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RY (test Signal)
RYRYRYRY... is a character string that was widely used to test a five-level teleprinter or RTTY channel. The characters ''R'' and ''Y'' are "01010" and "10101" in 5-bit ITA2 code, also known as Baudot. Thus they are Boolean complements of each other. Switching between the two characters is a stressful test for electromechanical teleprinters. Repeated over and over, ''RYRYRYRY...'' outputs a carrier wave that regularly and rapidly shifts back and forth in frequency. Test tapes were easily made with a repeating RY sequence. These were used by technicians to align the bias adjustment on equipment such as the 43A1 carrier channel terminal This signal pattern also provided a test for signal polarity; if polarity was reversed, the test signal would print as "SG". The corresponding string of complementary characters in 7-bit ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleprinter
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point (telecommunications), point-to-point and point-to-multipoint communication, point-to-multipoint configurations. Initially, from 1887 at the earliest, teleprinters were used in telegraphy. Electrical telegraphy had been developed decades earlier in the late 1830s and 1840s, then using simpler Morse key equipment and telegraph operators. The introduction of teleprinters automated much of this work and eventually largely replaced skilled labour, skilled operators versed in Morse code with Data entry clerk, typists and machines communicating faster via Baudot code. With the development of early computers in the 1950s, teleprinters were adapted to allow typed data to be sent to a computer, and responses printed. Some teleprinter models could also be used to create punched tape for Compute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioteletype
Radioteletype (RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link. Radioteletype evolved from earlier landline teleprinter operations that began in the mid-1800s. The US Navy Department successfully tested printing telegraphy between an airplane and ground radio station in 1922. Later that year, the Radio Corporation of America ( RCA) successfully tested printing telegraphy via their Chatham, Massachusetts, radio station to the RMS ''Majestic''. Commercial RTTY systems were in active service between San Francisco and Honolulu as early as April 1932 and between San Francisco and New York City by 1934. The US military used radioteletype in the 1930s and expanded this usage during World War II. From the 1980s, teleprinters were replaced by personal computers (PCs) running software to emulate teleprinters. The term radioteletype is used to describe both the or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baudot Code
The Baudot code () is an early character encoding for telegraphy invented by Émile Baudot in the 1870s. It was the predecessor to the International Telegraph Alphabet No. 2 (ITA2), the most common teleprinter code in use before ASCII. Each character in the alphabet is represented by a series of five bits, sent over a communication channel such as a telegraph wire or a radio signal by asynchronous serial communication. The symbol rate measurement is known as baud, and is derived from the same name. History Baudot code (ITA1) In the below table, Columns I, II, III, IV, and V show the code; the Let. and Fig. columns show the letters and numbers for the Continental and UK versions; and the sort keys present the table in the order: alphabetical, Gray and UK Baudot developed his first multiplexed telegraph in 1872 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boolean Logic
In mathematics and mathematical logic, Boolean algebra is a branch of algebra. It differs from elementary algebra in two ways. First, the values of the variable (mathematics), variables are the truth values ''true'' and ''false'', usually denoted by 1 and 0, whereas in elementary algebra the values of the variables are numbers. Second, Boolean algebra uses logical operators such as Logical conjunction, conjunction (''and'') denoted as , disjunction (''or'') denoted as , and negation (''not'') denoted as . Elementary algebra, on the other hand, uses arithmetic operators such as addition, multiplication, subtraction, and division. Boolean algebra is therefore a formal way of describing logical operations in the same way that elementary algebra describes numerical operations. Boolean algebra was introduced by George Boole in his first book ''The Mathematical Analysis of Logic'' (1847), and set forth more fully in his ''An Investigation of the Laws of Thought'' (1854). According to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASCII
ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control characters a total of 128 code points. The set of available punctuation had significant impact on the syntax of computer languages and text markup. ASCII hugely influenced the design of character sets used by modern computers; for example, the first 128 code points of Unicode are the same as ASCII. ASCII encodes each code-point as a value from 0 to 127 storable as a seven-bit integer. Ninety-five code-points are printable, including digits ''0'' to ''9'', lowercase letters ''a'' to ''z'', uppercase letters ''A'' to ''Z'', and commonly used punctuation symbols. For example, the letter is represented as 105 (decimal). Also, ASCII specifies 33 non-printing control codes which originated with ; most of which are now obsolete. The control cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Telecommunications
The history of telecommunication began with the use of smoke signals and drum (communication), drums in Africa, Asia, and the Americas. In the 1790s, the first fixed semaphore line, semaphore systems emerged in Europe. However, it was not until the 1830s that electrical telecommunication systems started to appear. This article details the history of telecommunication and the individuals who helped make telecommunication systems what they are today. The history of telecommunication is an important part of the larger history of communication. Ancient systems and optical telegraphy Early telecommunications included smoke signals and drum (communication), drums. Talking drums were used by natives in Africa, and smoke signals in North America and China. These systems were often used to do more than announce the presence of a military camp. In Azazel#Rabbinical Judaism, Rabbinical Judaism a signal was given by means of kerchiefs or flags at intervals along the way back to the high pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Test Items
Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), a Russian film * ''Test'' (2025 film), an Indian sports drama * Test (group), a jazz collective * ''Tests'' (album), a 1998 album by The Microphones * ''Testing'' (album), an album by ASAP Rocky Computing * .test, a reserved top-level domain * Software testing * test (Unix), a Unix command for evaluating conditional expressions * TEST (x86 instruction), an x86 assembly language instruction People * Test (wrestler), ring name for Andrew Martin (1975–2009), Canadian professional wrestler * John Test (1771–1849), American politician * Zack Test (born 1989), American rugby union player Science and technology * Experiment, a procedure carried out in order to test a hypothesis * Statistical hypothesis test, techniques to reach c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
