Dvb-T2 Guard Interval Optimization For Sfn

Abstract

Oromia Radio and TV Organization have launched analog terrestrial TV transmitters in different zonal parts of Oromia in 2008. All these transmitters broadcast analog signal in VHF frequency and MFN. These analog TV signals experience different distortions (ghosting) at receiving end from delayed (echoed) signal caused by different structures, buildings, wind farms and remote transmitter operating at the same frequency (co-channel).To identify distortions caused by multipath reflections and co-channel overlaps we have tested the pure generated RF signal at the Lab by generating 10MHz RF from Agilent Spectrum analyzer, the transmitted or reference monitor out signal from OTV transmitters found at Adama, Kechema site and Sabata, Furi site. These two transmitters operate at the same frequency and all of their parameters are the same.We have also measured the received input voltage at multipath environment i.e. Adama city at different places in which we have thought multipath reflections is high by using dipole antenna, DS1191 analyzer and TV set. We have got fluctuating input voltage at one place on our DS1191 and ghosted image on our TV set.For co-channel overlap environment i.e. Bishoftu city we have made measurements and OTV signal from the two transmitters are reaching the receiver and we have got two spectrums on our DS1191 analyzer and fluctuating input voltages at a place.We have also calculated the required ideal received input power/voltage at receiver by using Friis transmission calculator formula by only considering the free space path loss and not considering both multipath reflections and co-channel overlaps. We have compared and analyzed the measured and ideal received input voltage.Finally we have cancelled co-channel overlaps or interferences by guard interval insertions of DVB-T using ATDI ICS Telecom simulation software and recommended ORTO to migrate to DVB-T2 for mitigation of these problems.