In the atmosphere, a huge spectrum of signals for various services is very often transmitted wirelessly. Let's mention radio and TV modulation, data transmission, wireless telephony, internet, signal for mobile phones, navigation signals and many other services. This brings requirements for the description of the degradation effects of the atmosphere, which cause mainly:
- Signal attenuation
- Signal depolarization
- Signal phase delay
- Signal trajectory change
Significant atmospheric degradation is caused by hydrometeors (rain, hail, snow, ice crystals,…), fog, clouds, melting layer, air humidity on one hand, but also by wind on the other hand. The ionosphere also significantly affects the propagation of waves, but it can be used for the desired signal reflection.
At IAP, we are intensively focusing on the analysis and statistics of degradation effects of atmosphere on propagating signals, especially on their attenuation in atmosphere. We focus mostly on rain research, which is the most important degrading factor for radio links in our climate. On the other hand, for optical wireless links, we deal with the analysis of fog and clouds. This represents the acquisition of a physical description of the scattering of waves on raindrops or fog droplets and their clump. We must know, for example, the shape of drops, which we measure by distrometer. Other research tools include meteorological radar, rain gauge, humidity sensor, ceilometer, anemometer etc., etc. The results of our research serve as a basis for rational planning of wireless links.
Running international project with ESA
- Q/V Band Large Scale Spatio-Temporal Channel Models for Satcom Design and Operations. (No.4000129250/19/NL/AS), 2020-2021
Finished international projects:
- ESA Contract: Earth-space path propagation characteristics in the climatic conditions of the Czech Republic from Alphasat Ka/Q band experiment. No. 4000112723/14/NL/CBi, 2015-2018
- RADHYD (CEEC/NIS 7CZPJO48330, Swiss National Foundation: Exchange of ideas and development of algorithm for estimating precipitation by radar for operational applications in meteorology and hydrology, 1996-1997
- PADRE (Polarisation and Doppler Radar Experiment), project of European Economic Community Commision, 1994-1996
International COST projects:
- COST 235 (1991-1993)
- COST 255 (1996-1998)
- COST 75 (1997)
- COST 280 (2001-2005)
- COST IC0802 (2009-2012)
- COST IC1101 (2013-2015)
National project (Czech Science Foundation)
- GA205/96/1555: Processing and mapping of meteorological parameters for propagation modeling of radio waves in the troposphere, Principal investigator O. Fišer (1996-1998)
- GAČR 102/01/0029: Quality and reliability of modern telecommunication systems in the frequency bands of mm waves in the Czech Republic, co-investigatior: O. Fišer (2001-2003)
- GA102/05/0571: Methods increasing the reliability of wireless optical links, co-investigatior: O. Fišer (2005-2007)
- GAČR 102/08/0851: Advanced Communication Techniques for the Atmospheric Optical Channel, co-investigatior: O. Fišer (2008-2010)
- GAČR P102/11/1376, Research of the influence of degraded transmission conditions on the properties of future terrestrial broadband wireless systems, co-investigatior: O. Fišer (2011-2013)
National projects (Ministry of Education, Youth and Sports)
- MŠMT OC 255.10: Influence of cloud and precipitation on attenuation of radio waves in frequency bands Ku and higher, principal investigator O. Fišer (1996-1999)
- MŠMT OC 280.002: Precipitation analysis for the purpose of improved design of reliable radiocommunication links, principal investigator O. Fišer (2001-2005)
- MŠMT OC09027:Influence of clouds, fog and rain on optical and radio wireless connections, principal investigator O. Fišer (2009-2012)
- MŠMT LD13036: Influence of the atmosphere on the signal attenuation of wireless optical links with regard to the influence of turbulence and wind, principal investigator O. Fišer (2013-2015)
- Fišer, Ondřej - Brázda, Vladimír: Experimental Validation of FSO Channel Models. Optical Wireless Communications. Cham: Springer, 2016, s. 69-86. Signals and Communication Technology. ISBN 978-3-319-30200-3
- Fišer, Ondřej: The Role of DSD and Radio Wave Scattering in Rain Attenuation. In Imperatore, P.; Riccio, D. (ed.). Geoscience and Remote Sensing New Achievements. Vukovar : INTECH, 2010. pp. 1-508. ISBN 978-953-7619-97-8.
- CHLÁDOVÁ, Z., O. FIŠER, V. BRÁZDA a J. SVOBODA. Correlation of free-space optics link attenuation with sonic temperature. Optical Engineering. 2013, vol. 52, issue 3. DOI: 10.1117/1.OE.52.3.030503. ISSN 0091-3286.
- IJAZ, M, Z. GHASSEMLOOY, J. PEREZ, V. BRÁZDA a O. FIŠER. Enhancing the Atmospheric Visibility and Fog Attenuation Using a Controlled FSO Channel. IEEE Photonics Technology Letters. 2013, vol. 25, issue 13, s. 1262-1265. DOI: 10.1109/LPT.2013.2264046. ISSN 1041-1135.
- IJAZ, M., Z. GHASSEMLOOY, J. PEŠEK, O. FIŠER, H. LE MINH a E. BENTLEY. Modeling of Fog and Smoke Attenuation in Free Space Optical Communications Link Under Controlled Laboratory Conditions. Journal of Lightwave Technology. 2013, vol. 31, issue 11, s. 1720-1726. DOI: 10.1109/JLT.2013.2257683. ISSN 0733-8724.
- GRABNER, M, V. KVÍČERA a O. FIŠER. Rain attenuation measurement and prediction on parallel 860-nm free space optical and 58-GHz millimeter-wave paths. Optical Engineering. 2012, vol. 51, issue 3. DOI: 10.1117/1.OE.51.3.031206. ISSN 0091-3286.
- KVÍČERA, V., M. GRABNER a O. FIŠER. Long-Term Propagation Statistics and Availability Performance Assessment for Simulated Terrestrial Hybrid FSO/RF System. Eurasip Journal on Wireless Communications And Networking. 2011, Art. No 435262. DOI: 10.1155/2011/435262. ISSN 1687-1499.
- PEŠEK, J., O. FIŠER, J SVOBODA a V SCHEJBAL. Modeling of 830 nm FSO Link Attenuation in Fog or Wind Turbulence. Radioengineering. 2010, vol. 19, issue 2, s. 237-241. ISSN 1210-2512.
- KVÍČERA, V., M GRABNER a O. FIŠER. Propagation Characteristics and Availability Performance Assessment for Simulated Terrestrial Hybrid 850 nm/58 GHz System. Radioengineering. 2010, vol. 19, issue 2, s. 254-261. ISSN 1210-2512.
- FIŠER, O. a O. WILFERT. Novel processing of Tipping-bucket rain gauge records. Atmospheric Research. DEC 07-10, 2009, vol. 92, issue 3, s. 283-288. DOI: 10.1016/j.atmosres.2009.01.008. ISSN 0169-8095.
- KOLKA, Z., O. WILFERT a O. FIŠER. Achievable qualitative parameters of optical wireless links. Journal Of Optoelectronics and Advanced Materials. 2007, vol. 9, issue 8, s. 2419-2423. ISSN 1454-4164.
- KVÍČALA, R., V. KVÍČERA, M. GRABNER a O. FIŠER. BER and availability measured on FSO link. Radioengineering. 2007, vol. 16, issue 3, s. 7-12. ISSN 1210-2512.
- FIŠER, O. a V. KVĚTOŇ. Stability of rain-rate distribution: how many years to measure?: how many years to measure? Electronics Letters. 2006, vol. 42, issue 10, s. 567-569. DOI: 10.1049/el:20060326. ISSN 0013-5194.
- FIŠER, O. Site Diversity Gain Estimated from Rain Rate Records. Radioengineering. 2003, vol. 12, issue 1, s. 8-11. ISSN 1210-2512.
- ŘEZÁČOVÁ, D., O. FIŠER a L. R. SAEZ. Statistics of Radio Refractivity Derived from Prague Radiosounding Data. Radioengineering. 2003, vol. 12, issue 4, s.84-88. ISSN 1210-2512.
- FIŠER, O., M. SCHONHUBER a P. PEŠICE. First results of DSD measurement by videodistrometer in the Czech Republic in 1998-1999. Studia Geophysica et Geodaetica. 2002, vol. 46, issue 3, s. 485-505. DOI: 10.1023/A:1019591002211. ISSN 0039-3169.
- Dev, K.,Nebuloni R., Fišer, O., Brázda, V. Estimation of optical attenuation in reduced visibility conditions in different environments across free space optics link. IET Microwaves Antennas and Propagation. (2017),Volume 11, Issue 12, , 2017, pp. 1708 – 1713
- Ventouras, S. - Martellucci, A. - Reeves, R. - Rumi, E. - Fontan, F.P. - Machado, F. - Pastoriza, V. - Rocha, A. - Mota, S. - Jorge, F. - Panagopoulos, A.D. - Papafragkakis, A.Z. - Kourogiorgas, C.I. - Fišer, Ondřej - Pek, Viktor - Pešice, Petr - Grabner, M. - Vilhar, A. - Kelmendi, A. - Hrovat, A. - Vanhoenacker-Janvier, D. - Quibus, L. - Goussetis, G. - Costouri, A. - Nessel, J. „Assessment of spatial and temporal properties of Ka/Q band earth‐space radio channel across Europe using Alphasat Aldo Paraboni payload.“ International Journal of Satellite Communications and Networking. Roč. 37, č. 5 (2019), s. 477-501. ISSN 1542-0973