          

· RF - radio frequency

· R/T - receive/transmit

· SELCAL - selective calling

• sq – squelch sql - squelch

· SSB - single side band

· USB - upper side band

· VSWR - voltage standing wave ratio    

· xmit – transmit

 

 

General

The HF communication system supplies the flight crew with long range voice communication. The HF communication system can be used to communicate between airplanes and between airplanes and ground stations.

The HF communication radio uses frequency select and control signals to transmit and receive voice communication. The HF radio modulates an RF carrier signal with voice audio from the flight interphone system. During the receive mode, the HF radio demodulates the RF carrier signal. This isolates the voice audio from the RF signal. The HF transceiver sends the audio to the flight interphone system.

System Components

The HF communication system has two HF radios. These are

the components:

· Radio communication panel

· HF transceiver

· HF antenna coupler

· Common or shared HF antenna.    

The radio communication panel (RCP) supplies selected frequency information and control signals to tune the HF transceivers and make radio selections. You can use the RCP to select amplitude modulated (AM) or upper side-band (USB) operation. Use the RF sensitivity control to improve HF reception. The RCPs can select and control the frequency of any HF communication radio. The HF transceiver transmits and receives information. The transceiver transmit circuits use flight interphone audio to modulate an RF carrier signal. This voice information goes to other airplanes and ground stations.

The receive circuits demodulate the received RF carrier signal to isolate the audio. The received audio is used by the flight crew or other airplane systems.

The HF antenna coupler matches the antenna impedance to the

transceiver output over the HF frequency range. During the transmit mode, the antenna coupler receives modulated RF from the transceiver and sends it to the antenna. During the receive mode, the antenna coupler receives modulated RF from

the antenna and sends it to the transceiver. The HF antenna transmits and receives audio modulated RF signals.

External Interface

The HF communication system connects with these

components/systems:

 

· Remote electronics unit (REU)

· SELCAL decoder unit

· Air/ground relay

· Flight data acquisition unit (FDAU).

System Operation

The control panel sends selected frequency information and control signals to the transceiver. The audio control panel sends these signals to the REU:

· HF radio select signal

· Receive volume control

· Push-to-talk (PTT).

 

During transmit, microphone audio and PTT signals go to the HF transceiver through the REU. The transceiver uses the microphone audio to modulate an RF carrier signal generated in the transceiver. The transceiver sends the modulated RF

signal through the antenna coupler to the antenna for transmission to other airplanes and ground stations. Also during transmit, the flight data acquisition unit receives a PTT signal from the transceiver. The flight data acquisition unit uses the PTT for key event marking to record the transmit event. During receive, the antenna receives a modulated RF signal and sends it through the antenna coupler to the transceiver. The transceiver demodulates or isolates the audio from the RF carrier. The received audio goes from the HF transceiver to the flight interphone speakers and headsets through the REU. The SELCAL decoder unit receives audio from the HF transceiver. The SELCAL decoder unit monitors the audio for SELCAL calls that come from the ground station. The HF transceiver receives an air/ground discrete. The HF transceiver uses the discrete to calculate flight legs for internal fault memory.

 

 

Flight Compartment

The radio communication panels are on the P8 aft electronics panel. The audio control panels (ACPs) are part of the flight interphone system. The ACPs have an interface with the HF communication system through the REU. The captain and first officer ACPs are on the P8 aft electronics panel. The first observer ACP is on the P5 aft overhead panel.

 

 

 

The HF transceivers are on the E6-2 shelf.

 

 

ANTENNA COMPONENT LOCATIONS

General

The antenna couplers are inside the vertical stabilizer.

WARNING: MAKE SURE PERSONNEL STAY A MINIMUM OF SIX FEET (TWO METERS) AWAY FROM THE VERTICAL STABILIZER WHEN THE HF SYSTEM TRANSMITS.

RF ENERGY FROM THE HF COMMUNICATION ANTENNA CAN CAUSE INJURIES TO PERSONNEL.