Telemetry and control system with GSM communications☆
Introduction
Mobile communications have developed at breakneck speed in recent years. Mobile telephones today, with their various services [1] and types of network [2], are products of mass consumption, with very affordable prices, compact sizes and low energy consumption; the services that users may obtain from their mobile telephone depend above all on the operator supplying the service. Thus, apart from the typical telephony services (calls, SMS, voice mailbox, etc) there is also a trend towards incorporating new functions: geographical localisation of the mobile phone, news, advertisements to suit the user's geographical location, etc [3], [4].
One of the applications that have not yet been sufficiently developed is the interconnection of industrial systems (telemetry and control). ‘Telemetry’ can be defined as the capacity of capturing, processing and sending system data, while ‘control’ is understood as the capacity of acting on the system in question, generally in accordance with the data sent by the system itself. Both concepts assume the existence of a two-way communication channel.
Machine-to-machine (M2M) communication between mobile, portable or stationary devices (clients) and centralised servers is estimated to get an exponential growth in the coming years and certain studies rate its growth prospects as being even higher than that of the voice market [5]. This will open for new ways to utilise the networks. To illustrate the possibilities for M2M communication, e.g. devices can be used for remote control, surveillance, tracking, localisation and telemetry. This type of communication device is today often made up of a wireless module, containing the mobile station (e.g. an ordinary mobile station without display and buttons), and additional application specific software added by a system integrator. The device can then be connected to the equipment that shall be controlled, for example a surveillance camera, the computer within a car or a soft drink machine.
Without doubt one of the fields that has most spurred the data-transmission use of mobile telephony is telemedicine. This is a field with enormous healthcare advantages and has therefore received generous aid from public bodies such as the european commission. Ref. [6] shows the state-of-the-art wireless telemedicine system; different systems are analysed based on GSM, GPRS, Bluetooth or LAN technology and work on several prototypes developed in various research projects is shown.
One of the problems that might crop up when setting up a telemedicine system is the bandwidth. The transmission of a radiograph image, for example, might take up as much as 40–50 Mbytes. In many of these systems it is therefore necessary to set up information compression systems, such as the JPEG standards, always without any appreciable loss of information. It would seem to be unfeasible to use a conventional telephony channel such as GSM for transmitting this type of information but it could indeed be useful for transmitting other physiological signals requiring a narrower bandwidth, such as the electrocardiogram (ECG), body temperature, blood pressure, oxygen saturation, etc [7].
The mobile telephony technique can be used for telemetry and control functions when the following obtains:
- (i)
there is coverage
- (ii)
the data transmission delay (SMS or call) can be random, even within very wide margins.
- (iii)
when service interruptions are tolerable, meaning that it cannot be used in critical safety tasks.
The advantages of the system are its affordable cost, the existence of a communications infrastructure covering most regions and the fact that the system to be controlled can be on the move.
In a telephone communications system the two-way transfer of information can be carried out in two ways:
- •
Setting up of a call and transfer of information in data mode. This possibility allows data to be transferred at the rate of 9600 bps in the GSM network. Theoretically the speed is higher in GPRS (115 Kbps dedicating 8 time slots to a single call and not activating any data protection) although the normal rates in practice are 56 Kbps [8].
- •
Transfer of information by short messages (SMS), with a maximum message length of 160 characters.
In the first case, once the call has been set up, the maximum data transmission delay between sender and receiver is likely to be about several ms; in SMS mode, however, this delay is unpredictable, as it depends on the message handling centre (normal values would be about 20 s).
This paper presents a telemetry and control system for mobile-telephony interconnection of several elements of diverse functions; it therefore harnesses the advantages of the mobile telephony transmission network. The general system architecture is shown in Fig. 1; the aim is to set up a communication network formed by an indeterminate number of nodes (Portable Modules, PM), controlled by a personal computer in which the network control application is run (Control Centre, CC). Communications between the network elements is by way of mobile telephony data transfer using SMS or by setting up a call in data mode. Mobile telephony provides a two-way communications channel, with access to any point with cover and at a cost that depends mainly on the amount of data to be transferred.
The Control Centre is made up by a personal computer and the suitable communications system (normally one or more mobile telephones). The CC software obviously depends on the network characteristics, but it must in any case be able to handle communications (calls and SMS messages) and also provide for the following functions: allowing authorised users to add to or remove a PM from the system, allocating the telephone numbers, making operational queries, teleprogramming of the application software in each PM, fixing the alarm levels, etc.
The electronic system making up each one of the portable modules consists of a microcontroller-based electronic circuit, thus providing an open system that can be reconfigured at software level; the system can be adapted to the characteristics of the environment to be monitored and/or controlled. Another of its advantages is the possibility of modifying the application software that is running in the microcontroller (teleprogramming) by sending the appropriate command and software via the communications system.
The range of possible applications is vast. By way of example this system could be used for controlling a set of vending machines, lift machinery, tracking a fleet of vehicles on the basis of the cell that gives coverage to the mobile, low-speed image transmission and even telemedicine applications, such as the analysis of certain parameters and the sending of a patient's ECG to a control centre. The limitations of the system, based on the current limitations of the transmission channel, are determined by the amount of data to be transmitted per time unit. It will only be viable, therefore, when said amount is not very high.
The aim of this research work is to create a hardware platform for implementing M2M services, including telemedicine services. The success of the platform will be determined by the flexibility and capacity of the portable modules. It is vital for the system to have a high number of inputs/outputs and to be reprogrammable. It also needs to be economical in cost and consumption and re-scalable so that it can be used in a great variety of applications with the minimum modifications.
The main aim of this paper is to give a detailed description of the characteristics and possibilities of the portable modules. They have been designed with the idea of developing a basic hardware system, which could be used to solve a host of problems, with the minimum number of modifications or alterations to the original structure.
This paper has been broken down into the following sections: first of all a description is given of the hardware architecture of the portable modules; Section 3 shows the characteristics of the software that can be run on the microcontroller and explains how the application is remote-loaded. A description is then given of two applications that can be based on this platform: an application of the system for the analysis (Heart Rate Variability (HRV)) and transmission of a patient's ECG (Section 4) and another for the low-speed transmission of video images (Section 5). The article ends up by recapitulating the main ideas developed therein.
Section snippets
Hardware of the portable modules
The overriding idea in developing the portable modules was to keep them small in size and economical in energy consumption but with a high flexibility in terms of adapting them to various applications and also with ease of communications.
To this end a basic architecture has been designed (core) that is invariable in all portable modules (Fig. 2); the core has the minimum requisites of an autonomous system: power supply, a microcontroller and the mobile telephony communications channel. An
PM software
The microcontroller programme has been structured in two parts (Fig. 3):
- •
application: This is the programme that is run for the functions of telemetry and control (normal system application). It is housed in the microcontroller's internal FLASH memory. Its ability to write in the memory on line (without needing to stop the microcontroller) makes it possible to reprogramme the application. This part of the code is loaded by a data mode call with a suitable key for that purpose. An special
Implementation of an ECG pickup and processing system
The remote capture and analysis of physiological signals is a field of great interest, since it would significantly improve many patients' quality of life. There are several portable systems that perform that function, using radio-frequency links [10], mobile telephony [7], [11], Internet [12] or satellite communications [13] as the means of communication.
One of the signals that furnishes a great deal of information on the physical state of a patient is the ECG; the ECG signal has amplitudes in
System for transmission and/or analysis of video images
Another of the applications that can be carried out by a PM is the transmission and/or analysis of video images. The main limitations in this case are:
- –
the images have to be transmitted at low speed.
- –
if the algorithms are implemented in the μC, the automatic analysis of the images has to be very simple due to the computational load.
The image capturing system used is the 128×128 pixel artificial retina M64283FP (MITSUBISHI) [16] with analog output. One advantage of this integrated circuit is that
Conclusions
This article presents an electronic telemetry and control system with a communications system based on GSM technology. Used in conjunction with a microcontroller-based system and the remote-loading of the application, this system can be adapted to a host of applications. Results are shown of a system for the capture, analysis and transmission of a patient's ECG and another system for the transmission of video signals.
The use of other microcontrollers of the same family will allow the system to
Lucaino Boquete received a Ph.D. in Telecommunications in 1998, a degree in Telecommunications Engineering in 1994 and degree in Technical Telecommunications Engineering in 1987. He is currently a Lecturer in the Electronics Department at the Alcalá University (Spain). His research interests include bioengineering, computer vision, system control and neural networks. He is the author of more than 50 refereed publications in international journals, book chapters, and conference proceedings.
References (16)
Applications and services from 2nd to 3rd generation
International Conference on Communication Technology (ICCT'98)
(1998)- et al.
A novel generic distributed intelligent re-configurable mobile network architecture
Vehicular Technology Conference (VTC 2001) IEEE VTS
(2001) - H. Makino, I. Ishii, M. Nakashizuka, Development of navigation system for the blind using GPS and mobile phone...
- et al.
Wireless transfer of images from a digital camera to the Internet via a standard GSM mobile phone
IEEE Transactions on Consumer Electronics
(2001) - Emerging Opportunities in GSM Data Applications, Xircom Inc.,...
- et al.
Wireless telemedicine systems: an overview
IEEE Antenna's and Propagation Magazine
(2002) - et al.
A novel emergency telemedicine system based on wireless communication technology-AMBULANCE
IEEE Transactions on Information Technology in Biomedicine
(1998) - GPRS Data Services: Perspectives for Mobile Computing, Xircom Inc.,...
Cited by (26)
High-precision and low-cost wireless 16-channel measurement system for multi-layer thin film characterization
2013, Measurement: Journal of the International Measurement ConfederationCitation Excerpt :Wireless communication technology can separate the data acquisition circuit from the data processing circuit, thus avoiding the complex line connection and low bit error rate. Some of the most commonly used protocols in wireless communication systems are: Bluetooth [35], RF [36], WiFi [37], ad hoc protocols [38], or mobile telephony [39]. For a protocol to satisfy applications, it must be low power, highly portable, affordable, and reliable.
A portable wireless biometric multi-channel system
2012, Measurement: Journal of the International Measurement ConfederationCitation Excerpt :Some example papers describing the state-of-the-art in these two areas are provided below [21–25]. Some of the most commonly used protocols in wireless communication biomedical systems are: Bluetooth [26–30], ZigBee [31–33,17], WiFi [30], ad hoc protocols [7,34], MICS (Medical Implant Communication Service) [8] or mobile telephony [15,35]. In order for a protocol to satisfy these medical applications, it must be low power, highly portable, affordable, and reliable.
Web-based real-time temperature monitoring of shellfish catches using a wireless sensor network
2005, Sensors and Actuators, A: PhysicalRemote control of an ultrasonic motor by using a GSM mobile phone
2005, Sensors and Actuators, A: PhysicalReducing SCADA system nuisance alarms in the water industry in Northern Ireland
2015, Water Environment ResearchOff-grid telemetry system for hydrate inhibition on gas wells
2015, Proceedings of the 2015 16th International Carpathian Control Conference, ICCC 2015
Lucaino Boquete received a Ph.D. in Telecommunications in 1998, a degree in Telecommunications Engineering in 1994 and degree in Technical Telecommunications Engineering in 1987. He is currently a Lecturer in the Electronics Department at the Alcalá University (Spain). His research interests include bioengineering, computer vision, system control and neural networks. He is the author of more than 50 refereed publications in international journals, book chapters, and conference proceedings.
Ignacio Bravo Muñoz obtained in Telecommunication Engineering middle degree and Electronic Engineering degree from the University of Alcala (Spain) in 1997 and 2000, respectively; currently, he is working for his Ph.D in vision architectures based in FPGA's. Since 2002 he has been a lecturer in the Electronics Department of the University of Alcala. His areas of research are reconfigurable hardware and Electronic Design.
Rafael Barea received a Ph.D. degree in Telecommunications from University of Alcalá in 2001, a M.S. degree in Telecommunications from the Polytechnic University of Madrid in 1997 and a B.S. degree in Telecommunications Engineering with first Class Honours from University of Alcalá in 1994. He has been Lecturer in the Electronics Department at the University of Alcalá since 1994. His research interest include bioengineering, medical instrumentation, personal robotic aids, computer vision, system control and neural networks. He is the author of numerous refereed publications in international journals, book chapters, and conference proceedings.
Miguel Ángel Garcia Garrido obtained his Industrial Engineering middle degree and Electronic Engineering degree from the University of Alcala (Spain) in 1998 and 2001, respectively; currently, he is working for his Ph.D in Artifical Vision. Since 2000 he has been a assistant in the Electronics Department of the University of Alcala. His areas of research are Vision based detection system for autonomous urban transport vehicles.