PHYSICS SEMINAR by İbrahim Ölçer

Time: 14:30
Location: SCI 103


Speaker        : İbrahim Ölçer, TÜBİTAK BİLGEM

Title              : Novel Signal Processing Techniques for Fiber Optic Distributed Acoustic Sensing

Date              : Tuesday, November 12, 2019
Time             :
Cookie&Tea: SCI 103, 14:15
Place             : SCI 103

Web              :

The revolutionary technological advances in fiber optics have resulted in the production of various sensor devices for measuring temperature, pressure, and vibration.  Among these new sensor types, the phase-sensitive optical time-domain reflectometry (f-OTDR) is one of the most common methods which turns a standard telecom fiber into a dense array of virtual microphones by exploiting the inherent Rayleigh scattering phenomenon in the fiber optic cable.
By appropriate interrogation and detection schemes, the acoustic vibrations along the whole fiber length can be detected. This so-called distributed acoustic sensing (DAS) technology has attracted significant research interest for the last two decades to develop innovative and cost-effective approaches for intrusion sensing and protection of critical infrastructures. Besides its very effective use in the oil and gas industry, DAS technology is also evolving very fast to play an important role in passive seismology and observation of earthquakes.

In this seminar, after reviewing the basics of the f-OTDR operation and main detection problems, two novel approaches will be presented which are proposed to combat the background noise in DAS systems. Both methods utilize the correlation properties of the measured data and possess the constant false alarm rate (CFAR) properties. The first approach is the temporal adaptive processing of f-OTDR signals which is based on maximizing the signal-to-noise ratio (SNR) at the output of an adaptive linear filter. When the vibration frequency of interest is a priori known, it is called the adaptive matched filter (AMF). The second approach is based on the largest eigenvalue computation of the optical covariance matrix which does not require any prior information about the vibration frequencies. This technique is called the maximum eigenvalue detection (MED) and assisted by the random matrix theory for detection threshold derivation.

A real hardware platform called FOTAS, developed in TÜBİTAK BİLGEM was used to verify the efficacy of the proposed AMF and MED techniques.  The results of the extensive field tests, conducted in Gebze Campus of TÜBİTAK with both buried fibers underground and fibers on fences, will be presented.  Besides, recent earthquake observations with the FOTAS system will be discussed shortly.


Short Bio:
İbrahim Ölçer, married to Piraye Ölçer with two children, was born in Zonguldak (1970).  He received the B.Sc and M.Sc degrees in Electronics and Telecommunication Engineering from İstanbul Technical University (İTÜ) in 1992 and 1995, respectively.  He has been with the Scientific and Technological Research Council of Turkey (TÜBİTAK) since 1994, where he focused mainly on experimental research projects.

Between 1994 and 1996 he conducted his first research radar backscattering, specifically on inverse synthetic aperture radar (ISAR) imaging algorithms and developed an experimental ISAR system in the laboratory of the Space Technologies Department of Marmara Research Center.  He visited the German Aerospace Research Center (DLR) as a guest scientist upon completing his graduate study for a short period in 1995.  From 1997 to 2012, he was with the National Research Institute of Electronics and Cryptology (UEKAE). He was involved in the establishment of the infrastructure for testing and verification of the information security equipment for the Turkish Armed Forces (TAF). He also served as the national expert in A400M Project between 1998 -2008. In 2005, he was appointed as the coordinator of the TEMPEST Security Working Group of the A400M Project for 2 years.  From 2005 till 2012, he was also held responsible to conduct software-defined radio (SDR) related research activities where he led a team of 26 engineers.  The SDR related projects were mostly related to the spectrum surveillance activities and several accomplishments were made to replace the imported Signal Intelligence (SIGINT) technology with the national counterparts with his team.  These achievements later motivated several of the team members to found their businesses in the same field.  In 2012, he was with the Information Technologies Institute (BTE) where he commenced a project on microwave imaging of subsurfaces and interiors. Later, he started his doctoral study in Electrical and Electronics Engineering at Boğaziçi University the same year. In 2013, he worked in the National Metrology Institute (UME) to share expertise with the researchers working on high intensity focused ultrasound (HIFU).

Since 2014, he is the Deputy Director of UEAKE and responsible for three R&D departments.  Regarding his new responsibilities in the field of electro-optics and lasers technology, in parallel, he devoted his doctoral research to the development of fiber optic based sensor technology and spent significant effort to increase the nationwide awareness of new sensor technologies for homeland security.
His current research interests are signal processing for distributed fiber-optic sensing, microwave photonics, and SIGINT. İbrahim Ölçer feels proud of being a member of TÜBİTAK family for nearly 25 years and believes that imagination power fed by passion and patience is much more important than acquired knowledge for doing valuable work.