What's your first concern about installing security cameras for long distance monitoring such as a CCTV metropolitan surveillance system?
The first question that comes to your mind is "How to transmit the videos to a CCTV surveillance center"? That's when you think about wireless IP camera.
But the design of a wireless CCTV metropolitan project is not that simple and you can't just purchase some small wireless IP cameras such as the ones used for cloud recording, and install them around the city.
You need to learn about wireless transmission technology, so you can apply this knowledge to your project and have better chances to be successful.
So, in this article let's dive in into some theory about wireless devices and some other cool stuff. so in no time you will have a better understanding of the necessary concepts and best practices of a CCTV wireless design.
The wireless IP camera technology
I have really good news for you my friend. You just found the article that will explain everything you need to know about Wireless IP cameras and all the technology they use in such easy way to understand that you will be surprised how much you can learn from a single article. So keep reading...
In the image above you can see a happy woman using a laptop on a wireless network. She is happy because it's easy to access the Internet and also because she now can learn all this technical stuff on the Learn CCTV.com 🙂
OK, you are also here to learn more, so let's get started with my question to you: "what wireless frequency her laptop is probably using? "
Perhaps you are wondering what this thing with a woman and her laptop has something to do with a article about CCTV metropolitan project...
C'mom, you got answer this simple question, otherwise how can you understand all the technical details about Wireless IP cameras?
I'll tell you what, you just need to understand from the beginning what are the wireless devices frequencies, transmission speed, standards and a lot of other details necessary to become a really qualified professional
The wireless network frequency standards
The wireless network devices for commercial use such as the wireless routers you have at your home are designed according to technical standards with specific frequencies such as 2.4Ghz and 5Ghz.
Whenever you read about these standards, you find certain acronyms such as IEEE 802.11, which are actually used as a reference to keep everything documented by the IEEE ( Institute of Electrical and Electronics Engineers) which is an engineering group responsible for the creation of these universal well-known technical standards.
I will not go into details about the IEEE in this article, but keep in mind that the standards carry the group acronym followed by numbers and letters. The IEEE 802.11b for example is easily found in your wireless router label.
When you buy a wireless router, (also known as Access Point), you can see it has a label that shows the wireless standard it complies to as IEEE 802.11b, 802.11g or 802.11n.
They are the indication of the frequency and speed that the device uses for wireless transmission.
You can find the same information on your Wireless IP camera label.
Frequency and transmission speed
The first popular wireless standard was the IEEE 802.11b which has a 2.4GHz frequency and a transmission speed of up to 11Mbps.
I remember back on 2004 when our technical team used to discuss the issues related to this standard when designing the metropolitan surveillance system, there was no professional wireless IP camera at that time.
The first wireless network cards for computers and laptops were created in accordance with this standard to work with the frequency of 2.4Ghz.
Later another standard called IEEE 802.11g kept the same 2.4 Ghz frequency but increased the transmission speed from 11 Mbps to 54Mbps and the new computer and laptops started using such standard.
Back there was not easy yet to find a wireless IP camera, but that was not a problem to design the surveillance system, you are going to see why later.
Finally another standard called IEEE 802.11n came out and kept the same 2.4 Ghz frequency but increased the speed from 54Mbps to 300Mbps and now the new computers and laptops could also use such standard.
The important thing to understand here is that the standards have been keeping the 2.4GHz frequency and increasing the transmission speed *
* ( In addition to 2.4GHz, the IEEE 802.11n can also work with 5GHz)
See the summary of the IEEE 802.11 standard transmission speed
In most cases you will find laptops that are working with the 2.4GHz frequency and this answers the question I asked in the begging of this article about the woman using her laptop, remember ? Are you still there ? 🙂
I assume you are still reading and willing to learn more, so let's continue...
How about the CCTV wireless network?
What about it? Just buy any wireless IP camera and you are done ! Wait, wait... I'm just kidding, you can't do that before understand the concept...
In fact I'm glad you asked this question, after all you are here to learn more about the wireless technology to use it in your CCTV projects, aren't you?
Or maybe you want to install your own wireless camera....
Anyway, for your home CCTV surveillance project you can use the all-in-one wireless IP camera, but for that huge wireless metropolitan CCTV project with hundreds of IP cameras, it's better not even think about it.
So which of these three standards (802.11b, 802.11g, 802.11n) should I use in a metropolitan CCTV project ? Guess what... "None of them"
Say whaaat? Now you must be thinking that I'm crazy and that I should use the IEEE802.11n standard because it's faster probably a wireless IP camera can be found out there in any electronic store. So what's the catch ?
In fact, for a serious CCTV metropolitan system, it's not common to use the all-in-one style wireless IP camera. It's better to use professional IP cameras with wireless IP radios manufactured especially for use in CCTV projects.
For small projects with few cameras, you can use cheaper wireless radios, but for the huge ones, please just go with the best brand you can find.
Use the 802.11a standard
The 802.11a standard uses the 5GHz frequency and that makes a huge difference for the projects because there's less radio interference and more channels to work with. That's a better choice for the IP CCTV project.
Long time ago the wireless devices using the 802.11a (5GHz) standard were too way expensive, but that scenario has changed. Due to the technology evolution and more manufacturer competition the prices dropped a lot
So, you can buy professional wireless radios from different manufactures such as Proxim, Radwin, Cambium Networks, Fluid Mesh designed especially for IP CCTV application, so you can assure the best quality for your project.
Avoid to use 2.4GHz wireless radio
So it is simple, use wireless radio with the 5GHz frequency, and avoid using the 2.4GHz, unless your project is really simple and your are on a budget.
See the picture below that shows a professional wireless radio
Besides the frequency, there are still many others factors that will impact on the video transmission over wireless networks, all those details are taken into consideration by the professional wireless radio manufacturers.
Wireless radio license and homologation
Hey, did you know that there are many wireless IP CCTV projects that are illegal ? They don't have a license for operation just because people don't know they need one or sometimes the wireless radio are not homologated.
Let's start talking about the professional wireless radios for CCTV, so you can clearly understand how and why to use them. To make things easier to grasp, I'll use an real example of a metropolitan CCTV project that was implemented many years ago. Pay close attention to the history...
CCTV metropolitan case study
OK, so let's come back to the year 2004 when my technical team was facing a challenge. A small city's mayor wanted security cameras installed to monitor and record all main city entrances and buildings.
Everything should be monitored by the local police task force in a surveillance room, specially designed for that project.
Around 60 analog box cameras, and 5 PTZ (Pan Tilt Zoom) cameras. should be installed in the city. Each camera should transmit and store videos at 4CIF resolution at 30 FPs with 30 days recording .
If you don't understand some of the CCTV camera terms used here, just read the article: How security cameras work.
How to broadcast videos from CCTV cameras?
The first challenge was how to transmit videos from the security cameras to the CCTV surveillance center located few kilometers away, the first idea that came to our minds was to use fiber optics .
But use fiber optics would cost too much due to the need of running cables throughout the city using public poles. It's was really too complicated and the logistics and specialized jobs involved was huge.
The solution: use wireless radios
The decision to use wireless radios for the CCTV project was interesting but at that time (2004) there were no modern wireless radios designed for CCTV, so our team had to use the technology that was available.
And guess what... The technology available was the traditional wireless network routers used in homes offices. Those wireless routers were not the best solution to work for a metropolitan CCTV project due to the 2.4 GHz frequency and the 11 Mbps (nominal) speed limitation.
And of course, the wireless radios were not sturdy enough to work in an outdoor environment neither ready to work with intense network traffic.
The bad experience with traditional wireless radio
As I said earlier one of the problems was the use of the 2.4GHz frequency which is subject to a lot of interference from other devices, there were also performance problems in addition to the physical issues like temperature, humidity and even insects entering the box installed on the pole.
At first tests were done with this type of radio, connecting external antennas and installing the radios in boxes in the poles.
In the practical installation we face a lot of problems during the tests and adaptation for outdoor use.
I'll talk about the problems with 2.4 GHz frequency later, but basically, there are only three channels that can be used to avoid external interference.
This wireless router processing is another important factor, since traditional radios for internal applications are not designed for heavy traffic over long continuous period of time, Let's say 24 x 7 x 365.
Box on a pole
Over time the high temperature inside the box has become a problem and the use of fans in the opening of the box has brought other problems like moisture and insects ingress.
Over time, more suitable new boxes were emerging, but it was still a laborious solution to use for CCTV installation.
A better solution to our problem was needed,
Best wireless radios for CCTV
So the installation of boxes on poles was a tremendous headache. And at that time a solution such as all-in-one wireless IP camera with built-in wireless radio and antenna was not available at the market, and even of it was, this kind of device is not suitable for our metropolitan CCTV project.
In order to improve the system we started using sturdy wireless radios that were manufactured for outdoor application, although they were designed for data transmission and not for CCTV, they were at least more adequate for the CCTV metropolitan project we were working with.
Over time, new technologies were emerging and prices began to become more attractive, allowing us to use wireless radios that were specially manufactured for CCTV installation, and then the transmission of high quality videos from IP camera was became cheaper and easier .
Now without those huge and ugly boxes installed on the poles, the CCTV projects became more interesting. But is still necessary to have specialized knowledge to design a good wireless CCTV IP project for cities .
Best wireless radios for CCTV
Let's talk about the bandwidth required to broadcast the IP camera video over the wireless network. Just keep reading...
After installing the IP cameras to transmit video over a wireless network, do you measure the speed available for the video broadcast or you just read the information on the wireless radio box ?
The information that is written on the product's box is not the real one the will get in the field, so be really careful with this type of information.
Let's talk about that now...
The manufacturer's information
OK, let's simulate a scenario for an IP CCTV project with wireless transmission so you can better understand about bandwidth calculation.
You can find extra information about bandwidth and storage calculation in the article: CCTV storage calculation with formula and examples.
Let's say you are working on a project and need to transmit videos from 10 IP cameras with Full HD resolution and 15 FPS and you can't use cables or fiber optics, so the solution is to use a wireless network system.
You must have an idea about the bandwidth required for each camera. You can do that by checking the camera manufacturers calculator.
Working with a standard project with a Full HD resolution and 15 FPS (a really good video quality) an average of 2.5 Mbps per camera will be necessary for transmission. That's 25 Mbps for the 10 cameras.
So, could a 802.11g wireless radio with 54 Mbps network speed be a good solution for your project that only need 25 Mbps? The answer is NO.
Remember the 802.11g standard uses 2.4Ghz frequency and the network speed is nominal, that means in a real installation with some factors such as long distance links, interference, etc the network speed will drop.
Take a look at the wireless router below, this is a traditional model that will not be used for the professional CCTV project. So just don't take it.
Besides the fact that is possible to read the label information stating the 54Mbps network speed, after installing the wireless radio a measurement will show you that is not possible to have even half of that speed.
So, the traditional wireless radio is not good for you...
Why is the real speed is slower than expected?
Several factors can affect the final real speed of your project:
- Operation of the communication protocol
- Interference of other equipment
- Line of sight Installation
- Distance between transmitter and receiver
- Maximum transmission power used by the radio
When the wireless transmitter radio communicates with the wireless receiver there is a significant bandwidth loss because a constant confirmation is required. Is just like a conversation:
Transmitter: "I sent the packet"
Receiver "OK, I got the packet" or "I didn't get the packet, please send it again"
Other equipment working in the area will interfere with your system, and even with the wireless radio 11 channels, by using the 2.4GHz you will get stuck with the interference issue, doesn't matter if you keep changing channels because the 2.4 Ghz frequency spectrum is used by everybody.
If there is a partial block in the line of sight between the transmitter and receiver, there will also be a problem, even if the two devices can still "see" each other you must take Fresnel zone into consideration.
Don't worry... I will talk about the Fresnel zone later in this article.
The distance between the wireless transmitter and receiver will also influences the final speed, In addition to the power used for transmission.
Unfortunately you can't just install signals amplifiers to give extra power to the wireless radio, even if you know someone who has already done that, don't do it. unless your 100% sure about what your doing because amplifiers can make your devices work out of the allowed power range.
But what is the real speed of the project?
Each project is unique, so obviously there will be variations for each case, but on average the first factor (communication) already causes the radio to lose about 50% of the bandwidth, and following the next factors, it can reach less of 20 Mpbs on a radio with nominal speed of 54Mbps.
Please don't sell an IP CCTV project with wireless transmission without considering these factors
Someone will not be happy if the real transmission speed is not enough for the CCTV project.
That is why it is important to study and understand all the concepts presented here, so you will know what to use for the project.
But don't freak out. You can have professional wireless radios vendors helping you with the project. I'ts not that hard.
The initial design with the 10 IP cameras needed at least 25Mbps, so the traditional 54Mbps wireless radio is no longer adequate for the project.
There's also the issues with the device processing power and stability for this type of application that requires a 24/7 constant video transmission.
If you need the 2.4GHz, use the right frequencies
Understanding a little theory of wireless networks is necessary to develop a better CCTV project, so now let's move on and discuss the a little about wireless frequencies and channels, believe me it's very important.
It has been explained previously that it is currently best to use the 5 GHz frequency and leave aside the 2.4 GHz frequency, so it's time to understand the theory behind the technology. Don't worry, it's not rocket science.
Let's get straight to the point, when we buy a wireless radio to transmit the videos of the CCTV cameras from point A to point B, so is necessary to choose which radio model to use.
The biggest problem with the 2.4 GHz frequency
Have you noticed that when you are using the laptop to download something from the Internet and somebody turns the microwave oven and the Internet slow down or sometimes even get frozen?
This happens because the wireless router and the microwave oven work at the same 2.4GHz frequency, so there's a signal interference and the Internet on your laptop stop working.
When you install your cameras in an outdoor area to transmit the videos across the city, guess what happens.... you are not the only one who had this idea, there's a lot of other wireless radios working in the region using exactly the same frequency, so they interfere with your system.
There's still a chance to minimize the interference in your CCTV system, it's not the ideal way (use 5GHz would be better), but sometimes you have to use 2.4GHz, if that's the case just choose the right channels to work with.
What are the channels on the 2.4GHz frequency?
Each channel corresponds to a specific frequency, see the image:
Please take a look at the picture above and pay close attention to channels 1 and 5 to understand the explanation below.
The image above shows the channels that are available on a 2.4GHz wireless radio, Can you see that the channel 1 starts at the frequency of 2.412 GHz and ends at 2.434 GHz
==> I bet you did not find the 2.344, Am I right ?
Sorry friend, there's a catch here... the 2.434 is the sum of 2.412 + 22 MHz which is the size of the channel
Now look at the picture again and notice that channels 2,3,4 and 5 start at the same semicircle as channel 1, meaning they start before channel 1 finishes, so they are overlapping and getting interference from this channel.
Take a look again, see channel 1 finishes at 2.434 but the channel 5 starts at 2.432 (last dotted line inside channel 1 semicircle)
The conclusion is that channels 1,2,3,4 and 5 cause interference among themselves, By following the same principle channels 6,7,8,9 and 10 also cause interference among themselves.
Take a look one more time at channels 1, 6 and 11 Can you see that they don't cross their lines? meaning, they don't cause any interference among themselves, so those channels are "clean"
So, with 2.4GHz is better use channels 1,6 e 11 ?
Exactly, don't waste your time trying to use other channels. If your neighbor is using channel 1, you can't use channel 2,3,4 or 5 to escape the interference ... you must use channel 6.
Ideally, your neighbor on the left uses channel 1, you use channel 6 and the neighbor on the right uses channel 11, which would be the ideal situation for everyone to get rid of interference.
You can use a software called Net Stumbler on your laptop to scan the environment and see which channels are being used in your area, so you can choose the most suitable one following the "3 clean channels" rule.
Well, in the practical scenario you will find it difficult to work with only these 3 clean channels because of the amount of equipment in your area, which is why the other 5GHz frequency is better, since it allows you to have more free channels.
If you don't understand something, read the article again and do some tests at home, see what channels you use on your router and which channels are used by your neighbors, you can even improve the speed of your connection if you just change the channels to avoid interference.
Line of sight and Fresnel zone
When you are going to install a pair of wireless radios for video or data transmission from point A to point B, is necessary to consider the line of sight between the two devices. The transmitter has to "see" the receiver, so try to keep the line of sight as obstacles free as possible.
When you install a wireless radio in a building for example, just pay attention to obstacles such as buildings, towers, antennas, trees, mountains and other things that can obstruct the wireless radio signal.
But it is not enough to have only one clear view from one wireless radio to the next in a straight line, it is also necessary to consider an area around that central imaginary point.
The radio waves travel through the air from one point to another using an area similar to a football. This area is denominated the Fresnel zone.
So is necessary to calculate this Fresnel zone, or at least have an idea that obstacles around, below and above the direct line of sight can affect the transmission signal of the radios and this entails loss of transmission speed and stability of the system.
Important factors for wireless transmission
OK, let's review what's important for a good wireless CCTV system design:
- Work with frequency with less interference such as 5GHz
- Use wireless professional radios designed for CCTV
- Consideration of the actual speed x nominal speed
- Calculation of the bandwidth required for video transmission
- Plan the use of the correct wireless radio channels
- Be careful with the line of sight and Fresnel zone
Well, I'm sure you've learned a lot up to this point, unfortunately is not possible to consider all factors and details about wireless IP cameras and IP CCTV design in a single article, even one that is that long.
You still can learn a lot more about this subject, do don't hesitate to go through other articles available in this blog.
Want to become a better professional ?
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