SUPERVISION AND TELECONTROL OF A RADIO

BROADCASTING SYSTEM VIA INTERNET

Joan Aranda

Automatic Control and Computer Engineering Department

Universitat Politècnica de Catalunya (UPC)

Pau Gargallo,5. 08028 Barcelona

Eduard Sanz

Head of Telecontrol Systems Department

Difusió Digital S.T.S.A-Tradia

Key words: Telecontrol, Remote Supervision, Internet, SCADA, Radio broadcasting.

Abstract: In this paper a recent application is showed that uses Internet as a supervision tool and remote control of

a network of radio-TV relay stations to offer a better service to future clients. The relay stations network

occupies a region of about 30.000 km

. The operator of this telecommunications network counts with a

SCADA system which permits to the operator monitoring and control of the whole network. With the

presented application users of the network can access to real time information about relevant aspects of

the emission or change some parameters at anytime and from anywhere thanks to internet. The aspects of

access security and safe communications have been taken care specially.

1 INTRODUCTION

Telecontrol and remote supervision of industrial

applications have been growing up everywhere.

They are especially important on distributed systems

when they extend on a vast territory.

In this paper we show a particular

implementation on a radio broadcasting system, and

its relay stations network. The network extends for a

region of about 30.000 km

most of them occupied

by mountains with difficult road access to the relay

stations on winter.

The operator of this telecommunications network

(the operator, from now on) needs a telecontrol and

supervision system of its radio broadcasting system,

including infrastructures and equipment, to be

offered as a new service to its clients. The central

application of this system counts on a SCADA in

real time with a continuous polling against a

communications front-end. This SCADA

concentrates the communications with different

remote relay stations (fig 1).

The operator considered the viability to carry out

the implementation of a software application that

allows resolving the limitations of security of its

SCADA system and that makes possible the access

of a third party to supervising and remote control of

infrastructures property of the operator.

The addition of new functionalities that will be

attractive for this type of users, as radio stations or

TV channels, tries to be an added value for the

future clients. They will appreciate these

functionalities at the time of making the decision to

contract certain services of housing with the

operator.

Figure 1: General system architecture

INTERNET

Clien

WEB

SCADA

Front-End

375

Aranda J. and Sanz E. (2004).

SUPERVISION AND TELECONTROL OF A RADIO BROADCASTING SYSTEM VIA INTERNET.

In Proceedings of the First International Conference on Informatics in Control, Automation and Robotics, pages 375-378

DOI: 10.5220/0001143303750378

 SciTePress

2 OBJECTIVES

Our basic objective consists of analyzing the users’

requirements and designing an open telecontrol

system, using the existing infrastructure of remote

stations of telecontrol and the SCADA system,

property of the operator.

Initially, this service will be offered to the

operator clients, through a reduced bandwidth

communication channel (commuted telephone

network, for example).

We considered that the necessary functionalities

to make the product attractive to the client are the

following ones:

1. Monitoring of Telecontrol customized data at

client level (1 client - N signals).

2. The visualization of digital states of channels

connected to the system in "real time"

(depending solely of the bandwidth available).

3. The visualization of analogical measures in "real

time".

4. Visualization of a listing with the last events

generated by the channels that belong to a certain

client.

5. Possibility of including connections to other

static pages, or send a mail to the contact person

(webmaster).

6. Safe connection. The connection with the client

must be established through a safe connection,

with some type of certificate and encoding in the

case of control commands.

7. Execution of commands. Some actions will be

allowed to the client on certain channels, with

the necessary warning interface and user

agreement of the type of action that will be

executed. A log file of the commands sent by all

the users will be generated.

8. Movement between synoptic screens. The

administrator will be allowed to connect several

pages of clients, giving the possibility of moving

from one page to another just clicking over some

icon within the visualization area. A registration

of visits will be generated.

9. Storage of analogical measures. Analogical

values will be registered in time intervals defined

by the client and up to a maximum number of

values defined by the administrator. The

necessary interface for the selection of these

parameters will be designed.

10. Conversion functions and thresholds of

analogical measures. A simple conversion

function (proportional and offset) will be

implemented for the presentation of the

analogical values. In addition, maximum and

minimum values for a specific measurement will

be provided, so that, once surpassed those

thresholds, the corresponding alarm will be

triggered.

11. Evolution Graph of analogical measures. A

graph with the values of the obtained analogical

measures of the periodic interrogation of point 9

will be created dynamically.

12. Filtering of events. The user will be allowed to

filter the events by the obtained values.

13. Reports screen. A page for internal use will be

created to enable fast generation of reports with

the filtering of events described previously.

14. Automatic warning by email of certain events. A

necessary time of delay in the transitions from 1

to 0 and vice versa will be defined in order to

don’t disturb the client. A sent messages Log

File will be generated.

15. Automatic warning by SMS to GSM mobile

telephones. The telephone number will be chosen

by the user and a maximum number of messages

will be sent. Log with the sent messages will be

generated.

16. Slow video show. A page will be implemented

where slow video will be visualized (images

JPEG, GIF...). The sample time will be selected

by the user in relation with the bandwidth

available.

The most important processes must leave files of

log, giving the possibility of tracking possible

malfunctions. Also the operator wants to give this

service of supervision and remote integral control to

an undetermined number of clients. Under this

premise, the system must be easily scaleable.

3 SYSTEM DESIGN AND

SPECIFICATIONS

The proposed system shows incalculable value for

the clients of the operator, so it guarantees a

continuous test service anytime at anywhere. Thus,

the works of maintenance and tracking of failures or

incidences will be much more effective with a

system of the raised characteristics. The

determination of the origin of a problem will be

considerably faster and it will returns in a superior

quality service.

In order to understand usual problems we will

show up some examples. A typical client of the

operator could be a FM radio station. A technician in

charge of emitters and relay stations of this radio

station could need to know the nominal power exit

and other important parameters of the relay station

under which he/she is making field measures.

Another example: most of relay stations do not have

permanent personnel the twenty-four hours/day that

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can monitor (from the studies) the continuity of the

transmission. Thus, the possibility of connection

with a personal PC from the particular address of the

guard person would allow avoiding unnecessary

displacements.

For that reason the final solution is not bound to

a specific platform or communication channel. The

application will allow the remote connection using

the telephone lines, or even the connection by means

of a data line of a GSM movable telephone.

Given the uncertainty in the final number of

concurrent users, the use of an existing network like

Internet is valued very positively, in front of the

implementation of a specific remote access system

for the clients of this service.

3.1 The corporative control system

The hardware architecture of the control center is

formed by two servers HP9000, a disc Array and

two terminal servers of 16 ports each one, which

connect with the front-end of communications, as

well as two graphical consoles with 21"monitors.

The servers form a cluster MC/Service Guard,

connected by network and with the sufficient

redundancy so that an error in one of the

components does not interrupt in a significant form

the service. It counts on redundancy of LAN

interfaces, mirror discs and duplicity of ventilation

and power supplies, and also redundancy of CPUs in

the main server. The terminal servers connect with

the front-end of communications through a passive

commutation which is controlled by one of the high

availability processes of the MC/Service Guard

system.

The data management is made with an Oracle

relational database, for the historic and configuration

data, a real time data base that stores the values and

states of the system, an alarms data base that

manages the different events based on its critical

issue, and the operator answers to these events.

The system allows the supervision and

telecontrol of up to 254 remote stations on a same

communications line by using Gestel protocol. The

connection of these becomes through the corporative

network of cross-connect nodes, using V-24

interfaces and point-multipoint structures. At the

moment there are 10 remote lines operatives and

could be up to 16 with the existing hardware.

In its present configuration, the system reports

states, alarms and is able to execute commands in a

total of 92 remote locations, on a total of 780

equipments. The control carried out on these

equipments implies the configuration of 7400 digital

inputs, 1700 digital outputs and 500 analogical

measures. This information is captured by the

remote stations through input/output cards or via

RS-232.

The system also allows the communication with

other servers through UDP and TCP/IP, using the

standard SNMP (Simple Network Management

Protocol).

Figure 2: SCADA Interface: Synoptic screen for real time

operation on a television relay station.

3.2 Implementation

The proposed solution consists of the following

elements (figure 3):

1. Data base SQL Server 7.0: with information

about the clients, channels, parameters, etc. The

historical data are stored in the Oracle data base

of the server where the SCADA runs.

2. Data base ORACLE: Holds the historical

information of alarms and the configuration

parameters of the digital output signals.

3. The web server: Acts as application interface.

The client uses it to extract information from the

remote relay stations and to set up the required

services on its channels. The system

administrator has the corresponding Webpage

interface.

4. ActiveX Components: They supply essential

utilities for the assembly of the application.

5. NT Services: the system has three own services

in execution: tracking of digital channels,

tracking of analog channels and the registration

of the captured information.

The communication settles down through the

following sequence of operations (fig.4):

1. The Web server receives requests from the

clients, unloading static and dynamic images that

are kept in the client PC.

SUPERVISION AND TELECONTROL OF A RADIO BROADCASTING SYSTEM VIA INTERNET

377

2. The client makes the request of the telecontrol

information of the contracted services.

3. The server requests the information in real time

through protocol SNMP to the corporative

telecontrol system.

4. The server offers the information to the client

and it refreshes the representation in the local

machine. The operation takes place at the

frequency fixed by the system administrator.

5. In addition to the real time information, the client

can ask for historical information that the Web

server acquires from the corporative control

system data base.

Figure 3: Application data structure

Figure 4: System operation.

4 RESULTS

A friendly and functional interface has been

designed that allows the clients continuous

monitoring and remote control over the relay

stations network (figure 5).

It solves functional limitations of the SCADA

system as the massive management of alarms. This

kind of services and the automatic generation of

reports for the internal use of the own operator have

made of the developed application a profitable

investment, only for the own management of the

network quality.

In addition they have been introduced new

broadcasting service functionalities that will call the

attention of the potential clients. This will derive in

the benefit of new services to contract, as they can

be the transmission of slow video, the inclusion of

images to its own Web, monitoring cameras, transit

(through Digital Audio Broadcasting, for example),

beauty cams to show the weather conditions in

different places, etc. (figure 6).

A complete interface has been created to allow

the client changing some parameters without

depending on the availability of the system

administrator to carry out some service

modifications. For instance, the time between

captures of analogical values (sample rate) or the

email address where the user will receive the

notification of the events that he/she previously has

programmed.

Figure 5: Relay stations network of the operator

Figure 6: Real time video from a concentrator

REFERENCES

Orfali R., Harkey D. (1998) “Client/Server Programming

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Stallings, William, (1994) “SNMP, SNMPv2, and CMIP:

The practical Guide to Network-Management

Standards”, Addison-Wesley Publishing Company.

www.verising.com; Implementing Web Site Client

Authentification Using Digital Ids.

www.Microsoft.com:

ASP Technology Overview.

Implementing a Secure Site

with ASP

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