Automatic Identification System
АСОУ/ИТС)
What is an engineer on automated systems of information
Processing and control.
Text 1.
I study at North Caucasus Federal University. I’m a second-year student of tuition
by correspondence. My future specialty will be connected with computer systems
of information processing. The course of studies lasts 5 years and gives deep theoretical knowledge and practical skills of a specific job.
After graduating from the university, I’ll be an engineer in the field of computer technologies. I always wanted to work in the computer industry because its great advantage is in advanced developing technologies. I have already known a lot about simple computers and electronic digital computers. Today a new generation of modern computers is on service of all mankind.
Computers play a very important role in the modern life and are provided with hardware to improve communication. Millions of people around the world use the Internet, searching for information on different topics including art, business, government, news, informatics, international affairs, policy etc. .
People communicate through electronic mail, discussion groups, chat channels and other means of informational exchange. They share information, make commercial and business transactions. All this activity is possible because thousands of networks are connected to the Internet.
What’s information technology? Information technology studies the use of electronic equipment and computers in storing, analyzing and distributing information of all kinds, including words, numbers and pictures.
To know computers well we should know the programming languages, software and new programs, algorithms of computer work. Our aim is to study hard and master our knowledge.
Modern semiconductor technologies.
Text 2.
The first subdivision between modern semiconductor technologies is between bipolar semiconductor (BS) and metal oxide semiconductor (MOS), which are derived from normal transistors and field effect transistors respectively. As far as the user is concerned, the most important distinctions between the two are the following: BS circuits are basically low impedance devices which consume more power, cannot be packed so densely onto a chip
and are faster, whereas MOS circuits are high impedance devices which consume less power, are suitable for high density packing and are not so fast. The subdivisions of these two basic technologies obviously contain their own spread of characteristics, which lead to a blurring of the differences outlined above.
|
|
|
Transistor-transistor-logic (TTL), the best known bipolar logic family, is extremely popular for general purpose logic. Wide ranges of simple to medium complexity circuits are available such as NAND gates, registers, decoders, arithmetic units etc. There are several variations of standard TTL, the original ones being low power and high power TTL. Low power TTL is suitable for lower speed systems and high power TTL for higher speed circuits. These two variations are not as popular as standard TTL. Another important variation is Schottky TTL, which gives a greatly improved speed without increased power consumption. Nowadays, the Schottky process is usually applied to lower power TTL, saving of 80% in power consumption.
Emitter-coupled-logic (ECL) is an extremely fast bipolar technology which owes its speed to the non-saturating circuit principles employed. It’s rarely used in microcomputer systems, and will not normally be encountered. Its lack of popularity probably stems from the fact that it is difficult to use it.
Integrated-injection logic (I²L) or merged-transistor logic (MTL) is a bipolar technology which has many of the advantages of MOS circuits. It is fast and yet achieves both low power consumption and a high packing density. It is fairly new and is challenging MOS for microprocessor and memory applications.
P-channel MOS (PMOS) was the first technology to be used extensively and it is slowly compared with other MOS technologies and has been replaced by NMOS in most new designs. N- channel MOS (NMOS) is the technology in which most microprocessors are now fabricated. Modern developments in this technology are making it approach bipolar technologies in performance, whilst offering very high circuit densities. Complementary MOS (CMOS) employs both p-channel and N-channel field effect transistors on the chip and is thus a little bit more difficult to make. How-ever, it has the advantage of very low po-
power consumption and is therefore ideal for battery operated circuits. It is used both as a standard logic family in competition to TTL and as a microprocessor technology. Unlike other technologies, CVJS doesn’t require a highly stabilized power supply. When the correct supply voltage is used, it can be interfaced to TTL fairly easily.
|
|
|
Automatic Identification System
Text 3
The Automatic Identification System (AIS) is a system used by ships and Vessel Traffic Services (VTS) principally for identification and locating vessels. AIS helps to resolve the difficulty of identifying ships when not in sight (e.g. in fog, at distance, etc.) by providing a means for ships to exchange identification, position, course, speed, and other ship data with all other nearby ships and VTS stations. It works by integrating a standardized VHF transceiver system with an electronic navigation system, such as a LORAN-C (LOngRAnge Navigation Version C) or Global Positioning System receiver, and other navigational sensors on board ship (gyrocompass, rate of turn indicator, etc.).
The International Maritime Organization's (IMO) International Convention for the Safety of Life at Sea (SOLAS) requires AIS to be fitted aboard international voyaging ships of 300 or more gross tonnage, and all passenger ships regardless of size. It is estimated that more than 40,000 ships currently carry AIS class A equipment.[citation needed]
Each AIS transponder consists of one VHF transmitter, two VHF TDMA receivers, one VHF Digital Selective Calling (DSC) receiver, and links to shipboard display and sensor systems via standard marine electronic communications (such as NMEA 0183, also known as IEC 61162). Timing is vital to the proper synchronization and slot mapping for a Class A unit. Therefore, every unit is required to have an internal global navigation satellite system (e.g. GPS) receiver.[4] This internal receiver may also be used for position information. However, position is typically provided by an external receiver such as GPS, LORAN or an inertial navigation system and the internal receiver is only used as a backup for position information. Other information broadcast by the AIS, if available, is electronically obtained from shipboard equipment through standard marine data connections. Heading information and course and speed over ground would normally be provided by all AIS-equipped ships. Other information, such as rate of turn, angle of heel, pitch and roll, and destination and ETA could also be provided.
|
|
|
The AIS transponder normally works in an autonomous and continuous mode, regardless of whether it is operating in the open seas or coastal or inland areas. Transmissions use 9600 bit/s Gaussian minimum shift keying (GMSK) modulation over 25 or 12.5 kHz channels using the High-level Data Link Control (HDLC) packet protocol. Although only one radio channel is necessary, each station transmits and receives over two radio channels to avoid interference problems, and to allow channels to be shifted without communications loss from other ships. The system provides for automatic contention resolution between itself and other stations, and communications integrity is maintained even in overload situations.
Дата добавления: 2018-05-09; просмотров: 185; Мы поможем в написании вашей работы! |
Мы поможем в написании ваших работ!