|
Self-Organized Time Division Multiple Access
Self-organized time-division multiple access (STDMA) is a channel access method designed by Håkan Lans, based on time-division multiplexing. The term "self-organized" describes the manner in which time slots are assigned to users. Time-division multiple access (TDMA) divides a channel into Frame (telecommunications), frames, which furthermore are subdivided into a vast number of time slots. Users transmit in rapid succession, one after the other, each using their own time slot. One of the drawbacks of TDMA is that it requires a central station for slot assignment and time synchronisation. STDMA proposes for assigning slots without the involvement of a central station. Time synchronisation is usually taken care of using Coordinated Universal Time (UTC). STDMA is in use by the Automatic Identification System (AIS), a standard marine short-range coastal tracking system, and is the base of the International Civil Aviation Organization VHF Data Link#ICAO VDL Mode 4, VHF Data Link Mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Håkan Lans
Anders Håkan Lans (born 2 November 1947 in Enskede) is a Swedish inventor. He holds two patents: * a memory controller for a framebuffer: "Data processing system and apparatus for color graphics display". Framebuffer with memory controllers had been in common use for years at the time of this 1979 patent filing. * a calligraphic display "Arrangement for producing a pattern on a light-sensitive surface" STDMA Håkan Lans is the designer of a tracking system which makes use of a Self-Organized Time Division Multiple Access (STDMA) datalink. The STDMA datalink is currently in use in Automatic Identification System (AIS). AIS is a short range coastal tracking system which is mandatory aboard international voyaging ships with gross tonnage (GT) of 300 or more tons, and all passenger ships regardless of size. STDMA is also in use as one of the three physical layer models proposed for Automatic dependent surveillance-broadcast (ADS-B), a cooperative surveillance technique for air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-division Multiplexing
Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. This method transmits two or more digital signals or analog signals over a common channel. It can be used when the bit rate of the transmission medium exceeds that of the signal to be transmitted. This form of signal multiplexing was developed in telecommunications for telegraphy systems in the late 19th century, but found its most common application in digital telephony in the second half of the 20th century. History Time-division multiplexing was first developed for applications in telegraphy to route multiple transmissions simultaneously over a single transmission line. In the 1870s, Émile Baudot developed a time-multiplexing system of multiple Hughes telegraph machines. In 1944, the Britis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-division Multiple Access
Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity. Dynamic TDMA is a TDMA variant that dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream. TDMA is used in the digital 2G cellular systems such as Global System for Mobile Communications (GSM), IS-136, Personal Digital Cellular (PDC) and iDEN, and in the Digital Enhanced Cordless Telecommunications (DECT) standard for portable phones. TDMA was first used in satellite communication systems by Western Union in its Westar 3 communications satellite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame (telecommunications)
A frame is a digital data transmission unit in computer networking and telecommunication. In packet switched systems, a frame is a simple container for a single network packet. In other telecommunications systems, a frame is a repeating structure supporting time-division multiplexing. A frame typically includes frame synchronization features consisting of a sequence of bits or symbols that indicate to the receiver the beginning and end of the payload data within the stream of symbols or bits it receives. If a receiver is connected to the system during frame transmission, it ignores the data until it detects a new frame synchronization sequence. Packet switching In the OSI model of computer networking, a frame is the protocol data unit at the data link layer. Frames are the result of the final layer of encapsulation before the data is transmitted over the physical layer. A frame is "the unit of transmission in a link layer protocol, and consists of a link layer header followed by a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordinated Universal Time
Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT). The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted as CCIR Recommendation 374, ''Standard-Frequency and Time-Signal Emissions'', in 1963, but the official abbreviation of UTC and the official English name of Coordinated Universal Time (along with the French equivalent) were not adopted until 1967. The system has been adjusted several times, including a brief period during which the time-coordination radio signals broadcast both UTC and "Stepped Atomic Time (SAT)" before a new UTC was adopted in 1970 and implemented in 1972. This change also a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Civil Aviation Organization
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international scheduled air transport, air transport to ensure safe and orderly growth. ICAO headquarters are located in the ''Quartier international de Montréal, Quartier International'' of Montreal, Quebec, Canada. The ICAO Council adopts standards and recommended practices concerning air navigation, its infrastructure, flight inspection, prevention of unlawful interference, and facilitation of border-crossing procedures for international civil aviation. ICAO defines the protocols for Aviation accidents and incidents, air accident investigation that are followed by :Organizations investigating aviation accidents and incidents, transport safety authorities in countries signatory to the Chicago Convention on International Civil Aviation. The Air Navigat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VHF Data Link
The VHF Data Link or VHF Digital Link (VDL) is a means of sending information between aircraft and ground stations (and in the case of VDL Mode 4, other aircraft). Aeronautical VHF data links use the band 117.975–137 MHz assigned by the International Telecommunication Union to Aeronautical mobile (R) service. There are ARINC standards for ACARS on VHF and other data links installed on approximately 14,000 aircraft and a range of ICAO standards defined by the Aeronautical Mobile Communications Panel (AMCP) in the 1990s. Mode 2 is the only VDL mode being implemented operationally to support Controller Pilot Data Link Communications (CPDLC). ICAO VDL Mode 1 The ICAO AMCP defined this Mode for validation purposes. It was the same as VDL Mode 2 except that it used the same VHF link as VHF ACARS so it could be implemented using analog radios before VHF Digital Radio implementation was completed. The ICAO AMCP completed validation of VDL Modes 1&2 in 1994, after which the Mode 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Patent And Trademark Office
The United States Patent and Trademark Office (USPTO) is an agency in the U.S. Department of Commerce that serves as the national patent office and trademark registration authority for the United States. The USPTO's headquarters are in Alexandria, Virginia, after a 2005 move from the Crystal City area of neighboring Arlington, Virginia. The USPTO is "unique among federal agencies because it operates solely on fees collected by its users, and not on taxpayer dollars". Its "operating structure is like a business in that it receives requests for services—applications for patents and trademark registrations—and charges fees projected to cover the cost of performing the services tprovide . The Office is headed by the Under Secretary of Commerce for Intellectual Property and Director of the United States Patent and Trademark Office, a position last held by Andrei Iancu until he left office on January 20, 2021. Commissioner of Patents Drew Hirshfeld is performing the funct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reexamination
In United States patent law, a reexamination is a process whereby anyone—third party or inventor—can have a U.S. patent reexamined by a patent examiner to verify that the subject matter it claims is patentable. To have a patent reexamined, an interested party must submit prior art, in the form of patents or printed publications, that raises a "substantial new question of patentability". The Leahy-Smith America Invents Act makes substantial changes to the U.S. patent system, including new mechanisms for challenging patents at the U.S. Patent and Trademark Office. One of the new mechanisms is a post-grant review proceeding, which will provide patent challengers expanded bases on which to attack patents. Process A request for a reexamination can be filed by anyone at any time during the period of enforceability of a patent. To request a reexamination, one must submit a "request for reexamination" which includes (1) a statement pointing out each "substantial new question of p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
