This application note considers the design of frequency-
selective filters, which modify the frequency content
and phase of input signals according to some specification.
Two classes of frequency-selective digital filters
are considered: infinite impulse response (IIR) and finite
impulse response (FIR) filters. The design process
consists of determining the coefficients of the IIR or FIR
filters, which results in the desired magnitude and
phase response being closely approximated.
This sample program generates two sine waves called X and Y.
It will then calculate the normalized magnitude and phase of
the two waveforms using the following formulas:
Mag = sqrt(X^2 + Y^2)/sqrt(GainX^2 + GainY^2)
Phase = (long) (atan2PU(X,Y) * 360)
The program will prompt the user to change the gain and
frequency of the X and Y waveforms.
Abstract-In this paper, simple autonomous chaotic circuits
coupled by resistors are investigated. By carrying out computer
calculations and circuit experiments, irregular self-switching phenomenon
of three spatial patterns characterized by the phase
states of quasi-synchronization of chaos can be observed from
only four simple chaotic circuits. This is the same phenomenon
as chaotic wandering of spatial patterns observed very often from
systems with a large number of degrees of freedom. Namely, one
of spatial-temporal chaos observed from systems of large size can
be also generated in the proposed system consisting of only four
chaotic circuits. A six subcircuits case and a coupled chaotic circuits
networks are also studied, and such systems are confirmed
to produce more complicated spatio-temporal phenomena.
A MATLAB program has been written to investigate Orthogonal Frequency Division
Multiplexing (OFDM) communication systems. This program is valuable for future researchers
simulating systems that are too theoretically complex to analyze. Single-carrier QAM and multicarrier
OFDM are compared to demonstrate the strength of OFDM in multipath channels. Two
graphical user interface demonstrations show some of the basic concepts of OFDM.
The 4.0 kbit/s speech codec described in this paper is based on a
Frequency Domain Interpolative (FDI) coding technique, which
belongs to the class of prototype waveform Interpolation (PWI)
coding techniques. The codec also has an integrated voice
activity detector (VAD) and a noise reduction capability. The
input signal is subjected to LPC analysis and the prediction
residual is separated into a slowly evolving waveform (SEW) and
a rapidly evolving waveform (REW) components. The SEW
magnitude component is quantized using a hierarchical
predictive vector quantization approach. The REW magnitude is
quantized using a gain and a sub-band based shape. SEW and
REW phases are derived at the decoder using a phase model,
based on a transmitted measure of voice periodicity. The spectral
(LSP) parameters are quantized using a combination of scalar
and vector quantizers. The 4.0 kbits/s coder has an algorithmic
delay of 60 ms and an estimated floating point complexity of
21.5 MIPS. The performance of this coder has been evaluated
using in-house MOS tests under various conditions such as
background noise. channel errors, self-tandem. and DTX mode
of operation, and has been shown to be statistically equivalent to
ITU-T (3.729 8 kbps codec across all conditions tested.
Digital cellular telecommunications system (Phase 2+);
Technical realization of the Short Message Service (SMS)
Point-to-Point (PP)
(3GPP TS 03.40 version 7.5.0 Release 1998)
