Adaptive instantaneous frequency estimation: Techniques and algorithms

This thesis deals with the problem of the instantaneous frequency (IF) estimation of sinusoidal signals. This topic plays significant role in signal processing and communications. Depending on the type of the signal, two major approaches are considered. For IF estimation of single-tone or digitally-modulated sinusoidal signals (like frequency shift keying signals) the approach of digital phase-locked loops (DPLLs) is considered, and this is Part-I of this thesis. For FM signals the approach of time-frequency analysis is considered, and this is Part-II of the thesis. In part-I we have utilized sinusoidal DPLLs with non-uniform sampling scheme as this type is widely used in communication systems. The digital tanlock loop (DTL) has introduced significant advantages over other existing DPLLs. In the last 10 years many efforts have been made to improve DTL performance. However, this loop and all of its modifications utilizes Hilbert transformer (HT) to produce a signal-independent 90-degree phase-shifted version of the input signal. Hilbert transformer can be realized approximately using a finite impulse response (FIR) digital filter. This realization introduces further complexity in the loop in addition to approximations and frequency limitations on the input signal. We have tried to avoid practical difficulties associated with the conventional tanlock scheme while keeping its advantages. A time-delay is utilized in the tanlock scheme of DTL to produce a signal-dependent phase shift. This gave rise to the time-delay digital tanlock loop (TDTL). Fixed point theorems are used to analyze the behavior of the new loop. As such TDTL combines the two major approaches in DPLLs: the non-linear approach of sinusoidal DPLL based on fixed point analysis, and the linear tanlock approach based on the arctan phase detection. TDTL preserves the main advantages of the DTL despite its reduced structure. An application of TDTL in FSK demodulation is also considered. This idea of replacing HT by a time-delay may be of interest in other signal processing systems. Hence we have analyzed and compared the behaviors of the HT and the time-delay in the presence of additive Gaussian noise. Based on the above analysis, the behavior of the first and second-order TDTLs has been analyzed in additive Gaussian noise. Since DPLLs need time for locking, they are normally not efficient in tracking the continuously changing frequencies of non-stationary signals, i.e. signals with time-varying spectra. Nonstationary signals are of importance in synthetic and real life applications. An example is the frequency-modulated (FM) signals widely used in communication systems. Part-II of this thesis is dedicated for the IF estimation of non-stationary signals. For such signals the classical spectral techniques break down, due to the time-varying nature of their spectra, and more advanced techniques should be utilized. For the purpose of instantaneous frequency estimation of non-stationary signals there are two major approaches: parametric and non-parametric. We chose the non-parametric approach which is based on time-frequency analysis. This approach is computationally less expensive and more effective in dealing with multicomponent signals, which are the main aim of this part of the thesis. A time-frequency distribution (TFD) of a signal is a two-dimensional transformation of the signal to the time-frequency domain. Multicomponent signals can be identified by multiple energy peaks in the time-frequency domain. Many real life and synthetic signals are of multicomponent nature and there is little in the literature concerning IF estimation of such signals. This is why we have concentrated on multicomponent signals in Part-H. An adaptive algorithm for IF estimation using the quadratic time-frequency distributions has been analyzed. A class of time-frequency distributions that are more suitable for this purpose has been proposed. The kernels of this class are time-only or one-dimensional, rather than the time-lag (two-dimensional) kernels. Hence this class has been named as the T -class. If the parameters of these TFDs are properly chosen, they are more efficient than the existing fixed-kernel TFDs in terms of resolution (energy concentration around the IF) and artifacts reduction. The T-distributions has been used in the IF adaptive algorithm and proved to be efficient in tracking rapidly changing frequencies. They also enables direct amplitude estimation for the components of a multicomponent

Low-complexity estimation of CFO and frequency independent I/Q mismatch for OFDM systems

CFO and I/Q mismatch could cause significant performance degradation to OFDM systems. Their estimation and compensation are generally difficult as they are entangled in the received signal. In this paper, we propose some low-complexity estimation and compensation schemes in the receiver, which are robust to various CFO and I/Q mismatch values although the performance is slightly degraded for very small CFO. These schemes consist of three steps: forming a cosine estimator free of I/Q mismatch interference, estimating I/Q mismatch using the estimated cosine value, and forming a sine estimator using samples after I/Q mismatch compensation. These estimators are based on the perception that an estimate of cosine serves much better as the basis for I/Q mismatch estimation than the estimate of CFO derived from the cosine function. Simulation results show that the proposed schemes can improve system performance significantly, and they are robust to CFO and I/Q mismatch.

New strength : independent television companies in China’s television industry

As most of people know that all of mass media are state-owned in China, television stations are not exceptional to belong to the enormous state-owned system. But to date, with the economic reform in the broadcasting system and China entering into WTO, the television industry has increased greatly and the television market has matured with more and more competition. The players in China’s television industry have changed from the monologue of TV stations to multi roles of TV stations, production companies and overseas television companies, although TV stations are still the majority of China’s TV market. Especially, private television production companies are becoming more and more active in this market. In this paper, I will describe the development process and challenges of this group in China and ask whether the emergence of this group means for the whole China’s TV industry?

Independent television production, TV formats and media diversity in China

Beginning around 2003, television studies has seen the growth of interest in the genre of reality shows. However, concentrating on this genre has tended to sideline the even more significant emergence of the program format as a central mode of business and culture in the new television landscape. "Localizing Global TV" redresses this balance, and heralds the emergence of an important, exciting and challenging area of television studies. Topics explored include reality TV, makeover programs, sitcoms, talent shows and fiction serials, as well as broadcaster management policies, production decision chains and audience participation processes. This seminal work will be of considerable interest to media scholars internationally.

A new definition for today’s Chinese independent cinema

Different terminologies have been used to characterize the Chinese independent cinema in the 1990s. These definitions focus on the experimental practices outside the official production system and independent of official ideology. The film industry has had distinctive development since the entry of WTO in 2001. Private investors have played essential role in cinematic economy; strict censorship has been obviously relaxed; the film industry is being divided into two opposing extremes. Thus, it is necessary to give a new definition of the Chinese independent cinema. The definition of independent cinema in today China I suggest in the light of American independence is that any film that has not been financed, produced and distributed by majors is independent. At least four corporations are majors in the Chinese film industry. They are China Film Group Corporation, Huayi Brothers Corporation, PolyBona Film Distribution Corporation and Shanghai Film Group Corporation. Except the four majors, all the other film production or distribution companies are independents.

Liability of principal contractor for independent subcontractor considered by the High Court

Case note of Leighton Contractors Pty Ltd v Fox (2009) 258 ALR 673 ----- In Leighton Contractors Pty Ltd v Fox (2009) 83 ALJR 1086 ; 258 ALR 673 the High Court considered the liability of a principal contractor for the negligence of independent subcontractors on a building site. In its decision, the court considered the nature and the scope of the duty owed by principals to independent contractors.

Locking away the mysteries of fair basis : Lockwood v Doric in the High Court

This article updates a previous article on the Lockwood v Doric fair basing case in the Full Court of the Federal Court which was recently appealed to the High Court. The High Court's decision provides a new and welcome level of clarity in this difficult area of patent law. With this new clarity we can finally lock away some of the mysteries that have plagued the area for some time. Already, indications are that Lockwood's guidelines are being usefully applied in the Patent Office and Federal Court.

Culture independent analysis of greyback canegrub-associated microflora and microbial community comparison using subtractive hybridisation

Greyback canegrubs cost the Australian sugarcane industry around $13 million per annum in damage and control. A novel and cost effective biocontrol bacterium could play an important role in the integrated pest management program currently in place to reduce damage and control associated costs. During the course of this project, terminal restriction fragment length polymorphism (TRFLP), 16-S rDNA cloning, suppressive subtractive hybridisation (SSH) and entomopathogen-specific PCR screening were used to investigate the little studied canegrub-associated microflora in an attempt to discover novel pathogens from putatively-diseased specimens. Microflora associated with these soil-dwelling insects was found to be both highly diverse and divergent between individual specimens. Dominant members detected in live specimens were predominantly from taxa of known insect symbionts while dominant sequences amplified from dead grubs were homologous to putativelysaprophytic bacteria and bacteria able to grow during refrigeration. A number of entomopathogenic bacteria were identified such as Photorhabdus luminescens and Pseudomonas fluorescens. Dead canegrubs prior to decomposition need to be analysed if these bacteria are to be isolated. Novel strategies to enrich putative pathogen-associated sequences (SSH and PCR screening) were shown to be promising approaches for pathogen discovery and the investigation of canegrubsassociated microflora. However, due to inter- and intra-grub-associated community diversity, dead grub decomposition and PCR-specific methodological limitations (PCR bias, primer specificity, BLAST database restrictions, 16-S gene copy number and heterogeneity), recommendations have been made to improve the efficiency of such techniques. Improved specimen collection procedures and utilisation of emerging high-throughput sequencing technologies may be required to examine these complex communities in more detail. This is the first study to perform a whole-grub analysis and comparison of greyback canegrub-associated microbial communities. This work also describes the development of a novel V3-PCR based SSH technique. This was the first SSH technique to use V3-PCR products as a starting material and specifically compare bacterial species present in a complex community.

New strength of competition and innovation : China’s independent television production

The state-owned media system in China has evolved considerably since 1994 when the first independent TV production company was officially registered. Today, there are thousands of independent TV production companies looking for market opportunities in China. Independent production companies have facilitated the circulation of program trade and investment, and in the process have encouraged innovation and professionalization. This paper focuses on the evolution of independents and the changing face of the television market. It discusses the ecology of independent television companies in China and how government regulations are impacting on the TV production market. It argues that independent TV is providing a new strength for China‟s TV market, one often suspected of being imitative, propagandistic and lacking colour.