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OMA (time Signal)
OMA was the callsign of a Czech time signal station. The station was operated by the Astronomical Institute of Prague and the transmitters were located at RKS Liblice 1. The station transmitted in the LF band on 50 kHz with a power of 7 kW and in the HF band on 2500 kHz with 1 kW. A reserve LF transmitter was located at Poděbrady Poděbrady (; german: Podiebrad) is a spa town in Nymburk District in the Central Bohemian Region of the Czech Republic. It has about 14,000 inhabitants. It lies on the river Elbe. The town centre is well preserved and is protected by law as an u .... OMA, which could be also used for synchronizing radio controlled clocks, was shut down in 1995. OMA time signal transmitter was used to synchronize radio clock. The transmit time protocol was changed multiple times. Periodic service maintenance outages lasted for days. The decoding was done in discrete hardware. Commercial use of OMA time signal was limited by absence of highly int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time Signal
A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. Church bells or voices announcing hours of prayer gave way to automatically operated chimes on public clocks; however, audible signals (even signal guns) have limited range. Busy seaports used a visual signal, the dropping of a ball, to allow mariners to check the chronometers used for navigation. The advent of electrical telegraphs allowed widespread and precise distribution of time signals from central observatories. Railways were among the first customers for time signals, which allowed synchronization of their operations over wide geographic areas. Dedicated radio time signal stations transmit a signal that allows automatic synchronization of clocks, and commercial broadcasters still include time signals in their programming. Today, global navigation satellite systems (GNSS) radio signals are used to precisely distribute time signals over much of the world ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Institute Of Czech Academy Of Sciences
The Astronomical Institute of the Czech Academy of Sciences is a scientific institute headquartered at the Ondřejov Observatory, roughly 35 km southeast of Prague, Czech Republic. Research fields The institute focuses on stellar, solar and galactic astronomy; meteors; and the motion of cosmic bodies. It has about 70 permanent scientists, of which roughly 80% work in Ondřejov, and it is divided into the following departments. Solar physics The solar physics department studies the active phenomena in the solar atmosphere, including flares, active regions, sunspots, filaments, coronal mass ejections, and solar wind, using optical, radio, and X-ray waveband observations. Stellar physics The stellar physics department is focused on research of stars, primarily hot stars (class B), models of stellar atmospheres, dynamics of stellar winds, and relativistic astrophysics. This department uses the largest telescope in the Czech Republic, which has a large reflector ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RKS Liblice 1
RKS Liblice 1 was a facility for commercial long wave radio transmission located in the Czech Republic about east of Prague near Liblice. It used a T-antenna hung on two tall insulated towers built of lattice steel. The towers were demolished by explosives on August 11, 2004, as they were no longer needed. The time-signal broadcasts on VLF ceased in 1995 and the medium-wave broadcast of Czech Radio Programme 2 was transferred to the adjacent site with a super-power transmitter, Liblice II. See also * List of towers Several extant building fulfill the engineering definition of a tower: "a tall human structure, always taller than it is wide, for public or regular operational access by humans, but not for living in or office work, and are ''self-supporting' ... * OMA (time signal) External links Liblice 1Drawings of RKS Liblice 1- Mast 1 - SkyscraperPage.comDrawings of RKS Liblice 1- Mast 2 - SkyscraperPage.com Towers in the Czech Republic Former radio masts and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low Frequency
Low frequency (LF) is the ITU designation for radio frequencies (RF) in the range of 30–300 kHz. Since its wavelengths range from 10–1 km, 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 also use this band. Propagation Because of their long wavelength, low frequency radio waves can diffract over obstacles like mountain ranges and travel beyond the horizon, following the contour of the Earth. This mode of propagation, called ''ground wave'', is the main mode in the LF band. Ground waves must be vertically polarized (the electric field is vertical while the magnet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Frequency
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters). Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or " skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances and for mountainous terrains which prevent line-of-sight communications. The band is used by international shortwave broadcasting stations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poděbrady
Poděbrady (; german: Podiebrad) is a spa town in Nymburk District in the Central Bohemian Region of the Czech Republic. It has about 14,000 inhabitants. It lies on the river Elbe. The town centre is well preserved and is protected by law as an urban monument zone. Administrative parts Poděbrady is made up of town parts of Poděbrady I–V and villages of Kluk, Polabec, Přední Lhota and Velké Zboží. Etymology An ancient community and a small fortress originated near the ford. It is most likely that the position of this community is reflected in the present name of the town: ''pode brody'' = "below the ford". Geography Poděbrady is located about southeast of Nymburk and east of Prague. It lies in the Central Elbe Table lowland within the Polabí region. The Elbe River flows through the town. South of the town is located Poděbrady Lake. It is a large lake, created by the flooding of an excavated sandstone quarry. It is mainly used for recreational purposes. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Controlled Clock
A radio clock or radio-controlled clock (RCC), and often (incorrectly) referred to as an atomic clock is a type of quartz clock or watch that is automatically synchronized to a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock. Such a clock may be synchronized to the time sent by a single transmitter, such as many national or regional time transmitters, or may use the multiple transmitters used by satellite navigation systems such as Global Positioning System. Such systems may be used to automatically set clocks or for any purpose where accurate time is needed. RC clocks may include any feature available for a clock, such as alarm function, display of ambient temperature and humidity, broadcast radio reception, etc. One common style of radio-controlled clock uses time signals transmitted by dedicated terrestrial longwave radio transmitters, which emit a time code that can be demodulated and displayed by the radio controlled clock. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
