In the previous article we discovered the way in which the communication of an alarm panel can communicate with the central via the Internet. In this we will know in depth new communication links such as GPRS.by Daniel Banda
After the analysis presented in the previous edition it is likely that you have found more questions than answers, but at the same time, our companies cannot be allowed to move towards a future dictated by destiny without actively intervening in it.
Faced with the previous points about the form of communication between the alarm panel and the monitoring center, it was discovered and analyzed what each one could offer. This new article will expose the advantages and disadvantages of making physical connections to interface inputs; emulation of the telephone line and capture, and "pishing" of the communication bus between panel and keyboard.
IP monitoring has no standards today
With the passage of time these standards will be generated and we will realize it. At the moment, you have to think that you must have common sense, cost-benefit evaluation and care.
Some tips: if your company has a low panel diversification index, meaning that more than 80% of its subscribers have been provided with panels of a brand or better a brand and a model X, it may be useful to align with proprietary IP communicators of type 3. If instead, you receive wide varieties of panels, look for a model of universality.
The current costs of IP interfaces limit the application to the top 10% of each company's subscriber portfolio in terms of purchasing power. These costs come down daily and are unsustainable. The vast majority of electronic device manufacturers have their reach in the manufacture of type 1 and type 2 interfaces, but significant reductions can be expected.
Communication links
Beyond the common factor, all the equipment studied operates in TCP-IP protocol, TCP or UDP modalities. There are different types of networks and links to achieve communication between base and subscribers:
1. Internet network, wired or wireless access
- Access by DSL or ADSL via telephone line.
- Access by video cable or cablemodem.
- Wireless access over private networks.
- Wi-Fi or Wi-Max Internet access
- Other accesses.
3. Digital Cellular Network, CDMA-1X mode
4. Satellite networks
- BGan de Inmarsat
- Vsat
- Globalstar
- Other
In general of all those mentioned, the GPRS service has achieved an important takeoff, for this reason we will comment on some details of it:
What is GPRS?
GPRS (General Packet Radio System) is a packaged data transmission protocol between cell phone equipment and the Internet. The GSM mode of mobile cellular telephony, the most widespread on the planet, allows the operation of GPRS systems for data transmission between mobile phones and fixed stations.
To describe it quickly, I will say that all mobile phones have the ability to communicate on a TCP-IP intranet through cellular antennas (nodes). Through the gateways that the cell phone provider company has, mobile phones can arrive with their packets to the public Internet network and vice versa, these gateways are called APN (Access Point Name), and through them the data packets enter and leave the system from the Internet.
The TCP/IP protocol
TCP refers to a large accumulation of communication protocols that have been developed since 1970 from its predecessor Arpanet. We could say that TCP is the one that is responsible for transmitting the information and the IP is responsible for routing it, (taking the packet where the recipient is).
But TCP/IP alone is not enough, as a wide variety of hosts on the various computers can be attacked. We could go to the Finger host or the Telnet host and for that this protocol needs additional information which is what we call port.
The port is used to identify a particular service or application within a terminal. This is necessary because different services may be running on the same machine. The port tells the service that there is a client that wants to connect.
When they were designed, an agreement was reached on the reservation of a series of ports such as:
Application Port
80 httpy
20 and 21 FTP
70 Gopher
25 SMTP (email)
110 POP 3
23 Telnet
79 Finger
When choosing the alarm equipment for your network, it is very important to understand if they will communicate in TCP or UDP protocol.
The analogies that are usually used for these two protocols are that of the telephone and that of the radio. The phone (analogously TCP Protocol) needs someone on the other end of the line otherwise communication cannot be established. The radio, on the other hand, (UDP Protocol) emits and it does not matter if there is someone on the other side to receive the signals.
In general, alarm systems and interfaces use UDP because very little data is trafficked and because the connection structure is much simpler. In addition, it is not necessary to save connections (there is no password, no name). When using UDP there is no proper connection.
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