Things and Stuff Wiki - An organically evolving personal wiki knowledge base with an on-the-fly taxonomy containing topic outlines, descriptions, notes and breadcrumbs, with links to sites, systems, software, manuals, organisations, people, articles, guides, slides, papers, books, comments, videos, screencasts, webcasts, scratchpads and more. Quality varies drastically. Use the Table of Contents to navigate long pages, use the Small-ToC and Tiny-ToC header links on longer pages. Not that mobile friendly atm. #tnswiki on freenode IRC for feedback chat, or see About for login and further information. / et / em
- 1 General
- 2 Modulation
- 3 Signals
- 4 Amateur radio
- 5 Antenna
- 6 Radio control
- 7 Data
- 8 Mobile phone
- 9 Software-defined radio
- 10 Podcasts
- 11 RFID
- https://en.wikipedia.org/wiki/Wireless_communication - or sometimes simply wireless, is the transfer of information or power between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio waves. With radio waves distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones.
Somewhat less common methods of achieving wireless communications include the use of other electromagnetic wireless technologies, such as light, magnetic, ...used from about 1890 for the first radio transmitting and receiving technology, as in wireless telegraphy, until the new word radio replaced it around 1920. The term was revived in the 1980s and 1990s mainly to distinguish digital devices that communicate without wires, such as the examples listed in the previous paragraph, from those that require wires or cables. This became its primary usage in the 2000s, due to the advent of technologies such as LTE, LTE-Advanced, Wi-Fi and Bluetooth.
Wireless operations permit services, such as long-range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and receivers, remote controls, etc.) which use some form of energy (e.g. radio waves, acoustic energy,) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances.
- https://en.wikipedia.org/wiki/Wireless_telegraphy - the transmission of telegraphy signals from one point to another by means of an electromagnetic, electrostatic or magnetic field, or by electrical current through the earth or water. The term is used synonymously for radio communication systems, also called radiotelegraphy, which transmit telegraph signals by radio waves. When the term originated in the late 19th century it also applied to other types of experimental wireless telegraph communication technologies, such as conduction and induction telegraphy. Radio telegraphy often used manually-sent Morse code; radioteletype (RTTY) always uses mechanically generated and recorded characters.
- https://en.wikipedia.org/wiki/Link_budget - accounting of all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide, fiber, etc.) to the receiver in a telecommunication system. It accounts for the attenuation of the transmitted signal due to propagation, as well as the antenna gains, feedline and miscellaneous losses. Randomly varying channel gains such as fading are taken into account by adding some margin depending on the anticipated severity of its effects. The amount of margin required can be reduced by the use of mitigating techniques such as antenna diversity or frequency hopping.
A simple link budget equation looks like this: Received Power (dB) = Transmitted Power (dB) + Gains (dB) − Losses (dB). Note that decibels are logarithmic measurements, so adding decibels is equivalent to multiplying the actual numeric ratios.
- https://en.wikipedia.org/wiki/Transmitter - an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves.
- https://en.wikipedia.org/wiki/Radio_receiver - an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves (electromagnetic waves) and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.
- https://en.wikipedia.org/wiki/Frequency_agility - the ability of a radar system to quickly shift its operating frequency to account for atmospheric effects, jamming, mutual interference with friendly sources, or to make it more difficult to locate the radar broadcaster through radio direction finding. The term can also be applied to other fields, including lasers or traditional radio transceivers using frequency-division multiplexing, but it remains most closely associated with the radar field and these other roles generally use the more generic term "frequency hopping".
- https://en.wikipedia.org/wiki/Call_sign - also known as a call name' or call letters, historically as a call signal, or abbreviated as a call, is a unique designation for a transmitter station. In North America, they are used for all FCC-licensed transmitters. A call sign can be formally assigned by a government agency, informally adopted by individuals or organizations, or even cryptographically encoded to disguise a station's identity. The use of call signs as unique identifiers dates to the landline railroad telegraph system. Because there was only one telegraph line linking all railroad stations, there needed to be a way to address each one when sending a telegram. In order to save time, two-letter identifiers were adopted for this purpose. This pattern continued in radiotelegraph operation; radio companies initially assigned two-letter identifiers to coastal stations and stations aboard ships at sea. These were not globally unique, so a one-letter company identifier (for instance, 'M' and two letters as a Marconi station) was later added. By 1912, the need to quickly identify stations operated by multiple companies in multiple nations required an international standard; an ITU prefix would be used to identify a country, and the rest of the call sign an individual station in that country.
- A.T.V - probably the most extensive aerials site on the Internet and in 2017 we had 370,000 visitors with 810,000 page hits. In fact even “the trade” use this site. Actually, even we use it if we want to check up on anything to do with aerials !
- https://en.wikipedia.org/wiki/Antenna_feed - refers to several slightly different parts of an antenna system: The antenna feed is the wire or cabling (transmission line) that connects between the antenna and the radio, specifically called the feed line; The antenna feed is the location on the antenna where the feedline from the receiver or transmitter connects or attaches; The antenna feed is the matching system at the attachment point that converts the feedline impedance to the antenna’s intrinsic impedance, and makes any balanced-to-unbalanced conversion (if necessary).
- https://en.wikipedia.org/wiki/Feed_horn - In parabolic antennas such as satellite dishes, a feed horn (or feedhorn) is a small horn antenna used to convey radio waves between the transmitter and/or receiver and the parabolic reflector. In transmitting antennas, it is connected to the transmitter and converts the radio frequency alternating current from the transmitter to radio waves and feeds them to the rest of the antenna, which focuses them into a beam. In receiving antennas, incoming radio waves are gathered and focused by the antenna's reflector on the feed horn, which converts them to a tiny radio frequency voltage which is amplified by the receiver. Feed horns are used mainly at microwave (SHF) and higher frequencies.
- https://en.wikipedia.org/wiki/Horn_antenna - or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz. They are used as feed antennas (called feed horns) for larger antenna structures such as parabolic antennas, as standard calibration antennas to measure the gain of other antennas, and as directive antennas for such devices as radar guns, automatic door openers, and microwave radiometers. Their advantages are moderate directivity, low standing wave ratio (SWR), broad bandwidth, and simple construction and adjustment.
- https://en.wikipedia.org/wiki/Radio_spectrum - the part of the electromagnetic spectrum from 3 Hz to 3000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are extremely widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU).
Different parts of the radio spectrum are appointed by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum).
- https://en.wikipedia.org/wiki/Extremely_low_frequency - electromagnetic radiation (radio waves) with frequencies from 3 to 30 Hz, and corresponding wavelengths of 100,000 to 10,000 kilometers, respectively. In atmospheric science, an alternative definition is usually given, from 3 Hz to 3 kHz. In the related magnetosphere science, the lower frequency electromagnetic oscillations (pulsations occurring below ~3 Hz) are considered to lie in the ULF range, which is thus also defined differently from the ITU radio bands.
ELF radio waves are generated by lightning and natural disturbances in Earth's magnetic field, so they are a subject of research by atmospheric scientists. Because of the difficulty of building antennas that can radiate such long waves, ELF frequencies have been used in only a very few human-made communication systems. ELF waves can penetrate seawater, which makes them useful in communication with submarines. The US, Russia, and India are the only nations known to have constructed ELF communication facilities. The U.S. facilities were used between 1985 and 2004 but are now decommissioned. ELF waves can also penetrate significant distances into earth or rock, and "through-the-earth" underground mine communication systems use frequencies of 300 to 3000 Hz. The frequency of alternating current flowing in electric power grids, 50 or 60 Hz, also falls within the ELF band, making power grids an unintentional source of ELF radiation.
- https://en.wikipedia.org/wiki/Super_low_frequency - frequency range between 30 hertz and 300 hertz. They have corresponding wavelengths of 10,000 to 1,000 kilometers. This frequency range includes the frequencies of AC power grids (50 hertz and 60 hertz). Another conflicting designation which includes this frequency range is Extremely Low Frequency (ELF), which in some contexts refers to all frequencies up to 300 hertz.
- https://en.wikipedia.org/wiki/Ultra_low_frequency - frequency range of electromagnetic waves between 300 hertz and 3 kilohertz. In magnetosphere science and seismology, alternative definitions are usually given, including ranges from 1 mHz to 100 Hz, 1 mHz to 1 Hz, 10 mHz to 10 Hz. Frequencies above 3 Hz in atmosphere science are usually assigned to the ELF range.
- https://en.wikipedia.org/wiki/Very_low_frequency - radio frequencies (RF) in the range of 3 kHz to 30 kHz and corresponding wavelengths from 100 to 10 kilometres
- https://en.wikipedia.org/wiki/Low_frequency - LF is the ITU designation for radio frequencies (RF) in the range of 30 kHz–300 kHz. As its wavelengths range from ten kilometres to one kilometre, respectively, it is also known as the kilometre band or kilometre wave. LF radio waves exhibit low signal attenuation, making them suitable for long-distance communications. In Europe and areas of Northern Africa and Asia, part of the LF spectrum is used for AM broadcasting as the "longwave" band. In the western hemisphere, its main use is for aircraft beacon, navigation (LORAN), information, and weather systems. A number of time signal broadcasts are also broadcast in this band.
- https://en.wikipedia.org/wiki/Longwave - also written as long wave (in British and American parlance) or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with relatively long wavelengths. The term is an historic one, dating from the early 20th century, when the radio spectrum was considered to consist of long (LW), medium (MW) and short (SW) radio wavelengths. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'.
In contemporary usage, the term longwave is not defined precisely, and its meaning varies across the world. Most commonly, it refers to radio wavelengths longer than 1000 metres; frequencies less than 300 kilohertz (kHz), including the International Telecommunications Union's (ITU's) low frequency (LF) (30–300 kHz) and very low frequency (VLF) (3–30 kHz) bands. Sometimes, part of the medium frequency (MF) band (300–3000 kHz) is included.
- https://en.wikipedia.org/wiki/Medium_wave - the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz, using channels spaced every 9 kHz, and in North America an extended MW broadcast band goes from 535 kHz to 1705 kHz, using 10 kHz spaced channels.
- https://en.wikipedia.org/wiki/Shortwave_radio - radio transmission using shortwave frequencies, generally 1.6–30 MHz (187.4–10.0 m), just above the medium wave AM broadcast band.
Radio waves in this band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or skip propagation. Thus shortwave radio can be used for very long distance communication, in contrast to radio waves of higher frequency which travel in straight lines (line-of-sight propagation) and are limited by the visual horizon, about 40 miles. Shortwave radio is used for broadcasting of voice and music to shortwave listeners over very large areas; sometimes entire continents or beyond. It is also used for military over-the-horizon radar, diplomatic communication, and two-way international communication by amateur radio enthusiasts for hobby, educational and emergency purposes.
- https://en.wikipedia.org/wiki/160-meter_band - top band (AM), refers to the band of radio frequencies between 1800 and 2000 kHz
- https://en.wikipedia.org/wiki/High_frequency - between 3 and 30 MHz. It is also known as the decameter band or decameter wave
- https://en.wikipedia.org/wiki/Very_high_frequency - VHF, from 30 MHz to 300 MHz
- https://en.wikipedia.org/wiki/Ultra_high_frequency - UHF, between 300 MHz and 3 GHz, also known as the decimetre band as the wavelengths range from one meter to one decimetre
- https://en.wikipedia.org/wiki/Microwave - with wavelengths ranging from one meter to one millimeter; with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often restricting the range between 1 and 100 GHz (300 and 3 mm).
The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range. It indicates that microwaves are "small", compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study.
- https://en.wikipedia.org/wiki/Super_high_frequency - SHF, between 3 GHz and 30 GHz. This band of frequencies is also known as the centimetre band or centimetre wave
- https://en.wikipedia.org/wiki/Extremely_high_frequency - EHF, from 30 to 300 gigahertz. It lies between the super high frequency band, and the far infrared band which is also referred to as the terahertz gap. Radio waves in this band have wavelengths from ten to one millimetre, giving it the name millimetre band or millimetre wave, sometimes abbreviated MMW or mmW. Millimetre-length electromagnetic waves were first investigated in the 1890s by Indian scientist Jagadish Chandra Bose.
- https://en.wikipedia.org/wiki/Terahertz_radiation - also known as submillimeter radiation, terahertz waves, tremendously high frequency, T-rays, T-waves, T-light, T-lux or THz – consists of electromagnetic waves within the ITU-designated band of frequencies from 0.3 to 3 terahertz (THz; 1 THz = 1012 Hz). Wavelengths of radiation in the terahertz band correspondingly range from 1 mm to 0.1 mm (or 100 μm). Because terahertz radiation begins at a wavelength of one millimeter and proceeds into shorter wavelengths, it is sometimes known as the submillimeter band, and its radiation as submillimeter waves, especially in astronomy.
Terahertz radiation occupies a middle ground between microwaves and infrared light waves known as the terahertz gap, where technology for its generation and manipulation is in its infancy. It represents the region in the electromagnetic spectrum where the frequency of electromagnetic radiation becomes too high to be measured digitally via electronic counters, so must be measured by proxy using the properties of wavelength and energy. Similarly, the generation and modulation of coherent electromagnetic signals in this frequency range ceases to be possible by the conventional electronic devices used to generate radio waves and microwaves, requiring the development of new devices and techniques. Photon energy in THz regime is less than band-gap of nonmetallic materials and thus THz beam can traverse through such materials. The transmitted THz beam is used for material characterization, layer inspection and developing transmission images.
- https://en.wikipedia.org/wiki/Terahertz_gap - an engineering term for a band of frequencies in the terahertz region of the electromagnetic spectrum between radio waves and infrared light for which practical technologies for generating and detecting the radiation do not exist. It is defined as 0.1 to 10 THz (wavelengths of 3 mm to 30 µm). Currently, at frequencies within this range, useful power generation and receiver technologies are inefficient and impractical.
- https://en.wikipedia.org/wiki/Far_infrared - often defined as any radiation with a wavelength of 15 micrometers (µm) to 1 mm (corresponding to a range of about 20 THz to 300 GHz), which places far infrared radiation within the CIE IR-B and IR-C bands. Different sources use different boundaries for the far infrared spectrum; for example, astronomers sometimes define far infrared as wavelengths between 25 µm and 350 µm. Visible light includes radiation with wavelengths between 400 nm and 700 nm, meaning that far infrared photons have less energy than visible light photons.
- http://www.sigidwiki.com/wiki/Signal_Identification_Guide - wiki intended to help identify radio signals through example sounds and waterfall images. Most signals are received and recorded using a software defined radio such as the RTL-SDR, Airspy, SDRPlay, HackRF, BladeRF, Funcube Dongle, USRP or others. 
AM radio ranges from 535 to 1705 kilohertz, stations are possible every 10 kHz.
- http://www.erikyyy.de/tempest/ - crt transmitter
FM radio ranges in a higher spectrum from 88 to 108 megahertz, stations are possible every 200 kHz.
- C. Crane FM2 Digital Full Spectrum FM Transmitter
- http://www.vastint.com/en-us/products/usb-rds-low-power-fm-transmitter-v-fmt212r - usb audio, minicoax
- Aareff: 100mW PLL FM Stereo Transmitter - proper
Automatic Identification System
- https://en.wikipedia.org/wiki/AIS-SART - a self-contained radio device used to locate a survival craft or distressed vessel by sending updated position reports using a standard Automatic Identification System (AIS) class-A position report. The position and time synchronization of the AIS-SART are derived from a built in GNSS receiver (e.g. GPS). Shipboard Global Maritime Distress Safety System (GMDSS) installations include one or more search and rescue locating devices. These devices may be either an AIS-SART (AIS Search and Rescue Transmitter) (from January 1, 2010), or a radar-SART (Search and Rescue Transponder).
- https://en.wikipedia.org/wiki/Automatic_link_establishment - commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications. ALE is a feature in an HF communications radio transceiver system that enables the radio station to make contact, or initiate a circuit, between itself and another HF radio station or network of stations. The purpose is to provide a reliable rapid method of calling and connecting during constantly changing HF ionospheric propagation, reception interference, and shared spectrum use of busy or congested HF channels.
- https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System - an amateur radio-based system for real time digital communications of information of immediate value in the local area. Data can include object Global Positioning System (GPS) coordinates, weather station telemetry, text messages, announcements, queries, and other telemetry. APRS data can be displayed on a map, which can show stations, objects, tracks of moving objects, weather stations, search and rescue data, and direction finding data. In its most widely used form, APRS is transported over the AX.25 protocol using 1200 bit/s Bell 202 AFSK on frequencies located within the 2 meter amateur band.
- aprs.fi map - The positions of the amateur radio operators and their vehicles are received from the APRS-IS network on the Internet. Most of them are originally transmitted on amateur radio frequencies (typically around 145 MHz), and received and forwarded to the APRS-IS by igate stations run by clubs and individuals around the world. The positions of ships are received from the AIS frequencies by receiving stations around the world. If you wish to receive AIS transmissions and provide them to the service, you're more than welcome to do so.
- https://en.wikipedia.org/wiki/Telegraph_key - a switching device used primarily to send Morse code. Similar keys are used for all forms of manual telegraphy, such as in ‘wire’ or electrical telegraph and ‘wireless’ or radio telegraphy.
- YouTube: Iambic Keyer and Technique. CW Morse Code key - left for dot, right for dash, allows repetitions if either is held
- https://en.wikipedia.org/wiki/Q_code a standardized collection of three-letter codes all of which start with the letter "Q". It is a brevity code initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. To distinguish the use of "Q" codes transmitted as questions from those transmitted as statements, operators used the Morse question "INT" (dit dit dah dit dah) as a prefix to the "Q" code. Although Q codes were created when radio used Morse code exclusively, they continued to be employed after the introduction of voice transmissions. To avoid confusion, transmitter call signs are restricted; no country is ever issued an ITU prefix starting with "Q". Codes in the range QAA–QNZ are reserved for aeronautical use; QOA–QQZ for maritime use and QRA–QUZ for all services. "Q" has no official meaning, but it is sometimes assigned with a word with mnemonic value, such as "Queen's" (e.g. QFE = Queen's Field Elevation), "Query", "Question", or "reQuest".
- https://en.wikipedia.org/wiki/Digital_audio_broadcasting - DAB standard was initiated as a European research project in the 1980s. The Norwegian Broadcasting Corporation (NRK) launched the first DAB channel in the world on 1 June 1995 (NRK Klassisk), and the BBC and Swedish Radio (SR) launched their first DAB digital radio broadcasts in September 1995. DAB receivers have been available in many countries since the end of the 1990s.
Audio quality varies depending on the bitrate used and audio material. Most stations use a bit rate of 128 kbit/s or less with the MP2 audio codec, which requires 160 kbit/s to achieve perceived FM quality. 128 kbit/s gives better dynamic range or signal-to-noise ratio than FM radio, but a more smeared stereo image, and an upper cut-off frequency of 14 kHz, corresponding to 15 kHz of FM radio. However, "CD quality" sound with MP2 is possible "with 256…192 kbps".
An upgraded version of the system was released in February 2007, which is called DAB+. DAB is not forward compatible with DAB+, which means that DAB-only receivers are not able to receive DAB+ broadcasts. However, broadcasters can mix DAB and DAB+ programs inside the same transmission and so make a progressive transition to DAB+. DAB+ is approximately twice as efficient as DAB, and more robust.
- https://en.wikipedia.org/wiki/Digital_Radio_Mondiale - DRM, a set of digital audio broadcasting technologies designed to work over the bands currently used for analogue radio broadcasting including AM broadcasting, particularly shortwave, and FM broadcasting. DRM is more spectrally efficient than AM and FM, allowing more stations, at higher quality, into a given amount of bandwidth, using various MPEG-4 audio coding formats.
- https://en.wikipedia.org/wiki/Trunked_radio_system - two-way radio system that uses a control channel to automatically direct radio traffic. Two-way radio systems are either trunked or conventional, where conventional is manually directed by the radio user. Trunking is a more automated and complex radio system, but provides the benefits of less user intervention to operate the radio and greater spectral efficiency with large numbers of users. Instead of assigning, for example, a radio channel to one particular organization at a time, users are instead assigned to a logical grouping, a "talkgroup". When any user in that group wishes to converse with another user in the talkgroup, a vacant radio channel is found automatically by the system and the conversation takes place on that channel. Many unrelated conversations can occur on a channel, making use of the otherwise idle time between conversations. Each radio transceiver contains a microcomputer to control it. A control channel coordinates all the activity of the radios in the system. The control channel computer sends packets of data to enable one talkgroup to talk together, regardless of frequency.
- https://github.com/robotastic/trunk-recorder - Trunk Recorder is able to record the calls on trunked and conventional radio systems. It uses 1 or more Software Defined Radios (SDRs) to do this. The SDRs capture large swatches of RF and then use software to process what was received. GNURadio is used to do this processing because it provides lots of convenient RF blocks that can be pieced together to allow for complex RF processing. The libraries from the amazing OP25 project are used for a lot of the P25 functionality. Multiple radio systems can be recorded at the same time.
- https://en.wikipedia.org/wiki/Amateur_radio - also called ham radio, describes the use of radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communication. The term "amateur" is used to specify "a duly authorised person interested in radioelectric practice with a purely personal aim and without pecuniary interest;" (either direct monetary or other similar reward) and to differentiate it from commercial broadcasting, public safety (such as police and fire), or professional two-way radio services (such as maritime, aviation, taxis, etc.).
The amateur radio service (amateur service and amateur-satellite service) is established by the International Telecommunication Union (ITU) through the International Telecommunication Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with an identifying call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics and the host government's radio regulations. Radio amateurs use a variety of voice, text, image, and data communications modes and have access to frequency allocations throughout the RF spectrum to enable communication across a city, region, country, continent, the world, or even into space.
- Amateur-radio-wiki - This site aims to enable ham operators and curious alike to document, share and explore the fantastic world of amateur radio.
- ham-radio.com - site and it's hosted organizations offered as a free service to the Amateur Radio community.
- http://radio-hobby.org - Russian
- http://arstechnica.com/gadgets/2016/06/when-everything-else-fails-amateur-radio-will-still-be-there-and-thriving/ 
- Guerrilla Radio - How some inmates hack, rewire, and retool their radios to create walkie-talkies. 
- Fldigi - a modem program for most of the digital modes used by radio amateurs today: CW, PSK, MFSK, RTTY, Hell, DominoEX, Olivia, and Throb are all supported. It can help calibrate a sound card to a time signal and do frequency measurement tests.
- FreeDV: Open Source Amateur Digital Voice – Where Amateur Radio Is Driving The State of the Art - a Digital Voice mode for HF radio. You can run FreeDV using a free GUI application for Windows, Linux and OSX that allows any SSB radio to be used for low bit rate digital voice. Alternatively you can buy a SM1000 FreeDV adaptor that allows you to run FreeDV on any HF radio without a PC or sound card. If you are a hardware or software developer, you can integrate FreeDV into your project using the LGPL licensed FreeDV API. Speech is compressed down to 700-1600 bit/s then modulated onto a 1.25 kHz wide signal comprised of 16 QPSK carriers which is sent to the Mic input of a SSB radio. The signal is received by an SSB radio, then demodulated and decoded by FreeDV. FreeDV 700C is approaching SSB in it’s low SNR performance. At high SNRs FreeDV 1600 sounds like FM, with no annoying analog HF radio noise. FreeDV was built by an international team of Radio Amateurs working together on coding, design, user interface and testing. FreeDV is open source software, released under the GNU Public License version 2.1. The modems and Codec 2 speech codec used in FreeDV are also open source.
- http://linux.die.net/man/1/radio - in the xawtv package
- https://github.com/dh1tw/remoteAudio - a cross plattform audio streaming application, built for Amateur Radio purposes. The most typical use case for this software is the remote operation of an amateur radio station. remoteAudio is written in Go.
- https://en.wikipedia.org/wiki/Radio_control - the use of radio signals to remotely control a device. Radio control is used for control of model vehicles from a hand-held radio transmitter. Industrial, military, and scientific research organizations make use of radio-controlled vehicles as well.
- OpenSesame is a device that can wirelessly open virtually any fixed-code garage door in seconds, exploiting a new attack I've discovered on wireless fixed-pin devices. Using a child's toy from Mattel.
- https://en.wikipedia.org/wiki/Datacasting - the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital television, but may also be applied to digital signals on analog TV or radio. It generally does not apply to data which is inherent to the medium, such as PSIP data which defines virtual channels for DTV or direct broadcast satellite systems; or to things like cable modem or satellite modem, which use a completely separate channel for data.
- https://en.wikipedia.org/wiki/LoRa - a patented digital wireless data communication IoT technology developed by Cycleo of Grenoble, France, and acquired by Semtech in 2012. LoRa uses license-free sub-gigahertz radio frequency bands like 169 MHz, 433 MHz, 868 MHz (Europe) and 915 MHz (North America). LoRa enables very-long-range transmissions (more than 10 km in rural areas) with low power consumption. The technology is presented in two parts — LoRa, the physical layer and LoRaWAN, the upper layers.
- https://en.wikipedia.org/wiki/1G - refers to the first generation of wireless cellular technology (mobile telecommunications). These are the analog telecommunications standards that were introduced in the 1980s and continued until being replaced by 2G digital telecommunications. The main difference between the two mobile cellular systems (1G and 2G), is that the radio signals used by 1G networks are analog, while 2G networks are digital.
- https://en.wikipedia.org/wiki/2G - short for second-generation cellular technology. Second-generation 2G cellular networks were commercially launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991. Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted; 2G systems were significantly more efficient on the spectrum allowing for far greater wireless penetration levels; and 2G introduced data services for mobile, starting with SMS text messages. 2G technologies enabled the various networks to provide the services such as text messages, picture messages, and MMS (multimedia messages). All text messages sent over 2G are digitally encrypted, allowing for the transfer of data in such a way that only the intended receiver can receive and read it.
- Building a portable GSM BTS using the Nuand bladeRF, Raspberry Pi and YateBTS (The Definitive and Step by Step Guide) 
- https://en.wikipedia.org/wiki/Wireless_Application_Protocol - a technical standard for accessing information over a mobile wireless network. A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol. Introduced with much hype in 1999, WAP achieved some popularity in the early 2000s, but by the 2010s it had been largely superseded by more modern standards. Most modern handset internet browsers now fully support HTML, so do not need to use WAP markup for webpage compatibility, and most of them are no longer able to render and display pages written in WAP.
- Kannel - a compact and very powerful open source WAP and SMS gateway, used widely across the globe both for serving trillions of short messages (SMS), WAP Push service indications and mobile internet connectivity.
- https://en.wikipedia.org/wiki/SMS - Short Message Service is a text messaging service component of most telephone, World Wide Web, and mobile device systems. It uses standardized communication protocols to enable mobile devices to exchange short text messages. An intermediary service can facilitate a text-to-voice conversion to be sent to landlines. SMS was the most widely used data application, with an estimated 3.5 billion active users, or about 80% of all mobile subscribers, at the end of 2010.
SMS, as used on modern devices, originated from radio telegraphy in radio memo pagers that used standardized phone protocols. These were defined in 1985 as part of the Global System for Mobile Communications (GSM) series of standards. The protocols allowed users to send and receive messages of up to 160 alpha-numeric characters to and from GSM mobiles. Although most SMS messages are mobile-to-mobile text messages, support for the service has expanded to include other mobile technologies, such as ANSI CDMA networks and Digital AMPS. SMS is also employed in mobile marketing, a type of direct marketing.According to one market research report, as of 2014, the global SMS messaging business was estimated to be worth over $100 billion, accounting for almost 50 percent of all the revenue generated by mobile messaging.
- https://en.wikipedia.org/wiki/Multimedia_Messaging_Service - a standard way to send messages that include multimedia content to and from a mobile phone over a cellular network. Users and providers may refer to such a message as a PXT, a picture message, or a multimedia message. The MMS standard extends the core SMS (Short Message Service) capability, allowing the exchange of text messages greater than 160 characters in length. Unlike text-only SMS, MMS can deliver a variety of media, including up to forty seconds of video, one image, a slideshow of multiple images, or audio.
- https://en.wikipedia.org/wiki/Rich_Communication_Services - a communication protocol between mobile-telephone carriers and between phone and carrier, aiming at replacing SMS messages with a text-message system that is richer, provide phonebook polling (for service discovery), and transmit in-call multimedia
- https://en.wikipedia.org/wiki/3G - standing for third generation, is the third generation of wireless mobile telecommunications technology. It is the upgrade for 2G and 2.5G GPRS networks, for faster internet speed. This is based on a set of standards used for mobile devices and mobile telecommunications use services and networks that comply with the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. 3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV.
3G telecommunication networks support services that provide an information transfer rate of at least 0.2 Mbit/s. Later 3G releases, often denoted 3.5G and 3.75G, also provide mobile broadband access of several Mbit/s to smartphones and mobile modems in laptop computers. This ensures it can be applied to wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV technologies.
- https://en.wikipedia.org/wiki/4G - the fourth generation of broadband cellular network technology, succeeding 3G. A 4G system must provide capabilities defined by ITU in IMT Advanced. Potential and current applications include amended mobile web access, IP telephony, gaming services, high-definition mobile TV, video conferencing, and 3D television. The first-release Long Term Evolution (LTE) standard (a 4G candidate system) has been commercially deployed in Oslo, Norway, and Stockholm, Sweden since 2009. It has, however, been debated whether first-release versions should be considered 4G.
- Osmocom - an umbrella project regarding Open source mobile communications. This includes software and tools implementing a variety of mobile communication standards, including GSM, DECT, TETRA and others.
- Cellular Infrastructure - a group of Osmocom programs implementing cellular network infrastructure components for GSM, GPRS, EDGE, UMTS, HSPA, LTE and their associated interfaces and protocol stacks.
- OpenBTS - a Linux application that uses a software-defined radio to present a standard 3GPP air interface to user devices, while simultaneously presenting those devices as SIP endpoints to the Internet. This forms the basis of a new type of wireless network which promises to expand coverage to unserved and underserved markets while unleashing a platform for innovation, including offering support for emerging network technologies, such as those targeted at the Internet of Things.
- UmTRX - The industrial grade dual-channel wide-band SDR transceiver.
- UmSITE-TM3 - A complete mobile network in a single tower mounted base station, one of the key components of the Fairwaves GSM network architecture. Technical details: Osmocom or OpenBTS software suites (Osmocom by default). Ability to run GnuRadio and other SDR software. Output power - 3W per channel (6W total). UmSITE includes internal duplexers and amplifiers. 1-3 km coverage (with external antennas). Two independent TRX's, i.e. two ARFCNs. Based on UmTRX transceiver. Stable reference clocks: 26MHz TCXO (integer multiple of GSM sample rate) with 100ppb frequency stability. DAC for TCXO frequency fine tuning. Integrated GPS module for automatic TCXO frequency stabilization.
- http://wiki.opendigitalradio.org Opendigitalradio.org wiki] - Open digital broadcasting techniques based on software defined radio. Digital radio transmission and development must also become democratized for experimenters and small broadcasters. Opendigitalradio.org wiki is about creating a community for documenting and exchanging experimentations and gather information about existing small-scale DAB projects. Please read Introduction for more information. Opendigitalradio is a non-profit association based in Switzerland (page in french), offering also a broadcast infrastructure for temporary radio stations.
- FUNcube Dongle - originally designed with receiving signals from space
- Whitebox Handheld SDR - Low power, embeddable framework; inspired by cell phone and SDR architectures 
- Myriad RF is a family of open source hardware and software projects for wireless communications, and a community that is working to make wireless innovation accessible to as many people as possible.
- LimeSDR board provides a hardware platform for developing and prototyping high-performance and logic-intensive digital and RF designs using Altera’s Cyclone IV FPGA and Lime Microsystems transceiver.
- https://code.facebook.com/posts/1754757044806180/introducing-opencellular-an-open-source-wireless-access-platform 
- https://www.ettus.com/product/details/UB210-KIT - 70MHz to 6GHz
- http://sdr.osmocom.org/trac/wiki/rtl-sdr - RTL-SDR is a set of tools that enables DVB-T USB dongles based on the Realtek RTL2832U chipset to be used as cheap software defined radios, given that the chip allows transferring raw I/Q samples from the tuner straight to the host device.
The frequency range of the RTL2832U / E4000 is generally around 64MHZ to 1700MHz with a gap around 1100MHz to 1250MHz. The RTL2832U / R820T frequency range is 24MHZ to roughly 1850MHz with no gaps (found yet), and no DC offset spike.
RTL dongles have 2.4 MHz of useful bandwidth.
- YouTube: Decode APRS with RTL SDR (RTL2832U)
Broadcom Wi-Fi chips
- https://github.com/seemoo-lab/mobisys2018_nexmon_software_defined_radio - Proof of concept project for operating Broadcom Wi-Fi chips as arbitrary signal transmitters similar to software-defined radios (SDRs) 
- Osmo-fl2k - osmo-fl2k - Open Source Mobile Communications - Since rtl-sdr has been released a couple of years ago, cheap SDR receivers are ubiquitous. SDRs with transmission capability have become cheaper as well, but are still more expensive. osmo-fl2k allows to use USB 3.0 to VGA adapters based on the Fresco Logic FL2000 chip, which are available for around $5, as general purpose DACs and SDR transmitter generating a continuous stream of samples by avoiding the HSYNC and VSYNC blanking intervals.
running the "volk_profile" gnuradio utility will detect and enable processor specific optimisations and will in many cases give a significant performance boost.
- Gqrx is a software defined radio receiver powered by the GNU Radio SDR framework and the Qt graphical toolkit.
- LuaRadio is a lightweight, embeddable flow graph signal processing framework for software-defined radio. It provides a suite of source, sink, and processing blocks, with a simple API for defining flow graphs, running flow graphs, creating blocks, and creating data types. 
- liquid-dsp - a free and open-source signal processing library for software-defined radios written in C. Its purpose is to provide a set of extensible DSP modules that do not rely on external dependencies or cumbersome frameworks.
- FreeDV - a Digital Voice mode for HF radio. You can run FreeDV using a free GUI application for Windows, Linux and OSX that allows any SSB radio to be used for low bit rate digital voice.
- Identification Guide - wiki intended to help identify radio signals through example sounds and waterfall images. Most signals are received and recorded using a software defined radio such as the RTL-SDR, Airspy, SDRPlay, HackRF, BladeRF, Funcube Dongle, USRP or others.
- - OpenBTS is a Unix application that uses a software radio to present a GSM air interface to standard 2G GSM handset and uses a SIP softswitch or PBX to connect calls. (You might even say that OpenBTS is a simplified form of IMS that works with 2G feature-phone handsets.) The combination of the global-standard GSM air interface with low-cost VoIP backhaul forms the basis of a new type of cellular network that can be deployed and operated at substantially lower cost than existing technologies in many applications, including rural cellular deployments and private cellular networks in remote areas.
- http://www.hellointernet.fm/ - C.P. Gray & Brady Haran