Stylianos Kasampalis
Start date: 01/Oct/2011
Email: Stylianos.Kasampalis@brunel.ac.uk
Supervisor: Prof.John Cosmas & Pavlos Lazaridis
PhD Research Title: Modeling and coverage improvement of DVB-T networks
In order to take full advantage of DVB-T services and characteristics, field trials are required, comparing simulation and laboratory results with measurements. This is exactly the scope of this study, i.e. to provide accurate coverage prediction maps for DVB-T/DVB-T2 services and validate the simulation results with field measurements. The coverage prediction maps will be produced by a software using geographical altitude databases and various electromagnetic propagation models to be developed in the context of this PhD. Therefore, improved electromagnetic propagation models will be used and their accuracy will be extensively assessed by precision measurements performed by the electrical measurements laboratory (TU Thessaloniki) equipment.
The measurements equipment consists of a Rohde & Schwarz FSH-3 portable spectrum analyzer (100 kHz – 3 GHz), low-loss cable by Suhner, two high-precision calibrated biconical antennas by Schwarzbeck (25 MHz – 6 GHz), and the more recently acquired equipment, an Agilent portable spectrum analyzer (up to 6 GHz) and a log-periodic precision calibrated Schwarzbeck antenna (0.25 – 6 GHz). Furthermore, a complete DVB-T HD testbed has been already put in place at the campus of TU Thessaloniki by the laboratory of electrical measurements that can cover the entire city, and transmission experiments are taking place during the past 2 years. The testbed consists of a Rohde & Schwarz low power UHF DVB-T transmitter, a 11 dBd UHF antenna panel by Aldena placed on a tower of 10 m on top of the electronics building, a power UHF amplifier, an MPEG-4 (H.264) HD encoder with ASI output, a professional satellite receiver with ASI output.
The expected result of the PhD study should be in the first place to use and upgrade the existing DVB-T transmission site of the TU Thessaloniki in order to find ways to improve the geographical coverage of the transmitter, by using an optimum set of transmission parameters for DVB-T/DVB-T2, and, if this is not enough, other techniques such as for example: antenna diversity in transmission, antenna diversity in reception, gap-fillers, etc. Ultimately, exact models using the underlying physics of the coverage improvement mechanisms should be developed and incorporated into the TU propagation prediction software platform. A special module concerning the interference from other digital-analogue services should also be developed.
At this moment we are using the following software to make simulations and comparisons:
- The Radio Mobile program (Radio Propagation and Virtual Mapping Freeware). The Radio Mobile program is written and maintained by Roger Coudé,VE2DBE and is available from the Radio Mobile website. It is a freeware program based on the Longley-Rice Irregular Terrain Model (ITM) for calculating path loss and field strength. The program gets the elevation data of the terrain from the database of Space Shuttle Radar Topography Mission (SRTM) that is freely accessible through the internet and has a resolution of approximately 90 metres. The program produces a coverage map using input parameters such as, transmitter location, transmitted output power, working frequency, antenna type, radiation pattern, antenna gain, transmission line losses (including filters and dividers) and elevation data for the terrain.
- The SPLAT! program, an RF Signal Propagation, Loss, And Terrain analysis tool for the spectrum between 20MHz and 20GHz, by John Magliacane. It is a free software, and it is a Linux based program but there are two versions, made freely available by John McMellen, KC0FLR, and Austin Wright, VE3NCQ and run under Windows. SPLAT! produces reports, graphs, coverage maps, path loss, field strength, etc. It also gets the elevation data of the terrain from the database of Space Shuttle Radar Topography Mission (SRTM and is based on the Longley-Rice Irregular Terrain Model(ITM) as well as a newer Irregular Terrain With Obstructions (ITWOM v3.0).
Publications:
- Lazaridis P., Bizopoulos A., Lazarevska E., Zaharis Z., Papastergiou A., Kasampalis S., "A fully portable apparatus for surveillance of electromagnetic broadcast spectrum and measurement of electromagnetic radiation levels" WSEAS, 23-25/07/ 2009, Rhodes Island, Greece.
- Bizopoulos A., Lazaridis P., Paparouni E, Drogoudis D., Kasampalis S., Dalis I., Gavrilovska L., "Coverage prediction and validation for dvb-t services" ETAI Conference 16-19/09/2011, Ohrid.
