PBN

• PBN is the method of navigation that allows the aircraft operation on any desired flight path based on the performance of aircraft within the coverage of ground or space based navigation aids or within the limits of the capability of self contained  aids or combination of these.
• PBN now a days has become the utmost air navigation priority of global aviation communities.
• PBN can be used in developing efficient air route network and allows different ways to construct most direct routes.
• The PBN concept requires that the aircraft area navigation system performance  be defined in terms of accuracy, integrity, avaibility, continuity and functionality necessary to operate in the context of a particular airspace concept.

PBN helps to:

• Enhance the safety
• Increase ATC and airspace capacity
• Improve effeciency
• Enhance accessibility to the airports
• Reduce the impact on the environment

Ground Based Augmentation System( GBAS) and Satellite Based Agumentation System(SBAS)

GBAS uses monitoring stations at the airport to process signals from core constellations (currently GPS L1) and broadcasts corrections and approach path data to support precision approach operations. SBAS uses a wide network of ground stations and provides signals from Geostationary Earth Orbit (GEO) satellites to support operations over a large geographic area, from en-route down to approaches. Expected benefits from GBAS/SBAS implementation involve the enhancement of safety through the geometric vertical guidance for final approach and improvement of accessibility to regional airports in addition to the general benefits gained from PBN implementation, i.e. improvement of operational efficiency, increase of airspace capacity, reduction of noise and CO2 emission.

Necessity of Argumentation System:

The navigation system should meet four requirements.

Accuracy: accuracy in the means of position information. Is the position is correct?

Integrity: ability when the navigation system occur error and the ability to inform the situation within the certain time. Is the information right?

Continuity: ability to provide the navigation service continually. Does the service continue? What is the  availability ratio?

Availability: ability to have the accuracy, integrity and continuity. Is the availability ratio high?

VHF Radio

What does ATIS stand for in aviation?

ATIS (Automatic Terminal Information Service) is a recording that some airports broadcast in order to reduce frequency congestion. Current weather information, active runway information, NOTAMs, and other useful pieces of information are included in the ATIS.

What information does ATIS provide?

Automatic Terminal Information Service, or ATIS, is a continuous broadcast of recorded aeronautical information in busier airports. ATIS broadcasts contain essential information, such as weather information, active runways, available approaches, NOTAM, and any other information required by the pilots.

How often is ATIS updated?

ATIS is usually updated once an hour; 30 minutes at some airports. If the weather or airport conditions change significantly before the next version is due, a new message is recorded immediately with the word “special” added after the zulu time. This alerts pilots that a significant change has occurred.

What is Digital ATIS?

Digital ATIS is an enhancement of the Tower Data Link. Service (TDLS) and uses the Pre-Departure Clearance (PDC) System. microcomputer to automate the delivery of airport and terminal. area operational and meteorological information to aircraft.

For more information:
See pdf here
https://documentviewer.herokuapp.com/?state=%7B%22ids%22:%5B%221J69O72Q1Mbtru_6urn1toX7xNcsmWCVU%22%5D,%22action%22:%22open%22,%22userId%22:%22103808279837644644309%22%7D
see ppt here
https://documentviewer.herokuapp.com/?state=%7B%22ids%22:%5B%221b_aAMsIMa13Nc6nkfdQnQ3W8_HZi8OLQ%22%5D,%22action%22:%22open%22,%22userId%22:%22103808279837644644309%22%7D


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Air Traffic Controller Automation System

ATC Automation:
Automation systems provide the means of relaying essential information for the safe and orderly operation of Air Navigation Services (ANS). Data processing or automation includes a combination of hardware platforms and operating system software. Proper hardware and software configurations are essential for a safe and orderly ANS. Data processing or automation systems can be located anywhere at the ACC, on the airport, or in its vicinity or remote from the ACC or airport.

ATC Automation in Nepal:
Nepal introduced ATC automation system in 2013 by Avibit, Austria. It contains e-Strip called DIFLIS (Digital Flight Strip System) and Infomax system.
Avibit System:
Divided into following categories:

• software and hardware architecture
• system monitoring and control
• Avibit operating system
• DIFLIS
• InfoMax

Air Traffic Safety Electronics Personnel (ATSEP)

Air Traffic Safety Electronics Personnel-ATSEP:
The acronym ATSEP refers to Air Traffic Safety Electronic Personnel. This select group of technical specialists provide and support the electronics and the software used to operate and allow air traffic safety (ATS) systems. This includes communications, navigation and surveillance and air traffic management systems (CNS/ATM). The ATSEP group is comprised of technicians, engineers and computer software and hardware specialists.

Regulatory Environment for ATSEP

ATSEP are personnel proven competent in the installation, operation and/or maintenance of a communication, navigation and surveillance/air traffic management (CNS/ATM) system. It is the responsibility of the ANSP to define the scope of ATSEP activities (Doc 9868- PANS-TRG). ATSEP should have a detailed understanding of the regulatory environment in which ATSEP work.ATSEP training programmes should be clearly linked to ATSEP activities taking into consideration the ANSP's safety management and quality assurance systems as well as security concerns. National regulations may define the requirements with respect to age, knowledge, experience, skill and attitude for ATSEP. So ATSEP play a significant role in the safe operation of CNS/ATM systems.

Activities that ATSEP Perform

According to the International Civil Aviation Organization’s (ICAO) Manual on Air Traffic Safety Electronics Personnel Competency-Based Training and Assessment, ATSEP are responsible for duties that pertain to the use of ground electronic systems that are used to help control aircraft movements, including operational, maintenance, installation and management activities. The tasks performed by ATSEP  may be on a wide variety of CNS/ATM/ATS systems or equipment. This requires a wide range of competencies, expertise, knowledge and skills in the areas of electronics, computer science and computer networking. ATSEP activities can range from technician-level to high-level engineering tasks.

Operational Activities

ATSEP who perform operational activities are responsible for supervising, monitoring, controlling and real-time reporting of technical services that are supported by CNS/ATM electronic systems and/or equipment.

Maintenance Activities

ATSEP who perform maintenance activities are responsible for providing preventive maintenance, corrective repairs and/or updates or modification of CNS/ATM electronic systems and/or equipment .

Installation Activities

ATSEP who perform installation activities may perform tasks that are related to engineering activities, project management, specification, conception, validation, integration, testing and acceptance, safety assessments, calibration, certification, optimization and upgrade of supporting electronic systems and/or equipment for CNS/ATM.

Management Activities

Aside from technical activities, some ATSEP may work in areas related to:

• Safety management
  
• Network security management
  
• Quality management
  
• General management
  
• Teaching
  
• Assessment 
  ATSEP scope of activities
  

1. ATSEP may perform tasks on a wide variety of CNS/ATM systems and equipment requiring a wide range of competencies and expertise as well as knowledge and skills in electronics, computer sciences and network. In addition, ATSEP activities may be carried out from technician to high-level engineering. 
2. Scope of ATSEP activities defined on a basis of engineering lifecycle conception through design, operations and finally decommissioning.
3. Possible scope of ATSEP
1. Scope of operational activities: supervision, monitoring, control and reporting in real time of technical services, supported by electronic systems and /or equipment for CNS/ATM.
2. Scope of maintenance activities: preventive maintenance, corrective maintenance and/ or modification and updates of supporting electronic systems and/ or equipment for CNS/ATM.
3. Scope of installation activities: project management, specification, conception, validation, integration, test and acceptance, safety assessment, calibration, certification, optimization and upgrade of supporting electronic systems and/ or equipment of CNS/ATM, engineering activities. 

In addition to technical activities, others may be added related to management, teaching or assessment, safety management, security management (e.g. network) and quality management. With the introduction of new technologies, maintenance methods and design processes, states and ANSPs should regularly review the scope of ATSEP activities, to ensure that ATSEP maintain competencies appropriate to their current and future activates. Training programmes should be focused on the specific activities assigned to ATSEP.

European Approach to Safety Management for ATSEP Competency

ATSEP must now have a basic level of training in electronics and engineering. Individuals seeking a career in ATSEP must now achieve certain levels of competency through earning qualifications and system/equipment ratings. There are four disciplines for qualifications:

• Communication
  
• Navigation
  
• Surveillance
  
• Data Processing
  

The final stage for the acquisition of competence after obtaining the basic and qualification training would be system/equipment-related training.
This includes mentored training and onsite training.
Recognition and proof of competence for ATSEP is provided through records of training and experience with the safety management systems of service-provider organizations. However, some countries have decided that their ATSEP should have possession of their individual documents, including individual records of competence and/or evidence of appropriate professional qualifications.

 

E1-Radio Interface Converter (E1-RIC)

E1-RIC:
E1-RIC is an interface converter. It converts unframed HDB3 or AMI data of ITU G.703 E1 balanced or unbalanced interface into an interchangeable DTE interface module. E1-RIC operates at 2.048Mbps. It extracts data and the clock from the G.703 interface via a jitter attenuator to meet ITU G.823 requirements.
E1-RIC acts as a line transceiver. It provides protection from over-voltage and over current stress caused by lightning power crosses and other noise sources.
E1-RIC is an interface converters that connect Ethernet LANs over E1 circuits. This allows communication between devices with E1 interfaces and equipment with V.35,X.21,V.36 or RS-530 interfaces. E1-RIC is available with several WAN (DTE) interface options.It also supports auto-negotiation, allowing connection without additional configuration.
DTE interface:
E1-RIC can be ordered with one of the following DTE interfaces:

• V.35
• X.21
• V.36
• RS-530
• Ethernet:
• IR-ETH(Ethernet Bridge)
• IR-ETH/QN(Ethernet/Fast Ethernet bridge with VLAN support)
• IR-IP (IP router)

E1-RIC Application:
E1-RIC is typically used to connect between a G.703 network and a DTE. The DTE can be a multiplexer, a bridge, a router etc. Figure below illustrates a typical E1-RIC application.

Figure: Typical Application

Block Diagram of E1-RIC:
Figure below shows the functional block diagram of E1-RIC.

Figure: E1-RIC Block Diagram

Timing Reference:

E1-RIC supports three clock modes:

• Internal, derived from its internal oscillator.
• External, supplied by the attached DTE.
• Receive, recovered from the received line signal.

Technical Specification:

Front Panel Indicators:
Figure below shows E1-RIC front panel. The front panel indicators are described in table below.

Remote Control Air Ground (RCAG) System

RCAG System Understanding:
RCAG:- Remote Control Air-Ground
RCAG is a facility for a/g communications of VHF and UHF controlled remotely by ACC. This allows direct communications between a control facility and aircraft in a remote area. RCAG system mainly deals with:

1. Remote Control and Monitoring System (RCMS)
2. Multi-Access Remote Control System (MARC)

Multi-Access Remote Control System (MARC):
MARC is a Remote Control and Monitoring system (RCMS) software package designed to monitor, and provide engineering control of an Air Traffic Control (ATC) radio system. A typical system comprises a number of remote radio sites that are operated from an Air Traffic Control centre. The remote sites may be part of a single airport complex or can be located over a wide geographical area. Note that MARC is an engineering facility that does not affect air traffic controllers normal usages of the radio system.
MARC contains two software packages namely: Navigator and Configurator.
Navigator is the software that runs when MARC is in use. It presents a series of graphical screens that show the user's radio system, or some part of it.Status indications provide a visual guide to system, site and equipment serviceability. Additionally, Navigator provides control functions, allows some automatic events to be programmed and generates historical system data.
The Configurator is the software used to define the user's radio system and compile the screens that are used by Navigator.
 MARC can operate with radio systems containing up to 30 Control Central Equipment (CCEs), 999 remote radio sites and 7992 radios. The radio system is monitored, and  control functions initiated from, a Personal Computer (PC) normally located at the air traffic center. A series of graphical screens provide monitoring and control functions.
MARC Functions:
Following monitoring and control functions are available through MARC;

1. Monitoring functions: 
1. Monitors the complete system and indicates any site where a fault is detected on the main screen. 
2. Monitors the site and indicates any faulty radio, remote site equipment or MARC data link. Also monitors any alrams that have been configured and indicates which are active on site screen.
3. Monitors each radio and indicates the nature of any fault on equipment screen.
2. Main and Standby Switching:
1. Automatic Switching: The standby equipment becomes operational should a fault be detected on the main equipment.
2. Manual Switching: The main or standby equipment can be manually selected as operational.
3. Automatic Events: Some, or all, radios configuraed as main/standby pairs can be pre-programmed to switch from the main to standby (or vice-versa) once at any predetermined time, or at regular periods.
3. Control Functions:
1. Frequency Change: The operating frequency of any radio can be changed or any stored frequency channel can be recalled.
2. Radio Parameters: Many radio parameters can be changed.
3. User Configurable outputs: A number of user outputs can be configured at the remote sites. These outputs can be used to switch building services on and off; for e.g. lighting circuits. The configurable outputs are activated/deactivated from the MARC-PC.
4. BIT Tests:
1. BIT test: A BIT test can be initiated on any radio.
2. Automatic Events: Some, or all radios can be pre-programmed to perform a BIT test once at any predetermined time or at regular periods.

In addition to the monitoring and control functions, MARC makes a number of reports available for display or printing. The reports include current and historic data pertaining to the radio system.

Voice Communication Control System

What is VCCS?
VCSS is a computerized voice communication system for direct communication between pilots and air traffic control officers, and between air traffic control working positions in the ATC Centre, ATC Tower and Rescue Coordination Centre, by using pre-set aeronautical frequencies, direct communication lines and telephone lines.
VCCS controls and connects together various voice communication systems used for Air Traffic Management (ATM) such as VHF Tx/RX, telephone, and other ATC communications. 
It also provides an internetworked chain & backbone for numerous interfaces acting as an exchange for all the interfaces put together. It works on various IT protocols customized for each set of facility. We can interface diagram of VCCS can be shown as shown in figure below:

Features of VCCS

• Standard radio and telephone functions
• extended radio and telephone functions
• customized radio and telephone functions
• short term recording
• Instant replay
• Radio Voting
• Failsafe PPT
• Customer defined options

VCCS Simplify Diagram:

Typical VCCS Environment:

VCCS Hardware consists of following components:

Central Equipment (CEQ), 

Position Equipment (PEQ) and 

Voice Communication Management System (VCMS).
The general block diagram of VCCS is shown below:

Hardware Configuration:
General hardware configuration consists of 

1. central equipment
2. position equipment

Central Equipment: 

GAREX Administrative Package (GAP):

GAP is an application program that runs on the Voice Communication Management System (VCMS). GAP is started in the same way as all Windows type applications. GAP requires a valid username and password. This is done for security reasons, both to ensure that no unauthorized personnel change the set-up of the system, and also to be able to set different privileges for the different user types. GAP is used for:

•  reconfiguration of the setting in the VCS central equipment.
• reconfiguration of roles for the operator positions.
• displaying the diagnostic and error messages.
• installation and removal of hardware from the VCS central equipment.

GAP also includes a stastics tool. GAP is not critical to ongoing ATC operations. The GAREX central switch contains all the data necessary for controllers to continue ATC operations using the resources they have already been allocated. The switch also contains all the data necessary to restart itself with the chosen default configuration of roles and resources after the return of power if an outage should even occur.
 The main functions of the GAP are:

• Reconfiguration of the GAREX 220.
• Receive and store reconfiguration transections initiated from the controller working position equipment.
• Send configuration data to GAREX 220 at GAREX 220 power up.
• Receive, store, and present diagnostics messages from all GAREX 220 sub-systems.
• Generate systems parameters and layout reports.
• Produce and display call statistics.

Voice Communication Management System (VCMS)
The VCMS is a complete system for managing all assests within the Voice Communication Control System (VCCS)- including both Air-Ground and Ground-Ground communication. The VCMS is a collection of discrete application programs on a dedicated industry-standard server, running Microsoft Windows Server with an Oracle database. The server is equipped with Ethernet interfaces for connection to the GAREX 220 central equipment.

VCMS is  used to accurately diagnose system failures down to LRU level across all VCCS assests, with the minimum of delay, to monitor system performance, to record events and to provide service and equipment status. The VCMS server is included in the Central Equipment rack, monitor, keyboard and mouse for connection to server and mounting on desk.

The VCMS application include:

•  Diagnostics Graphical Display (DGD), an application used for monitoring the GAREX and identifying the source of faults.
• GAREX Administrative Package (GAP), an application used for control of the GAREX  configuration management and statistics.

The VCMS applications are multi-user so that the same application may be in use at up to 5 VCMS user interfaces concurrently. Changes performed from one VCMS terminal will be reflected at the other VCMS terminal. The VCMS is not directly involved in the Air-Ground voice path. Communication will current configuration will continue even if the VCMS is unavailable-as will role selection from the user positions. In case of VCMS failure, the monitoring messages will be stored in the central equipment. These message will be forwarded to the VCMS when it comes online after a failure.
VCMS applications:

Diagnostic Graphical Display (DGD)
DGD application provides the human-machine interface of the GAREX 220 monitoring and maintenance system. The DGD application handles these aspects of the Voice Communication Management System (VCMS):

• Monitoring of VCCS services and equipment.
• Diagnostics of equipment failures, including help to locate and replace failing parts.
• Means to  switch between main and standby radio transmitters, select radio receivers and disable equipment during maintenance.

The DGD software connects to the Oracle database on the VCMS server and displays the data in the database in a user-friendly and intuitive way. 

The top-level display for managing the VCCS will look similar to the figure below, which is an example screen-shot.

figure: DGD main and detailed view

The same basic display will be used for each VCCS but the contents will adopt to each VCCS configuration regrading the number of operator positions, channels, telephone interface etc. The overview display gives the latest status of all VCCS services. The definition of what colors are used for what purpose is configurable.

DGD event log:

All DGD events in the system shall be logged in the DGD event log for later analysis. The DGD event log records events for at least the last 24 hours. The following actions are all defined as events and stored in the event log:

• Logon and logoff by users, including failed logon attempts.
• Engineering role changes by users.
• Changes in technical state of services and equipment.
• Changes in acknowledge state of services and equipment.
• Changes to user notes in the alarm list.
•  Changes in maintenance state of equipment.
• Selection and deselection of equipment.
• Changes in engineering role configurations.
• Changes to engineering roles and user accounts.

The DGD event log is available through a button at the top of the main screen and will appear in the detailed view area. Several DGD event logs may be opened at the same time. In the example below, the detailed view area has been expanded to give a better overview of the events.

 

The DGD event log features extensive functions for selecting information to be displayed. This includes column sectors and filtering. The DGD event log may also be printed or exported to a file for further processing.

Air Navigation Services (ANS)

Aeronautical Telecommunication Network (ATN)
ATN is a global inter-network that provides digital communications necessary to the automated systems that include; air traffic service communication (ATSC), aeronautical operational control (AOC), aeronautical administrative communication (AAC), and aeronautical passenger communication (APC).
The ATN is composed of a network infrastructure and applications, and provides the global communication for ground-ground(G/G) and air-ground (A/G) services. The major components of ATN network are routers (intermediate Systems) including G/G routers and A/G routers, and communication sub-networks including air-ground and ground-ground sub-networks. The ATN applications includes, among others

• Context Management (CM)
• Controller-pilot data link communication (CPDLC)
• Air traffic service message handling services (AMHS)

The applications are hosted by the End Systems (ES). The Aeronautical Fixed Telecommunication (AFTN) and the Message Switching Systems are being incrementally replaced by a regional ATN ground network and AMHS.

 AMHS technology is the enabler for graphical depiction of aeronautical data through the automation system, thereby enhancing the performance and efficiency of the air traffic services. This will bring significant improvement in service delivery and air safety to the travelling public.

AMHS replace the legacy of AFTN connectivity which could cater to only small textual messages wherein binary attachements containing aeronautical maps, weather charts, digital NOTAM etc can be exchanged.

ATS Message Handling System (AMHS)
The ATS Message Handling System (AMHS), which has been defined in the ICAO Aeronautical Telecommunication Network (ATN) standards, is intended to be a replacement for the current Aeronautical Fixed Telecommunications Network (AFTN). AFTN is a store-forward messaging service for conveyance of text messages using character-oriented procedures.AFTN messages are forwarded on a hop-by-hope basis using pre-configured routes that are the most expeditious to affect delivery to the addressee. AFTN has diversion routing lists agreed to by the Administrations operating the communication centres where the AFTN switches reside. These lists are statically configured and used to immediately reroute traffic in the event of a circuit outage in a fully automatic communication center and to manually reroute traffic within 10 minutes in a non-fully automatic communication center.
Under AFTN procedures the sending station will hold messages transmitted, and in the event that continuity of message traffic is not maintained, they are re-transmitted. Continuity of message traffic is supervised using sequence numbers applied to all traffic over a particular channel. The AFTN system is depicted in the figure below:

Figure: AFTN system

OSI X.400 Message Handling System:

The ATS Message Handling System is based on the OSI X.400 Message Handling System. It is important to note that the X.400 Message Handling System is not a physical system with actual physical entities but rather is an architecural model for specifying functions or services provided by logical entities and the protocols between these logical entities and the protocols between these entities. The X.400 Architecture and Protocols can be depicted in the figure below:

The outer infrastructure is the message handling system (MHS), which is a generic messaging system from the perspective of MHS users. The inner infrastructure is the Message Transfer System (MTS), which provides the store and forward capability of the MHS. The MTS consists of a network of Message Transfer Agents (MTA).
 MTAs are message routers, they functions as routers at the message level to forward messages across the MHS. MTAs forward messages using the recipient Address in the message.MTAs communicate with one another using the P1 protocol, which defines a message envelope and contains routing and control information and thus determine how message exchange occurs among MTAs.
User Agent (UA)
MTS users within the MHS are either User Agents (UA) or Message Stores (MS). A UA functions to permit the user to send and receive mail. It is essentially a unit of software that interacts with the MTS on behalf of a user. UAs communicate with one another using the P2 protocol. The P2 protocol defines the content and format of an interpersonal message.
Message Stores (MS)
A MS is a unit that stores messages on behalf of a UA.When a MTA has a message to deliver to a UA it delivers it to the MS instead of the UA. The UA can then retrive the message from the MS at its convenience. A UA communicates with a MS using the P7 protocol. The P7 protocol defines procedures for message submittal, message retrieval, and message administration.
MTS users communicate with MTAs using the P3 protocol which defines procedures for message delivery and as in the case for the P7 protocol defines procedures for message submittal and message administration.
Access Unit (AU):
The AU is simply a gateway to another communication system. In the original X.400 specifications, AUs were expected to provide an interface to pre-X.400 technologies such as telex, and teletex. ICAO defines two AUs.

• AFTN/AMHS Gateway
• CDIN/AMHS Gateway

Almost all AUs provide gateway service to TCP/IP mail service in the form of an X.400 to SMTP gateway.

Basic ANS chart:

Some standard abbreviations used in aviation communication:

AGC: Automatic Gain Control
ATC: Air Traffic Controller
BIT:Built-in test
CAS:channel associated signalling
CCE: Control centre equipment
E1-RIC: E1- radio interconnect
E-BIT: external bit signal
HPA: High Power Amplifer
IBSU: In-band signalling unit
IDF: Intermediate distribution frame
LRU: Line replacement unit
MARC: Multi-access remote control
PCU: Protocol conversion unit
PTT: Press to transmit
RCMS: Remote control and monitoring system
RSSI: Radio signal strength indication
VCCS:Voice control and communication switch
VFP: Virtual front panel
VOGAD: Voice-operated gain adjusting device

T6T50 W VHF multimode transmitter:
It is intended for use in fixed ground environments such as airports and en-route centres. The transmitter operates voice and ICAO defined data modes at frequencies 118-136.975MHz for the standard model and 112-155.975MHz for the extended frequency model. Dependent on the software loaded into the radio there are two operating modes:

1. AM-Voice : This software provides voice via 4-wire E & M, E1 or VOIP. It provides SNMP (Simple Network Management Protocol) via Ethernet, and MARC via RS232, RS422, E1 and Ethernet. For VOIP operation it requires VOIP Configurator Application (VCA) software.
2. VHF Data Link (VDL) mode 2:VHF Data Link (VDL) Mode 2 radios support Controller Pilot Data Link Communications – sending information between aircraft and ground stations. It is latest upgrade to the VHF data link communications . VDL Mode 2, in its broadest sense, is the term that is used to describe a suite of air-ground protocols that increase the data rate of the air-ground link to 31,500 bits per second. VDL Mode 2 allows transitioning from an infrastructure that relies on character-oriented ACARS protocols for end-to-end delivery of messages to one that uses bit-oriented Aeronautical Telecommunications Network (ATN) protocols using the same VHF ground and aircraft radios.

The transmiiter may be connected to suitable control equipment using a variety of analog and digital methods. These include:

• 4-wire audio and signalling using analog lines
• An E1 digital link
• Ethernet links.

The transmitter is a single frequency synthesised radio that can operate with 25KHz and 8.33KHz channel spacing. The radio recognizes frequencies entered in ICAO format and automatically adjusts to the correct channel spacing. For multichannel operation up to 100 preset frequency channels can be stored in the radio for immediate recall; any combination of 8.33KHz and 25KHz channel spacing can be stored.

Transmitter RF characteristics:

• Output Impedance: 50 Ohms
• RF power output: The RF carrier output is adjustable in 1W steps from 5 W to 50 W.Output power is automatically controlled under the following conditions:
• Frequency range
• Low supply voltage
• High VSWR
• High RF PA temperature
• Rise Time
• Duty Cycle
• channel spacing
• offset carrier
• Harmonic outputs
• spurious outputs: The spurious outputs are less than -46dBm for modulation depths upto 90%, measured at greater than 500KHz from carrier in the frequency range 9KHz to 4GHz. There are no coherent spurious outputs above the spectral mask at less than 500KHz.
• Inter-modulation

Transmitter modulation characteristics:

• Modulation Depth
• Hum and Noise
• Frequency Response
• Distortion
• Residual FM
• VOGAD (AM-Voice only): TheVOGAD has an operational range of 30dB with the threshold level set at 10dB below the average speech line level setting. Within the VOGAD range the modulation depth remains at the set level +/- 10%.

Transmitter Control:

• Audio inputs: Audio can be  connected via the 600 ohm balanced line inputs.
• PTT: The transmitter can also be keyed via a direct PTT  input, via phanton keying superimposed on the audio lines and through PTT tone signalling over the audio lines.
• PTT Time out: The PTT time out period is adjustable from 2 to 510 seconds in 2 seconds of steps or it can be disabled.
• PCM Voice: Digitized voice can be  connected to the transmitter via the E1 or IP interfaces. 
• E1-64kbit/sec digitized 8-bit A-law encoded PCM voice can be connected to the transmitter via the T1/E1 connector. Audio uses TS1 and keying is achieved using the four associated CAS bits on TS16.
• VOIP- 64kbit/sec digitized 8-bit A-law encoded PCM voice can be connected to the transmitter via the IP connector using VOIP Ethernet protocols.

VDL Mode 2:

VDL mode 2 uses CSMA differentially encoded 8-phase shift keying (D8PSK) using a raised cosine filter with alpha = 0.6. Information is differentially encoded with 3 bits per symbol transmitted as changes in phase rather than absolute phase. The data stream is divided into groups of 3 consecutive data bits, least significant bit first. Zeros are padded to the end of transmissions if needed for the final channel symbol.

 VDL mode 2 parameters are identical to AM-Voice mode with the following exceptions.

• RF power output
• RF power Rise Time
• RF Power Decay Time
• Channel Spacing
• Harmonic Outputs 
• Spurious Outputs

VDL mode 2 modulation characteristics:

• Modulation rate:  The symbol rate is 10500 symbols/second, resulting in a nominal bit rate of 31500 bits/sec.
• RMS Phase Error: The RMS phase error is less than 3 degree. The error magnitude is less than 6 %.

Color code for standard RJ 45:

Color     Abbreviation
White    W
Red        R
Black     BK
Yellow   Y
Blue       B
Grey       G
Orange   O
Green     G
Brown    BR
Violet     V

Radio Communication Frequency used in Nepali Aviation
Kathmandu

• Ground(GND/SMC FC/CD)   121.9MHz/121.75MHz
• Tower(TWR)[Main/Standby]   118.1/118.5MHz
• Area Control (ACC)[Main/Standby]   126.5/124.7MHz
• Approach Control (APP)[Main/Standby]   120.6/125.1MHz
• Digital Air Traffic Information System(D-ATIS)   127MHz
• Emergency(EMG)   121.5MHz
• SSB EAST: 5805.5KHz /6607.0KHz
• SSB WEST:5858.0KHz

Outside Kathmandu 

Only Tower (TWR)

Bajhang (VNBG)   122.50MHz

Bajura(VNBR)   122.50MHz

Bhairahawa(VNBW)   122.50MHz

Bharatpur(VNBP)   122.30MHz

Bhojpur(VNBJ)   122.30MHz

Biratnagar(VNVT)   123.80MHz

Bhojpur(VNBJ)  122.30MHz

Chandragadi(VNCG)  122.50MHz

Dang(VNDG)  122.30MHz

Dhangadi(VNDH)  122.30MHz

Dolpa(VNDP)  122.50MHz

Janakpur(VNJP)  122.50MHz

Jomsom(VNJS)  122.50MHz

Jumla(VNJL)  122.50MHz

Kangeldanda(VNKL)  122.30MHz

Khanidanda(VNKD)  122.50MHz

Lamidanda(VNLD)  122.50MHz

Lukla(VNLK)  122.30MHz

Mahendranagar(VNMN)  122.30MHz

Manang(VNMA)  118.30MHz

Meghauli(VNMG)  122.50MHz

Nepalganj(VNNG)  118.30MHz

Palpa(VNPL)  122.50MHz

Pokhara(VNPK)  123.80MHz

Rajbiraj(VNRB)  118.30MHz

Ramechhap(VNRC)  122.50MHz

Rara(VNRR)  122.50MHz

Rukum(chaujahari)(VNCI)  122.50MHz

Rumjatar(VNRT) 122.30MHz

Salley(VNSL)  122.50MHz

Sanfebagar(VNSR)  122.50MHz

Simara(VNSI)  118.30MHz

Simikot(VNST)  122.50MHz

Surkhet(VNST) 122.50MHz

Thamkharka(VNTH)  122.30MHz

Tumlingtar(VNTR)  123.95MHz

Taplejung(VNTJ)  122.50MHz