Saturday, May 18, 2013

Great Price Antennas Direct ClearStream4 HDTV Antenna for $90.75

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Models : C4
By : Antennas Direct
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Antennas Direct ClearStream4 HDTV Antenna Overviews

The ClearStream 4 Antenna Receives Free Over-The-Air Digital and Hd Programming with No Monthly Cable or Satellite Fees. The ClearStream 4 Uhf Antenna is also capable of short range high Vhf reception. Stunningly efficient, the ClearStream 4 is ninety percent smaller than patrimony antennas, with unmatched range and power in its category. Developed organize software allows these 20-Inch X 28-Inch antennas to be smaller and more remarkable across the whole Uhf Dtv spectrum contribution consistently high gain. The Developed organize allows up to 98% of the available broadcast signals to positively reach the incoming antenna cable rather than being lost to impedance mismatches. The patented ClearStream 4 Tapered Loop organize receives Uhf channels with a range of 65+ miles. It is engineered for drive and stamina using anodized aluminum for corrosion resistance, and it’s easy to assemble.

Antennas Direct ClearStream4 HDTV Antenna Features

  • ClearStream antennas characterize a new breakthrough
  • Video-antennas
  • Consistent gain straight through the entire Uhf Dtv channel spectrum

WiFi networks (802.11) are being implemented to improve productivity, add convenience, and decrease costs. There will soon be new options. AT&T is currently launching WiMax service in major cities in the U.S. New satellite service from EutelSat in Europe, and ViaSat in the U.S., will provide additional options.

If there is high network utilization, today's wireless LAN products can behave unpredictably. There is a large bandwidth available (83.5 MHz), but even so, the 2.4Ghz frequency band can sometimes become crowded with other 2.4Ghz devices like Bluetooth, microwave ovens, and cordless phones. However, currently, most enterprise WiFi networks have relatively low utilization. In the future, as wireless LANs assume a more central role, interference problems could become more critical.

Antennas Direct ClearStream4 HDTV Antenna

Key Attributes

WiFi Internet For Buildings and Cities

  • High Data Rates.
  • 802.11b: 11 Mbps, uses direct sequence spread spectrum (DSSS) modulation with Complementary Code Keying (CCK).
  • 802.11g, 54 Mbps, uses orthogonal frequency-division multiplexing (OFDM) modulation to increase the throughput.
  • 802.11g systems operate in the same 2.4GHz spectrum as the 802.11b systems and is backward compatible with existing 11b infrastructure. The term used to describe these devices is dual-band. Like 802.11b, 802.11g is limited to three non-overlapping channels.
  • Reasonably priced.
  • Weather Tolerant.
  • Line of Sight is required for longer ranges (more than 1/4 mile).
  • Maximum Wattage for the Transmitter (without FCC licensing) is 1 Watt.
  • Half-Duplex Protocol: the system receives or transmits, but not simultaneously.

Access points and wireless routers have an advantage over laptop and desktop cards because they have a higher output power and therefore have the ability to send a signal further then most laptop and desktop cards. When a higher-gain antenna is installed on a desktop card the output power of that device is now increased closer to the output level of the access point or wireless router therefore equaling the two devices. In some cases, the antennas of both the access point/wireless router and the desktop/laptop card may need to be replaced. This is if the distance you are attempting to achieve is greater than the capabilities of the access point/wireless router when using the antennas that came with your card.

Wireless network cards come in a couple of flavors, including a PCI card for workstations and PC cards for laptops and other mobile devices. They can act in a decentralized client-to-client mode, or in a centralized client-to-access point mode. An access point is essentially a hub that gives wireless clients the ability to attach to the wired LAN backbone. In a decentralized mode, the wireless network card is configured to talk with other wireless network access cards that are within its range. Decentralized client-to-client (also know as peer-to-peer) WLANs are useful for small roaming workgroups that do not require access to the LAN backbone. The plug and play capabilities of most wireless network cards make setup easy.

The use of more than one access point in a given area is facilitated by the use of cell structures, which are similar to what mobile phone providers use to maintain your coverage area. One of the benefits to roaming mobile users is the ability for one access point to automatically hand off communication to the next access point in a roaming cell.

When connecting two or more buildings it is best to first establish a wireless bridge between the two points in the backbone. If you want to be wireless within a building, once the building-to-building bridge is created, then attempt to establish a wireless network within each building or location. Desktops, laptops, and other client devices will not work reliably if the access point/wireless router is not resident in the building where the access point/wireless router is located.

Unobstructed Line-Of-Sight

802.11b and 802.11g at 2.4GHz requires unobstructed visual Line-Of-Sight (LoS). There should not be trees, terrain, or structures between your two (antenna) points. Radio waves at this frequency will not penetrate metal, steel, concrete, stone, etc. However, dry wall, sheet rock, and wood usually are not a problem.

Surrounding the visual Line-Of-Sight is the "Fresnel zone". Any obstructions that come into the Fresnel zone, although not obstructing the visual Line-Of-Sight, may also slow down, hinder and affect your signal. The radio waves may deflect off of those obstructions. This is called Near Line-Of-Sight. Although you may see a slight signal with nLoS situations, your data transfer rate may decrease. An obstruction that cuts across the visual Line-Of-Sight and prohibits an optical visual between the two antennas in your bridge is considered Non-Line-Of-Sight.

You may find in your bridge application that the two antennas can visually see each other through spaces and breaks in an obstructing tree or tree line. Additionally, weather, RF interferences, and other site variables can have an effect on your signal too.

Security

Extensible Authentication Protocol, or EAP, is a universal authentication framework frequently used in wireless networks and Point-to-Point connections. EAP can provide a secure authentication mechanism between the client and NAS. EAP can support multiple authentication mechanisms, such as token cards, smart cards, passwords, and public key encryption authentication.

  • 802.11i is WiFi (802.11g) with better security. Authentication mechanisms are automatically changed frequently, preventing hackers from gaining access.
  • 802.11n, this standard is still in the approval stage, with final approval expected in 2009. It uses multiple-input multiple-output (MIMO), a signal processing technique for transmitting multiple data streams through multiple antennas. It offers five times the throughput (300 Mbps) and up to twice the range compared to the 802.11g standard. Equipment meeting the draft standard is already available, but there is no guarantee that networks built under today's 802.11n draft standard will be software upgradeable to the final ratified standard.

W-CDMA

W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network and where much of the mobile broadband industry is heading if they aren't already there. W-CDMA is the standard used in UMTS networks, which have been deployed in much of Western Europe, Japan, and is also used by AT&T Mobility (among other smaller carriers) in America. Verizon has also announced plans for service.

W-CDMA is a European standard designed to support data transmission rates of 144 Kbps for use in vehicles, 384 Kbps for pedestrian use and up to 2 Mbps for use indoors.

The Near and the Very-Near Future: LTE, and WiMax

In major metropolitan areas in the U.S., WiMax should available late in 2008. Sprint will make its commercial WiMAX debut in Baltimore in September. WiMax supports peak data speeds of about 20 MBPS, but, as with most broadband technologies, that bandwidth will be shared amongst users. On average, a user will see data rates between 1 MBPS and 4 MBPS.

Most major wireless carriers are skipping WiMax, planning instead to build out networks using a similar technology called Long Term Evolution (LTE), a successor to current cellular technology. WiMax has a head start on LTE, which won't be ready until 2010. These two technologies are referred to as 4G networks (Current state of the art mobile phone technology for accessing the Internet is called 3G). If mobile broadband service is important to you, these products will be very attractive. Unlike rivals GSM and CDMA, both 4G networks are based on "Orthogonal Frequency Division Multiplexing" (OFDM), also sometimes referred to as "discrete multi-tone modulation". Since both LTE and WiMax are based on similar technology, a unified standard is possible in theory, and discussions are ongoing. Motorola has said 85% of the technology and work for WiMax equipment will be reused in its designs for LTE equipment.

WiMAX and LTE can deliver large amounts of bandwidth operating at the low power levels necessary for mobile devices. Another advantage of WiMax/LTE is its ability to communicate out of line-of-sight (unlike conventional WiFi), and to communicate into large buildings, in theory making dropped calls, typical of today's cell phones, a thing of the past. A company called MobiTV will utilize the WiMAX network for the broadcast of TV, including HDTV. VoIP (telephone service) has already been deployed on WiMAX networks in other parts of the world.

Although the WiMax boasts over 275 WiMax deployments throughout the world (mostly small regional operators), the only place where WiMax has been a business success is in Russia, where existing broadband infrastructure was very poor. In emerging markets without extensive broadband infrastructure (DSL, cable), WiMax has an advantage over W-CDMA. Many cell-phone operators have invested in existing networks that naturally evolve into W-CDMA.

WiMax (Worldwide Interoperability for Microwave Access) will be similar to cellular coverage, but with Wi-Fi's speed and lower cost. With players like Intel leading the way to make sure WiMax chips are built into future laptops, there is a lot of money riding on this technology.

  • (WiMax is) "the most important thing since the Internet itself." Intel

WiMax technology will allow an operator to build a wireless network over a large area (city) that will allow high-speed connections to the Internet. As with early cell phone coverage, rural areas will be the last to receive service, but WiMax has a communication range of up to 30 miles.

WiMax supports peak data speeds of about 20 Mbps, but, as with most wireless technologies, that bandwidth will be shared amongst users. The average will see user data rates between 1 Mbps and 4 Mbps.

One problem has been that forecasts for WiFi subscriptions used to justify the investment in WiMax have been overly optimistic. Between 15% to 30% of an area's population was expected to subscibe to WiMax, but only 1% to 2% have subscribe so far according to Glenn Fleishman, Wifinetnews.com

WiFi networks, including the newer technologies like WiMax and LTE, will continue to become more prevalent in the future. The technology may not be the most important impediment to implementation. Because the same companies that currently operate land-line internet access, would be the companies to invest in large scale WiFi networks, the motivations are complicated. New competition from broadband service satellites, like ViaSat, that will be launched in the next 2-3 years will prod them on, hopefully.

WiFi Internet For Buildings and Cities

Brian Bradshaw is a Certified Technical Specialist (InfoComm CTS). Areas of expertise include Video, HDTV, Audio, Computation, WiFi, Satellite Systems, and Communications. He has a communications technology business in Plano, Texas (Dallas). More information can be found at his Website:
http://bradshaw-vacuum-technology.com

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