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Reducing Line Loss

Reducing Line Loss

In a three-phase circuit, line loss is an indicator of energy dissipated as heat due to the resistance of transmission lines. To address this, incorporating transformers into the system—a step-up transformer at the source and a step-down transformer at the load—is a strategic solution. Two three-phase transformers are introduced to improve this.
With a step-up transformer at the source, the voltage is increased, thereby reducing the current in the transmission lines since power loss in...

Upsampling

Upsampling

Managing signal sampling rates is essential in digital signal processing to maintain signal integrity. A decimated signal, characterized by a reduced frequency range due to its lower sampling rate, can be upsampled by inserting zeros between each sample. This upsampling process expands the original spectrum and introduces repeated spectral replicas at intervals dictated by the new Nyquist frequency. To refine this zero-inserted sequence, it is passed through a lowpass filter with a cutoff...

Downsampling

Downsampling

When considering a sampled sequence with zero values between sampling instants, one can replace it by taking every N-th value of the sequence. At these integer multiples of N, the original and sampled sequences coincide. This process, known as decimation, involves extracting every N-th sample from a sequence, thereby creating a more efficient sequence.
The Fourier transform of the decimated sequence reveals a combination of scaled and shifted versions of the original spectrum. This...

Boundary Conditions: Lossless Lines

Boundary Conditions: Lossless Lines

Consider a single-phase, two-wire, lossless transmission line terminated by an impedance at the receiving end and a source with Thevenin voltage and impedance at the sending end. The line, with length, has a surge impedance and wave velocity determined by the line's inductance and capacitance.
At the receiving end, the boundary condition states that the voltage equals the product of the receiving-end impedance and current. This relationship is expressed as a function of the incident and...

Lossless Lines

Lossless Lines

In electrical engineering, a lossless transmission line is characterized by a purely imaginary propagation constant and a resistive characteristic impedance. The ABCD parameters, which describe the relationship between the input and output voltages and currents, indicate an equivalent π circuit with an imaginary series impedance and a shunt admittance. This results in a transmission line that, when the product of the phase constant (beta) and the length of the line is less than pi, exhibits...

Lossy Lines and Overvoltages

Lossy Lines and Overvoltages

Transmission-line series resistance and shunt conductance cause three primary effects: attenuation, distortion, and power losses.
Attenuation
When constant series resistance and shunt conductance are present, voltage and current equations are modified. The propagation constant indicates that voltage and current waves consist of both forward and backward traveling components. These waves attenuate as they propagate, with the attenuation factor related to the resistance and conductance. In a...

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Related Experiment Videos

Improved lossless intra coding for H.264/MPEG-4 AVC.

Yung-Lyul Lee¹, Ki-Hun Han, Gary J Sullivan

¹Department of Computer Engineering, Sejong University, Seoul, Korea 143-747. yllee@sejong.ac.kr

IEEE Transactions on Image Processing : a Publication of the IEEE Signal Processing Society

|September 5, 2006

Summary

A new lossless intra coding method enhances H.264/MPEG-4 AVC by using sample-by-sample differential pulse code modulation (DPCM) for improved bit rate reduction. This advanced technique offers significant data compression without increasing complexity.

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Area of Science:

Digital video compression
Image and video coding standards

Background:

H.264/MPEG-4 AVC standard utilizes multidirectional spatial prediction for intra coding.
Existing methods reduce spatial redundancy by predicting samples within data blocks.

Purpose of the Study:

To introduce a novel lossless intra coding method enhancing the H.264/MPEG-4 AVC standard.
To improve compression efficiency for lossless intra prediction.

Main Methods:

Implemented sample-by-sample differential pulse code modulation (DPCM) for spatial prediction.
Retained block structure for residual difference entropy coding.

Main Results:

Achieved approximately 12% bit rate reduction compared to the previous H.264/AVC lossless intra coding method.
Demonstrated minimal complexity penalty despite pipeline dependencies.

Conclusions:

The new samplewise DPCM-based lossless intra coding method offers superior compression efficiency.
The method is being adopted into the H.264/AVC standard due to its performance benefits.