Wireless Video Cameras .com 

With our years of experience we have found many ways to make things work that goes against the norm, this is why we are the preferred company for integrators and those who look outside the box.

Wireless 101 Education

FM Analog 2.4GHz and 5.8GHz

Thank you for checking us out, we hope to give you a crash course education here to help you better understand the basics of  video transmission in the microwave bands.

This is a quick education to help you get started, please feel free to call us anytime for more detail explanation or question.

Ground Based, Point to Point, Fixed Transmitter and Receiver Location:

We first start off with the understanding that we are transmitting video and audio on 2.4GHz and 5.8GHz band. The most common system used is FM Analog which can transmit and receive up to 525 lines of resolution which is a industry standard. The transmitter RF output power varies from 50mV at 3 Meter Range to 1-WATT based on the ratings, FCC Part 15, FCC Part 97, and FCC Part 90 approvals for different types of application such as License Free for all types of usage to Hobby, non commercial, to Business and Law Enforcement. The normal video and audio input and output signal is rated at 1 volt peak to peak again an industry standard. The transmitter is the part the video and audio inputs are connected to transmit the video and audio signal wirelessly to the receiver which receives the video and audio and connects to a TV, DVR or VCR type of devise to view or record. The higher the frequencies, 2.4GHz and 5.8GHz gives us more band width to transmit higher lines of resolution and the video looks more like broadcast quality you would except from your TV. The transmitter transmits the signal one way on a preset channel (frequency) and performs its best when we have a direct line of site between the transmitter and receiver. We need to make sure we have control of the 2.4GHz or 5.8GHz band with-in 75 to 100 foot radius around the receiver which receives the signal. The items we need to be concerned about are 2.4GHz and 5.8GHz home version wireless telephone systems. These wireless phones normally operate with spread spectrum technology which means when it is powered up, both ends, base station and hand set they continuously hunt for clear channels and frequency hop up and down the band. This will create white lines our video picture and sometimes popping noise in the audio. In cases with apartments, condos, and shopping malls we can not control the 2.4GHz or 5.8GHz band so we do not recommend usage in these areas. With a single dwelling home we can control the frequency and choose one band over the other if there are wireless phone system already in the home. If you have a wireless computer network in most all cases it will be a 802.11G system which is on 2.4GHz and locked onto a single channel, generally this does not cause any interference and the channel can be changed if it conflicts with the video frequency. 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. To over come this we need to either increase the transmitter power or add a higher gain receiver antenna to pick up the weaker signal. 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, good luck hunting. The ranges we rate our equipment is based under ideal conditions which is defined as in the desert with low to no humidity with the transmitter and receiver off the ground about 10 to 20 feet at a 300 foot and higher for longer ranges. The long range transmitter and receivers are effected by what we refer to as "Ground Effect" the greater the distance we transmit the great the height off the ground. When we transmit 15, 20, 30, or 40 miles remember the the earth is round so for a 40 mile range you should plan having the transmitter and receivers about 60 to 80 above the ground. Another factor is salty air, if you are anywhere near the beach the salty air will reduce the range by 1/4 to 1/3 of the rated distance. In all cases we want to use a system that is rated a greater amount than the actual distance. If you measure out 800 foot distance between the transmitter and receiver we would recommend a1300 foot, you want to plan for less than ideal condition so that if or when the weather changes we are covered.

Moving Transmitter:

When we transmit inside a building and walking around we are subjected to RF reflections, this is when the metal objects inside the building reflect the transmitted signal back to the receiver causing the receiver to receive more than the original signal and  the picture flickers / blinks. To understand better how this works think of the transmitter signal like a light bulb and all of the metal inside the build are mirrors reflecting the light back to your eyes (receiver). As you can imagine you would have a difficult time locating the original source of the light. If we were to take this outside in the open we would have no problems, everything would work fine. Transmitting inside a build can be accomplished using a C-OFDM system which we will talk about near the end of this lessons. 

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