Primary Surveillance Radar Day 2

is the time it takes for a data packet to be received by the remote computer

Latency

Can be accomplished by both channel redundancy, or natural redundancy though message repetition, or both.

Redundancy

In order to achieve the maximum data throughput and minimum transmission delay, the size of the frame information field should be dynamically determined by transmission parameters such as __________ of channel used

Quality

There is a definite requirement to use a Data Link Control (DLC) procedure to support the exchange of radar related data (such as using the ASTERIX message structure).Such DLC should provide _______

Error Detection

is a coding scheme that repeats the bits across a channel to achieve error-free communication.

Repetition codes

is a bit that is added to a group of source bits to ensure that the number of set bits (i.e., bits with value 1) in the outcome is even or odd

Parity Bits

is a modular arithmetic sum of message code words of a fixed word length (e.g., byte values)

Checksums

include parity bits, check digits, and longitudinal redundancy checks

Checksum schemes

is a non-secure hash function designed to detect accidental changes to digital data in computer networks; as a result, it is not suitable for detecting maliciously introduced errors.

Cyclic redundancy checks (CRCs)

are particularly easy to implement in hardware, and are therefore commonly used in digital networks and storage devices such as hard disk drives.

CRCs

has favorable properties that make it well suited for detecting burst errors.

cyclic code

ASTERIX stands for

All Purpose Structured Eurocontrol Radar Information Exchange

The data exchanged over the communication medi um between the different users shall be classified into ___________

Data Categories

Data Categories for standard civil and military applications;

Data Categories 000 to 127

Data Categories reserved for special military applications;

Data Categories 128 to 240

Data Categories used for both civil and military non-standard applications.

Data Categories 241 to 255

In ASTERIX, the purpose of such a classification shall be to:

1. allow easy identification of data

2. Facilitate the dispatching of the data to the appropriate application task in the receiving unit

3. Establish a certain hierarchy among the data based on their priority.

is the smallest unit of information defined and standardized. For each Data Category, a Catalogue of Data Items shall be standardized.

Data Item

True or False: Each Data Item shall be given a unique reference which unambiguously identifies this item in the relevant catalogue.

True

The Data Item symbolic reference shall consist of an eight-character reference of the form

Innn/AAp

indicates that this represents a Data Item

I

is a three digit decimal number which Data Category to which this indicates the Data Item belongs (000 to 255)

nnn

is a two digit decimal number which indicates the type of data (position, speed)

AA

is a one digit decimal number which may indicate up to 10 different representations of the Data Item.

p

For the purpose of communication, the various Data Items shall be assigned to _______, each having a length of an integral number of octets and referenced by a Field Reference Number (FRN)

Data Fields

For the purpose of communication, the various Data Items shall be assigned to Data Fields, each having a length of an integral number of octets and referenced by a __________

Field Reference Number (FRN)

The correspondence between Data Items and Data Fields shall be standardized for each relevant application by the ___________ concerning this application.

User Application Profile (UAP)

is the mechanism whereby the correspondence between Data Items and Data Fields shall be standardized for each application making use of the ASTERIX message structure.

User Application Profile (UAP)

shall be considered as a control table attached to the message assembly/disassembly programs resident in the relevant processing systems.

User Application Profile (UAP)

It essentially defines which of the catalogued Data Items will be used, their length (where applicable), their assignment to the Data Fields and any specific requirements which need to be standardized for the successful transmission and interpretation of the messages

User Application Profile

shall contain the information of the same Data Category needed by a given application

Record

field of variable length, indicating which Data Fields are pre sent in the Record and in which order

Field Specification (FSPEC)

The length of a Record is implicit from its structure and shall always be a multiple of an ______

octet

comprising a fixed number of octets.

Fixed length Data Fields

containing a primary part of predetermined length, immediately followed by a number of secondary parts, each of predetermined length.

Extended length Data Fields (Variable length)

The Data Block shall consist of:

1. One-octet field Data Category (CAT)

2. Two-octet field Length Indicator (LEN)

3. One or more Record(s) containing data of the same category.

Each Record is of variable length but aligned on an octet boundary. The length of a () is thus variable but shall always be a multiple of an octet.

data block

True or False: The maximum size of a Data Block shall be mutually agreed between data sources and users.

True

True or False: Each Data Field is associated with one and only one Data Item, as defined by the UAP.

True

True or False: The length of a Record is implicit from its structure and shall always be a multiple of an octet.

True

shall have either an implicit or an explicit length (multiple of an octet) depending on the Data Item assigned to each of them.

Standard Data Fields

The length of such Data Fields shall be either fixed or variable.

Implicit Length Data Fields

Repetitive Data Fields, being of a variable length, comprising a one-octet ______ signalling the presence of N consecutive sub-fields each of the same pre-determined length.

Field Repetition Indicator (REP)

These Data Fields shall start with a one-octet length indicator giving the total field length in octets including the length indicator itself.

Explicit Length Data Fields

In order to achieve maximum transmission efficiency the ASTERIX message structure allows the ________ in a way to achieve the shortest possible Data Blocks.

packing of Data Fields

two complementary field sequencing methods:

1. The Ordered Field Sequencing Organisation

2. The Random Field Sequencing Organisation

shall be the standard method of Record composition.

The Ordered Field Sequencing (OFS) organisation

When Data Fields with FRNs greater than seven have to be transmitted the FSPEC extension mechanism shall be used. This is achieved by assigning a special meaning to the LSB of any FSPEC octet called ________

FX: Field Extension Indicator

shall allow the FSPEC field to be kept short, even if Data Fields with a low rank order (i.e., high FRN) have to be occasionally exchanged.

Random Field Sequencing (RFS) Organization

One SAC shall be assigned to each country. SAC stands for

System Area Codes

True or False: One country can have multiple SAC used for Civilian and Military.

True

The individual () shall be assigned by the National Administration concerned within the area identified by the SAC and will be published in the ASTERIX Standard as soon as they are notified to the Surveillance Task Force on Radar Data Exchange.

System Identification Code (SIC)

Radar Service Messages

(CAT-02)

Three types of radar service messages

1. Sector Crossing Messages

2. North and South Marker Messages

3. Activation/Stop of Blind Zone Filtering Messages

The transmission of such messages shall be synchronized (possibly with some delay) with the antenna rotation.

Sector Crossing Messages

When these messages are used, they shall signal, independently of the sector crossing messages and as quickly as possible, the crossing of the local geographical North (respectively South) azimuth by the antenna.

North and South Marker Messages

The maximum length of the corresponding FSPEC is

two octets

identification of the radar station from which the data are received.

Data Source Identifier

this data item allows for a more convenient handling of the messages at the receiver side by further defining the type of transaction.

Message Type

eight more significant bits of the antenna azimuth defining a particular azimuth sector.

Sector Number

absolute time stamping expressed as UTC time.

Time of Day

Radar target reports shall be transmitted either in the form of () or () generated by a local tracking system at the radar site.

plots or tracks

RMCDE stands for

Surveillance Message Conversion and Distribution Equipment

is the name of a system designed to distribute the surveillance information to a community of user systems.

RMCDE

is a Multibus II based multiprocessor system composed of a number of subsystems (processor and IO boards) connected through a parallel data bus.

RMCDE

offers additional capabilities to manage the surveillance data flow like data validation, conversion and filtering.

RMCDE

The main component in RADNET

RMCDE

The combination of harmonisation, MUAC data needs and the emergence of computer network technology led the way to the development of an X.25 based surveillance data distribution network.

RADNET

The format for surveillance data

ASTERIX

takes care of the data routing within the network and acts as a gateway between sensors and ATC users.

RMCDE

is one of the first systems in the ATC domain that provided what now would be called publish/subscribe services.

RMCDE

True or False: Each user in connected to RADNET can subscribe to surveillance data provided by any of the other RMCDEs in the network.

True

is a bit-oriented code transparent synchronous data link layer protocol developed by the International Organization for Standardization (ISO).

High-Level Data Link Control (HDLC)

is a group of protocols or rules for transmitting data between network points (sometimes called nodes).

High-Level Data Link Control (HDLC)

Data is organized into a unit called () and sent across a network to a destination that verifies its successful arrival.

frame

also manages the flow or pacing at which data is sent.

High-Level Data Link Control (HDLC) protocol

is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.

X.25

consists of packet-switching exchange (PSE) nodes as the networking hardware, and leased lines, plain old telephone service connections or ISDN connections as physical links.

X.25 WAN

is a family of protocols that was popular during the 1980s with telecommunications companies and in financial transaction systems such as automated teller machines.

X.25

was originally defined by the International Telegraph and Telephone Consultative Committee (CCITT, now ITU-T) in a series of drafts and finalized in a publication known as The Orange Book in 1976.

X.25

is a family of computer networking technologies commonly used in local area networks (LANs) and metropolitan area networks (MANs).

Ethernet

It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3, and has since been refined to support higher bit rates and longer link distances.

Ethernet

uses coaxial cable as a shared medium, while the newer Ethernet variants use twisted pair and fiber optic links in conjunction with hubs or switches

10BASE5 Ethernet

Systems communicating over Ethernet divide a stream of data into shorter pieces called ______

frames

As per the OSI model, Ethernet provides services up to and including the________

data link layer

is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km (124 miles).

FDDI (Fiber Distributed Data Interface)

is based on the token ring protocol

FDDI protocol

FDDI protocol is based on the __________ protocol.

token ring

frequently used on the backbone for a wide area network (WAN)

FDDI

Message type code for Polar Vector

(001)

Message type code for SOP

254

Message type code for EOP

255

Category for Weather Messages

008

PA stands for

PREAMBLE

SD stands for

Start of Delimiter

FC stands for

Frame Control

DA/SA stands for

Destination/Source Address

PDU stands for

Protocol Data Unit

FCS stands for

Frame Check Sequence (CRC32)

ED/FS stands for

End Delimiter/Frame Status