Frequency response diagrams of a system include detailed and recognizable ‎information about the structural and parameter effects of the transfer function model ‎of the system. The information are qualitatively and quantitatively obtainable from ‎simultaneous consideration of amplitude ratio and phase information. In this paper, ‎some rules and relationships are presented for making use of Frequency response ‎information in order to identify the structure of rational and irrational models in a ‎heuristic manner. Estimation of the values of the parameters are also accomplished in ‎a graphical trial and error procedure. As an example, the heuristic method was applied ‎for identifying the simplified model of a rotary cement kiln from the Frequency ‎response information of the analytically derived model of the system. The analytical ‎model of the kiln, used in this paper, was obtained elsewere in a detailed procedure ‎with some assumptions and by using initial and boundary conditions. Results obtained ‎from identification of the simplified model for rotary cement kiln not only reveal the ‎application of the heuristic method for model identification, but also demonstrate the ‎appearance of unstable poles and zeros in the model of the system‏.‏

Purpose: To compare electroretinogram (ERG) characteristics in patients with retinitis pigmentosa (RP) and normal subjects using Frequency Domain analysis.Methods: Five basic ERG recordings were performed in normal subjects and patients with a clinical diagnosis of RP according to the ISCEV (International Society of Clinical Electrophysiology of Vision) protocol. Frequency Domain analysis was performed by MATLAB software. Different Frequency Domain parameters were compared between the study groups.Results: Peak Frequency (Fmod) of flicker and oscillatory responses in RP patients showed significant (P<0.0001) high pass response as compared to normal controls.Peak Frequency (Fmod) of the other responses was not significantly different between the two groups.Conclusion: In addition to conventional ERG using time Domain methods, Frequency Domain analysis may be useful for diagnosis of RP. Oscillatory and flicker responses may be analyzed in Frequency Domain. Fast Fourier transform may reveal two distinct high pass responses (shift to higher frequencies) in Fmod. Time and Frequency Domain analyses may be performed simultaneously with many modern ERG machines and may therefore be recommended in RP patients.

In this paper we propose a new space diversity scheme for broadband PLC systems using orthogonal space-time block coding (OSTBC) transmission combined with single-carrier Frequency-Domain equalization (SC-FDE). To apply this diversity technique to PLC channels, we first propose a new technique for combining SC-FDE with OSTBCs applicable to all dispersive multipath channels impaired by impulsive noise. The proposed technique is then applied to indoor and outdoor PLC channels under different channel scenarios in the presence of background and impulsive noises. We perform the simulations for SISO, MISO and MIMO configurations and show that a significant SNR gain is achieved when SC-FDE is combined with diversity techniques. We also compare our proposed technique with OFDM using Alamouti code for broadband PLC and show the superiority of our technique.