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Wilmington, North Carolina once had a thriving Black middle class and an elected interracial government. In 1898 white supremacists used violence to overthrow that government, kill Black residents and drive many others from the city.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
In radio engineering, a transverter is a radio frequency device that consists of an upconverter and a downconverter in one unit. Transverters are used in conjunction with transceivers to change the range of frequencies over which the transceiver can communicate.
In electrical power engineering, a transverter is a universal electrical power converter that can combine, convert, analyze and control any combinations of DC or AC power.
Although not as convenient as a wide-range radio, amateurs who have invested a great deal of money or time in a fine-quality radio may find it more economical to extend the radio's range when new bands become available, rather than replace it. Some transceiver manufacturers are supportive of add-on transverters, and design in circuitry and cabling attachments for them.
Transverters are most commonly used in amateur radio to convert radio transceivers designed for use on the HF or VHF bands to operate on even higher frequency (microwave) bands. A transceiver used in this fashion is referred to as an IF radio, indicating that it connects into the "intermediate frequency" electronics in the chain of transceiver stages.
Common transceiver/transverter combinations include transverters for 50 MHz, 70 MHz, 144 MHz, 222 MHz, and 432 MHz designed for use with 28 MHz IF radios, and transverters for 50 MHz, 902 MHz, 1296 MHz, 2304 MHz, 3456 MHz, 5706 MHz, and 10368 MHz designed for use with 144 MHz IF radios. Some transverters include transmit/receive switching built into the design, whereas other units require external switching. The use of external switching is popular in applications where preamps and amplifiers are included.
Some transverters are built into waterproof enclosures for installation on a radio tower or other antenna support structure to get the device as close as possible to the antenna so as to reduce signal loss in the transmission line.
The high-speed multimedia radio article discusses the radio transceivers that use 802.11 (WiFi) with transverters to achieve Wireless Broadband communication in the frequency bands reserved for Amateur radio operators.
Transverters can also be used in applications where the transverter frequency is lower than the transceiver frequency, and the design constraints in these cases are often more relaxed. Several low frequency bands are available around the world to amateur radio operators, licensed experimental stations, and some unlicensed hobbyists. Transverters for these LF bands generally use HF transceivers as the IF radio.
Some transverters are used for communications where one or more of the stations are underground, such as mines, or underwater, such as shallow-water submersibles.
Historically "transverter" was the name for an electromechanical device, invented in Britain in the 1920s, to produce high-voltage direct current from AC sources for efficient power distribution over long-distance lines.[1]
Modern transverters are even more versatile, and generally all solid-state. They are used to convert and combine different types of electrical power such as solar panels, batteries, wind generators, fuel cells, the grid, generators, and both DC and AC loads. By automatically analyzing and converting the power between different voltages and AC or DC, the transverter enables energy to flow between all types of devices.
With the advent of the Smart Grid transverters are becoming very popular since they combine renewable energy, demand management, and community energy storage within the home or office. Transverters also locally correct for power factor, which creates significant reductions in transmission loss for the grid. [2]
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
In radio engineering, a transverter is a radio frequency device that consists of an upconverter and a downconverter in one unit. Transverters are used in conjunction with transceivers to change the range of frequencies over which the transceiver can communicate. In electrical power engineering, a transverter is a universal electrical power converter that can combine, convert, analyze and control any combinations of DC or AC power.
Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. The interval of time between events is called the period. It is the reciprocal of the frequency. For example, if a heart beats at a frequency of 120 times per minute (2 hertz), its period is one half of a second. Special definitions of frequency are used in certain contexts, such as the angular frequency in rotational or cyclical properties, when the rate of angular progress is measured. Spatial frequency is defined for properties that vary or occur repeatedly in geometry or space. The unit of measurement of frequency in the International System of Units (SI) is the hertz, having the symbol Hz.
A heterodyne is the result of mixing two signals in a nonlinear device to produce new frequency components, notably sum and difference frequencies of the original signals. This process, called heterodyning, is fundamental to signal processing and radio systems. The term originated with Reginald Fessenden, who in 1908 described a “heterodyne receiver” in which a locally generated oscillation interacts with the received signal to produce “beats of an audible frequency.” In that paper he also referred to his 1902 patent describing such a system, although the term heterodyne was not used there. In a typical implementation, signals at frequencies f₁ and f₂ are applied to a nonlinear element such as a frequency mixer, producing components at f₁ + f₂ and f₁ − f₂, along with additional intermodulation products arising from the device nonlinearity. One of these components is selected by filtering for further use, while the others are rejected. Heterodyning is not limited to radio frequencies; the same principle applies across the electromagnetic spectrum, including infrared and optical systems, where it is used in coherent detection techniques. Heterodyne frequencies are related to the phenomenon of beats in acoustics. A major application of the heterodyne process is in the superheterodyne radio receiver circuit, which is used in virtually all modern radio receivers.
Rockwell Collins, Inc. was a multinational corporation headquartered in Cedar Rapids, Iowa, providing avionics and information technology systems and services to government agencies and aircraft manufacturers. It was formed when the Collins Radio Company, facing financial difficulties, was purchased by Rockwell International in 1973. In 2001, the avionics division of Rockwell International was spun off to form the current Rockwell Collins, Inc., retaining its name. It was acquired by United Technologies Corporation on November 27, 2018, and since then operates as part of Collins Aerospace, a subsidiary of the RTX Corporation (formerly Raytheon Technologies).
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →The Greenwood District.
