Alarm messages on the Internet: feasibility, installation and use features.
First of all, I will warn you that in the article, in order not to advertise either myself or competitors, there are no mentions of specific brands and models of products. Do not be upset, specific products can easily be «googled» using Yandex. I will consider the general principles, arguments for choosing the Internet as a medium for transmitting messages.
Why are we even talking about using the Internet? It’s not just a tribute to fashion, like it’s the 21st century, blah-blah-blah and all that. In fact, the Internet is a unified digital data transmission network. Every day more and more different information is transmitted via the Internet, and not via specialized channels. We are talking specifically about abandoning various specialized methods of delivering information. Remember, not long ago, there were wired loudspeakers in every apartment. Where are they now? Moreover, in many apartments it is difficult to find a socket for a wired telephone – why do you need one if every family member has their own mobile phone in their pocket? Many of my friends rarely use cell phones anymore, because why carry a phone if you can also call from a computer, and the sound is much better. I don’t consider myself to be very special, but I haven’t watched TV for several years, at least not the news. This doesn’t mean that I’m not interested in them – I read, listened to and watched them, but not on TV. The same videos of all news stories are available on the Internet, and you can play them several times, with translation, or listen to the original text, or you can immediately read and watch an interview with the opposite side. News information on the Internet is much more accessible, more conveniently organized and transmitted more quickly. Why do I need a TV? Etc.
And what do we have in the field of transmitting security alarm messages? We have an amazing variety. In some places, transmission via switched telephone lines is still used. About 40 years ago, this was the only way: you call the control panel, your telephone line is switched from the PBX to the control panel, and any disconnection of this line causes an alarm and, as a result, the departure of an alarm group. Until now, the main technology of non-departmental security is transmission on a subcarrier, on a busy telephone line. That is, regardless of the use of a telephone in parallel, at a higher frequency, there is transmission of security signals. From a technical point of view, this is no less difficult — all the same, it is necessary to physically place a special repeater on the PBX and connect it to your line, which will receive these signals. And, by the way, the amount of transmitted data is still measured in units of bits.
In general, message transmission channels are divided into those using a ready-made infrastructure and those requiring the creation of a new infrastructure. All methods requiring the placement of special equipment on the PBX are related to the creation of a new infrastructure. By the way, radio channel systems also belong to the same category, since they require either the allocation of frequencies or the construction of a network of repeaters that provide acceptable coverage of the city. All this not only increases the cost of creating a system, but also the maintenance of this infrastructure itself is expensive, and over time it becomes more and more expensive, since it becomes obsolete and begins to conflict with new technologies. Thus, many are familiar with the problems of combining an ADSL modem and a security alarm on one telephone line.
What options are currently used for the existing infrastructure? Via dial-up lines (with dial-up via a regular phone), via cellular networks (GSM) and, finally, via the Internet. Strictly speaking, the concept of the Internet includes both cellular networks and telephone lines, but unifies them, eliminating their differences. If you choose the Internet, then you can use any modem — wired, cellular, cable or whatever else will be invented next year. The choice is up to the designer, depending on which channel works more reliably at a particular site. Moreover, in most houses in large cities, the Internet has long been present without modems at all — as a local network, and you do not even think about how the local network of your home is connected to the Internet — this is the concern of the company that connected your network. Moreover, by choosing a unified option — the Internet, you forget about the hassle of backup channels for transmitting messages — it is enough to provide backup channels for connecting to the Internet in standard ways, there is no need to install several different specialized modules for transmitting messages over different networks. The central alarm unit has an Ethernet connector, and everything else is a matter of technology, well-developed by specialists. You will receive the quality of service for which you are ready to pay. Security alarm specialists will ensure the operation of the alarm and the transmission of messages to the unified connector, without delving into the details of communication networks. And communications specialists provide reliable communication, without going into what signal needs to be transmitted. Specialization, and therefore the result will be better quality, cheaper, and faster — if necessary, the Internet can be connected in half an hour, at least as a temporary communication line (buy a cellular modem in a nearby supermarket).
In addition to the simplicity and versatility of the connection method used, Internet technologies provide an incomparably greater bandwidth. On the one hand, this is not necessary for security systems, where, in principle, it is usually necessary to transmit only a few bytes of information every few minutes, or even once a day. On the other hand, the Internet immediately provides the capabilities of both audio verification and video verification — all in one channel, as long as the end equipment supports the appropriate standards. At any time when you want to expand the capabilities of your equipment, you can do so. But try adding video transmission if messages are sent over a busy telephone channel?
Many people say that the Internet, in principle, does not guarantee reliable delivery of messages. In principle, yes, indeed, it does not. And does anyone guarantee the operation of the telephone line? And the operation of the radio channel? Yes, a broken telephone line will be detected and an emergency team will be dispatched. On the other hand, it is quite easy for any not very qualified intruder to break the line. Moreover, to break many lines in different houses at once — let the police run around. But it is very difficult to disrupt data transmission on the Internet (to disrupt Internet connectivity, as experts say). Disruption of Internet connectivity is considered the greatest (moral) crime against Internet freedom. Although, of course, we all remember both provider failures and provider wars, during which the Internet to the neighboring house, if at all, went through Finland and California. However, in practice, only some governments (Chinese, for example) can voluntarily disrupt Internet connectivity. Doing this for the sake of robbing an apartment is obviously unprofitable. And it is not the robbed individuals who will be looking for the criminal, but the telecommunications companies that have lost considerable income. It was 10 years ago, at the dawn of Internetization, that local home networks were provided by groups of student enthusiasts and their reliability was low. Now even not very large companies that grew out of those groups of enthusiasts work very reliably and stably, data transmission equipment of the appropriate class with good lightning protection and channel backup is used. And in most apartments, the Internet is provided by one of several large companies, whose own security service is comparable in number to the entire non-departmental security of a small city.
And, as already mentioned, the Internet connection can be easily duplicated over several channels from different providers, so that disruption of all communication channels at once is absolutely unrealistic. There are many alternative channels — a separate local home network, a coaxial cable of a TV antenna, ADSL over a telephone line, cellular networks (there are several of them, at different frequencies and different modulation technologies), WiFi and WiMax, and finally, dial-up wired modems still exist.
Thus, it is relatively easy to ensure the reliability of the connection: several different technologies – and the criminal will have to sweat to disable the communication line, and such actions as suppressing radio channels of cellular networks or WiMax networks will be immediately noticed by the relevant network operators.
Let's look at the technical issues. I have always recommended that security specialists focus on security and leave the establishment of a communication channel to communications specialists. However, it is necessary to understand what solutions are possible and how connecting a security alarm differs from connecting a computer.
Firstly, Internet security message transmission units usually have a standard Ethernet connector. However, cheap, common household Internet access terminal devices (modems) often have a USB connection, as they are designed to connect a computer. To connect devices such as message transmission modules to the central monitoring station, as well as several computers, a special router is required. An ordinary computer can serve in this role, but then it must be constantly on and work reliably for weeks and months without the presence of people. Or you need to use more expensive devices (modems), which already have an Ethernet interface.
The technical problems do not end there. If you are serious about ensuring a reliable connection (two different channels), then the easiest way is to install two different modems (for example, ADSL and WiMax) with Ethernet connectors and additionally a so-called dual-WAN router. Everything will work almost by itself, and you will not have to deeply study the principles of managing Internet routing, channel balancing methods, etc. Or you can install one miniature (fanless) computer with the simplest USB modems as a router and call a good system administrator to configure Linux on this router. This may be cheaper if you yourself are an experienced system administrator.
For comparison, let's consider how a communication channel is backed up if it is not via the Internet. For most equipment, there is no way. If the manufacturer has provided a single connection method, for example, a dial-up telephone line, you will not be able to connect even two telephone lines if you have a spare. Of course, many manufacturers of security equipment provide the possibility of backing up, for example, via a GSM/GPRS channel. These are not cheap devices, but you will not have to additionally install and configure an external garland of equipment. On the other hand, general-purpose Internet access equipment is becoming cheaper at an amazing speed, and most importantly, it is much more reliable and easier to install: it is produced and used in thousands, if not millions of copies. In the event of failure of such equipment, it can be replaced in a few minutes by buying a suitable modem or router at a nearby stall. And specialized equipment for security alarms, although it is initially designed as more reliable, nevertheless, due to the small circulation, it is much slower to bring to a flawless state. And the more multifunctional it is, the more problems it may have, the more expensive it is, and the less likely it is that it can be replaced with an analogue even from the same manufacturer. In case of a breakdown, you will have to look for an identical product to replace it.
And finally, a fly in the ointment. Currently, the only known standard and widely supported protocol for message transmission is the Contact-ID protocol for tone signal transmission over a dial-up line. In addition to Contact-ID for transmission over telephone lines, there is a newer SIA format, which is more informative but less common. As for protocols over the Internet, these are mostly closed internal protocols of individual manufacturers (often these are some proprietary variations on the theme of Contact-ID messages only over TCP-IP, naturally incompatible with each other) and work only with the central monitoring station produced by the same company. Or, in general, equipment with declared transmission over the Internet is oriented only to connection with a browser from a computer or to sending messages by e-mail. It should be said that three years ago, the same SIA released a standard for the format of messages over IP networks, developed on the basis of its SIA message format, but try to find equipment that uses it. Probably, soon there will be a lot of such equipment. Or maybe not soon.