home Internet Data transmission over a voice channel megaphone. CSD from "MTS": data transmission "by voice. How the subscription fee is calculated

Data transmission over a voice channel megaphone. CSD from "MTS": data transmission "by voice. How the subscription fee is calculated

Hi all!
With this publication, we begin a series of articles about devices and technologies involved in the process of energy metering and energy saving. In such articles, we will rely only on our own experience and the experience transmitted to us by users of the Eldis electronic dispatcher.

Let's start slowly.

Today we have a generalized topic on the menu about CSD technology and modems using this data transfer technology. We decided not to look for differences between the two identical pictures, but to analyze CSD modems, as such, without getting personal.

Surprisingly, but the CSD modem, when communicating with its fellow modems, uses an information transfer technology called CSD.

CSD (Circuit Switched Data) is a digital data transmission technology in GSM networks. The same network that each of us uses several times a day, or even spends the main part of the weekday in it. I say hello to the technical support department =)

The CSD coverage area corresponds to the GSM coverage area, which is due to the use of a voice channel for information transmission. Today, this is the main advantage and disadvantage of this technology. But first things first.

At the birth of CSD, the benefits were not limited to this, due to the lack of alternatives. The information transfer rate over CSD is 9.6 Kbps, while the bandwidth of modern 4G is 1 Gbps (kilobit - 10 to the 3rd power, gigabit - 10 to the 9th power). The technology involves the simultaneous communication between two devices, by analogy with talking on a mobile phone or how a fax works.

CSD works in GSM networks, which implies that for such a service, if we suddenly need it, we need to contact the operators mobile communications. Yes, yes, these are the same guys who sell SIM cards for phones, and then offer new tariffs every month. Let's find out what they offer us today.

CSD traffic for mobile operators was of value until every person had a mobile phone, and the price of communication fell to a minimum, due to high competition between operators.

Why User Growth mobile phones began to kill interest in CSD?

The fact is that when transferring data from one device to another, CSD occupies a channel voice communication, which can be used for its intended purpose and at a higher price.

Also, as a standard for the transmission of information in the arsenal of operators, there is an alternative with a higher throughput and not loading voice channels: GPRS, 2G, 3G, 4G.

In this regard, mobile operators are constantly increasing tariffs for CSD and, as far as possible, obsolete it.

Today, the CSD service in most cases exceeds the price even for a faster and more modern GPRS and is present only in specialized tariffs that include CSD packages for several thousand minutes that operate within one region and one operator cellular communication.

Thus, cellular operators act as a catalyst in the process of destroying CSD technology.

Letter to JSC "Eldis" from JSC "MegaFon"

Retirement from CSD will not go unnoticed, and no, the retirement of this technology will not be accompanied by a lavish celebration with tea and cookies, on the contrary, it will be painful for the most part. This technology successfully implemented and used to transfer evidence from various electronic appliances installed in hard-to-reach places.

Let's move on to our favorite topic.

After the release of 261 FZ, which required the installation of metering devices in each apartment house, the task of prompt collection of readings from all installed computers became acute.

Without constant monitoring of energy metering units, there can be no question of any energy efficiency, and putting a person for observation on each computer is a very expensive pleasure.

Then CSD modems came to the rescue, attracting with their low cost (about 4 thousand rubles) and prevalence. most standard software, which is included in the set of modern calculators, supports work on CSD, for example: VKT-7 Easy2, Prologue, ArchiVist, Rise of the joint venture, TesmaStat, StatReport and others.

With the advent universal programs for remote collection of readings from metering devices through various data collection and transmission devices (modems), CSD modems have another problem undeniable advantage- the possibility of simultaneous work in several energy accounting systems.

Thus, when working in one or another system for collecting readings from metering devices of the Eldis type, the owners of CSD modems do not take any risks and at any time can transfer their metering units to another similar system, unlike GPRS modems.

Sadly, not only CSD technology, but also modems operating on it, are at risk of disappearing from the shelves.

Recently, most manufacturers of radio components have begun to produce budget versions of SIM modules that do not have the function of working in CSD mode. A striking example is the upgrade of the SimCOM Sim900 line to Sim800. Now only one module from the entire 800s line has CSD mode. There is a suspicion that the next series of modules will be completely without CSD.

In total, the following can be distinguished as minuses of CSD modems:

slow information transfer rate;
the speed of polling calculators directly depends on the number of polling modems installed on the server, due to the impossibility of parallel communication of one CSD modem with several;
high price traffic. About 1.25 rubles per minute, for the same money you can transfer 1 MB of information via GPRS (for text information it's really a lot. For comparison: the entire work of Leo Tolstoy “War and Peace” takes up less than 4 mb.);
obligatory setting of the modem to work with the calculator is carried out using a computer via the RS-232 interface, which is not available on modern PCs and laptops;
the presence of only one data transfer interface or RS-232 or RS-485;
inability to remotely configure and update software;
threat of withdrawal from production;
the threat of eradication of CSD support by cellular operators;
the modem is disconnected from the dispatching system by default, it is connected only for the period of data transfer and cannot always be online.

Despite all the shortcomings and antiquity of CSD technology, there are not enough fingers of both hands to count the manufacturers of CSD modems. Until the technology has become obsolete and has not been completely replaced by mobile operators, there is a good demand for it. The device is not difficult to manufacture and has a wide range of applications.

Basically, competitive modems do not differ much from each other. Most often, the main distinguishing feature is the case and the logo on it, less often the sim module. If we talk about the market leaders in terms of prevalence, we can distinguish: iRZ, Teleofis and Siemens.

Let's summarize.

Modems based on CSD technology, despite their wide popularity, are on the verge of extinction due to the threat of discontinuation of components for them. Also, over time, the likelihood of mobile operators refusing to sell CSD services increases, as well as a constant increase in prices for CSD traffic.

The cost of CSD-modems by leaps and bounds is approaching the cost of modern modems that support GPRS operation. Affects both the rise in price of the first, and the cheapening of the second.

When choosing a data transmission device for installation at a dispatching facility, we recommend paying attention to a CSD modem only if there is no alternative connection at the facility, otherwise it is better to pay extra and purchase a modern GPRS device or take a universal option - GPRS/CSD.

Note!
Not all modems whose specifications indicate operation via GPRS can independently communicate via GPRS, limited to the good old CSD.

This is often a clever marketing ploy by manufacturers that allows misleading consumers and selling a CSD modem at the price of GPRS.

The trick is that the modem, without the help of additional equipment, be it a calculator or a computer that will send specialized AT commands to it, is not able to initialize the GPRS connection. Heat calculators capable of sending such commands to the modem and making it work via GPRS are, for example, SPT943 and TMK-N120.

Let's return to the problem with GPRS coverage.

Cases of the absence of a GPRS signal in the CSD coverage area are not a myth, and have happened more than once in our practice: in the Tver region (Ostashkov), in some cities of the Pskov region and even in the Krasnogorsk district of the Moscow region.

Based on statistics obtained in the process of surveying customers of the Eldis electronic dispatcher, modems operating only on CSD technology are currently installed in approximately 75% of objects in relation to total number equipped with transmitters. Complete failure mobile operators from the provision of data transmission services via CSD will entail huge costs for the re-equipment of dispatching facilities.

Every month, the number of CSD-modems connected to Eldis is significantly increasing, and with it, the monthly traffic for CSD-connection is also growing. The graph below shows statistics on the use of CSD traffic by all modems operating on this technology in the electronic dispatcher for the current year.

Dynamics of CSD traffic usage by Eldis users

With this article, we do not urge you to urgently remove old modems and buy new data transmission devices, but we warn you about possible difficulties soon.

We accept requests for a review of devices from the list of supported equipment. We promise an objective assessment and adequate criticism of any device. In case we do not have enough materials to review the device you proposed, sorry, we will postpone it for later.

An important role and incentive for writing articles is played by the presence of comments.

Thank you for your attention! That's all for today.

All modems of the RX series are configured by default to transmit data using the CSD protocol.

First, let's take a look at what CSD is and why modems work in this mode by default.

1. What is CSD?

Let's go to the Wiki for information:

Circuit Switched Data(CSD) is a data transmission technology developed for GSM mobile phones.

The CSD uses one time slot to transmit data at 9.6 kbps to the Network and Switching Subsystem (NSS), where it can be transferred via the equivalent of a normal modem connection to the telephone network.

The CSD call works very much like a regular voice call on GSM networks. A single time interval is allocated between the phone and base station.

Data transfer to GSM networks has been improved since the advent of CSD. Because the maximum speed data rate for a single timeslot is 9.6 kbps, many operators allocate two or more timeslots for CSD calls.

To work with this technology, it is necessary to order a CSD service connection from a mobile operator (if this service no longer connected).

In most cases, the CSD service is disabled by default.

We can draw up the principle of interaction [program<=>modem<=>modem<=>device]

Those. the program starts sending AT commands to the modem's interface port, the modem, in turn, with its SIM cards, makes a voice call to a number SIM phone card installed in another modem.

The remote modem answers the call.

This creates a communication channel between the two modems through which we can send or receive any data.

2. Interrogation of equipment by CSD

To understand how access to a meter or any other equipment works, to configure it or read readings, let's look at a simple example:

Interrogation of the counter Mercury 230 ART-01 PQRSIN with two modems TELEOFIS RX101-R4 and TELEOFIS RX108-R4

Initial data:

Counter Mercury 230

The RX101-R4 modem has USB-B interface connection to a PC, so it will be the calling modem.

The RX108-R4 modem has an RS485 interface and is connected to the Mercury 230 meter, so it will be a Receiving modem.

Two SIM cards with a positive balance and activated CSD service

Software Universal meter configurator Mercury, for connection to the meter: Download configurator

Let's define the connection scheme:

Let's connect our modems according to the above diagram.

For RX101-R4, install drivers on a PC (Only drivers, you don’t need to connect the modem to the Internet!):

For RX108-R4, nothing needs to be installed.

Let's open the survey program:

In our example, the connected modem is assigned a COM15 port.

Fill in the parameters for communication with a remote modem

Enter SIM number receiver modem cards

Type of interface through which we will make a request (GSM)

And we press the button Connect

We see the connection process

The process of obtaining information can be observed at the bottom of the window

After 100% filling, we will see the read information from the counter

After we receive all the necessary information and perform desired settings must not be forgotten break established connection not to waste money.

Additional Information.

CSD (Circuit Switched Data) is a data transmission technology developed for GSM mobile phones.
GPRS (eng. General Packet Radio Service - “packet radio communication common use"") - an add-on for mobile technology GSM communications for packet data transfer.
GPRS allows the user of a cellular network to exchange data with other devices in the GSM network and with external networks, including the Internet. GPRS assumes billing by the amount of transmitted / received information, and not by the time spent online with CSD.
In CSD mode, connection with remote device set according to his phone number, because this technology uses data transmission over voice channels.
In GPRS mode, connection with a remote device is made by its IP address. For GPRS, communication channels are allocated according to the residual principle after voice channels, i.e. cellular operators have higher priority voice channels than GPRS channels.

IMPORTANT : not all modems can be configured in such a way that after power-on the modem is ready to receive a connection in GPRS mode (to connect to the modem, the IP address of the modem and the TCP port “listened” by the modem are specified).

(same as in computers), either built into the phone or attached to it. Due to audio quality limitations, these systems had a maximum data rate of 2.4 kbps. At the same time, the use of GSM oriented audio compression speech, actually means that the data transfer rate using such a modem connected to the phone will be even lower than in traditional analog systems. With the advent digital data transmission in GSM, CSD gave practical direct access to the digital signal, allowing higher speeds to be achieved.

The CSD call works very much like a regular voice call on GSM networks. There is a single time interval between telephone and base station. A dedicated "sub-time slot" (16 kbps) is established between the base station and the transcoder, and finally another time slot (64 kbps) is allocated for data transmission between the transcoder and the switching center: Mobile Switching Center(MSC).

In MSC, it is possible to convert the signal to analog form and encode it using PCM. It is also possible to use digital signal according to the standard ISDN and transfer it to the remote access server.

Data transmission in the GSM network has been improved since the advent of CSD. At the moment 2006, many GSM operators provide CSD service. Because the maximum data rate for a single timeslot is 9.6 kbps, many operators allocate two or more timeslots for CSD calls.

Technology development

HSCSD (English ) is a system based on the same principles as CSD, but designed to provide faster connectivity. Speed increased to 57.6 Kbps

ECSD - data transfer technology EDGE through the CSD channel.

On the other hand, GPRS (English General Packet Radio Service) provides already packet data directly from your mobile phone.
And, in fact, EDGE (English Enhanced Data Rates for GSM Evolution] ) and UMTS (English Universal Mobile Telecommunications System ) provide access with much more high speeds data transmission, but still compatible with the GSM standard.

Just about the complex. Programs. Iron. Internet. Windows

Data transmission over a voice channel megaphone. CSD from "MTS": data transmission "by voice. How the subscription fee is calculated

Technology development

see also

See what "Circuit Switched Data" is in other dictionaries: