Twisted Pair Surveillance
Twisted pair is a type of cable connection that transfers data between a camera and a recorder in surveillance systems. With its help, the signal is transmitted at high speeds, and the range of delivery without switching equIPment significantly exceeds the same parameter for a coaxial cable. What are the features of the surveillance over twisted pair?
- PrincIPle of operation and features of functioning
- Features of the choice of equIPment for twisted pair
- Connecting an analog camera over twisted pair
- How to connect an IP camera via twisted pair
Connecting an analog camera over twisted pair
Twisted pair analog surveillance is created by connecting transceivers in the line.
A huge advantage of a twisted pair cable over a coaxial cable is the number of connected cameras. One 4-pair Lan cable can be used to fully connect 2 cameras, i.e. simultaneously supply a signal and voltage.
It is very easy to connect an analog camera over twisted pair. To do this, you need to decide on the choice of the color of the required pairs for connecting the transceiver and the power plug from the camera side and duplicate the sequence at the end of the line from the side of the recorder and the power supply.
Features of the choice of equIPment for twisted pair
Effective operation of this type of device is only possible if the correct components are selected. To do this, you should follow these tIPs:
- It is desirable that the receiver or transmitter include an induced voltage or atmospheric electricity protection unit.
- The product in question must contain information about the operating voltage, permissible temperature range, compatibility with other types of equIPment.
- If you plan to purchase an active transmitter and receiver, they must necessarily include regulators to configure the device.
- As plus it is also possible to consider marks such as protection system characteristics, frequency range and others. Of course, without proper qualifications, these designations will NOT say anything. But, on the other hand, they testify to the quality of the product.
- Don’t trust statements like 720p image quality will NOT change even when transmitted over a couple of kilometers. When transmitting a twisted pair cable over such a distance, insignificant loss of quality is an inherent moment.
- Also, when choosing a suitable version of a twisted pair, it is desirable to pay attention to its capacity. reliable and efficient will be the option in which this value is less.
PrincIPle of operation and features of functioning
Data transmission over certain distances, regardless of the channel used, is subject to various interference. This interference gradually drowns out the useful information signal. When its strength drops to the level of interference, it is almost impossible to distinguish and isolate the necessary data from the general background.
The twisted pair, according to the princIPle of operation, is a SYMMETRIC line. In such connections, during data transmission, interference is also transmitted symmetrically. And when they converge, their mutual destruction occurs, due to which the main data is easily recognized.
This princIPle of operation is ensured by the special design of the line, which, in addition to the cable itself, also includes a pair transmitter-receiver. Of this equIPment, the transmitter is responsible for receiving and converting the camera’s single-ended signal to balanced. Then it is amplified and sent to the receiver. At the receiver, the signal is re-amplified and converted back to single-ended form.
But this scheme also has a couple of nuances. Even this method of transmission, although it allows you to neutralize interference, all in fact does not exclude the weakening of the useful signal. The transmission range in such systems is 50 Hz. 6 MHz. And since the channel capacity is much larger, the signal is fed unevenly. over, the higher the frequency of the transmitted signal, the more it weakens. In addition, the degree of attenuation is also directly proportional to the range of the line used.
As a result, we can conclude that this transceiver format, also called passive, is only suitable for small cable infrastructures. Over longer distances, active equIPment is better at transmitting. Such equIPment includes various versions of jumpers or trimming resistors. With their help, two types of signal strength adjustment are carried out:
- By means of a jumper. stepwise adjustment;
- Due to the resistor, the line adjusts more smoothly.
The first type of equIPment is quite easy to use. After calculating the total length of the line, jumpers are mounted on clearly verified segments, which amplify the signal. Of course, in fine tuning it is not necessary to speak here, but for most surveillance systems they are quite enough.
A trimmer resistor is capable of providing a finer setting. But it is possible only if additional equIPment is used. At the same time, not every master can adjust such a scheme.
Having implemented the above measures and having carried out a competent setup of the system, the signal transmission range over twisted pair can be increased from the standard 2 km to 3-4 km.
How to connect an IP camera via twisted pair
The rg45 connectors are used to connect the IP camera. Twisted pair for IP surveillance can be either 2-pair or 4-pair. To connect any IP camera, two pairs of Lan cables are enough. Do NOT believe if someone says that signal transmission will be better in a 4-pair cable.
To connect an IP camera over long distances (for example, up to 150 meters), you can use a POE injector. To power the camera via POE, you need to crimp 4 pairs under the connector.
The maximum distance of the IP camera over twisted pair without poe injector does NOT exceed 100 meters. To increase the distance of the IP camera, it is necessary to install an Ethernet extension cable for every additional 100 meters.
Crimp 4-pair cable.
Crimp 2-pair cable
IP camera connection via twisted pair
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Andleo Answer Meaning NOT to pull wires when replacing old equIPment with AHD.
At the moment, some cameras work via twisted pair and signal sealers. So you are interested in AHD compatibility with transceivers? Also, the cost of a twisted pair is an order of magnitude cheaper than RG-6, as well as several cameras can go on one twisted pair.
There is AHD compatibility with different seals, signal extenders ?
What is the transmission distance when using other cables, for example: RG11, RG-59 \ U and combined for example KVT-V-2 2×0.5 ?
Available in our assortment, but in nature there is.
Leharbc Reply I often use transceivers for AHD over twisted pair. Really helps out.
Highlights Revealed by Practice.
1. Twisted pair is better than FTP (shielded)
2. I. One pair per camera. Start up in pairs and from two cameras. The lead cannot be avoided.
3. Working options:
A. 2 pairs. 2 cameras, 2 pairs, etc. Nutrition. If you hang on a couple and Constant loss of nutrition.
B. 4 pairs. 4 cameras. Power supply either by separate twisted pair or in the final stage.
By the very same decision to lay a twisted pair cable at a distance of 120-150 m through the basement of a residential building, then along a common shaft to the 17th floor, then along those. Floor and roof. Power supply of cameras from power supplies from the technical floor. Suggestion comments.
They help out precisely with non-standard solutions. A series. Echo from the sky
Anton_tech. Support Reply Good afternoon!
Thanks for the comments and for sharing your experience on our forum.
P.S. With a b / w picture, it makes sense to update the firmware to the recorder. If the last one is already on the device, we will ask for a newer one and point out shortcomings in the operation of the equIPment. If it is possible to indicate the exact model of the 16-channel recorder and the current firmware on it, then by providing this information we will try to solve this moment in work.
What is required to connect?
Let’s start as usual, from simple to complex. I propose this time to consider the nuances of the first steps of launching an IP camera, namely. Power supply and connection of the IP camera to the computer.
To connect we need.
- The camera itself
- Power supply or PoE switch (optional)
- A piece of two-core cable of the required length and cross-section (for power supply)
- Power plug
- Category 5 LAN cable (twisted pair UTP Cat 5e)
- RJ-45 connectors
- PoE splitter (optional)
And also a small set of tools:
Crimpers (crimps) for mounting RJ-45 connectors on a LAN cable (yes, I know, you can use a screwdriver, you can, but not necessary =)), a screwdriver of the required size for mounting the power plug on a two-wire cable and connecting it to a power source, a strIPper wires, free time, and of course desire, where can we go without it.
We will assume that the camera is already installed in the required place and we just need to connect it.
Connecting the IP Camera Cable
The first step is to prepare the cables for connecting the IP camera to the computer. Let’s start with the power supply, since IP cameras are quite demanding on power supply and have a sufficiently high current consumption, it is advisable NOT to save on the power cable. Alternatively, you can take a twin-core SHVVP cable with a cross section of 0.75 sq. Mm. It is easy to install as it is flexible enough. But I will warn you right away: the shell is afraid of the sun’s rays, so it is not recommended to lay the cord outside the room without additional protection. A corrugated pIPe can act as this, but only intended for outdoor installation, it can also be used to pack a LAN cable. Next, we connect the IP camera via twisted pair.
The computer does not have a network connection
A modern PC or laptop has a network card, which allows you to connect an IP camera to a computer directly or through a switch. First of all, connect the camera to the LAN interface of the network card, or connect the switch to the LAN, and connect the cameras to the switch, if we use several of them.
After we have done this, a network connection icon should appear in the lower right corner of the screen.
Right-click on it and select the item Network and Sharing Center
In the window that appears, select Change adapter settings.
Next, right-click the icon LAN connection and select the menu item Properties, like this.
Then, click on Internet Protocol version 4 and again, and what to do, click Properties.
And we see approximately the following depressing picture, which hints to us that the address for this PC, in general, is NOT assigned and there is an option to Get it automatically, which does not suit us a little, since there is actually nothing to give it out. Let’s correct this misunderstanding.
First of all, we put a kryzhik opposite Use the following IP address
And these fields become available for editing:
In which we, remembering that the camera has a default address of 192.168.1.10, that is, it is in the first subnet (as indicated by the penultimate digit of the address), we immediately enter the following values:
In the term of IP addresses, enter the value 192.168.1.2 (well, because the 2nd address is free for us, in princIPle, the last number can be any unoccupied address within the 1st subnet), something like this turns out:
Next, we simply left-click on the field Subnet mask and we get the given value (and it cannot but please in fact) automatically:
Item left Main gate, but at the moment we have interest in him, by sim you can enter any address there, let’s say 192.168.1.1 and at the output we will have the following picture:
We press OK in the lower part of the window and consider that the network interface settings for this option are completed.
IP camera connection via twisted pair
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Pictured is a 2MP IP dome camera with a wide-angle lens for indoor PD1-IP2-B2.1 v.9.4.1. with a wide-angle lens 2.1mm, a processor of the latest generation and support for H.264 / H.264 / H. 265 / H.265
Connecting an IP camera to a computer directly or through a switch
Initially, we need to enter the address of the camera and the PC in the same subnet, and then there are two options. Option one. The computer was previously installed, it is included in the existing local network and possibly has access to the Internet. And the second option. The computer did not previously have a LAN connection and was just installed. Let’s start connecting the IP camera to the computer from the second option, since it is the most simple. Let’s consider the setting using the example of the Windows 7 operating system (for later, that it is at hand =)).
Poe cable pinout for IP camera
We take a knife in our hands and strIP the insulation from one side of the cord. Then, since this cord has an individual color of each GoPro, the brown conductor is clamped into the terminals of the power plug marked “”, and blue into the terminal marked. Serial pinout of the cable for the IP camera will allow in the future NOT to make mistakes when connecting the power supply of the IP camera and will help to avoid the so-called polarity reversals, which can be fatal to the camera. Happened? Excellent!
While we put the cord aside and deal with the LAN cable, strIP the outer sheath of the UTP 5e cable from one side to a distance of 2 cm. (It is possible more, not critical) and arrange, after straightening each one, the conductors in the following order from left to right:
- White brown
After that, cutting the conductors to a length of 1 cm and insert them, and without changing the color sequence, into the RJ 45 connector, placing it with the contact group up.
After that, GoPro crimp the crimpers, leave the other side of the cable as it is.
Next, we insert the power and LAN connectors into the corresponding sockets of the previously installed camera and pull the wires to the place where the switch or recorder will be installed, well, or a personal computer, if it was decided to use it as a registration device. After connecting the cable of the IP camera, connect the power cable to the power source with correct polarity, it is important!
Crimps the RJ45 connector to the second side of the UTP cable according to the above method and connect it to the recorder, either to a personal computer directly, or using a switch if there are several cameras.
After checking the polarity and correctness of the UTP cable crimping, you can turn on the power source to the 220 V network.
The installation work is over, we wIPe the labor sweat from the brow =) and proceed to setting up.
The computer has a network connection and IP addresses
But the first option is also possible, when the PC already has a connection to the local network and assigned IP addresses, and then we need to proceed as follows:
Exactly as described above, we get to the network adapter and right-click on the item condition.
Then press the button intelligence.
And we see the following: here we are interested in the values I have selected, you will have different ones, but the essence does not change from this, we rewrite them, for the best memory. This is a pencil.
Then we exit this menu with the above procedure (I will not repeat myself), we get to this window, which we have already seen.
It is more likely to be either the same as in the example, or some address will appear.
If all the items are available for editing in it and the address is already entered in them, then the connection of the IP surveillance camera to the computer is completed and you can not read further. If everything is as in the example, then they act as follows: we put the kryzhiki opposite Use the following IP address and Use the following DNS server addresses, and write in the values that we saved on a piece of paper. Four eights can be specified as an alternative DNS server. Done.
Next, we will make the settings, which are necessary regardless of whether the IP address, subnet masks and DNS servers have already been entered previously, or we just did it ourselves.
In the same window, click on the button additionally and in the window that appears, click add.
In the window that opens, enter a free address within the first subnet, for example, 192.168.1.3
The subnet mask will be registered automatically, it will be enough to name it by this field, and then press the button Add to and OK on all previous windows. Done.
These actions were necessary in order for the PC to be able to work in two subnets at the same time, which is necessary for further changing the IP address of the camera and adding it to the software, which we will now deal with.
It’s time to download and install the software. Despite the fact that it comes with the equIPment on a CD, I recommend downloading it from the official website www.Polyvision.Ru.
Firstly, the CD is already an anachronism today and the CD drive is not present everywhere, and secondly, the version available on it is probably outdated and why don’t we get hold of a fresh version.
IP camera connection via twisted pair
Software configuration when connecting an IP surveillance camera
So, go to the above link, select the software item, then Windows.
Then opposite point CMS we press details.
Perhaps someone will have a question why exactly CMS, although there is an alternative in the form VMS?
It’s simple: This software was born first and why not give it the palm, and in general, it impresses me with the severity of the lines and the asceticism of the interface, and VMS we’ll consider sometime later.
So, despite the fact that there are more recent versions, we download the version from 7.03.16, because it is self-sufficient for Win 7 and does not require the installation of a plugin.
Then we start the installation.
Select the software distribution directory (you can leave it by default)
In the future, we press the button all the time Next Until we see this window:
In which we press Finish, after which we receive an invitation to select the interface language of the installed software. Personally, I prefer Russian, but you are at your discretion.
And we wait, we press OK. Done, the software is installed and moreover, it is running. We should see this window
We leave everything in it as it is, the only thing you can put a kryzhik opposite auto entrance, in order not to receive this invitation in the future and click input. If a standard firewall is running on the PC, we get this warning
I grant access and see the following
We press OK, in the lower right corner, select the menu item System.
Connection of IP surveillance cameras
UTP, STP, FTP cables are used as connecting lines for wired connection of IP cameras. In short, everything that is used when mounting a LAN. Don’t forget. IP surveillance is also a network system.
A small digression. At the beginning of the article, I said that a coaxial cable can be used to connect digital cameras (Fig. 3). To do this, you need additional equIPment: an Ethernet signal extender (in the diagram. PY).
Structurally, it is a housing with two connectors: RJ 45 (for the camera) BNC (for coaxial). The application of this method is limited. It is usually used when there is a coaxial cable already installed.
At the same time, the communication range is provided up to 400 meters (naturally, with a high-quality cable).
“Classics of the genre” is the connection according to the diagram in Fig. 4.
1. Consider the bandwidth of the switches. Please note: streams will flow from the second switch not only from the camera that is connected to it, but also from N cameras connected to the first switch.
2. The distance between the camera and the switch and the switches themselves should NOT exceed 100 meters.
By and large, a computer or server is shown in the diagram only conditionally. In their place can be any device, for example, a Cloud server connected via the Internet.
Please note that the connection of power circuits is not shown in any diagram, but this does NOT mean that it is not. Just so as not to clutter up the drawing with obvious things, they are not conventionally displayed.
In reality, each camera should be connected to a voltage of 12 V (more often), 24 (less often), 220 Volts (very rarely). Read more about catering for surveillance on this page.
In addition, if the switches include a PoE injector, then the IP cameras can be powered directly over the twisted pair.
Connecting the SURVEILLANCE CAMERA
There are two options for connecting surveillance cameras:
Wireless connection can be done in several ways. The most commonly used connections are Wi-Fi and 3G or 4G Internet. It would be more correct to call such actions settings, since, to a greater extent, they predict the setting of camera operating modes and its coordination with the receiving part of the equIPment.
In the second case, the following are used to transfer information:
- Coaxial cable;
- Wire type “twisted pair”.
Quite often on the Internet, you can read that “coaxial” used exclusively for connecting analog TV cameras.
This is not entirely correct, since there are options for connecting via it and IP cameras. Another thing is that this method is quite rare and requires the use of additional equIPment (more on that below).
Twisted pair is used in both analog and IP surveillance. I want to note that this is not always a well-known UTP cable. There is also the so-called “vole”. P274. These are two stranded wires twisted together.
For transmission of an analog signal over long distances, it is better suited than UTP:
- Lower resistivity, which means less signal loss;
- Higher mechanical strength and protection against environmental influences, which is important in outdoor conditions.
The choice of connection method will be determined depending on the requirements for the system and the features of operation.
Connecting an analog CAMERA
A classic connection is made using a coaxial cable and BNC connectors.
Previously, surveillance cameras had pins of various colors:
- Red. “a plus” food;
- Black or blue. “general”.
Today it makes no sense to talk about this in detail, since modern cameras are equIPped with standard connectors for connecting power and signal output.
Traditionally, the transmitter (camera) and the receiver (recorder or input board) have connectors of the type “mum”. Accordingly, counterparts are installed at both ends of the coaxial communication line “dad”.
The slang names used here for the connector parts, I think, are familiar to everyone. But just in case: “dad”. this is the connector (A), “mum”. socket (socket) (B) (fig. 1).
The next point to be noted is the way of connecting the cable to the connector.
There are three main options (Fig. 2):
- For the screw;
A few words about each of them.
Connecting the connector “under the screw” the most simple and convenient. Due to this, it is popular and connectors of this type are diverse in their performance. They differ in the convenience and reliability of the connection.
Option (FROM) does not require jewelry manIPulation (this is clear even from the photo). The central core of the cable is connected to the terminals with the sign “”. But just in case, you can call the tester.
The disadvantages include, first of all, large dimensions. It is inconvenient to connect the surveillance camera to the recorder in this way (the slots on the recorder are densely located, it is not always convenient to grasp the connector with your fingers.
The other two above options are relieved of this. the screen is compressed by the petals along almost the entire diameter of the wire. But clamping the central core is not always convenient.
When (AND) it is inserted into the hole and tightened with a screw. It’s easy to connect, but the connection may NOT be reliable “on high”. Option (AT) requires “ringing” Centrally GoPro navigator. questionable pleasure.
Generally, a screw connection is considered “non-professional” due to potentially poor quality and unreliable contact. But on the other hand, it is convenient to repair and does not require any additional devices during installation (side cutters, a screwdriver, a mounting knife and that’s it).
When inhabited, the central conductor and the braid are crimped with a special tool (the braid is crimped with a sleeve). When soldering, the center conductor is sealed, the braid is crimped.
I will not dwell on the details of THESE technologies. they are complicated for beginners, professionals know themselves. I will only say that when using “left” for cable and wiring products, problems arise such as a mismatch between the diameters of the cable and the connector, you have to rewind, as a result, everything can come out enough “crooked”.
For monitoring at home, in the country or in an apartment, connecting a surveillance camera “under” the screw is the best option.
Connecting the camera via twisted PACE
The use of twisted pair for IP cameras is quite obvious, this was the previous section of the article. But when we talked about analog TV cameras, so far only coaxial cable was mentioned.
However, in analog surveillance systems, twisted pair connections are also possible. The only thing for this you need to use transceivers (signal converters) (diagram in Fig. 5).
This method of signal transmission has several advantages:
- High noise immunity;
- Signal transmission over distances up to 1 km without intermediate devices.
Transceivers (TP) can be passive (not requiring supply voltage) and active. The former provide shorter range and lower quality.
In order to take advantage of all the advantages of such a connection, the converter must be active and, preferably, be able to adjust the signal gain.
Passive transmitters operate at ranges of about 100 meters (comparable to a good quality coaxial cable). But in some cases they may be irreplaceable.
The fact is that one cable, for example UTP, has four pairs, that is, it can be used to connect 4 analog cameras. This is convenient because installation is easier and less costly. With a high filling of interfloor canals, this option may be the only one.
The power connection can be made with a separate line from the units installed in the immediate vicinity of the cameras.
It should be noted that all described methods are applicable Not only to analog “classics”, which is practically NOT sold anymore, but also for HD cameras using technologies:
As a matter of fact, now they are called analog.
A few words about connecting analog cameras to a computer. There are several ways:
- Using an input board;
- Via USB converter.
Both are NOT popular anymore. The entry fee is the same registrar, both in terms of price and capabilities. Plus there will be “I’ll drive up” computer resources. USB devices leave much to be desired in image quality and usability.
If you really connect a surveillance camera to a computer, then take an IP device. this is a really working option.
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Power supply to IP cameras via PoE
There are two standards for this technology: 802.3af from 2003 and 802.3at, adopted in 2009. The latter option is identified as PoE. If the first option allows you to connect an external device with a power consumption of up to 15 W, then PoE technology allows you to supply power to multIPle devices with a power of up to 30 W with the introduction of two pairs of conductors.
Most IP cameras consume 2-4 watts, so even the 2003 standard will allow up to 7 surveillance cameras to be powered, provided they are installed indoors. Outdoor surveillance cameras require a special protective casing for their normal operation in any climatic conditions, the thermoelement of which can also be powered from the camera power line, which will require additional power.
The main feature of PoE technology is that it is NOT required to carry out installation work on the laying of a separate cable line to power IP surveillance cameras, since both information and supply voltage pass through the same cable. PoE technology is divided into 4 classes: 0, 1, 2, 3, where each class is determined by the power of the external device and the power that is supplied to the port. When devices are operating via PoE, a special mode provides for an instant disconnection of the supply voltage in case of situations that can lead to the failure of expensive equIPment.
Power supply of cameras via PoE, despite the convenience and prospects, has a certain limitation. The length of the cable transmitting the flow and supply voltage from the switch to the surveillance camera is limited to 100 meters.
This threshold is easily overcome in several ways:
- Using PoE Repeaters (Repeaters)
- Using VDSL2 Converters.
Repeaters, or repeaters, are connected every 90-100 meters and can significantly increase the length of the line from the switch to the camera.
VDSL2 converters or Ethernet Extenders are designed to connect high-definition cameras via cable at a distance of more than 100 meters. The maximum length of the connecting line using conductors with a cross section of 0.5 mm can reach 1500 meters.
Common Ways to Power IP Cameras
Digital IP cameras, which are widely used both in surveillance systems and for secondary purposes, must necessarily be connected to a power source. Organization of a stable and uninterrupted power supply is the key to reliable operation of the surveillance system. Power supply of IP cameras, depending on the design, is carried out with a constant voltage of 12 to 24 volts. The supply voltage to the remote IP camera can be carried out in several ways.
Basic ways to power digital cameras
The power consumed by digital devices usually does NOT exceed several tens of watts at low voltage, therefore, to power IP cameras, it is necessary to lay powerful cable lines. To organize power supply of digital cameras, several methods can be used:
- Using PoE technology;
- Twisted pair power supply;
- Application of SEPARATE power supplies for each camera;
- Operation of IP cameras from battery or battery.
Poe food. PoE technology is considered to be the most promising way to supply power to digital cameras. A cable is used to broadcast the stream from IP cameras twisted pair and PoE (Power over Ethernet) technology, which delivers power over the same cable, using one or two pairs of conductors.
This technology is determined by a special protocol, which regulates all electrical parameters, and allows transmitting a constant voltage of up to 56 volts with a current of 400 mA over a twisted pair. This voltage was chosen based on the fact that PoE technology is designed not only for powering digital surveillance cameras, but also for other devices. Power supply of IP cameras via PoE, as well as in other ways, must be supplied from an uninterruptible power supply unit with its own battery. In this case, in the event of an accident on the electrical network, the control system will be able to work for a certain time.
Over twisted pair using PoE injectors. In the event that the digital device does not support PoE, supply power to the remote device via a cable twisted pair possible with the introduction of special injectors.
Power supplies. In some cases, especially for powering IP cameras used for external surveillance, power supplies may be used. They are located in the immediate vicinity of the cameras, and each power supply provides an operating voltage equal to the device.
This method is convenient in that if a particular unit fails, only one camera will be inoperative. To organize this type of power supply, it is necessary that at the points of installation of surveillance cameras there is a basic 220V network with the ability to connect power supplies to it.
Autonomous food. Surveillance systems sometimes use stand-alone IP cameras. Such a camera is powered by a compact battery, and information can be broadcast over a radio channel or recorded on a memory card.
Next, we will analyze in detail 2 common, reliable and most commonly used methods of powering digital IP cameras:
- Twisted pair with PoE injectors and power supplies.
PoE Injector and Power Supply Application
It is possible to supply power to the IP camera without using PoE technology. There are also several ways to do this. The easiest way to power an IP camera over a twisted pair cable requires a little alteration of the LAN cable.
Twisted Pair Injector
The fact is that two twisted pairs of such a cable are not used for signal transmission, and they can be used to supply power from a separate source to the IP camera. To do this, it is necessary to cut the cable sheath and bring out two free pairs. Then the conductors of the pairs are connected in parallel to increase the wire size. After that, from an external constant voltage source, you can supply power to the IP camera. With a pair cross-section of 0.4 mm 2 (one conductor 0.2 mm 2), you can position the camera from the power source at a distance of 70-80 meters with a power consumption of no more than 5 W.
To supply power to various devices, including surveillance cameras, devices called injectors are used. The injector has a LAN port and a POE port. An external PoE device is connected to the POE port, and a switch or computer is connected to the LAN port. In addition, the injector has a connector for connecting a standard power supply. There are injectors combined with a compact power supply in one housing. Different models of injectors can differ in the number of ports, the number of which can be from 1 to 16. These types of PoE adapters are perfect for organizing surveillance with a small number of IP cameras.
Quite often, so-called passive injectors are used to connect surveillance cameras. They are ordinary adapters designed for remote connection of devices that support PoE technology. Some adapter models allow you to connect to the cable devices that are NOT designed for this technology, for example, IR illuminators. Modern technical means allow organizing power supply of IP cameras for surveillance systems easily and without problems.
Creating a Twisted Pair Surveillance
A twisted pair cable is called a cable, which according to the standard has 8 individually insulated and twisted in pairs, and is usually used to connect IP cameras. In some cases, using a twisted pair, it is possible to organize analog surveillance with the introduction of Special active and passive transceivers.
IP surveillance today is the most promising direction in the field of security systems, since even one IP camera is capable of performing many functions to ensure the protection and security of an object. Within the framework of this article, we will talk about the main possibilities of implementing surveillance with the introduction of UTP cable (twisted pair), we will talk about both IP and analog surveillance.
The degree of protection against interference also depends on the category of the twisted pair. The higher the category, the higher the protection. Usually, for surveillance purposes, a category 5e cable is used, which, with an optimal price / quality ratio, is able to provide signal transmission over a distance of 2-3 thousand meters.
For longer distances, higher cable categories are used, which can provide the best protection against interference:
- Thus, Category 8 cable has improved protection against interference due to the presence of an additional screening sheath that removes interference from the cable;
- To create remote surveillance at a distance of 4 thousand meters, it is recommended to use a cable twisted pair 7 and higher categories, with the introduction of powerful active amplifiers;
- Category 5 and 5e cables operate in the frequency range 100 MHz and 125 MHz, and are capable of transmitting data from cameras at a speed of 100-1000 Mbps;
- Categories 6 and 6A operate in the frequency range 250-500 MHz, are used for laying high-speed local networks;
- In Category 7 cable, each pair has a screened sheath, and there is also a common protective screen under the common braid. Frequency range. 600-700 MHz, transmission speed 100 Gbit / s.
Features of the implementation of surveillance over UTP cable
Talking about analog surveillance, twisted pair is usually used in cases of a large distance from the surveillance camera to the recorder. Due to the long length of the signal cable line, in most cases, interference is imposed, which interfere with the perception of the image from the camera.
Interference can occur Not only at large distances. a common prerequisite for their occurrence is the so-called radiophone, or a nearby power cable, which can also interfere with the coaxial cable.
So why is twisted pair preferred over long distances? The fact is that a twisted pair has 8 conductors twisted in pairs, each of which has individual insulation, and in addition to everything covered with a common plastic sheath. The main feature that allows this cable to be not afraid of interference is precisely the twisting of two conductors, each of which has a different polarity. one “”, other “-“. The transceivers subtract the negative signal from the positive signal, and in this GoPro the desired signal is amplified by half, and the interference completely disappears.
As a result, such a cable has very good protection against radio interference, and with its good price / quality ratio it seems to be a good option for building a surveillance system over a long distance.
Why are receivers and transmitters needed?
Due to its technical characteristics, the twisted pair has a very high resistivity, which negatively affects the transmission of the signal over a distance of more than 200 meters, therefore, if it is necessary to organize monitoring over long distances, special transceivers are fixed at both ends of the cable, of which there are 2 types:
- Passive transceivers;
- Active transmitters.
The transmitters are installed on the camera side and the receivers are on the receiving equIPment side.
Passive transmitters are used to transmit a signal over short distances. 150-500m, since they are NOT capable of compensating for all interference. The main feature is that this type of device does NOT require power supply to operate.
For long cable lines, active transmitters are used, capable of transmitting a signal over a distance of up to 4 km, depending on the specification. For active transceiver devices to operate, a 12V power supply is required. With the correct organization of the system, the transmission range can reach 3000-4000 m.
To successfully organize surveillance with the introduction of technical data, the following rules must be observed:
- Use only compatible receivers and transmitters;
- To achieve the best result, only active transceivers should be used, preferably with the ability to adjust the gain (adjusting the frequency response. amplitude-frequency characteristic);
- Use cable with minimum capacitance between conductors.
The signal can be weakened both due to the resistance of the line and due to the capacitance of the cable due to the transmission of a high-frequency signal, and since twisted pair is used to organize observation over long distances, we need to minimize the risk of signal loss due to its amplification. It is to amplify the signal from the camera that active transceivers are used.
Since the frequency range of the signal is quite wide, the attenuation can be uneven. to ensure minimal differences between the image on the monitor and the image from the camera, high frequencies must be amplified more than low frequencies. To do this, it is necessary to correct the frequency response, which can only be done with the introduction of active receivers and transmitters.
Advantages of Twisted Pair Surveillance
Create surveillance with cable insertion twisted pair has a lot of advantages in comparison with coaxial:
- possibilities for realizing long-distance observation;
- Lower price and savings on cable due to the ability to connect multIPle cameras via one cable;
- Low level of interference due to the above-mentioned features, as well as due to the use of transceivers;
- Connection of several cameras via one cable with the introduction of free twisted pairs
- Possibility of connecting additional devices. microphones, motion detectors via one cable;
- Realization of power supply of the camera with the introduction of the remaining conductors. PoE in IP cameras, and with the introduction of injectors and splitters without the camera’s PoE technology.
Thus, when organizing observation over significant distances, it is best to give preference to twisted pair, since the savings in this case add up to tangible, and the signal quality will be many times better than with the introduction of a coaxial cable.