Full-Text PDF
Contents
1. Available online http it rs online com web generalDisplay html id raspberrypi accessed on 21 May 2014 Raspberry Pi Raspberry Pi Tutorials Available online http www youtube com user RaspberryPiTutorials videos accessed on 21 May 2014 Wikipedia Raspberry Pi Available online http en wikipedia org wiki Raspberry_Pi accessed on 21 May 2014 Microchip MCP9700 Datasheet Available online http www alldatasheet com datasheet pdf pdf 195312 MICROCHIP MCP9700A html accessed on 21 May 2014 Honeywell HIH 5031 001 Datasheet Available online http www alldatasheet com datasheet pdf pdf 345574 HONEY WELL HIH 503 1 001 html accessed on 21 May 2014 Why Buy PIC Microcontrollers MCUs and dsPIC Digital Signal Controllers DSCs Available online http www microchip com pagehandler en us products picmicrocontrollers accessed on 21 May 2014 How to Choose the Right Platform Raspberry Pi or BeagleBone Black Available online http makezine com magazine how to choose the right platform raspberry pi or beaglebone black accessed on 21 May 2014 Arduino vs Raspberry Pi Comparison Available online http codeduino com information and news hardware arduino vs raspberry pi accessed on 21 May 2014 Labiot H Afifi H de Santis C Wi Fi Bluetooth ZigBee and WiMax Springer Berlin Germany 2007 Gislason D ZigBee Wireless Networking Newnes Burlington MA 01803 USA 2008 Digi ZigBee2. In Proceedings of the 2006 IET International Conference on Wireless Mobile and Multimedia Networks Hangzhou China 6 9 November 2006 pp 1 4 Prasad R Velez F J OFDMA WiMAX Physical Layer In WiMAX Networks Springer Netherlands Heidelberg Germany 2010 pp 63 135 COMMSCOPE SSPX310M Argus Quad Antenna 3300 3800 MHz 65 Horizontal Beamwidth Manual Electrical Tilt Not Upgradeable Available online http www commscope com catalog andrew product_details aspx id 5280 accessed on 21 May 2014 ZyXEL HES 319M Outdoor WiMAX CPE Manual Available online http www manualowl com m Zy XEL MAX318M Manual 348786 accessed on 21 May 2014 Linear Technology LTC3863 Datasheet Available online http www alldatasheet com datasheet pdf pdf 494524 LINER LTC3863 html accessed on 21 May 2014 Jutasolar CMP12 JUTA Datasheet Available online http www jutasolar com accessed on 21 May 2014 PCE Instrument Ltd PCE FWS 20 Meteorological Station with Touch Screen Available online http www industrial needs com technical data meteorological station pce fws20 htm accessed on 21 May 2014 Cagnetti M Leccese F Trinca D A New Remote and Automated Control System for the Vineyard Hail Protection Based on ZigBee Sensors Raspberry Pi Electronic Card and WiMAX J Agric Sci Technol B 2013 3 853 864 Air Interface Specification for Portable Internet IEEE 802 16 1 2012 WiBro Available online https www google it url s
3. card managing all the synchronization tasks for both the sensor cards and the server Usually only one time a day it by means of a specific switch activates the Raspberry Pi downloading onto it the acquired data After that the Raspberry Pi stores this data and can send it toward the server If there are particular requests by the server such as more pictures in a per day or more environmental measurements the Raspberry Pi will change the internal cycle variables to satisfy these exigencies driving also its ARDUINO and the sensor cards Sensors 2014 14 9297 The Raspberry Pi is a small barebones computer conceived with the intention of providing low cost computers and free open source software It is a credit card sized computer powered by the Broadcom BCM2835 system on a chip SoC This SoC includes a 32 bit ARM1176JZEFS processor clocked at 700 MHz and a Videocore IV GPU It also has 256 MB of RAM in a POP package above the SoC The Raspberry Pi is powered by a5 V micro USB AC charger While the ARM CPU delivers real world performance similar to that of a 300 MHz Pentium 2 the Broadcom GPU is a graphics core capable of hardware decoding several high definition video formats In that regard the Videocore IV GPU is rather potent as it is capable of hardware decoding 1080p30 H 264 with bit rates up to 40 Mb s The Raspberry Pi features HDMI and composite video outputs two USB 2 0 ports a 10 100 Ethernet port SD card slot General Purpose
4. 14 9292 this aim many efforts have been made by researchers to explore satisfying solutions e g some studies are addressed to the realization of specific multi tier architecture which decouples the measurement of data from both their memorization and presentation to the final users 17 Usually these researches use Wireless Sensor Networks WSNs as the first level of the architecture In fact WSNs provide autonomous and reliable operations which reduce the overall costs for structural health monitoring to just a few percentage of those of a conventional cabled monitoring system 15 Data locally stored are then sent to a remote server using a gateway connected to the Internet where simply using a browser the end users can access the information Among these researches an interesting artistic in field application for building preservation is presented in 18 where SMARTBRICKS are used as platform to connect sensors to the local gateway in 19 a WSN transmits the data using the Bluetooth technology in 20 2 400 2 483 GHz transmitters designed for their special button sensors are used while in 17 21 22 ZigBee tx rx devices are used Other works aim to improve the already optimal performances of the WSNs e g in 23 a new approach to maximize power saving of the singular nodes is developed while in 24 the use of solar energy to supply the sensors is investigated Other interesting works are instead focused on the software ma
5. 27 An ARDUINO board consists of an Atmel 8 bit AVR microcontroller with complementary components to facilitate programming and incorporation into other circuits An important aspect of the ARDUINO is the standard way that Sensors 2014 14 9294 connectors are exposed allowing the CPU board to be connected to a variety of interchangeable add on modules known as shields The ARDUINO board exposes most of the microcontroller s I O pins for use by other circuits It provides 20 digital I O pins six of which are analog inputs connected to a 10 bits ADC Several plug in application shields are also commercially available The shield has been designed by us and it is connected to a temperature sensor and a humidity one The first is MCP9700 with an accuracy of 4 C over the 0 70 C temperature range 35 The second is a HONEYWELL model HIH 5031 001 with an accuracy of 3 over the 0 100 humidity range 36 The need to limit the power consumed obliged us to choose electronics with reduced consumption The ARDUINO is particularly suited for low energy applications because it is provided with a sleep mode with very low power consumption that is extremely useful when the card is not acquiring data Other devices such as data acquisition electronic cards based on Microchip microcontroller 37 Raspberry Pi 38 or Beaglebone 39 could be used Table 1 lists some principal characteristics of these devices Table 1 Arduino vs Microchip microcont
6. 6 Figure 6 Distance between the site and the BTS with elevation profile Orte Q r i a S BTS TRO0I8W Soriano Nel Cimino WKF Taille KA Vignanello nr a4 Magliano Sabina i b 210 m Om 248 42 345043 M2 S455 ARS Je osm A G oxleeaith Fahrica dijRoma Wr ie lt Data di acquisizione delle immagini 8 7 2013 42927 32 66 N 12 09 35 16 E elev 355m alt 31 35 km x Even if the church is placed out of the WiMAX estimated cell edge the WiMAX radio link has been successfully tested using the outdoors model HES 319M Customer Premise Equipment CPE 54 the links have been correctly established with poor but stable radio parameters that can still guarantee a QPSK1 2 modulation in UpLink and QPSK3 4 in DownLink As shown in Figure 7 DownLink RSSI at the CPE is about 80 dBm Received Signal Strength Indication while UpLink RSSI at the BTS is about 110 dBm We could not expect higher performances in UpLink since it is strictly dependent on the maximum output power of the CPE the carrier operator profiles and the average traffic load on the BTS Sensors 2014 14 9307 In order to verify the real available bandwidth on the WiMAX connection the software tool Iperf version 2 0 5 63 64 has been used to check the TCP throughput the results are shown in Table 5 where for a single CPE the optimal number of parallel data streams to obtain the maximum throughput is equal to 5 Default settings of the
7. An Internet Based Interactive Embedded Data Acquisition System for Real Time Applications IEEE Trans Instrum Meas 2009 58 522 529 Sensors 2014 14 9309 13 14 15 16 17 18 19 20 21 22 23 24 25 26 2T 28 Chane C S Mansouri A Marzani F S Boochs F Integration of 3D and multispectral data for cultural heritage applications Survey and perspectives Image Vision Comput 2013 31 91 102 Balsamo A Chimienti A Grattoni P Nerino R Pettiti G Rastello M L Spertino M Active vision applications to cultural heritage acquisition and monitoring J Cult l Herit 2006 7 98 109 Kruger M Long Term Wireless Monitoring of Historic Structures Lessons Learned from Practical Applications In Proceedings of the 6th European Workshop on Structural Health Monitoring Dresden Germany 3 6 July 2012 Leccese F Remote Control System of High Efficiency and Intelligent Street Lighting Using a ZigBee Network of Devices and Sensors IEEE Trans Power Deliv 2013 28 21 28 D Amato F Gamba P Goldoni E Monitoring heritage buildings and artworks with Wireless Sensor Networks In Proceedings of the 2012 IEEE Workshop on Environmental Energy and Structural Monitoring Systems EESMS Perugia Italy 28 29 September 2012 pp 1 6 Mecocci A Abrardo A Monitoring Architectural Heritage by Wireless Sensors Networks San Gimignano A Case Study Sensors 2014 14 7
8. between these and the hub In both cases the ARDUINO of the hub is on for 24 h trying to call the apparently broken sensor cards if they answer the synchronization procedure is activated otherwise the hub considers the ARDUINO card broken and an alarm signal is memorized and sent to the server If the problem is between the hub and the server it could be due to the breakage of the server or of the hub or a communication problem In the last two cases the server registers the absence of new data when requested It repeats the request for one day and if there is no an answer an alarm message is activated and sent using a web service to the e mail address es of the researchers In case of the breakage of the server only a check made by the researchers can solve the problem In this case the Sensors 2014 14 9299 Raspberry Pi tries to establish a connection with the server for three hours after that using the GPRS modem it sends an SMS alarm to the mobile phone s of the researchers 3 7 Communication Layer Being the Raspberry Pi a powerful little computer it could be used also as a server This would imply a constant activation of the hub with unavoidable loss of energy during the idle time a particularly negative condition when there are no mains To avoid wasting energy the system has been conceived to be turned on only during the short period of sensor data collection In this way the data could be viewed only in a very little ti
9. coordinator role in the ZigBee network has also the role to activate the hub opening the supply switch Even this card is normally in sleep mode When the watchdog goes up the ARDUINO wakes up itself and when prefixed drives the power electronic switch designed by ourselves that connects Sensors 2014 14 9303 the Raspberry Pi and the battery At this point the Raspberry Pi is supplied and after the initializing phase starts the procedure for requesting data from the sensors Completed this phase when it is the time to send data toward internet the Raspberry Pi drives the ARDUINO asking it to close the power switch which supplies the GPRS or the WiMAX or the satellite modem After the initializing time the Raspberry Pi sends the data through the modem Managing in this way the hub it is in sleep mode for the most part of the day The ARDUINO absorption has already been described while for the Raspberry Pi the consumption in the on phase is lower than 500 mA For the modem consumption it depends by the type of transmission For a GPRS modem the consumption is about 300 mA fora WiMAX system it is about 35 mA 48 V while for the satellite connection it is about 1 A In our application they are normally activated once every day to upload the data but the interval is programmable Exceptions to a normal set up are also planned There are three kind of possible exceptions on the sensor side synchronization problem between cards and hu
10. every day the Raspberry Pi section is switched on it acquires data from its ARDUINO card and then it opens a connection with the remote server and uploads the data inside The ancient church is far from any wired telephone lines luckily both GPRS and WiMAX signals are present in the area while we do not use the mains to test the supply section realized by ourselves The PV panel has been placed on the roof of the church as is the WiMAX antenna 4 1 Layer 1 2 Tests In order to verify the overall functionality and seek better performance of the ZigBee network some tests have been performed As said some tests were performed at the Electric and Electronic Laboratory Measurements of Roma Tre University while others were performed in the real scenario for overall two months In order to validate the choice to use ZigBee technology the first test aimed to verify the behavior of the ZigBee transmitters receivers under variable real life conditions clear weather rain proximity of electrical or electronic devices possibly interfering with the transmission such as a Wi Fi Access Points the second aimed to confirm the reliability of the communication in the real scenario The first tests were performed both outdoors considering one or more obstacles like trees or hills and indoors considering one or more walls between the transmitter and the receiver All tests were carried out using the Standard XBee modules with patch antenna which is the
11. hardware used in the sensor card while the X CTU software provided by Digi MaxStream has been used as test program 100 000 transmission tests were carried out for each case using an appropriate adapter to simulate the retransmission X CTU tool using a terminal connected to an XBee module sends a packet through the network and verifies that the data are correctly returned back from the XBee module which has received the packet The obtained results using the minimum transmission power available are very satisfactory all packets arrive to their destination and are correctly returned obtained an average reliability up to 99 95 Table 4 shows the results of the ZigBee communication reliability tests Table 4 ZigBee reliability tests XBee Standard Patch Antenna Outdoors Sunny Rainy 50m 100 m 50m 100 m No obstacles 100 99 99 99 98 99 97 Tree 99 97 99 96 99 98 99 96 XBee Standard Patch Antenna Indoors more than 10 m from WiFi AP 1 Wall 2 Walls 3 Walls 100 99 98 99 96 XBee Standard Indoors 5 m from WiFi AP 1 Wall 2 Walls 3 Walls 99 98 99 88 99 96 Sensors 2014 14 9305 The first test inside the church has been strongly conditioned from the location of the fresco the hub has been placed at about 3 m in front of the fresco inside the chapel while the sensor cards were placed very close to the fresco Considering the short distance in perfect line of sight between the sensor cards
12. necessary repairs the battery size is at least equal to 10 Ah It is supplied by a 12 V 10 Wp PV panel The charging process must be conducted according to the battery features capacity voltage chemistry efc producing current until the battery has been completely charged and then replaced by a stand by current to compensate the battery self discharge The chosen battery recharger CMP12 JUTA of HARBIN Hopeful STAR 56 provides voltage regulation of battery charging as a function of temperature and has a built in electronic protection to contrast overloads short circuits and overvoltages 4 Experimental Set Up Test and Results To verify the behavior of the system some tests have been executed both in laboratory and in a real scenario The latter is the church of Santa Maria del Soccorso located in Corchiano about 70 km from Rome Italy latitude 42 345043 longitude 12 345546 where a sixteen century wall painting is located The church is viewable on the Internet at the site http www prolocorchiano com il nostro paese Sensors 2014 14 9304 le chiese madonna del soccorso while the picture viewable in Figure 4 is a fresco by the Zuccari brothers placed in a lateral chapel called Paradise Chapel in Italian Cappella del Paradiso Two sensor cards equipped with a temperature sensor and a humidity one make up the first layer as indicated in Section 3 The cards have been programmed to collect data each 1 h One time
13. operational time of the entire system it is aimed at the minimization of energy consumption 3 Materials and Methods In this section the materials and methods used to realize our acquisition system will be shown First of all the layered architecture which represents the conceptual base of our system will be described then following the presented structure a detailed description of the single layers will be shown A comparison with other technologies will also be provided to justify the use of a device rather than others Sensors 2014 14 9293 3 1 The Layered Architecture As Figure 1 shows the whole measurements system has been conceived as a layered structure This approach allows focusing on the specific functionalities of each single layer The first layer measures the environmental parameters the second takes the pictures and the third shows the collected data Each layer is autonomous from the others and communicates with the others through an intermediate communication layer Figure 1 Block Scheme of the measurements system the layered architecture Layer 1 Measurements Layer 3 remote server Local hub based on ARDUINO ZigBee and ADSL GPRS WiMAX Communication Wi Fi satellite Layer Communication Layer The first layer is made using electronic control units connected to sensors placed directly in the environment to be monitored The units are based on ARDUINO technology 27 The seco
14. 57 2297 2303 Benghanem M Measurement of meteorological data based on wireless data acquisition system monitoring Appl Energy 2009 86 2651 2660 Wang Y Mir F A M Siew W H Digital wireless data acquisition system for measurement in high voltage substations In Proceedings of the IEEE Power Engineering Society General Meeting Montreal QC Canada 18 22 June 2006 Peng X Ying X An Embedded Electric Meter Based on Bluetooth Data Acquisition System In Proceedings of the 2010 Second International Workshop on Education Technology and Computer Science ETCS Wuhan China 6 7 March 2010 pp 667 670 Zong Q Bao W The dairy cattle data acquisition system based on PDA In Proceedings of the 2010 the World Automation Congress WAC Kobe Japan 19 23 September 2010 pp 65 69 Bettiol A A Udalagama C Watt F A new data acquisition and imaging system for nuclear microscopy based on a Field Programmable Gate Array card Nucl Instrum Methods Phys Res Section B 2009 267 2069 2072 Sreelal S Jose S Varghese B Suma M N Sumathi R Lakshminarayana M Nayak M M Data acquisition and processing at ocean bottom for a Tsunami warning system Measurement 2014 47 475 482 Abdallah M Elkeelany O Alouani A T A low cost stand alone multichannel data acquisition monitoring and archival system with on chip signal preprocessing IEEE Trans Instrum Meas 2011 60 2813 2827 Alkar A Z Karaca M A
15. 70 778 Rodriguez Sanchez M C Borromeo S Hernandez Tamames J A Wireless Sensor Networks for Conservation and Monitoring Cultural Assets IEEE Sens J 2011 17 1382 1389 Neri A Corbellini S Parvis M Arcudi L Grassini S Piantanida M Angelini E Environmental monitoring of heritage buildings In Proceedings of the Ist IEEE Workshop on Environmental Energy and Structural Monitoring Systems EESMS Crema Italy 25 September 2009 pp 93 97 Joo J Yim J Lee C K Protecting cultural heritage tourism sites with the ubiquitous sensor network J Sustain Tour 2009 17 397 406 Zhang J Huynh A Ye Q Gong S Remote sensing system for cultural buildings utilizing ZigBee Technology In Proceedings of the 8th International Conference on Computing Communications and Control Technologies Orlando FL USA 6 9 April 2010 Capella J V Perles A Bonastre A Serrano J J Historical building monitoring using an energy efficient scalable wireless sensor network architecture Sensors 2011 77 10074 10093 Altun A A Remote Control of the Temperature Humidity and Climate in the Beehives with Solar Powered Thermoelectric System J Control Eng Appl Inform 2012 14 93 99 Xia M Dong Y Xu W Li X Lu D MC Multi Mode User Centric Design of Wireless Sensor Networks for Long Term Monitoring ACM Trans Sens Netw 2010 9 39 Chiriac M Basulto D Lopez E Prieto J Castilloand J C Collad
16. I O Expansion Board GPIO connector and analog audio output It only costs 25 31 34 The ARDUINO card is connected to the Raspberry Pi by the serial port and sends information following the standard serial protocol Figure 2 shows an image of the naked without its box hub Figure 2 The hub core Raspberry ARDUINO with the XBee module and the Camera Connected to the hub there is also a high resolution camera directly driven by the Raspberry Pi The camera is a Logitech HD Webcam C525 with a resolution of 8 Megapixels 47 To obtain the best view an external 12 V LED flash light driven by the hub software accompanies the webcam The flash is always connected to the hub and supplied by the battery Normally the flash is disconnected by the battery to avoid energy loss When the researchers request a picture the hub drives the supply circuit that gives energy to the LEDs The flash is switched on for two seconds before the picture is taken Obviously the use of flash must be authorized in order not to cause damage to the painting The pictures are collected by the Raspberry Pi and sent along with the environmental data toward the server where it will be then available for further analysis by the researchers Sensors 2014 14 9298 3 6 Hub Software The software on the hub is developed in C Language It allows to the hub to collect data coming from the ARDUINO cards to collect pictures of the painting to also drive the lamp and finall
17. RF Modules Available online http www digi com accessed on 21 May 2014 ZigBee Alliance ZigBee Application Note Available online http www zigbee org accessed on 21 May 2014 EETIMES ZigBee Application Note Available online http www eetimes com accessed on 21 May 2014 Allegro MicroSystems LLC ACS756 Datasheet Available online http www allegromicro com en Products Part_Numbers 0756 0756 pdf accessed on 21 May 2014 802 15 4 and ZigBee Available online ftp ftp1 digi com support images XST ANO21a ZigBee 20and 20802154 pdf accessed on 21 May 2014 Logitech Logitech HD Webcam C525 Available online http www logitech com it it product hd webcam c525 accessed on 21 May 2014 Sensors 2014 14 9311 48 49 50 51 52 53 54 55 56 57 58 59 60 6l Huawei E220 HSDPA USB Modem User Manual Available online http help optuszoo com au img cms zoohelp connected huawei_e220_hsdpa_usb_modem_user_manual pdf accessed on 21 May 2014 Sivaneasan B So P L Gooi H B Siow L K Performance Measurement and Analysis of WiMAX LAN Communication Operating at 5 8 GHz IEEE Trans Ind Inf 2013 9 1497 1506 Lee C K Li S N Hui S Y A design methodology for smart LED lighting systems powered by weakly regulated renewable power grids IEEE Trans Smart Grid 2011 2 548 554 Chen D Wang M A Home Security ZigBee Network for Remote Monitoring Application
18. S General Packet Radio Service GPRS is a very widely deployed wireless data service available with most GSM networks It offers throughput rates of up to 114 kbps enabling mobile handsets to access online services at a similar speed to a dial up modem but with the convenience of being able to connect from almost anywhere GPRS enables people to enjoy advanced feature rich data services such as e mail on the move multimedia messages social networking and location based services The RaspBerry Pi is connected to a GPRS modem which allows establishing a communication with the remote server When the software sends an instruction to send data the Raspberry Pi switches on the modem and send the files The modem used is the Huawei E220 USB dongle modem 48 A similar modem is also connected to the server in such a way to receive the data coming from the hub Sensors 2014 14 9300 3 7 2 WIMAX Despite the diffusion of the GSM GPRS systems it is not always present in the areas where the sites may be located In fact in rural areas such as ours a base station for GPRS communication may not be economical in case of low traffic making the service not profitable for a provider Usually the distance covered by a base station is about a hundred meters and in any case not more than a few kilometers 49 Worldwide Interoperability for Microwave Access WiMAX technology is a wireless solution based on the IEEE 802 16 standard which allows to ove
19. Sensors 2014 14 9290 9312 doi 10 3390 s140509290 sensors ISSN 1424 8220 www mdpi com journal sensors Article A New Acquisition and Imaging System for Environmental Measurements An Experience on the Italian Cultural Heritage Fabio Leccese bae Marco Cagnetti F Andrea Calogero n Daniele Trinca z Stefano di Pasquale r Sabino Giarnetti and Lorenzo Cozzella Science Department University of Roma Tre Via della Vasca Navale 84 00146 Rome Italy E Mails ing marco cagnetti gmail com M C andrea spawn86 gmail com A C cico80 gmail com D T stefano dipasquale uniroma3 it S P sgiarnetti uniroma3 it S G Mathematics and Phisics Department University of Roma Tre Via della Vasca Navale 84 00146 Rome Italy E Mail lorenzo cozzella uniroma3 it Author to whom correspondence should be addressed E Mail leccese uniroma3 it Tel 39 06 5733 7085 Received 15 February 2014 in revised form 5 May 2014 Accepted 19 May 2014 Published 23 May 2014 Abstract A new acquisition system for remote control of wall paintings has been realized and tested in the field The system measures temperature and atmospheric pressure in an archeological site where a fresco has been put under control The measuring chain has been designed to be used in unfavorable environments where neither electric power nor telecommunication infrastructures are available The environmental parameters obtained from the lo
20. a t amp rct j amp q amp Kesrc s amp source web amp cd 3 amp cad rjak amp uact 8 amp ved OCDoQFjAC amp url http 3A 2F 2Fcommittee tta or kr 2Finclude 2FDownload jsp 3Ffilena me 3Dchoan 252F 2012 1537 TEEE 2B802 16 1 2012 pdf amp ei 5S1 U6_dMe364QTP9IICwCQ amp usg AFQ CNHhovV5FYyprqdDwVNcAkmFMBQdY w amp sig2 MpDvbQc8GsUV g d3 y6EEY A amp byvm bv 67229260 d bGE accessed on 21 May 2014 Ota K Matsue H Miyazawa S Nanamatsu S Hirata Y Hasui A Yamazaki M Namera T Fukui H Harvey M et al Link Budget Analysis and Field Experiments on Mobile WiMAX System in Azumino City In proceedings of 2011 IEEE Global Telecommunications Conference Houston TX USA 5 9 December 2011 pp 1 5 Definition of RSSI Available online _ http wireless agilent com wireless helpfiles 89600B WebHelp subsystems 802 1 60fdma Content ofdma_symtblerrdata_rssi htm accessed on 21 May 2014 Sensors 2014 14 9312 62 Pidutti M Design How To 802 16 Tackles Broadband Wireless QoS Issues Available online http www eetimes com document asp doc_id 1272053 accessed on 21 May 2014 63 What is Iperf Available online http iperf fr accessed on 21 May 2014 64 Wikipedia Iperf Available online http en wikipedia org wiki Iperf accessed on 21 May 2014 2014 by the authors licensee MDPI Basel Switzerland This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license
21. act although the Beaglebone has analog inputs to acquire analog signals its power consumption is higher than that of the others making it less competitive for extreme applications such as ours while the Raspberry Pi has no native analog inputs The cost is the element that makes ARDUINO the best choice in fact although the basic cost promotes the microcontrollers the need to Sensors 2014 14 9295 use external components to work strongly increases the overall cost narrowing the gap Even more important is the time to develop and test the electronics equal to one month while the ARDUINO is immediately ready 3 3 ZigBee Communication Layer The ZigBee protocol provides an open standard for low power mesh wireless networking of monitoring and control devices Working with the IEEE 802 15 4 standard which focuses on low rate personal area networking and defines the lower protocol layers i e the physical layer or PHY and the medium access control layer or MAC ZigBee adds network structure routing and security e g key management and authentication to complete the communications suite On top of this robust wireless engine ZigBee profiles provide target applications with the interoperability and intercompatibility required to allow similar products from different manufacturers to work seamless defines the upper layers of the protocol stack from network to application including application profiles ZigBee uses the license free ISM ba
22. and hub the communication test always realized by the previously described procedure gave us 100 of reliability More interesting were the tests to verify the maximum allowable distance between the hub and the sensor cards considering that inside the church there are two rows of five columns each and the maximum usable diagonal distance is approximately 27 m Even in this case the transmission tests gave us a correct messages reliability equal to 100 Putting the hub outside the church we registered a quickly decrease in the ability to recognize the signal in fact just 5 m from the fa ade of the church about 33 m the distance between the hub and the sensor cards the hub is unable to correctly receive the sent data Once verified the reliability of the ZigBee communication technology for our aims we tested the acquisition cards in the field for two months to verify the overall reliability of the Layers 1 2 To accelerate the test phase we stressed the sensor cards fixing the sending time to once every minute The acquired data were constantly sent to the hub and no strange values were memorized Other tests aimed to verify the behavior of the system if some faults were simulated First of all we tested the synchronization recovery procedure both changing in the sensor cards the time to send data and changing in the hub the watchdog delay In both cases the system synchronizes itself again Then we simulated a sensor card broken switching one
23. as been conceived as a computer to collect data It is located in a place equipped with Ethernet which allows it to be reached from anywhere and mains which provide constant electrical energy Being the server a work instrument viewable by authorized experts in the field following the right path it is possible to find the pictures and data files inside the right directory By screening the images they can decide a prompt on site intervention to protect the painting On it a web oriented software allows authorized researchers to see the data from all over the world Figure 4 shows the first page of the website where on the left one can see the graph with the data coming from the sensors while on the right the frame where the images can be shown is illustrated with an example image In other secondary pages it is possible to set the other control parameters such as the number of pictures taken per day etc Figure 4 The website SYSTEM STATUS SYSTEM MESSAGE z EE i 10083014 223910 10 04 2014 at 22 59 10 10 04 2014 at 22 59 10 z zZ Z Q 2 x wi gt E s re o z Ke WI Mt Relative Humidity HOUR Clicking on the picture you can enlarge the image as shown in Figure 5 Sensors 2014 14 9302 Figure 5 The zoomed image 3 9 Supply Layer Considering the real possibility of having no mains at the site where the painting is placed as already explained the system has been designed to be stand alone t
24. b or on the hub side The first is caused by a broken sensor card or by the sudden absence of energy from the battery pack In both cases the sensor cards do not transmit anything toward the hub which does not know if the card is broken or if there is a synchronization problem therefore it activates a 24 h internal timer During this time the hub is always on and constantly pings the cards that have not replied If they answer the exception is a lack of synchronization and the time alignment procedure is executed This procedure sets the ARDUINO clock again to avoid misalignment Instead if the internal timer reaches 24 h the cards are evidently broken and an alarm procedure is initiated Moreover the hub could also have problems These could be due to the hub or due to the connections to the Internet In both cases an alarm procedure is initiated by the server which immediately shows on the pc software the problem and contemporaneously sends an alarm to the e mail s of the researchers In this way they are quickly informed of the status and can decide what to do In case the problem is the connection and the hub is working correctly the hub tries to send data with a frequency four times quicker not once a day but more times every day Considering the overall consumption considering the worst case in which the hub could be on for a day and considering a reasonable autonomy of one week to allow the researchers to prepare the mission and make the
25. cal monitoring are then transferred remotely allowing an easier management by experts in the field of conservation of cultural heritage The local acquisition system uses an electronic card based on microcontrollers and sends the data to a central unit realized with a Raspberry Pi The latter manages a high quality camera to pick up pictures of the fresco Finally to realize the remote control at a site not reached by internet signals a WiMAX connection based on different communication technologies such as WiMAX Ethernet GPRS and Satellite has been set up Keywords control systems for heritage remote control for wall painting monitoring of cultural heritage wireless networks ZigBee ARM processor artworks preservation Sensors 2014 14 9291 1 Introduction Wall Painting is a very diffuse art expression in Italy Three marvelous universally known examples are the Sistine Chapel of Michelangelo in Vatican City the Last Supper of Leonardo da Vinci in Milan and the Scrovegni Chapel of Giotto in Padua Considering the artistic and scientific relevance of these works the efforts made to their conservation is remarkable The favorable geographic collocation of these paintings often placed in big cities helps the scientists whose monitoring efforts are often almost exclusively dedicated to preserve them However the vastness of the Italian Artistic Heritage extends across both time and geography having left traces fro
26. cking the environmental conditions of sites where frescoes are located The article is divided in the following sections in Section 2 we present a brief description of the state of the art that allows defining the problem In Section 3 starting from the description of the architecture of the system materials and methods used to realize the system are described justifying their choice through comparison with other competitive technologies Before the conclusions in Section 4 some tests realized in the field and their results will be presented 2 State of the Art Data Acquisition System DAS for the measurement of physical entities are very common and successfully used in many fields 1 8 Their use is also growing in some less conventional areas 9 12 and they are seeing more and more applications in the preservation of cultural heritage 13 14 principally in the environmental control of museum rooms On the contrary due to the lack of reliability 15 the lack of specific devices that allow overcoming the communication network access problems typical of remote sites the absence of devices that meet the real control researchers needs and the reduced energy autonomy in absence of electrical network DAS are rarely used for preservation of cultural heritage applications placed in remote sites Scientific progress leads to a constant and continuous improvement renovation that allows overcoming the existing limits 16 With Sensors 2014
27. e CPE is Power over Ethernet PoE 802 3 a f compliant and it runs at 48 VDC so a DC DC step up boost has been required to make the CPE working in our system We used a LTC3863 55 mounted on its 1286 A demonstration circuit in order to boost up the 12 V from solar panel to the 48 VDC needed at the CPE PoE connector 3 7 3 Satellite Connection Modern satellite Internet service is typically provided to users through geostationary satellites that can offer high data speeds Satellite Internet generally relies on three components a satellite in geostationary orbit a number of ground stations known as gateways that relay Internet data to and from the satellite and a VSAT very small aperture terminal dish antenna with a transceiver located at the subscriber s premises and connected to a modem which links the user s network with the transceiver Satellite Internet services can be provided in two different scenarios one way and two way communications One way communication requires a terrestrial support link for upload for example the GPRS network two way communication is only satellite suitable for our needs For our tests the Tooway internet satellite service with the ViaSat RM4100 and a 70 cm diameter dish antenna was chosen the Sensors 2014 14 9301 ViaSat modem provides an Ethernet connection to the Raspberry Pi operating at 20 Mbps in downstream and 6 Mbps in upstream mode 3 8 Remote Server The Remote Server h
28. e hub 3 5 Layer 2 Local Hub The aim of layer 2 is to collect data coming from the sensor cards and organize them in ASCII files ready to be read by whatever editor program This function is generally executed by a Personal Computer PC 12 16 which by means of its operative system offers all the functionalities needed to collect and show the data Unluckily the use of PCs often has problems which could be critical in particular applications like ours For example the electrical energy consumption could be too high when a battery is used the reliability of a PC in a hostile environment too humid and or too dusty could be less than what is necessary and a more reliable PC such as an industrial one could be expensive on a limited budget In order to face these problems a hub composed by an ARDUINO with a ZigBee tx rx and a Raspberry Pi card has been used As already shown in Table 1 ARDUINO is advantageous for acquiring data from analog sensors but it has not all the software features offered by Raspberry Pi and Beaglebone necessary to create an internet connection In order to limit the energy needs of the hub the ARDUINO card plays a fundamental role in the management of the system In fact because its low power consumption it is better to use it as a data collecting card instead of the Raspbery Pi and to use the latter only for the data transmission to the server It wakes up at a prefixed time and collects data coming from the sensors
29. h Indicator RSSI are the considered radio parameters which allow verifying the reliability of a WiMAX connection The first is a parameter that judges the quality of the WiMAX signal The higher the value of the CINR the biggest throughput a link can maintain The second is a measurement of the total received power of the Sensors 2014 14 9306 frame preamble and is used by the subscriber station to determine the received signal level from the BS 61 The 802 16 standard supports link adaptive modulation and channel coding AMC and it adapts to signal degradation by dropping to a lower modulation 62 in order to maintain a constant bit error rate BER of 1 x 10 The AMC is controlled on the BS side and it applies the Modulation and Coding Schemes MCS which defines the most suitable modulation rate for current radio channel and leads to the highest data rate possible WiMAX uses mainly quadrature amplitude modulation QAM with its more powerful 64 QAMS 6 in downstream mode it is optional in upstream 59 Maximum modulation upstream is usually 16 QAM3 4 The nearest BTS antenna offering the WiMAX service is located near Orte about 13 2 km away from the site of interest Even if the distance is quite large and beyond the cell size of the BTS the area covered by the BTS estimated at about 10 km through simulations the situation is still lucky since it is almost in LOS Line Of Sight as shown in the elevation profile of Figure
30. hanks to the energy coming from alternative energy sources The advantages which may result from these kinds of power supplies are remarkable and well known In fact avoiding the expensive wiring of the supply network there are considerable savings and greater easiness of implementation To minimize the battery capacity and the energy required from the solar panel the circuit has been designed to utilize the lowest power possible This goal has been achieved through the complex management of the first and second layers The ARDUINO cards switch themselves on only when the internal watchdog wakes up after a pre fixed time established during the design phase according to the exigencies of the researchers In our application we decided to activate the sensors card every h During the wake up mode the cards use about 100 mA while during the sleep mode the cards absorb 200 uA The slot time associated to the wake up mode is normally 1 s This time includes the uncertainty joined with the synchronization with the hub which at the same time should be on and ready to establish the connection with the sensor cards Considering a normal set up during the day the ARDUINO cards are waked up for 24 s while the sleep time is equal to 23 h 59 min and 36 s This allows an energetic autonomy of the cards of about 1 5 year with four AA batteries of 1 5 V and 2200 mA At the same time the ARDUINO placed on the hub and connected to the Raspberry Pi which takes the
31. http creativecommons org licenses by 3 0
32. m prehistory to the present day and everywhere on the Peninsula In Italy there is scarcely a place that does not have precious artistic evidence that deserves special attention and care Many times the paintings are located in distant and abandoned places which often are not supported by adequate infrastructure The impossibility to transport the wall paintings poses serious logistical difficulties more than with any other artistic expression Considering the delicate nature of the paintings and their vulnerability to environmental conditions continuous monitoring is crucial to program a timely conservative intervention At the moment for the most part of the artistic heritage this monitoring is realized in loco obliging the researchers to frequent trips In the absence of more precise information on the paintings conditions these trips are obviously poorly planned In fact the occurrence of any problems altering the environmental conditions can be sudden and catastrophic for the paintings and a monitoring schedule too dilated in time may not be sufficient to raise awareness about a threat with sufficient time to enable the appropriate protection and preservation actions A data collection system able to convey behavior information to a remote site is a valuable tool for researchers whose transfers to the workplace can then be arranged based on needs This work shows a measurement platform based on the latest technologies which allows remotely che
33. m to also better view specific particulars of the object under control The communication layers use the ZigBee technologies for local data transmission and GPRS WiMAX and satellite technologies for the remote connection The energy for the system is provided by an ad hoc supply system based on PV panels designed taking into account a series of designing constraints which guarantees the most efficient energy Sensors 2014 14 9308 management of the whole system Test in the field have shown the reliability and the efficacy of the proposed system Author Contributions The authors contributed equally to this work Conflicts of Interest The authors declare no conflict of interest References 10 11 12 Belmili H Salah Med A C Haddadi M Larbes C Design and development of a data acquisition system for photovoltaic modules characterization Renew Energy 2010 35 1484 1492 Yuan Y Xu Q Guan X Liu Z Industrial high speed wireless synchronous data acquisition system with real time data compression Measurement 2013 46 3482 3487 Mukaro R Carelse X F A microcontroller based data acquisition system for solar radiation and environmental monitoring IEEE Trans Instrum Meas 1999 48 1232 1238 Panahi S S Ventosa S Cadena J Manuel Lazaro A Bermudez A Sallares V Piera J A Low Power Datalogger Based on Compactflash Memory for Ocean Bottom Seismometers IEEE Trans Instrum Meas 2008
34. me window making them de facto inaccessible A remote server allows overcoming this issue Supposing that the mains are always available it is always switched on and can always receive data coming from the local hub when it sends them To communicate with the server the local hub can exploit different communication protocols wired like ADSL or wireless as Wi Fi GPRS WiMAX or satellite connections The first was not taken into account in our application because it is imaginable that if in a place there is an Ethernet jack mains are also present so the place cannot be considered as hostile The same considerations can be made for Wi Fi In fact Wi Fi equipment has a limited transmission range this implies that a Wi Fi repeater must be placed near the transmitter and always connected to the mains and to an ADSL line This favorable scenario was not expected in our case Table 3 shows a synthetic performance comparison between these technologies while in the next subsections these technologies are better described Table 3 WiMAX vs other communication technologies WiMAX ADSL Wi Fi GPRS Satellite Communication Wireless Yes No Yes Yes Yes Up to 70 km Everywhere Up to 5 km Everywhere the Distance Covered Up to 100 m nae from the CPE with cable from the BS signal satellite is on Subscription Costs About 20 About 20 About 20 About 20 About 100 Availability in s Medium High No No Medium Yes rural area 3 7 1 GPR
35. nagement of the WSN 25 26 All these studies have been developed for environments considered non hostile where electrical energy and telecommunication facilities are available in fact they usually use a personal computer as local gateway and to send local data they use the Global System for Mobile GSM communication protocol as telecommunication infrastructure Although partially inspired by the cited works our system was created to be used in hostile scenarios without any available communication facility and without power availability incorporating a power supply coming from alternative energy sources such as solar energy and the ability to transfer data through all the possible communication technologies available on the market such as GPRS WiMAX and satellite connections The system has the very significant benefit of using standard technologies such as ARDUINO and ZigBee allowing high reproducibility and at the same time it uses innovative technologies like the Raspberry which reduces the costs compared to a traditional Personal Computer system The flexibility of these technologies enables a high scalability of the number and type of sensors that can be used simultaneously The use of an efficient device like the Raspberry grants the ability to take high quality pictures of the monitored work of art and to make them available to researchers At the same time the logic managing the system is innovative because in order to extend the
36. nd layer performs the role of a local hub It collects data from sensor control units and sends them out on demand or at preset times This is realized by means of a device based on an ARM processor 28 30 in our case a Raspberry Pi 31 34 To communicate the first and the second layer use ZigBee transmitters receivers The information gathered by the Raspberry Pi will be then sent via Internet to a remote server easily accessible by researchers The hub can be connected to the Internet via any communication protocol whose selection is realizable by software GPRS ADSL Wi Fi WiMAX or satellite connection The third layer is realized by the server which shows the collected data and pictures It by means of a mask can also communicate with the hub e g asking it to execute some activities rather than automatically The last layer is the supply one which provides energy to the hub 3 2 Layer 1 Measurements The aim of the first layer is to get measurements of environmental entities in the room where the wall painting is placed The system is realized by some sensors directly connected to an ARDUINO electronic card also called sensor cards in the remainder of the article The choice of this card compared to other possibilities 16 was due to its characteristics which have made it a standard for low frequency control applications ARDUINO is an open source electronics prototyping platform based on flexible easy to use hardware and software
37. nds which provide unrestricted geographic use 40 44 In the proposed system the ZigBee layer provides the wireless network with the ability to send the environmental parameters read by the ARDUINO cards to the local hub or vice versa to send commands from the hub to the acquisition cards The communication network is realized using the XBee radio modules by MaxStream already equipped with an on chip antenna 45 46 The characteristics of high radio sensitivity which reduces the probability to receive corrupted packets less than 1 the good operational range tens of meters indoors and the low power consumption are particularly suitable for battery powered applications as ours In particular to operate the two way radio transmission the necessary current is approximately 50 mA with a 3 V DC source To insure a further power reduction the sleep mode ensures a current draw of less than 10 pA Nevertheless the choice to use ZigBee technology is due to its performance Table 2 shows the performance of ZigBee against those of other two famous technologies used for short range wireless communications Bluetooth and Wi Fi As the table shows both Wi Fi and Bluetooth have higher bit rates than ZigBee but the higher power consumption suggests that the ZigBee technology is the best candidate to create a sensor network for our application Furthermore studies have proved that ZigBee is more affordable in terms of power consumption and costs than com
38. o A Science and Technology for the Conservation of Cultural Heritage Rogerio Candelera M A Lazzari M Cano E Eds CRC Press Boca Raton FL USA 2013 pp 383 386 ARDUINO Corp Available online http arduino cc accessed on 21 May 2014 Jiang L Z Sun J Xiang Y Application of the Environments On line Monitoring Data Acquisition System Based on ARM 9 In Proceedings of the 2008 International Workshop on Education Technology and Training and 2008 International Workshop on Geoscience and Remote Sensing ETT and GRS 2008 Shanghai China 21 22 December 2008 pp 813 816 Sensors 2014 14 9310 29 30 31 32 33 34 35 36 37 38 39 40 Al 42 43 44 45 46 47 Zhang J Li A Li J Yang Q Gang C Research of real time image acquisition system based on ARM 7 for agricultural environmental monitoring In Proceedings of the 2011 International Conference on Remote Sensing Environment and Transportation Engineering RSETE Nanjing China 24 26 June 2011 pp 6216 6220 Wang J Wei W The common data acquisition system based on Arm9 In Proceedings of 2011 10th International Conference on Electronic Measurement amp Instruments ICEMI Chengdu China 16 19 August 2011 pp 324 327 Raspberry Pi Applications with Raspberry Pi Card Available online http www raspberrypi org accessed on 21 May 2014 Raspberry Pi Raspberry Pi Information Note
39. of them off Even in this case the system correctly works sending an error message to the server Other tests aimed to verify the rightness of the data coming from the sensors this is the reason why a PCE FWS 20 57 58 Meteorological Station MS has been used Within the uncertainty range of the sensors and of the MS the measurements realized with our systems were similar to the MS ones 4 2 Layer 2 3 Tests For the hub we simulated all the possible errors managed by the software The breakage of the ARDUINO card which does not allow the ZigBee communication quick battery discharge that signals a problem with the PV panel no connection with the Internet and faults of the Raspberry Pi In all cases the server correctly signals the problem Considering the special features of a WiMAX system even for the previously described system some reliability test have been performed Due to the decay of the working distance with introduction of obstacles leading to multi path fading the IEEE 802 16 1 standard 58 59 does not provide any range data achievable with WiMAX devices Our system works in a rural area some kilometers away from the Base Station essentially in a Line of Sight LOS scenario obtained by mounting the receiving antenna on top of an extendable tripod and placing the system on the roof of the church whilst the BS was on the roof of a building itself 60 Carrier to Interference plus Noise Ratio CINR and Received Signal Strengt
40. petitive technologies 3 29 31 Table 2 ZigBee vs some other wireless network Feature ZigBee Wi Fi Bluetooth IEEE standard 802 15 04 802 11b g 802 15 01 Main application Control Broadband Mobile devices Number of network devices Up to 65 000 32 7 Bit rate 20 250 kb s 11 54 Mb s 720 kb s Range 100 m 100 m 10m Battery life 100 1000 days 1 5 days 1 7 days Sensors 2014 14 9296 3 4 Measurements Software To ensure the lowest possible power consumption the firmware which drives the sensor cards is conceived to be put the card into sleep mode when it does not need to work The ARDUINO cards are managed by software written in C that executes the following steps 1 wakes up from the sleep mode 2 reads data from the sensors 3 enables the XBee module 4 sends a connection packet toward the hub 5 if the hub answers the ARDUINO sends the data otherwise waits a connection packet coming from the hub when it arrives the ARDUINO sends the message 6 disconnects the Xbee module 7 goes into sleep mode The awakening of the sensor cards is set during the programming phase and managed by the internal watchdog of the ARDUINO In case of lack of synchronism between the sensor cards and the hub the cards remain switched on awaiting the synchronization commands from the hub The hub using a specific variable updated in its program changes the number of cycles of the watchdog of the sensor card to time align it with th
41. program fix the duration of the single test reported in the second column while the third column shows the average bandwidth in that time interval and in this scenario the UpLink throughput is enough to upload a standard 8 MP JPG picture in about 1 min Figure 7 Monitoring of the radio parameters 25 00 20 00 Uplink CINR dB Downlink CINR dB 15 00 10 00 5 00 OCC san I aOd OdOd Od OUd Od Od Od OdOdOdOUdD DRE DORENEBDaTJT ACSC nn ATA NOM THON KH On NMNOKHAANMMNTTIN Ww Oe ddodddadnda Uplink RSSI dBm 80 00 Penarth gt A y PREP Downlink RSSI dBm 100 00 120 00 i ia all PEN i vert 140 00 Table 5 Throughput performance Client Connecting to Iperf Server TCP port 5001 TCP Window Size 16 0 Kbyte Direction No of parallel streams Interval s Bandwidth Uplink 5 17 5 135 Kbps Downlink 5 13 3 3 56 Mbps 5 Conclusions Exploiting new technologies a new acquisition system for wall painting remote control has been realized and tested in the field The architecture used provided an affordable and reliable system particularly suitable for hostile environments which have no wired Internet connections and mains The system is able to locally check some environmental parameters and send them towards a remote server easily accessible by researchers and experts in the field Moreover the system offers the possibility to send high definition pictures allowing the use of digital zoo
42. rcome this problem reaching distances of tens of kilometers 50 51 and providing Internet service also in rural areas By splitting the bandwidth into multiple narrowband channels WiMAX allows data transport over multiple broad frequency ranges achieving high data rates due to the use of orthogonal frequency division multiplexing OFDM 52 Our system uses a base station BS able to spread a WiMAX single carrier TDD service at 3 4845 GHz center frequency and a bandwidth of 10 MHz As transmitting antenna the BS uses an Argus model SPPX310M 65 deg Horizontal cut 6 5 deg Vertical cut 53 for a total transmitting power of 55 dBm EIRP The antenna was placed outside on the roof of the church To communicate between the heritage site and the BS a Huawei branded HES 319M outdoor WiMAX Customer Premises Equipment CPE 54 has been used To reliably send data at high speed the CPE is equipped with a 3 5 GHz 45 Cross Polarization built in directional antenna with a maximum power at antenna port of 26 dBm and 14 dBi antenna gain Furthermore it avoids any type of interference with the ZigBee standard due to its different operating frequency The WiMAX module uses 64QAM5 6 modulation for the downlink when the Carrier to Interference plus Noise Ratio CINR is higher than 30 dB and 16QAM3 4 for the uplink Instead when the CINR is lower than 10 dB the link is still possible but using QPSK1 2 modulation because it is more robust at higher noise levels Th
43. rollers Raspberry Pi and Beaglebone Arduino Microchip uC Raspberry Pi Beaglebone Base price in US 35 2 10 25 50 External electronic to make an Sin 0 25 25 0 acquisition card for our aim Time required to develop the ar 0 1 month 0 1 month support external circuitry Power draw 50mA 5 V 20mA 5V 150mA 5V 250mA 5V Operating system Custom Custom Linux Linux Suited for Hardware Hardware Software Software 3 14 Digital 5 28 Depends by the 8 Digital 65 Digital Number of I O pins 6 PWM 6 analog version 5 14 analog 0 Analog 7 analog 2 USB hosts 1 USB host 1 micro USB 1 mini USB Peripherals None None i power 1 10 100 client 1 10 100 Mbps ethernet Mbps ethernet Internet Via shield Via shield Yes Yes As Table 1 shows the choice of which device to use to realize the sensor cards depends both on the personal experience of the users in the programming and in the design of electronic cards and on the type of project one wants to develop If you want to do a software project the Raspberry Pi and the Beaglebone are surely the best choice Their audio video and internet capabilities make them the winners in this aspect There is no need to attach external components so there is no real need to learn electronics and they have the possibility of driving both a GPRS modem and a WIMAX one If you want to do a hardware project the ARDUINO and the Microchip microcontroller family are the best choice In f
44. y to send the collected information on the Internet toward a server always seeking the greatest energy savings The software steps are the following Figure 3 Figure 3 Flow chart of the hub software The ARDUINO card of the hub wakes up itself from the sleep mode Switch on the ARDUINO card of the hub and sends a connection packet toward the sensors using the XBee module Wait until does not receive the answers management of the exceptions The hub asks card by card the environmental data and memorizes them in a ASCII file with the tumestamp year month day hour minute second Synchronize the ARDUINO sensor cards s the time to send data ward the serve Yes Switch on the Raspberry Pi and take the picture if requested Activate the Raspberry Pi activate the connection with the server switching on the ADSL modem or the GPRS or the WiMAX one or the satellite tx and sends the ASCTI file management of the exceptions and receive the particular requests from the sever Switch off the internet connection Set the hub to satisfy the specific requests coming from the server put the hub in sleep mode Wait the pre fixed time The algorithm also manages the exceptions There are two kinds of exceptions an interruption of the information flux between the sensor cards and the hub and between the hub and the server The first can be caused by breakage of the sensor cards or by the lack of synchronization
Download Pdf Manuals
Related Search