Interference

Coaxial cable is very unstable to electromagnetic interference, which are created by various operating devices. Therefore, watching and downloading with this cable is a very problematic task.

As for the twisted pair cable, its construction is specially designed to protect against radio interference. Both common screens and separate screens are used for each pair of twists.

Advantages of Twisted Pair Surveillance

Creation of surveillance with the introduction of twisted pair cable has many advantages over 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.

A little about the history of transmission over twisted pair

Sometimes you hear how another modern company declares itself to be the “founder” of the princIPle of transfer

To clarify this issue, I would like to report the information we know: back in the eighties of the last century, the Novgorod NPO VOLNA was serially using the princIPle of signal transmission in the production of PTU (industrial television installations). Twisted pair equivalents were used in the hardware setup. The equIPment was different, but the princIPle was already known.

So the one who is trying to convince you that it was he who “invented” the princIPle of transmission over twisted pair is either trying to mislead you, or is mistaken himself

Range and signal transmission rate

Twisted pair is characterized by the ability to transmit signals over long distances and at higher speeds. Provided that a special amplifier is used, there may be no signal loss at all.

As for coaxial transmission lines, their operation, and accordingly the signal attenuation coefficient, will be affected by many factors, the effect of which cannot be excluded. This is the quality of the metal used, and the cross-section of the conductor, and the external temperature, electromagnetic interference, etc.

SF / UTP

This type of twisted pair does not have individual shields for SEPARATE twists. Shielding is provided by a common screen in the form of foil and braid, which are located under the outer insulating layer. The cable is suitable for connecting analog and IP cameras, providing high-quality signal transmission.

Everyone who has connected a twisted pair knows that, in addition to twisted pairs, an uninsulated metal conductor can also be present in the cable, which provides contact between the elements of the screen when it is damaged, which can occur in the event of arrogantly bending or stretching.

Twisted pair wire SF / UTP

The above cables can be produced in solid or multi-core versions. Single-core cable is not used for laying long routes that provide loading from surveillance cameras.

For this task, a multicore twisted pair is better suited, but provided that a signal amplifier is used, which eliminates signal losses when loading over long distances.

Advantages and Disadvantages of Analog Cameras

• Most of the cameras produced and almost all the old-style devices have rather limited functionality, but this problem is solved in new models that have received a hardware Motion Vector, built-in microphone and speakers, or a connector for their connection;
• There are certain restrictions for integration with digital security systems and access control systems;
• The signal is not encrypted during transmission.
• Difficulties in scaling and transitioning the system to digital technologies.

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.

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 a special design of the line, which, in addition to the cable itself, also includes a transmitter-receiver pair. 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.

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.

The voltage supply over the twisted pair cable is correct for a distance NOT exceeding 30 meters. With an increase in the distance beyond 30 meters, a voltage drop will begin due to the small section of the cable.

Ease of installation

Despite the fact that the coaxial cable is characterized by increased strength and resistance to mechanical stress, its installation is much more difficult.

Installation of twisted pair cable for surveillance systems

Using a twisted pair cable, you can connect devices with a minimum bending radius when cornering. Also, the twisted pair is easier to fit into the mounting boxes.

Twisted Pair Surveillance: Work Pattern and Signal Rate

Observation has received wide practical application in various security complexes.

To organize effective surveillance at the facility, it is important to ensure high-quality signal transmission within the protected facility.

In the process of signal transmission, it suffers attenuation and attenuation, which can lead to the impossibility of broadcasting the transmission from the camera to the receiver.

To eliminate this, twisted pair is used, which is a symmetrical signal transmission line in which interference cancels out, excluding the attenuation of the transmitted signal.

Surveillance over twisted pair can be used in systems that broadcast a picture using both digital IP cameras and analog cameras.

Power supply on the same cable

Many modern cameras do not have a special output, through which power supplies can be connected.

In this case, using a twisted pair cable would be the best option. In addition to the fact that the signal can be loaded through it and power can also be transmitted for the operation of the cameras.

For this, Power over Ethernet technology is used, which includes several standards for transmitting power to devices.

This can be the 802.3af standard, which supports the total power of connected devices equal to 15 W, as well as the 802.3at standard, which supports 24 W.

The use of a twisted pair will allow you to significantly save on installation work and cable, since you DO NOT have to lay a separate line for power supply.

Another advantage of twisted pair connection is that it can transmit a signal from 4 cameras in parallel, while for coaxial cable only one camera is supported.

Range and signal transmission rate

Twisted pair is characterized by the ability to transmit signals over long distances and at higher speeds. Provided that a special amplifier is used, there may be no signal loss at all.

As for coaxial transmission lines, their operation, and accordingly the signal attenuation coefficient, will be affected by many factors, the effect of which cannot be excluded. This is the quality of the metal used, and the cross-section of the conductor, and the external temperature, electromagnetic interference, etc.

SF / UTP

This type of twisted pair does not have individual shields for SEPARATE twists. Shielding is provided by a common screen in the form of foil and braid, which are located under the outer insulating layer. The cable is suitable for connecting analog and IP cameras, providing high-quality signal transmission.

Everyone who has connected a twisted pair knows that, in addition to twisted pairs, an uninsulated metal conductor can also be present in the cable, which provides contact between the elements of the screen when it is damaged, which can occur in the event of arrogantly bending or stretching.

The above cables can be produced in solid or multi-core versions. Single-core cable is not used for laying long routes that provide loading from surveillance cameras.

For this task, a multicore twisted pair is better suited, but provided that a signal amplifier is used, which eliminates signal losses when loading over long distances.

Ease of installation

Despite the fact that the coaxial cable is characterized by increased strength and resistance to mechanical stress, its installation is much more difficult.

Using a twisted pair cable, you can connect devices with a minimum bending radius when cornering. Also, the twisted pair is easier to fit into the mounting boxes.

PrincIPles of data transmission over twisted pair

Twisted-pair analog surveillance provides that the composite signal is sent from the camera to a twisted-pair transmission line.

It is unbalanced and unIPolar. To convert this signal for transmission, it is initially loaded into a special electronic converter unit.

It can be part of a surveillance camera or used as a separate external device.

With the help of this converter, the signal is converted into two symmetrical ones, which have opposite phases.

It is this signal that is used for transmission over twisted pair. It is characterized by less interference and the influence of both internal and external electromagnetic interference.

On the receiving side, a twisted pair is connected through the use of equIPment that converts the differentiated signal back, and also amplifies it.

Thus, an analog signal will arrive at the input of the recorder or the second receiving device, which has already been filtered from interference and amplified, which will allow high-quality observation.

A similar signal transmission procedure occurs when digital IP cameras are used. In this situation, a digital signal will be received at the output.

Signal amplifiers, receivers and transmitters

High-quality signal transmission with the required gain, when used, twisted pair, is possible in the case of using a number of additional devices. These include amplifier, signal receivers and transmitters. The listed equIPment can be passive and active.

For networks, the range of which does not exceed 500 m, and the load of which is small, passive devices are used, and in case of the need to transmit signals over twisted pair over long distances, active devices are installed, since at such distances the signal attenuates more and the quality of the broadcast may decrease.

As an example of devices used to connect an analog or digital camera via twisted pair, the following can be cited: NV-653T, RA-CD, AL-208.

NV-653T refers to an active signal transmitter, which has a built-in amplifier.

It can be used to connect outdoor or external cameras, providing high quality transmitted black and white or color images.

Signal download using this device can be carried out at distances up to 1.5 km. The device has built-in lightning protection and a switch for transmission distance ranges. Can be used in CCTV systems as a standalone device or paired with active receivers.

RA-CD is an active receiver, which can be used in cases where the signal is connected and loaded using a twisted pair or coaxial cable.

The device can be used with a passive transmitter when connecting systems with a cable length of up to 500 m or with active transmitters if the line length is up to 1.2 km.

AL-208 is a passive device that can perform a dual function when outdoor or indoor cameras are connected. It successfully transmits and receives signals within 350 m.

What is twisted pair

Unlike coaxial cable, twisted pair has multIPle conductors, which are individually insulated and twisted into pairs.

Due to this, it is possible to significantly reduce internal and external interference, providing download and high quality of the broadcast signal over sufficiently long distances.

Interference

Coaxial cable is very unstable to electromagnetic interference, which are created by various operating devices. Therefore, watching and downloading with this cable is a very problematic task.

As for the twisted pair cable, its construction is specially designed to protect against radio interference. Both common screens and separate screens are used for each pair of twists.

Purpose of signal transceivers and their types

The modern market offers a wide variety of technical devices that allow you to enhance the signal quality and transmission range over twisted pair. Typically, twisted-pair cable is used when there is a need to lay a connecting line over a distance of 150 meters. There are two main types of transceiver devices:

• Passive transceiver;
• Active transmitter.

Passive transmitters are among the transmitting devices that DO NOT require a 12V power supply for operation. With the help of such mechanisms, information can be transmitted over a distance of 150 to 500 m. An active signal transmitter allows information to be transmitted over a distance of over 500 meters. The maximum operating range of the device is 1500 m.To operate these devices, a power supply with a voltage of 12 V is required. Using the simplest devices, a signal is transmitted over a distance of no more than 300 m.

In addition to the above types of transmitters used when connecting the system via a twisted pair, there are several second types of similar devices:

• Via WI-FI network;
• Wireless Radio Channels.

To control the transmission of information in the IP surveillance system, a special transmitter is used to amplify the signal. WI-FI technology is digital, so it cannot be applied to analog equIPment. It is advisable to use a transmission mechanism if the equIPment is wired. In the case of installing wireless cameras, the system does not require a complete set of additional devices.

On. twisted pair signal transmitter:

Wireless radio channel transceivers can be used when installing a small control line, for example, for 1-2 cameras. The most common application for radio channel transmitters is in home surveillance. When connecting analog cameras to the TV, you can use a kind of amplifier of the quality and range of signal transmission. Installation of such a unit is not required in the case of mounting cameras equIPped with a built-in radio channel module.

The princIPle of signal transmission using twisted pair

Regardless of which type of transmitting device is chosen (passive transceiver or active), the princIPle of operation is the same. The transmission mechanism converts the incoming signal. The signal that comes to the input is unIPolar. After conversion, the signal becomes bIPhase and balanced. This is necessary for the subsequent transmission of the signal over the twisted pair.

A special receiver is installed at the other end of the line, which processes the incoming notification and makes it differential. As a rule, an amplifier is connected to the second receiver, suppressing interference and improving signal quality. As a result of such processing, a signal is sent to the input receiving device, which is free from interference. This signal is standard and composite.

Passive transmitters, as already mentioned, operate at a distance of no more than 500 m. Such mechanisms are inexpensive and are used for small rooms. Provided that the components of the surveillance system are located close, active receivers transmit a signal at a distance of up to 1000 m.Active transmitting equIPment must receive a two-phase power supply to ensure a symmetrical supply of quality information.

On. connecting the transmitter to the camera:

A twisted pair signal transmitter is required to create a surveillance system

In terms of their complex composition, protective systems can be autonomous or integrated. To control the events taking place in the protected area, it is enough to use a surveillance system. Cameras will capture and transmit information in the state of the object in the current time mode. When designing a complex of observation lines, the question of organizing signal transmission over long distances often arises.

As practice shows, to connect all components of the control system with each other, you can use a coaxial cable, twisted pair or wireless connection method. The recorder or monitor is often located at a considerable distance from the camera. In this case, you need to take measures to enhance the quality and range of the transmitted signal. Coaxial cable is not highly immune to interference and is expensive. Recently, most often used to transfer information twisted pair.

How to connect the transceiver?

In practice, signal transmitters are called transceivers. To connect one camera, you need to use two transmitters. One is installed near the camera, and the second is directly near the recorder. The transceiver is equIPped with two terminals to indicate polarity. One of the four twisted pairs of the cable line is connected to the terminals. Typically, each wire has a specific color. To make the connection correctly, you need to act in accordance with the annotation.

Since the twisted pair cable contains four cables, the same number of devices can be connected to the system at the same time. Any surveillance complex can be supplemented with cameras, and you need to choose equIPment that matches the number of installed channels. If an active transceiver is selected, power must be supplied to each camera individually. The connection of cameras in the system can be serial or parallel.

The following advantages of using receiving and transmitting devices can be distinguished:

• Simultaneous transmission of several different signals;
• Use of pre-laid cable lines (for example, for a computer network);
• Prevention of galvanic isolation and ensuring system immunity to interference.

1.3. Small-size transmitters Si-116T, Si-116TВ

The Si-116T transmitter mounts directly to any standard camera using a BNC connector. Provides galvanic isolation and the simplest protection of the camera from impulse noise (“spark protection”). Does not require power supply (passive). Parameters are given in table. 3. The Si-116TB transmitter is connected to the camera using a terminal block, other characteristics are the same.

The transmitters of this group have the following characteristic features:

• Forms the power supply of the camera 12 V / 0.2 A;
• Provide galvanic isolation in the signal and power supply circuits;
• Provide multi-stage protection of the camera against overvoltage and lightning discharges in the power supply and image transmission circuits;
• Can be operated outdoors at temperatures from 40 ° С to 40 ° С;
• Sealed to IP65.

Single-channel transmitters Si-112T; Si-113T; Si-115T differ in the distance of transmitted images (see Table 3).
Si-174T four-channel transmitter has similar specifications to Si-115T.

Twisted Pair Transmitters

The design of the transmitters is described in more detail in the article “Features of image transmitters over twisted pair”. Transmitters can be roughly divided into the following groups:

Application area:

• The shops
• Warehouses
• Office buildings
• Residential buildings

Features of the device:

• Easy installation. Computer unshielded twisted pair (instrumentation, UTP) is connected to the device via standard RJ-45 connectors.
• Si-171M / F devices are used as image transmitters.
• Provides image and power transmission at a distance of up to 200 m with a total signal attenuation of less than 3 dB and a resolution of the transmitted image of 500 TVL.
• A 2-pair or 4-pair connecting cable of the KVP2 (UTP2), KVP4 (UTP4) brands is used.
• Current consumption of connected cameras up to 200 mA.
• Smooth adjustment of the supply voltage of each camera from 12 V to 14 V. RIPple in the power supply circuits less than 10 mV.
• Dimensions 2U.
• Protection against the effects of impulse noise on the mains

220 V / 50 Hz and power supply circuits of cameras.

Overload protection in each channel. Overload indication.

Thermal protection of the device

1.4. Transmitters Si-162B, Si-162Bi, Si-163Bi

Transmitters are structurally made in the form of boards, similar to Si-162, Si-162i.

1.1. Si-112T sealed transmitters; Si-113T; Si-115T; Si-174T

Designed for joint work with small-sized outdoor cameras (such as MVK-16 MVK-18 and their analogues).

Notes:

• All transmitters, except for Si-170M / F, have a galvanic isolation (transformer) along the signal transmission circuit.
• All transmitters, except for Si-116T, Si-116TB, Si-170M / F, have protection for cameras against overvoltage, lightning discharges, impulse pickups and interference along the power supply circuits and signal transmission lines with a separate ground terminal.
• Transmitters Si-116T, Si-116 TB, Si-170M / F have a circuit for limiting differential interference induced on the signal transmission line.
• The casing modules Si-161A, Si-161i, Si-162, Si-162i, Si-163i control the casing thermal heater.
• The Si-161i thermohousing module preheats the camera at a low ambient temperature before applying a supply voltage to it (Fail-safe camera operation).
• Transmitters Si-112T, Si-113T, Si-161A, Si-161i are active, with pre-corrected frequency response. Si-112T is designed to operate at a distance of at least 1000 m and not more than 2000 m (for TPP0.5 cable). Si-113T, Si-161A, Si-161i are designed to work at a distance of at least 300 m and no pain of 1500 g
• Image transmission distances for second-hand receivers may differ from the values ​​shown in the table.

Is different:

• Miniature design that allows you to install it directly on equIPment (quad, recorder, etc.);
• Smooth adjustment of contrast and image clarity;
• Powered by an unregulated 11-18 V source.

The modification of the Si-116RF receiver is designed for installation in a gap in the cable communication line.

TWISTED PACE SUPERVISION

It makes sense to consider the topic of the twisted pair cable, touched upon at the beginning of the article in more detail. The fact is that due to the ability to successfully resist induced interference, surveillance systems over twisted pair can provide significantly greater ranges than equIPment connected via coaxial cable.

For such a connection, conventional analog surveillance cameras plus transceivers are used. Actually. On the side of the camera. The transmitter is on the side of the observation post. Receiver. When organizing observation in this way, the following rules should be followed:

• Receiving devices. Gears Must be compatible with each other,
• Use only active (supply voltage) equIPment,
• It is desirable that it has the ability to adjust the gain (frequency response correction),
• Use a twisted pair cable with the lowest possible capacitance between wires.

Now. A few explanations to the above.

Since the connection of a surveillance camera via twisted pair is aimed at providing a transmission range of about 1000 meters or more, we need to minimize the level of the useful signal. Where can he go? At low currents, losses due to line resistance are not very significant. serious wire-to-wire leakage due to cable capacitance as we transmit a high frequency signal.

In any case, the signal will be attenuated, so it should be boosted. That is why active transceivers must be used for twisted pair. However, amplification. That’s not all. The signal occupies a wide range of frequencies, so the attenuation will be uneven within this range. Amplitude correction is needed. Frequency response (AFC), which, again, can only be provided by active equIPment.

The last in this section. If you are an advanced installer, then you probably don’t need this material. If you are installing your first surveillance system on your own, then for the convenience of adjustments, it is not bad if the connected equIPment has discrete (preset) settings for lines of various lengths.

Connectors FOR connecting CAMERAS

For analog cameras, BNC connectors are used. Various designs can provide a BNC socket for a signal, a plus-separate connector for supplying power supply (directly on the case or on a flexible lead). option 1.

In the absence of a Special connector (3 flexible wires are displayed), the connection diagram of option 2 is used. The colors of the wires are given in the passport, most often used

• Black. common
• Red- “” power
• Yellow (green, blue). signal.

Note that if the common wire is one, it is common for the signal and supply voltage. The supply voltage can be 12 Volts DC. more often, 220 Volts AC. less often or 24 V DC.

BNC connectors for cameras are structurally according to the connection method: threaded, soldered, crimped, screw. The most difficult connectors to install are soldered, much easier for a screw (justified if the central core is flexible), crimping requires a special tool. I consider the optimal threaded connection of the connector, however, the connection for soldering is more reliable.

Several photos of the process of connecting surveillance cameras can be found here.

The last figure conventionally shows the main elements of the cable and connector, their mutual pairing.

Connecting the SURVEILLANCE CAMERA

There are two main ways to connect a surveillance camera.

• Coaxial cable (for observation, it has a characteristic impedance of 75 Ohm) directly to processing devices (monitor, recorder, multIPlexer, quad, etc.).
• Twisted pair cable (transmitter and receiver are used).

The second method (the diagram is shown on the left) is used when the camera is far from the signal processing devices.

It should be noted that the transmitter-receiver pair also performs signal conversion to match the coaxial cable (unbalanced link) with the twisted pair (balanced link). A twisted pair can be a specialized cable, TPP wire (vole). The optimal number of turns per meter of line is 20.

The supply voltage can be connected with a separate wire, for example, ball screw, or you can use a combined cable that combines a coaxial cable with power wires. True, the combined observation cable is somewhat inconvenient during installation. I want to Pay attention, when applying power, when choosing the cross-section (length) of the wires, you should take into account the voltage drop on the connecting line (see Ohm’s Law).

SURVEILLANCE CABLE

We immediately cut off the topic of IP systems. They use a twisted pair cable of various categories, designed to organize local area networks. The choice here is quite limited and the difficulties presented should NOT.

There are two main types of trunks for analog surveillance systems:

• Coaxial cable,
• Twisted pair wire.

Let’s start with the latter. “Vitukha” used in network systems for analog equIPment is far from ideal. I omitted the theoretical calculations and the calculations, I will immediately give a practical conclusion. In this case, it is best to use a CCI telephone cable to connect the equIPment. With this, though concisely, we figured it out. Moving on to coaxial.

Here, too, everything is ambiguous. Coaxial cable is designed to transmit a television signal. That is high frequency and rather narrow bandwidth. The signal spectrum is much wider and starts from 50 Hz. Therefore, the specific technical characteristics of this cable will give us little. Thus, we use the following criteria:

• The central core of the cable and its sheath should ideally be copper,
• The larger the cross section of the central GoPro. All the better,
• Characteristic impedance should be 75 Ohm.

Further, there are “little things” that we will walk through in passing:

Power supply method.

For our surveillance system, you can choose a combined cable, that is, coaxial, United by an outer layer of insulation with power. Its use is advisable if the power supply is installed in the immediate vicinity of the recorder. Otherwise, the cable of this design will have to be cut to a considerable length or use additional switching devices, but they should be laid with ordinary power wires.This is laborious and inefficient.

For outdoor laying of switching circuits for monitoring, you should choose a coaxial cable for outdoor use, that is, of the appropriate temperature range and moisture resistance. This, however, does not eliminate the need to seal the joints and inputs. A perfectly obvious thing.

This is the main thing that can be said about the choice of cable for connecting cameras of analog surveillance systems.

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