The 6th IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications 15-17 September 2011, Prague, Czech Republic
RF Spectrum Monitoring and Management System Based on an RF Receiver Multi-server Architecture Octavian Postolache1, Pedro Silva Girão2, Sérgio Antunes3 , Fernando Tavares3 1
2
Instituto de Telecomunicacoes, Av. Rovisco Pais, 1049-001 Lisboa, Portugal, e-mail:
[email protected] Instituto de Telecomunicacoes, IST/DEEC, Av. Rovisco Pais, 1049-001 Lisboa, Portugal, e-mail:
[email protected] 3 ANACOM, 2ANACOM, Alto do Paimão, 2745-467, Barcarena, Portugal, e-mail:
[email protected]
Abstract—–In this paper the authors describe an extension of a distributed spectrum monitoring and management system that already works and that includes four main nodes corresponding to the different ANACOM’s spectrum monitoring centers located at Portuguese islands and continental Portugal. Due to the necessity to perform special monitoring actions in regions where the existing spectrum monitoring system has a limited coverage, a set of remote RF spectrum monitoring units were designed and implemented based on the use of “plug-in” low cost RF receivers. Considering that each remote RF monitoring node is characterized by Internet connection using 3G/UMTS modems with USB interface, a client/server architecture was implemented. Each remote station includes an RF receiver as hardware and a server application developed in LabVIEW that permits to control the RF receiver locally but also from the client application installed on the base stations using the web browser functionalities. Additional functionalities such as RF spectrum occupancy tests automatic control, data logging, RF receiver audio broadcasting, remote unit IP and data file secure transfer, were implemented on the server side while tasks such multiserver remote control, SSH file transfer control, data analysis and report generation functionalities were implemented on the client side of the application.
international organization with the role of standardizing emerging new systems and fostering common global policies in the domain of telecommunication technologies and thus is an important player also in the management of the radio-electric spectrum. In Portugal, the tasks of radio-electric spectrum management, monitoring and control are performed by the Autoridade Nacional de Comunicações (ANACOM), using a set of distributed RF monitoring systems that coimbine the Rohde&Schwars technology and [2], [3] the results of fruitful collaboration through the research and service projects celebrated between the Instituto de Telecomunicações (IT) and Anacom [4]-[6]. Taking into account that the RF spectrum monitoring requires a good logistic and efficiency, a global instrumentation network connecting the different ANACOM spectrum monitoring and control centers (SMCC) was proposed and its implementation has been an interesting challenge to the authors that collaborate in order to implement reliable solutions in the area of RF instrumentation networking. Thus, were developed RF instruments and interfaces to assure the integration of different SMCCs instruments in an ANACOM’s global RF monitoring network. Starting with the Azores SMCC [4], which was elected as the prototype node, the collaboration between Instituto de Telecomunicações and ANACOM went on and automation and integration of other SMCCs was carried out. In the last years, was placed on a new challenge to the IT-ANACOM collaboration: to extend the capabilities of the already implemented distributed RF spectrum monitoring system by including additional nodes that use the public Internet service to connect to the monitoring remote nodes implementing a multi-client – multi server architecture. This paper is organized as follows: section II presents the hardware of the distributed monitoring system architecture and network architecture, in section III the RF spectrum monitoring server software is introduced, section IV presents the RF spectrum monitoring client software including data analysis, and in Section V we state our conclusions.
Keywords—distributed systems; virtual instrumentation; client server architecture; RF spectrum occupancy measurements
I.
INTRODUCTION
Nowadays, the proliferation of electronic and telecommunication systems requires the RF spectrum monitoring; otherwise it becames no longer possible to assure the correct operation of those devices and systems. Thus, national and international bodies produced rules and regulations to minimize EMC related problems. Portugal, as a member of the European Union (EU), had to translate into Portuguese law first, in 1992, EMC Directive - 89/336/CEE and in 2007 the new EMC Directive 2004/108/CE of the European Parliament and of the Council to define the governing rules of the EMC in Europe. The International Telecommunications Union [1], which succeeded in 1934 the International Telegraph Union created in 1865, is probably the most important __________________________________________________________ Instituto de Telecomunicações, Fundação para a Ciência e Tecnologia and ANACOM Portugal supported this work.
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II.
RF SPECTRUM MONITORING NETWORK
IF2: 16 kHz. The SMA RF input is connected to AX71C antenna that is a compact VHF/UHF omnidirectional receiving and transmitting antenna for professional and consumer surveillance and monitoring applications. The antenna covers the frequency range of 25MHz to 1500 MHz.
The ICP-ANACOM RF spectrum monitoring and management is done using a set of spectrum monitoring and control centers distributed in continental Portugal and in the archipelagos of Madeira and Azores situated in the Atlantic Ocean. Each of the island centers, CMCEM for Funchal (Madeira) and CMCEA for S. Miguel (Azores) presents a double RF spectrum monitoring functionality including an additional node characterized by ADSL Internet access that controls the RF spectrum monitoring remote stations provided with 3G/UMTS Internet access. The geographical distribution of the extended monitoring network is presented in Figure 1.
B. Internet Connectivity In order to assure the remote node Internet connectivity, a Huawei E173U HSDPA USB Stick is used, the Internet service provider used in the present application being chosen according to 3G/UMTS network coverage. Particularly for the Azores Islands, the TMN Portuguese mobile Internet provider was considered because it assures the best coverage, while for continental Portugal and Madeira Portuguese 3G/UMTS operators Vodafone and TMN were both considered because both assure good 3G/UMTS service coverage. Using the Internet support, the remote stations are accessed by the base stations (SMCC) expressed by a PC with 1Mb/s ADSL Internet connection. Each SMCC is configured with static IP, while in the remote station case the IP is dynamic. As part of client server architecture, the remote stations were designed as servers while the base stations were designed as clients. III.
Figure 1. The remote and base stations distribution associated with the extended RF spectrum monitoring system (RS_A1, RS_A2, RS_A3 – Azores remote station, RS_M1, RS_M2 – Madeira remote station, RS_S1 – Barcarena remote station, CMCES – South base station, CMCEN – North base station, CMCEM – Madeira base station, CMCEA – Azores base station)
SPECTRUM MONITORING NETWORK: SERVER APPLICATION
The server application software developed at the remote station level is based on LabVIEW web server capabilities [7]. Besides publishing the same type of documents as other Web servers such as Apache HTTP server, the LabVIEW built-in Web server can also publish pictures of running LabVIEW applications (running VIs) and permits to obtain the control of VI’s GUI remotely. Each remote station will run a Web server that assures the availability of the RF receiver remote control.
A. RF Spectrum Monitoring Station The remote station hardware is mainly expressed by a WR-G315i RF receiver from WiNRADiO. It is a software-defined high-performance VHF/UHF receiver characterized by 9 kHz to 1800 MHz, extendable to 3500 MHz input frequency. The receiver is “plug-in-PC” considering its PCI compatibility. A 600 : audio output line is connected to the input line of the PC sound card for performing the audio monitoring tasks. The receiver has its own on-board DSP and does not rely on the PC sound card for its performance. As the DSP performs the final stage IF filtering and all demodulation, this receiver is entirely software-defined. This means that additional demodulation or decoding modes can be added through the software change, which makes this receiver compatible with the virtual instrumentation concept: on hardware different functionalities achieved by software. Other characteristics of the WR-G315i receiver are: AM, AMS, LSB, USB, DSB, ISB, CW, FM, wide-FM, 1 Hz tuning resolution, scanning speed 50 channels/s, intermediate frequencies IF1: 109.65 MHz
A. Virtual Instrument Tasks The main VI that is published by the Web server and accessed through the Internet connection by the client application installed in the base station performs the following main tasks: - login/logout & identification (Id: user name and password)/UserIdent; - remote control of WR-G315i receiver/automatic and manual mode/WRctrl; - database occupancy table management: create, replace, update, delete/AutdBase; - filling of the selected occupancy table of the database with RF receiver setting and occupancy task details /AutdBase; The flowchart associated with remote station server software is presented in Figure 2.
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START Identification user: pass:
Id OK
y
n D
logout y
n
STOP RF rec. ctrl
n
y fill the occup. database
aut. Ctrl? y
Figure 3.
n
aut. occup. ctrl
man. occup. ctrl
n
Using the remote access by the user from base station (e.g. Barcarena station – client side) new spectrum occupancy table for automated control of the RF scanning task can be fill out remotely. Elements of this table are: date and time of the programmed tasks, the RF receiver internal settings, and the file name associated with saved occupancy data. On the Scan tab the user will select the spectrum occupancy table name (e.g test5) and the receiver will start scanning according to date and time specifications.
Task over? y
y
Task n over? y
Figure 2.
D Task over?
Spectrum occupancy measurement - graphical user interface with details
n
Server application flowchart
B. Graphical User Interface Regarding the login task, the user name corresponds to the base station name, while the password is introduced and compared internally with the password previously stored in a configuration file associated with the remote station server software. After successful identification, all of the tabs associated to the server main tasks become visible and the user can choose between different actions. Thus, if the user selects the WRctrl tab, the remote control of the RF receiver can be done. As the main functionalities included at the WRctrl level are mentioned the RF receiver settings: demodulation type, bandwidth, and automatic gain control selection, squelch level (Figure 4). The measurement type can be selected between the Scan and Measurements, which means the measurement of emission level (dBuV) for different frequencies included in a frequency band defined by the Start freq classic, Stop freq classic (e.g. 98MHz and 105MHz) and step freq. In Figure 4 are presented the results obtained for particular scanning band.
D. IP Information Transfer and RF Receiver Audio Broadcasting In order to permit the access to the server application, the IP is delivered using an additional application, AutoInfoIP, which periodically transmits the IP of the remote station to the base stations that run CopSSH. CopSSH is an open source SSH server and client implementation for windows systems [8]. Thus, on the client side it is automatically created by the AutoInfoIP a text file including the IP of the remote station. The RF receiver audio streaming was done using the VLC audio streaming server [9] and a particular developed script command on the client side. IV.
RF SPECTRUM MONITORING NETWORK: CLIENT APPLICATION AND RESULTS
The client application software developed at the remote station level is mainly based on the Internet Explorer browser automation using the ActiveX functions included in the application developed in LabVIEW. The use of LabVIEW application and not a simple HTML access page is related to the necessity to automatically access the Web pages of the remote station when the IP is stored in a file in the remote station and also to include the spectrum occupancy analysis software module at the client level. As it can be observed in Figure 3 and Figure 4, the server Web page appears as an object of an ActiveX container [10], the user making the selection of the remote station pages (server pages) through a set of
C. Database Support Considering the simplicity of the application and the available LabVIEW database functions (NI LabVIEW database connectivity toolkit), on the first version of server application were implemented a set of Microsoft Access local database.
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radio buttons (RemS_A1, RemS_A2,….) presented on the bottom of the GUI (Figure 4).
Figure 4.
graphical representation is also implemented by the data analysis module.
Server application control GUI
Additionally, in the client application were included functionalities such as SSH data file transfer and RF receiver audio server control. The file transfer control uses a script command associated with WinSCP software, this command being integrated in the client application software using System Exec function. The data that is obtained at the base station level is processed by the spectrum occupancy analysis module. The spectrum analysis module fully developed in LabVIEW is characterized by different functionalities such as: - occupancy spectrogram display (Figure 5); - channel detection and channel occupancy computation; - occupancy characteristics: max, min mean, median. The detected peaks (corresponding to RF emissions) are compared with previously stored authorized frequencies and the anomalous emissions are noticed using alarm generation procedure or are included in the daily reports in *.doc format. Thus, using the implemented client analysis software, the spectrogram associated with 98MHz -105MHz frequency band can be graphical represented (Figure 5).
Figure 6.
V. CONCLUSIONS The implementation of an extended RF spectrum monitoring system, including a multi-server architecture that permits to perform the automatic and manual control of the spectrum occupancy tasks through an RF receiver control and data analysis was done. Client server software architectures were developed using different technologies including LabVIEW web server associated with RF receiver remote control, CopSSH associated with secured data file and IP file transfer and VLC audio streaming server associated with RF receiver audio remote monitoring. Different tests were carried out in order to highlight the flexibility and the reliability of the implemented distributed virtual instrument. REFERENCES [1] [2]
[3] [4]
[5]
[6]
Figure 5.
Spectrum occupancy characteristics graph
[7]
98MHz-105MHz RF spectrum occupancy
[8]
Figure 6 presents the spectrum occupancy characteristics. Additional occupancy test concerning the evolution of the emission level during 24 hours and
[9]
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ITU Document 1/198-E available at : http://www.itu.int/ITUD/ study_groups/SGP_1998-2002/SG1/Documents/2001/198E.doc Rohde&Schwarz, “Spectrum Monitoring and Management System”, on-line at http://www2.rohde-schwarz.com/ file_5632/argus_en.pdf ITU “Spectrum Monitoring and Compliance”, on line at: http://www.ictregulationtoolkit.org/en/Section.1281.html, Octavian Postolache, Pedro Girão, Fernando Tavares, “Remote operation of instruments and measuring systems,” Proc. 4th Conference on Telecommunications, pp. 579-582, Aveiro, Portugal, June 2003. O. Postolache, P. Girão, S. Antunes, F. Tavares; "Global instrumentation network for broadband rf spectrum monitoring," Proc Conf. on Telecommunications - ConfTele, Sta Maria da Feira, Portugal, Vol. 1, pp. 1 - 4, May, 2009. P. Girão, O. Postolache, S. Antunes, F. Tavares, "Automated and Remote Operated System for Spectrum Monitoring and Control in Portugal," Proc IEEE International Conf. on Industrial Technology, Vina del Mar, Chile, Vol. 1, pp. 145 - 148, March, 2010. National Instruments, “Web Services in LabVIEW” on line at: http://zone.ni.com/devzone/cda/tut/p/id/7350 SourceForge, “ CopSSH - OpenSSH for Windows”, on-line at: http://www.itefix.no/i2/copssh Eliot Phillips, “How-To: Stream almost anything using VLC”, online at: http://www.engadget.com/2005/11/29/how-to-streamalmost-anything-using-vlc/
