|
Phil Karn
Phil Karn (born October 4, 1956) is a retired American engineer from Lutherville, Maryland. He earned a bachelor's degree in electrical engineering from Cornell University in 1978 and a master's degree in electrical engineering from Carnegie Mellon University in 1979. From 1979 until 1984, Karn worked at Bell Labs in Naperville, Illinois, and Murray Hill, New Jersey. From 1984 until 1991, he was with Bell Communications Research in Morristown, New Jersey. From 1991 through to his retirement, he worked at Qualcomm in San Diego, where he specialized in wireless data networking protocols, security, and cryptography. He is currently the President/CEO oAmateur Radio Digital Communications (ARDC) a non-profit foundation funded by the sale of part of its IP address space (44/8). ARDC manages the remaining portion of its address space by providing financial grants to amateur radio and related groups. He has been an active contributor in the Internet Engineering Task Force, especially in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutherville, Maryland
Lutherville is a census-designated place (CDP) in Baltimore County, Maryland, United States. As of the 2010 census it had a population of 6,504. Prior to 2010 the area was part of the Lutherville-Timonium CDP. Within its borders lies the Lutherville Historic District. Geography Lutherville is located at (39.4240, −76.6177). According to the United States Census Bureau, the CDP had a total area of , all land. The town is located north of Baltimore City along York Road (Maryland Route 45). It is bordered on the north by Timonium, on the west by Interstate 83, on the south by Towson, and on the east by the Hampton neighborhood. The boundary between Lutherville and Timonium is Ridgely Road. Lutherville is located in the Piedmont region of the United States, and lies in the humid subtropical climate zone, with hot and humid summers leading into winters that are chilly but not extreme by American standards. The average annual snowfall is and average annual precipitation i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globalstar
Globalstar, Inc. is an American satellite communications company that operates a low Earth orbit (LEO) satellite constellation for satellite phone and low-speed data communications. The Globalstar second-generation constellation consists of 24 low Earth orbiting (LEO) satellites. History The Globalstar project was launched in 1991 as a joint venture of Loral Corporation and Qualcomm. On March 24, 1994, the two sponsors announced the formation of Globalstar LP, a limited partnership established in the U.S., with financial participation from eight other companies, including Alcatel, AirTouch, Deutsche Aerospace, Hyundai, and Vodafone. At that time, the company predicted the system would launch in 1998, based on an investment of $1.8 billion. Globalstar received its US spectrum allocation from the FCC in January 1995 and continued to negotiate with other nations for rights to use the same radio frequencies in their countries. The first satellites were launched in February 1998, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dayton Hamvention
The Dayton Hamvention is one of the two largest amateur radio convention (or hamfest) in the world. It is held each May in the Dayton, Ohio area and draws attendees from various parts of the world. Since 2017, it has been held at the Greene County Fairgrounds in Xenia, Ohio near Dayton. Prior to this it was held each May at the Hara Arena in Trotwood, Ohio. The first Hamvention occurred on March 22, 1952 at the Biltmore Hotel in Dayton (QST March 1952). Hara Arena had been the home of Dayton Hamvention since 1964. The Hara Arena announced its closure in 2016 with the 2017 Hamvention being forced to move as a result. The 2019 Hamvention drew 32,462 paid attendees over its three days, and offered a wide variety of activities for amateur radio enthusiasts, including: * 5 parallel tracks of forums, classes, and demonstrations covering all aspects of the hobby. * 6 buildings full of commercial exhibit space, where major amateur equipment manufacturers put their newly announced produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AO-40
AMSAT-OSCAR-40, also known as AO-40 or simply OSCAR 40, was the on-orbit designation of an amateur radio satellite of the OSCAR series. Prior to launch, the spacecraft was known as Phase 3D or "P3D". AO-40 was built by AMSAT. AO-40's project manager was Peter Guelzow of AMSAT-DL, the German AMSAT organization. Mr Guelzow holds amateur call sign DB2OS. History Design, construction and launch Following the failure of the Phase 3A launcher, design studies were undertaken and construction started for two successor satellites, that became AO-10 (Phase 3B) and AO-13 (Phase 3C) respectively. After the launch of AO-13, design commenced for a Phase 4 satellite. This idea was later shelved, and design of Phase 3D (on-orbit name: AO-40) was undertaken under direction of the project team based in Germany, involving amateur radio payloads from many countries in Europe. Assembly was done at AMSAT's Spacecraft Integration Facility in the 'Free Trade Zone Building' at the Orlando In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase-shift Keying
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication. Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits. Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal such a system is termed c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio Satellite
An amateur radio satellite is an artificial satellite built and used by amateur radio operators. It forms part of the Amateur-satellite service. These satellites use amateur radio frequency allocations to facilitate communication between amateur radio stations. Many amateur satellites receive an OSCAR designation, which is an acronym for Orbiting Satellite Carrying Amateur Radio. The designation is assigned by AMSAT, an organization which promotes the development and launch of amateur radio satellites. Because of the prevalence of this designation, amateur radio satellites are often referred to as OSCARs. These satellites can be used free of charge by licensed amateur radio operators for voice ( FM, SSB) and data (AX.25, packet radio, APRS) communications. Currently, over 18 fully operational amateur radio satellites are in orbit. They may be designed to act as repeaters, as linear transponders, and as store and forward digital relays. Amateur radio satellites have helpe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forward Error Correction
In computing, telecommunication, information theory, and coding theory, an error correction code, sometimes error correcting code, (ECC) is used for controlling errors in data over unreliable or noisy communication channels. The central idea is the sender encodes the message with redundant information in the form of an ECC. The redundancy allows the receiver to detect a limited number of errors that may occur anywhere in the message, and often to correct these errors without retransmission. 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. ECC contrasts with error detection in that errors that are encountered can be corrected, not simply detected. The advantage is that a system using ECC does not require a reverse channel to request retransmission of data when an error occurs. The downside is that there is a fixed overhead that is added to the message, thereby requiring a h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency-shift Keying
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission in the VLF and ELF bands. The simplest FSK is binary FSK (BFSK). BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information. With this scheme, the 1 is called the mark frequency and the 0 is called the space frequency. Modulating and demodulating Reference implementations of FSK modems exist and are documented in detail. The demodulation of a binary FSK signal can be done using the Goertzel algorithm very efficiently, even on low-power microcontrollers. Variations Multiple frequency-shift keying Continuous-phase frequency-shift keying In principle FSK can be implemented by using completely independent free-running oscillat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Callsign
In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. 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 onboard ships at sea. These were not globally unique, so a one-letter company identifier (for instance, 'M' and two letters as a Marconi station ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Operating System
A network operating system (NOS) is a specialized operating system for a network device such as a router, switch or firewall. Historically operating systems with networking capabilities were described as network operating systems, because they allowed personal computers (PCs) to participate in computer networks and shared file and printer access within a local area network (LAN). This description of operating systems is now largely historical, as common operating systems include a network stack to support a client–server model. History Early microcomputer operating systems such as CP/M, MS-DOS and classic Mac OS were designed for one user on one computer. Packet switching networks were developed to share hardware resources, such as a mainframe computer, a printer or a large and expensive hard disk. As local area network technology became available, two general approaches to handle sharing of resources on networks arose. Historically a network operating system was an operating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio
Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communications. 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 Radio Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual station licenses with a unique identifying call sign, which mus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISEE-3
The International Cometary Explorer (ICE) spacecraft (designed and launched as the International Sun-Earth Explorer-3 (ISEE-3) satellite), was launched 12 August 1978, into a heliocentric orbit. It was one of three spacecraft, along with the mother/daughter pair of ISEE-1 and ISEE-2, built for the International Sun-Earth Explorer (ISEE) program, a joint effort by NASA and European Space Research Organisation, ESRO/European Space Agency, ESA to study the interaction between the Earth's magnetic field and the solar wind. ISEE-3 was the first spacecraft to be placed in a halo orbit at the Earth-Sun Lagrange point. Renamed ICE, it became the first spacecraft to visit a comet, passing through the plasma tail of comet 21P/Giacobini–Zinner, Giacobini-Zinner within about of the nucleus on 11 September 1985. NASA suspended routine contact with ISEE-3 in 1997, and made brief status checks in 1999 and 2008. On 29 May 2014, two-way communication with the spacecraft was reestablished ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
