DESIGN & IMPLEMENTATION OF POLYPHASE FILTER TO DENOISE OFDM SIGNALS

An amazingly effective digital transit system that carries multiple carriers that meet in conjunction with each other over a period of time is known as the Orthogonal Frequency Division Multiplexing (OFDM) system. Among the traditional symbols, there is a need to include a group of guards. However, in OFDM systems this is not required. Although there is an overlap of side bands from each carrier, no interference is involved within the signals found here as they are orthogonal in relation to each other. This research work is based on a wireless channel to reduce the rate of error using space-time trellis codes. In this research project, the minimum error rate is reduced over wireless channels using space time codes and poly-phase filters. The proposed modular simulation is performed at MATLAB and the results show that the minimum bit error rate decreases in the network.

Low Complexity Non Maximally Coefficient Symmetry Multi Rate Filter Bank for Wideband Channelization

For extracting the individual channels from input signal of wideband, Software Radio Channelizer was often used on multi-standard wireless communication. Despite the effective channelizer design that decreases the complexity of computational, delay and power consumption is challenging. Thus, to promote the effectiveness of the channelizer, we have provided the Non-Maximally Coefficient Symmetry Multirate Filter Bank. For this, a sharp wideband channelizer is designed to be using the latest class of masking responses with Non-maximally Decimated Polyphase Filter. Moreover, coefficient symmetry is incorporated into the Non-Maximally Coefficient Symmetry Multirate Filter Bank to improve the hardware efficiency and functionality of the proposed schemes. To prove the complexity enhancement of the proposed system, the design is analyzed with communication standard with existing methods.

Low Complexity Non Maximally Coefficient Symmetry Multi Rate Filter Bank for Wideband Channelization

For extracting the individual channels from input signal of wideband, Software Radio Channelizer was often used on multi-standard wireless communication. Despite the effective channelizer design that decreases the complexity of computational, delay and power consumption is challenging. Thus, to promote the effectiveness of the channelizer, we have provided the Non-Maximally Coefficient Symmetry Multirate Filter Bank. For this, a sharp wideband channelizer is designed to be using the latest class of masking responses with Non-maximally Decimated Polyphase Filter. Moreover, coefficient symmetry is incorporated into the Non-Maximally Coefficient Symmetry Multirate Filter Bank to improve the hardware efficiency and functionality of the proposed schemes. To prove the complexity enhancement of the proposed system, the design is analyzed with communication standard with existing methods.

Research of Methods for Suppression of Parasitic Components in RF Quadrature Modulator Output Signal Spectrum

The quadrature modulators and demodulators are widely used to create modern wireless communication systems. It is important to ensure high quality of the transmitted signals in order to have the exchange of information without loss or failure. From the point of view of the spectral decomposition of the signal (Fourier series decomposition), the useful component of the spectrum must be much larger than all other components. The carrier (LO frequency and spurious sideband are the most critical and undesirable quadrature modulator output signal spectral components. In the work, in the course of the research using the methods of suppressing the parasitic components, based on minimizing phase, amplitude and current imbalances in various nodes of the quadrature modulator circuit, have been revealed. In order to realize suppression, the special digital-to-analog converters are used in conjunction with a polyphase filter on varicaps, a phase-shifting block and current sources. The effectiveness of these methods is confirmed by the achievement of suppression of parasitic components in prototypes of 50 dB or more. It has been stated that the phase unbalance minimization is more effective than the amplitude unbalance minimization to sideband suppression. It has been revealed that the use of a phase-shifting block is a more suitable architecture to control the phase unbalance. The obtained results can be useful in the design of high-precision radio frequency units for various purposes.

Design Method for a Broadband Quadrature Signal Generator

There are certain difficulties in the development of a broadband generator of quadrature signals (QSG) on a SiGe BiCMOS technology. The problem of linearity and broadband matching is the most difficult to solve. When designing QSG in a wide frequency band, there is a problem of forming a quadrature signal using traditional solutions using a polyphase filter or a digital D-trigger. The use of only one method for forming a quadrature signal is impossible due to the limiting features of the electronic component base of SiGe BiCMS technology. To solve this problem, we propose a structure that allows us to develop a broadband quadrature signal generator with an operating frequency range from 10 MHz to 6 GHz, using the method of dividing the operating frequency band. At frequencies from 1 to 6 GHz, the quadrature signal is generated using a polyphase filter, and at frequencies less than 1 GHz using a frequency divider. Using this method, the following characteristics of the FCS have been achieved: the difference in the amplitudes of quadrature signals is less than 0.3 dB; the VSWR is less than 1.6 over the entire frequency range; the transmission coefficient is not less than -2 dB at a 0 dBm heterodyne power; at a frequency of 6 GHz P1dB of at least 3 dBm. The experimental results are in good agreement with the simulation data.