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Automated Maritime Telecommunications System
Automated Maritime Telecommunications System (AMTS) is a commercial mobile radio service used within the United States. It operates within the VHF frequency range, just above the North American Band III television range, and offers both voice and data communications to maritime customers. The system is operated by a network of private carriers across the country, with coverage primarily including coastal and inland waterways. History In 1981, the FCC proposed the Inland Waterways Communication System (IWCS), a commercial maritime radio service with the proposed purpose of expanding private maritime communication and that was to operate from 216 to 220 MHz.R. Eckert: ''Guidance for Evaluating the Potential for Interference to TV From Stations of Inland Waterways Communications Systems'', Federal Communications Commission Office of Science and Technology, 1982 Earlier reports had studied the feasibility of using this frequency band, but warned of the high probability of adjace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band III
Band III is the name of the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 174 to 240 megahertz (MHz). It is primarily used for radio and television broadcasting. It is also called high-band VHF, in contrast to Bands I and II. Broadcast Television North America The band is subdivided into seven channels for television broadcasting, each occupying 6 MHz. Europe European Band III allocations vary from country to country, with channel widths of 7 or 8 MHz. The standard channel allocations for European countries that use System B with 7 MHz channel spacing are as follows: The Irish (8 MHz) system is shown below. Oceania Australia has allocated 8 channels in Band III for digital television, each with 7 MHz bandwidth. Russia and other former members of OIRT Russian analog television is transmitted using System D with 8 MHz channel bandwidth. Radio The band came into use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adjacent-channel Interference
Adjacent-channel interference (ACI) is interference caused by extraneous power from a signal in an adjacent channel. ACI may be caused by inadequate filtering (such as incomplete filtering of unwanted modulation products in FM systems), improper tuning or poor frequency control (in the reference channel, the interfering channel or both). ACI is distinguished from crosstalk. Origin The adjacent-channel interference which receiver A experiences from a transmitter B is the sum of the power that B emits into A's channel—known as the "unwanted emission", and represented by the ACLR (Adjacent Channel Leakage Ratio)—and the power that A picks up from B's channel, which is represented by the ACS (Adjacent Channel Selectivity). B emitting power into A's channel is called adjacent-channel leakage (unwanted emissions). It occurs for two reasons. First, because RF filters require a roll-off, and do not eliminate a signal completely. Second, due to intermodulation in B's amplifiers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Channel Frequencies
The following tables show the frequencies assigned to analog broadcast television channels in various regions of the world, along with the ITU letter designator for the transmission system used. The frequencies shown are for the channel limits and for the analog video and audio carriers. The channel itself usually occupies 6, 7 or 8 megahertz of bandwidth depending on the television transmission system in use. For example, North American channel 1 occupies the spectrum from 44 to 50 MHz. See Broadcast television systems for a table of signal characteristics, including bandwidth, by ITU letter designator. Analog television broadcasts have been phased out in most regions, having been replaced by digital television broadcasts. International normalization for analog TV systems International broadcasting television frequencies are divided in two part of the spectrum; the Very high frequency or "VHF" band and the Ultra high frequency or "UHF" band. VHF Americas (most coun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balanced Budget Act Of 1997
The Balanced Budget Act of 1997 () was an omnibus legislative package enacted by the United States Congress, using the budget Reconciliation (U.S. Congress), reconciliation process, and designed to balance the federal budget by 2002. This act was enacted during Bill Clinton's second term as president. According to the Congressional Budget Office, the act was to result in $160 billion in spending reductions between 1998 and 2002. After taking into account an increase in spending on Welfare and Children's Healthcare, the savings totaled $127 billion. Medicare cuts were responsible for $112 billion, and hospital inpatient and outpatient payments covered $44 billion. In order to reduce Medicare (United States), Medicare spending, the act reduced payments to health service providers. However, some of those changes to payments were reversed by subsequent legislation in 1999 and 2000. Overview The Balanced Budget Act was introduced on June 24, 1997, by Republican Party (United Stat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Radiated Power
Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power in watts that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity (signal strength or power flux density in watts per square meter) as the actual source antenna at a distant receiver located in the direction of the antenna's strongest beam (main lobe). ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. It is equal to the input power to the antenna multiplied by the gain of the antenna. It is used in electronics and telecommunications, particularly in broadcasting to quantify the apparent power of a broadcasting station experienced by listeners in its reception area. An alternate parameter that measures the same thing is eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Force Space Surveillance System
The AN/FPS-133 Air Force Space Surveillance System, colloquially known as the Space Fence, was a U.S. government multistatic radar system built to detect orbital objects passing over America. It is a component of the U.S. space surveillance network, and according to the U.S. Navy was able to detect basketball sized () objects at heights up to . The system ceased operation in September 2013. Plans for a new space fence began with sites at the Kwajalein Atoll in the Marshall Islands, along with an option for another radar site in Western Australia. It became operational on March 28, 2020. The operation's headquarters were at Dahlgren, Virginia, and radar stations were spread out across the continental United States at roughly the level of the 33rd parallel north. Description There were three transmitter sites in the system: * 216.983 MHz at Lake Kickapoo, Texas () (Master transmitter) * 216.970 MHz at Gila River, Arizona () * 216.990 MHz at Jordan Lake, Ala ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
