by Julián Arcila
Wireless data transmission systems are becoming, thanks to certain features, leading players in the security environment. Every day, it is more common to see that integrators resort to this technology to send video signals, audio, alarms, and different types of data for the fulfillment of certain functions.
VENTAS DE SEGURIDAD offers in this edition a concise article that fundamentally seeks to unravel the origins of this technology and its application in the security segment. It is important to note that this medium does not recommend any system, but is limited to analyzing the various solutions offered in the market.
One aspect to keep in mind is that although this technology offers great advantages such as a greater security environment, in addition to the practicality that implies not having to resort to cables for sending data, it is also true that it has its limitations, so each potential client must be based on a previous analysis to make a choice according to their needs and capabilities.
What is changing the streaming environment in this segment? When and how do you start applying this technology in the field of electronic security? What are its advantages and disadvantages? These questions will be answered by experts such as Gabriel Apel (Argentina/Xiden), Italo Martinena (Argentina/DX Control), Ricardo Abreu (Venezuela/Electronic Security & Control), Juan Carlos George (Mexico/Sistemas de Automatizaciones), Horacio Cantú (Mexico) and Juan Manuel Pérez (Colombia/Unión Eléctrica).
A bit of history
There were basically two elements that gave rise to wireless communication: the theory that there were electromagnetic waves, raised in 1860 by the British James Cleck Maxwell; the confirmation of the existence of these, which was done twenty years later by Henry Rudolf Hertz; and the invention of the electric telegraph in 1890 by Guglielmo Marconi.
Wireless communications have gone through three basic stages: a pioneering one, where the events mentioned in the previous paragraph can be included; the pre-cell era, in which security activities are beginning to be carried out with mobile radios, in addition to the enabling of certain frequency bands and the commercialization of the first mobile phones; and the cellular, which began in 1980 with the distribution of the first analog cellular equipment and which continues indefinitely hand in hand with the coming advances.
The first wireless equipment, such as that used by Marconi, was characterized by being quite simple and basically consisted of a transformer with one end of its secondary connected to a rod or antenna and the other to ground; in that model, the transformer primary is part of the circuit. When the switch is closed, the current that circulates through it varies over time, so the primary of the transformer induces a current in the secondary. The ratio of turns in the transformer is such that in the secondary a high voltage is generated, allowing the antenna to radiate electromagnetic waves.
Over the years, Marconi's apparatus was gaining in popularity, but it also gave rise to other scientists deciphering the cause why electromagnetic signals followed the curvature of the earth; Kenelly (United States) and Heaviside (England) independently developed a theory in which it was proposed that in the atmosphere there was a layer composed of electrically charged particles that reflected electromagnetic waves. According to the above, when a signal from a place A sent the wave was reflected and returned to the surface at point U, the earth reflected this signal back to the ionosphere and this succession was repeated again until the signal reached its destination in R.
Exploring new markets
The same development in the field of telecommunications was opening a ditch so that this technology could be applied in other areas, and it was in this way that it came to electronic security.
The first applications date back several years, as indicated by Ricardo Abreu. But Horacio Cantú, a security consultant, added additional elements to understand the beginnings and explained that in the early years the systems were not supervised and this made wireless applications more expensive than a traditional wired one, and they were also less secure, but in their favor they had to offer comfort and status. "Back then, the security issue wasn't that important; the need to make them monitored arises from the requirement to have more secure wireless systems and the exact knowledge of the alarm point. The monitoring allows that when a sensor runs out of battery or is removed from the place the user of the system has the knowledge that something happened, "he said.
Cantú recalled that these systems were initially implemented in residential applications, because this technology did not satisfy banking standards at that time. Manufacturers then developed more reliable systems for installations with high reliability requirements.
Today the application of this technology, according to Juan Manuel Pérez, has been extended to a wide range of frequencies, which includes 900 Mhz, 2.4 Ghz, 4.9 Mhz, 5.2 to 5.8 Ghz and 31.8 Ghz.
From A to B and then to C
The operation of security systems based on wireless transmission media is not very complicated and basically involves two elements: a transmitter and a receiver; Repeaters (another type of transmitters) are used to expand the coverage area. It is also important, and indispensable to understand the concept of networks, because it is from this that you can identify the different elements that interact in a wireless network.
To start it is important to talk about the means that the wireless signal uses to travel from one place to another. As Ricardo Abreu explained, particularly in the alarm segment, there are two means to send signals to monitoring stations: GPRS and GSM, but Horacio Cantú mentioned other important systems such as CDMA, EVDO, EDGE, 1X, 3G. "These telephone systems allow us to send signals using cellular telephony and without the need to use radio, using data SIM cards and often also voice cards, "said Abreu.
He added that there are other ways to transmit the information, such as radio frequency waves, which are mainly those used in CCTV and some alarm systems, but this is the initial technology and is already out.
Cantú added that in most cities the radio spectrum is saturated, and that is why the trend is towards digital compression and bandwidth optimization.
Now, moving on to the necessary equipment, Juan Carlos George, president of Automation Systems, explained that a typical wireless connection requires a transmitter and a receiver, equipment that serves to send the images of a camera from a remote point to a control room. Another fundamental and perhaps the most important element is that of digitization, which is the one that executes the compression algorithm. At present, he added, "mesh networks are giving a great advantage, since wireless networks can be established that can grow progressively, offering important alternatives for the video security industry, all this without being very expensive."
Starting from the basic scheme of transmitter and receiver, Italo Martinena, president of DX Control, delved into what would be the type of transmission and said: "if the transmissions are unidirectional, the transmitter is installed on the premises to be protected and the receiver in the monitoring center, so that it receives all the enabled transmitters."
But at this point a question arises: is the right equipment enough to make a wireless transmission?
Other factors to analyze
When you are going to implement a security system that will transmit without cables, several factors must be taken into account that in the end will be the ones that will guarantee the sending of a signal with high communicative capacity. Such factors can be divided into topographical, physical and technical, and the latter in turn include the hardware of the equipment that will process the information. There are also legal aspects that should not be overlooked.
In this sense and starting with the topography, experts such as Italo Martinena recommended paying close attention to this point, especially if we talk about radio frequency alarm transmission; for example, in mountainous areas it is recommended to install a repeater in the mountain. "It is advisable that it be stored and forward, since it will receive and transmit on the same frequency; this avoids having to have transmitters on different frequencies."
Gabriel Apel added that the main element to consider is the possibility of view between sender and receiver, but without neglecting the regulation and current rules of the spectrum to define if it will be in a free band or a regulated band, to proceed to request the corresponding permits.
Subsequently, Ricardo Abreu referred to the quality of the same signal that is being sent and recommended: "As for the alarms the signals should be as clean as possible, electronic noises (Nosie and Ripple) are the number one enemies of a wireless signal. The best way to know this is when we are in close proximity to a transmission plant, a police station, or a power source; these produce so much interference in the line that the transmission is very poor, reducing its propagation capacity. This is most evident when it comes to sending a message from a cell phone inside a power plant: the signal is too poor and you can never send it." However, these latter concepts are being overtaken by the same design of the vast majority of equipment available on the market.
Now then. There is another element that must be taken into account and that is the bandwidth capacity of the medium used, this mainly when talking about CCTV over IP systems. In accordance with the above, Juan Carlos George suggested analyzing the compression medium to be used, as well as the number of images that are intended to be sent for each segment or for each wireless connection. "From the above we will be able to really correctly specify the connection needs or restrict the cameras according to what we have available."
However, some experts claim that the above argument is partially true since there are additional factors that limit the transmission medium itself and that are inherent in the network and the compression algorithm that travels through that medium, as well as the characteristics of the hardware used for this function.
Juan Manuel Pérez, engineer of the integrating firm Unión Eléctrica, agreed with Apel and recommended, when carrying out a wireless transmission of CCTV, to take into account the transmission frequency of the link, especially to review those concerning the licensing of frequencies by the authorities of each country. "An important novel element is whereas the 4.9 Ghz band has already begun to be used for wireless electronic security; but to have a good installation there are other factors such as evaluating the line of sight between sender and receiver; perform computer simulations on the theoretical power that can be achieved, from the topography of the terrain and climatic conditions. An important factor is that all elements sensitive to climatic factors must be protected against transients, in addition to carrying traditional overload and short circuit protection devices."
Pros and cons
At present we have an environment that is favoring technological advances. There is a greater openness to changes in different technology segments, the costs per use of the same technology have been reduced and electronic security has benefited from it, allowing someone to monitor your company's cameras from the same network or, failing that, receive alarms on your cell phone, via GSM.
But when analyzing technology, we must bear in mind that any manifestation or advance has its limitations, as well as its comparative advantages.
For Ricardo Abreu, the great advantage offered today by wireless systems is that they offer the possibility of being active in 99.99% when it comes to data. The big disadvantage is the cost of the hardware.
Juan Manuel Pérez corroborated the proposition that wireless transmission means have their advantages and disadvantages. He said: "Among the advantages we can count that the trend of wireless systems to cut expenses is very favorable, they do not require cabling, neither fiber optic nor copper, in addition to offering transmission almost in real time and at low cost of IP packets. They also have their disadvantages: if there are many antennas near a customer's signals there can be a lot of interference, there is limited bandwidth and cost is still a not very competitive factor."
As I stated at the beginning of the note, the spectrum of wireless transmission is quite wide, and to understand it thoroughly it is necessary to accumulate other knowledge. Although today the cost of hardware is an unbalanced element, the advances made in security implementations based on this form of shipping suggest that very positive years are coming for those who have been exploring this technology. For now, an important question arises: how much will the market take to reduce equipment costs for these purposes? This question could be answered in the coming months.
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