We recommend to purchase a system that has twice the range for the distance you require.

For example if you need to send your signal 800ft. Clear-Line-of-Sight range use our 2000ft. range wireless video transmitter and receiver system (our W58N15-20).

We can transmit through plastic and glass as if it was not there, when we transmit through normally constructed walls, dry wall, wood, and insulation, the wall will trap a small amount of moisture which will attenuate the transmitted signal a little bit, the more walls the more signal loss. Red brick is made of clay which is earth, we can not transmit through earth, concrete is made with rocks and the rocks have iron which can block the signal. Concrete is sometimes unpredictable in that if we test out the wall we might find a gap in the mix which has less rocks and we have a stronger signal passage for the signal to find a way through. Trees are also for analog wireless video systems. The leaves and branches also have moisture which kills the analog wireless video signal.  Do not use analog wireless video systems if you have applications with obstructions or obstacles which may block the signal.

We recommend to always maintain Clear-Line-of-Sight between the transmitter and receiver with no obstructions.

If you application has obstructions or a few tree then we recommend our 2.4Ghz Digital OFDM systems or our Digital COFDM transmitters and receivers set at lower frequencies.

The signal is a half-duplex (one way) signal sent only from the transmitter to the receiver. Each of our systems is factory set on one of eight available channels (optional 32 are available). This is done through an internal dip switch. Each system comes labeled with the factory set channel setting. Most systems come preset on Channel 1. For multiple systems we use the ODD channels so all the receivers can be mounted on the same pole inches from one another. If more than 4 systems are used in the same general area we recommend that all the ODD Channel receivers be mounted near each other and all the EVEN Channel receivers mounted together. The EVEN Channel receiver should be mounted at least 25 to 50ft. away from the ODD Channel receivers.

In order for the systems to work properly you need to make sure there are no other systems on the same 5.8GHz frequency (channel) within a 50 to 75 foot radius around the receiver which receives the signal. Think of the signal like and AM radio station blasting out to a transistor radio. If you have 2 radio stations on the same channel or frequency the most powerful signal will be picked up. If the two signals have spacing between the channels then you can receive both signals on 2 separate radios with no problems. Our systems work very similar to this example.

Since we have 8 channels (different frequencies with optional 32 channels) for our 5.8Ghz wireless video transmitter and receiver systems multiple units can easily work in the same general area as long as you follow the rules above.. The transmitter always needs to be set on the same channel (frequency) as the receiver you are sending the video signal to.

See this link for our: 5.8Ghz Long Range Video Systems

Moving Transmitters and Digital Wireless Video Systems:

When we transmit inside a building, in urban areas with buildings and/or are using a system as a mobile wireless video transmitter, the signal is subjected to RF reflections. These signal reflections are caused by metal or solid objects that reflect or bounce the transmitted signal back to the receiver. With analog systems this Multi-Pathing or Ground Plane Effect causes video distortion and the result is unwatchable video. The only option for applications

where the transmitter and/or the receiver may be moving or is in an area blocked by some obstructions is a DIGITAL wireless video transmitter and receiver. We offer several digital wireless video solutions, OFDM Spread-Spectrum system and our Digital COFDM wireless video transmitter and receiver system. Our COFDM system is completely custom made-to-order and uses factory preset frequencies from 300Mhz to 5.8Ghz. The power output of these systems is available from 100mW to 20 Watts through optional external power amplifiers.

See this video for analog wireless video system compared to a digital wireless video system:

WirelessVideoCameras.com from Eric Shepherd on Vimeo.

Note: You will see the video break up (distortion) at approx. the 1 minute point of the video. (this this not 1080 HD video, only showing the difference between Analog RF transmission & Digital RF transmission)

OFDM – Orthogonal Frequency Division Multiplexing is a technology that transmits multiple signals simultaneously over a single transmission path on a single channel. Each signal travels within its own unique frequency range, carrier, which is modulated by the video, data. The spread spectrum technique distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the “orthogonal” in this technique which prevents the demodulators from seeing frequencies other than their own. The benefits of OFDM are high spectral efficiency, resiliency to RF interference, and lower multi-path or reflection, distortion.

Indoor & Moving Transmission C-OFDM Digital Video

C-OFDM – Coded Orthogonal Frequency Division Multiplexed transmission technology provides a superior means of transmitting wireless information in high multipath environments. C-OFDM systems use 2000 coded carriers within the main signal; each carrier is coded modulated for signal robustness.

The loss of one or many coded carriers have no impact on the video received. Adjustable guard intervals minimize multipath interference. The system also uses Forward Error Correction coding, further increasing signal reliability. Multipathed signals are summed at the receiver, actually aiding in signal quality. C-OFDM systems have become the standard for transmission in Europe.

1. 1. FDM transmitters involves three major components: A signal encoder, a modulator, and an RF transmitter. MPEG, MPEG 2, MPEG 4 & H.264 are the industry standards for encoding an NTSC or PAL signal, the modulation scheme is C-OFDM.

1. 1. • 99.99% Perfect Video Picture with Zero Color Shift
      • Freedom of Movement Inside Buildings With Out Losing Video & Audio
      • Upgrade Option Available to Transmit in HDTV
      • License Free with Long Reaching Ranges

 

Wireless Video Installation Basics 101

• Always perform a site survey to make sure you have Clear-Line-of-Sight with no obstructions between the Transmitter and the Receiver.
• Always mount the Transmitter and Receiver at least 10 feet higher than any obstruction. Always aim the Transmitter antenna enclosure Directly at the Receiver antenna enclosure.
• When using multiple systems in the same area, Always install all even channel Receivers 25 to 50 feet from odd channel Receivers. This will eliminate the chance of interference.
• Contact Wireless Video Cameras.com Technical Support if you have any questions.

 

Wireless Video Installation Basics 101 Examples

The below installation diagrams should be used to help you plan your wireless system installation carefully for the best results possible.

The above installation image illustrates that it is important to mount your wireless transmitter & receiver on poles to raise them above any obstructions. Besides raising them, it is equally important to make sure that there is a direct line of sight between them.

When positioning your wireless transmitter and/or receiver units on roof-tops, provide a clear line-of-sight and avoid the possibility of signal multi-pathing by raising them on poles or locating them on the edge of the roofs.

The ground plane can cause multi-path issues and can significantly affect the range of your wireless transmission.

 

Fresnel Zone & Long Range Wireless Video Basics

• 1. 1. • The Fresnel Zone is the area around the visual line-of-sight that radio waves spread out into after they leave the antenna. You want a clear line of sight to maintain signal strength, especially for 5.8 GHz wireless systems. This is because 5.8 GHz waves are absorbed by water, like the water found in trees.
        • Typically, 20% Fresnel Zone blockage introduces little signal loss to the link. Beyond 40% blockage, signal loss will become significant.
        • This calculation is based on a flat earth . It does not take the curvature of the earth into consideration. The effect of this is to budge the earth in the middle of the link. It is recommended for long links to have a microwave path analysis done that takes this and the topography of the terrain into account.
        • The formula for determining the radius of the widest point of the fresnel zone (in meters) is:

   

• 17.32 * square root of ( d /4 f)

  where d is the distance (in kilometers) between the two antennas and f is the frequency (in GHz) at which you are transmitting.

  1. 1. • The formula for determining the radius of the widest point of the fresnel zone (in feet) is:

   

• 72.05 * square root of ( d /4 f)

  where d is the distance (in miles) between the two antennas and f is the frequency (in GHz) at which you are transmitting.

 

Fresnel Zone Clearance and Antenna Height Calculator

Radio Frequency Line-of-sight

At UHF and microwave frequencies, when you deploy an RF link between two distant sites you need to make sure you have “line of sight” between the two antennas. But at these frequencies “line of sight” does not simply mean that from one site you can “see” the other. When your distance exceeds, say, 5 miles (8 Km), you need to take into account the following factors:

1. 1. • The curvature of the earth.
      • Fresnel Zone clearance.
      • Atmospheric refraction.

The figure below illustrates these concepts with an exaggerated representation of a long link. The following sections describe these effects.

Fresnel Zone Definition

The Fresnel zone is a long ellipsoid that stretches between the two antennas. The first Fresnel zone is such that the difference between the direct path (AB in the figure below) and an indirect path that touches a single point on the border of the Fresnel zone (ACB) is half the wavelength.

If a significant portion of the Fresnel zone is obstructed the receive-signal-strength at the receiving antenna can be greatly attenuated. A rule of thumb is that you need at least 60% of the first Fresnel zone clear of any obstructions in order for the radio wave propagation to behave as if it is in “free space”. “60% of the first Fresnel zone” means a narrower ellipsoid with a radius that is 60% of the radius of this first Fresnel zone.

Even though at 2.4 GHz half of the wavelength is only 2.4 inches (6.2 cm), at long distances the radius of this ellipsoid can be quite large. For example, with a link distance of 31 miles (50 Km) the radius of this (60%) ellipsoid at the mid-point is 77 ft (23 meters). You can use the calculator to compute this radius at any point in between the two antennas. You may also change the percent value of the first Fresnel zone you wish to clear.

Atmospheric Refraction

Under normal atmospheric conditions radio waves do not propagate in a straight line, they actually bend slightly downward. This is due to “refraction” in the atmosphere which affects radio waves propagating horizontally. To take this downward bending into account, we perform all the path calculations using a larger value for the earth radius, such that we can then consider the radio waves as propagating in a straight line.

In the Fresnel zone calculator you can change the earth radius multiplying factor (the “k factor”) to take into account

different atmospheric conditions. Under normal conditions the “k factor” is 4/3. However unusual weather conditions can cause significant changes to the refraction profile. For a high reliability link you may want to use a lower value for the k factor.

Repeater Systems to Achieve Clear-Line-of-Sight

Repeater Systems using multiple Wireless Video Transmitters & Receivers may be used to achieve Clear-Line- of-Sight to enable use when obstructions are in the way.

NOTE: Transmitter (TX 1) connects to the camera and sends the signal to Receiver (RX 1). These 2 units will be set on Channel 1. The video output from RX 1 will connect to the video input of TX 2. TX 2 will send its video signal to RX 2. RX 2 connects to a monitor or NVR. These 2 units (TX 2 & RX 2) will be set on Channel 3.

Antenna Towers to Achieve Clear-Line-of-Sight

Air-Craft Grade Aluminum Antenna Towers are the perfect low-cost solution to get above most obstructions to achieve Clear-Line-of-Sight. Light-weight, easy to install and come in 10ft. sections

Purchase directly from:

PALCO ELECTRONICS

Toll-Free: 1-888-282-1313

Universal Antenna Towers Are Easy To Install

Do it yourself or hire a local contractor…

See the link below for an easy installation guide

http://www.palcoelectronics.com/tower_installation.aspx