|
FT8 Video
FT8 (short for Franke-Taylor design, 8-FSK modulation) is a Frequency-shift keying, frequency shift keying digital List of amateur radio modes, mode of radio communication used by some amateur radio operators worldwide. Following release on June 29, 2017, by its creators Joseph Hooton Taylor Jr., Joe Taylor, K1JT, and Steve Franke, K9AN, along with the software package WSJT (amateur radio software), WSJT, FT8 was adopted rapidly, becoming the most popular digital mode recorded by automatic spotting networks such as PSK Reporter within 2 years. Introduction FT8 is a popular form of digital weak signal communication used primarily by amateur radio operators to communicate on amateur radio bands with a majority of traffic occurring on the High frequency, HF amateur bands. The mode offers operators the ability to communicate despite unfavorable conditions such as those seen during low Solar cycle, solar activity, high RF noise, or with QRP operation, low transmitter power. With adva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sideband
In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, that are the result of the modulation process. The sidebands carry the information transmitted by the radio signal. The sidebands comprise all the spectral components of the modulated signal except the carrier. The signal components above the carrier frequency constitute the upper sideband (USB), and those below the carrier frequency constitute the lower sideband (LSB). All forms of modulation produce sidebands. Sideband creation We can illustrate the creation of sidebands with one trigonometric identity: :\cos(A)\cdot \cos(B) \equiv \tfrac\cos(A+B) + \tfrac\cos(A-B) Adding \cos(A) to both sides: :\cos(A)\cdot +\cos(B)= \tfrac\cos(A+B) + \cos(A) + \tfrac\cos(A-B) Substituting (for instance) A \triangleq 1000\cdot t and B \triangleq 100\cdot t, where t represents time: :\underbrace_\cdot \underbrace_ = \underbrace_ + \underbrace_ + \un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Amateur Radio
Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software company Computing and technology Hardware *Digital electronics, electronic circuits which operate using digital signals **Digital camera, which captures and stores digital images ***Digital versus film photography **Digital computer, a computer that handles information represented by discrete values **Digital recording, information recorded using a digital signal Socioeconomic phenomena *Digital culture, the anthropological dimension of the digital social changes *Digital divide, a form of economic and social inequality in access to or use of information and communication technologies *Digital economy, an economy based on computing and telecommunications resources *Digital rights, legal rights of access to computers or the Internet Oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FT8 Video
FT8 (short for Franke-Taylor design, 8-FSK modulation) is a Frequency-shift keying, frequency shift keying digital List of amateur radio modes, mode of radio communication used by some amateur radio operators worldwide. Following release on June 29, 2017, by its creators Joseph Hooton Taylor Jr., Joe Taylor, K1JT, and Steve Franke, K9AN, along with the software package WSJT (amateur radio software), WSJT, FT8 was adopted rapidly, becoming the most popular digital mode recorded by automatic spotting networks such as PSK Reporter within 2 years. Introduction FT8 is a popular form of digital weak signal communication used primarily by amateur radio operators to communicate on amateur radio bands with a majority of traffic occurring on the High frequency, HF amateur bands. The mode offers operators the ability to communicate despite unfavorable conditions such as those seen during low Solar cycle, solar activity, high RF noise, or with QRP operation, low transmitter power. With adva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tweet (social Media)
A tweet (officially known as a post since 2023) is a short status update on the social networking site Twitter (officially known as X since 2023) which can include images, videos, GIFs, straw polls, hashtags, mentions, and hyperlinks. Around 80% of all tweets are made by 10% of users, averaging 138 tweets per month, with the median user making only two tweets per month. Following the acquisition of Twitter by Elon Musk in October 2022, and rebranding of the site as "X" in July 2023, all references to the word "tweet" were removed from the service, changed to "post", and "retweet" changed to "repost". The terms "tweet" and "retweet" are still more popular when referring to posts on X. Content The service has experimented with changing how tweets work over the years to attract more users and to keep them on the site. The character limit was originally 140 characters when the service started, had media attachments no longer count in the mid-2010s, and doubled altogether in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forward Error Correction
In computing, telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels. The central idea is that the sender encodes the message in a redundant way, most often by using an error correction code, or error correcting code (ECC). The redundancy allows the receiver not only to detect errors that may occur anywhere in the message, but often to correct a limited number of errors. Therefore a reverse channel to request re-transmission may not be needed. The cost is a fixed, higher forward channel bandwidth. The American mathematician Richard Hamming pioneered this field in the 1940s and invented the first error-correcting code in 1950: the Hamming (7,4) code. FEC can be applied in situations where re-transmissions are costly or impossible, such as one-way communication links or when transmitting to multiple receivers in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Positioning System
The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It does not require the user to transmit any data, and operates independently of any telephone or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It provides critical positioning capabilities to military, civil, and commercial users around the world. Although the United States government created, controls, and maintains the GPS system, it is freely accessible to anyone with a GPS receiver. Overview The GPS project was started by the U.S. Department of Defense in 1973. The first prototype spacecraft was launched in 1978 an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Time Protocol
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-Network latency, latency data networks. In operation since before 1985, NTP is one of the oldest Internet protocols in current use. NTP was designed by David L. Mills of the University of Delaware. NTP is intended to synchronize participating computers to within a few milliseconds of Coordinated Universal Time (UTC). It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions. Asymmetric Routing, routes and network congestion can cause errors of 100 ms or more. The protocol is usually described in terms of a client–server model, bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WWV (radio Station)
WWV is a Shortwave radio, shortwave ("high frequency" or HF) radio station, located near Fort Collins, Colorado. It has broadcast a continuous time signal since 1945, and implements United States government frequency standards, with transmitters operating on 2.5, 5, 10, 15, 20, and 25 Hertz, MHz. WWV is operated by the U.S. National Institute of Standards and Technology (NIST), under the oversight of its Time and Frequency Division, which is part of NIST's Physical Measurement Laboratory based in Gaithersburg, Maryland. The term WWV is not an abbreviation and does not stand for anything (see WWV (radio station)#Establishment, below). WWV was established in 1919 by the Bureau of Standards in Washington, D.C., making it one of the oldest continuously-operating radio stations in the United States. NIST celebrated WWV's centennial on October 1, 2019. In 1931, the station relocated to the first of three suburban Maryland sites, before moving to a location near Fort Collins i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eb/N0
In digital communication or data transmission, E_b/N_0 (energy per bit to noise power spectral density ratio) is a normalized signal-to-noise ratio (SNR) measure, also known as the "SNR per bit". It is especially useful when comparing the bit error rate (BER) performance of different digital modulation schemes without taking bandwidth into account. As the description implies, E_b is the signal energy associated with each user data bit; it is equal to the signal power divided by the user bit rate (''not'' the channel symbol rate). If signal power is in watts and bit rate is in bits per second, E_b is in units of joules (watt-seconds). N_0 is the noise spectral density, the noise power in a 1 Hz bandwidth, measured in watts per hertz or joules. These are the same units as E_b so the ratio E_b/N_0 is dimensionless; it is frequently expressed in decibels. E_b/N_0 directly indicates the power efficiency of the system without regard to modulation type, error correction coding or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continuous Wave
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle accelerator having a continuous output, as opposed to a pulsed output. By extension, the term ''continuous wave'' also refers to an early method of radio transmission in which a sinusoidal carrier wave is switched on and off. This is more precisely called interrupted continuous wave (ICW). Information is carried in the varying duration of the on and off periods of the signal, for example by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves were also known as "undamped waves", to distinguish this method from damped wave signals produced by earlier ''spark gap'' type transmitters. Radio Transmissions before CW Very early radio transmitters used a spark gap to produce radio-frequency oscillations i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
