This website uses cookies to ensure you have the best experience. Learn more

Convolutional Coding Essay

1494 words - 6 pages

Each parity bit is taken from the corresponding D FF then ran through an XOR gate that does the mod 2 addition to output the parity bit. This circuit creates a physical generator polynomial that the message is fed through, creating the encoded message.
Another method of encoding is done through a state table diagram. This is a diagram that tracks which parity bit is output depending on which state it’s in and which state it is transitioning to, which depends on the input bit received. To make our state diagram we first need to understand the parity bit equations above. We will make a 4 state diagram that makes it very simple to understand Convolutional encoding. To illustrate the example above we need a starting state, the start from which we haven’t yet received the message we want encoded. We call this state 00, which correspond to the bits we have received so far, and two bits because our constraint window is k = 3.

Starting in state 00, say we receive a 0, we will stay in this state since we received a 0 and the system is causal, making the parity bits output be 00. Now we receive a 1, we move to the next state 10, which is the order of the message bits received, and output parity bits 11. Now we’re in state 10, we receive a 0, we then move to state 01 and the parity bits will be 11. This is continued for the length of the message, at which the state diagram is reset and awaits a new message to start. You can tell that this type of encoding scheme needs two bits of memory to remember the present bit thats received and the previous bit, while the output still depends on the entered bit. This method of encoding can also be done using circuitry using shift registers and D flip flops as previously mentioned. Shift registers will not be covered in depth due to the complexity of the circuitry.
The receiver doesn’t know the path the encoder took to accurately replicate which state the encoder is in. This is left to the decoder that will be discussed in the next section that goes over maximum likelihood decoding and the Trellis diagram.

Convolutional decoding:

Convolutional decoding is most typically done in two ways, maximum likelihood decoding and using a trellis diagram, called Viterbi decoding. The problem is most decoding methods have no idea which series of states the state diagram used to encode the message, and the decoder has no idea whether the encoded message was altered in transmission. Since the decoder has no idea, it needs to make the best guess as to which message was sent. The decoder that picks the best possible or most likely is a maximum likelihood decoder. In order to know whether the encoded message was most likely, we must use the smallest Hamming distance to find the minimum distance between the transmitted and received message. We can only assume that the encoded message didn’t get irreversibly changed in transit as to most likely be another message. The problem with maximum likelihood decoding is that we must...

Find Another Essay On Convolutional Coding

Revolutionary Work of Art Essay

1890 words - 8 pages Walter Benjamin emphasizes in his essay, “The Work of Art in the Age of its Technological Reproducibility” that technology used to make an artwork has changed the way it was received, and its “aura”. Aura represents the originality and authenticity of a work of art that has not been reproduced. The Sistine Chapel in the Vatican is an example of a work that has been and truly a beacon of art. It has brought a benefit and enlightenment to the art

Enlightenment Thought in New Zealand Schools

1594 words - 6 pages In this essay I will be looking at how the political and intellectual ideas of the enlightenment have shaped New Zealand Education. I will also be discussing the perennial tension of local control versus central control of education, and how this has been affected by the political and intellectual ideas of the enlightenment. The enlightenment was an intellectual movement, which beginnings of were marked by the Glorious Revolution in Britain

Psychological Egoism Theory

2240 words - 9 pages The theory of psychological egoism is indeed plausible. The meaning of plausible in the context of this paper refers to the validity or the conceivability of the theory in question, to explain the nature and motivation of human behavior (Hinman, 2007). Human actions are motivated by the satisfaction obtained after completing a task that they are involved in. For example, Mother Teresa was satisfied by her benevolent actions and

How Celtic Folkore has Influenced My Family

1587 words - 6 pages Every family has a unique background that influences the way they live and interact with other people. My parents, who emigrated from Ireland to the States with my three brothers in 1989, brought over their own Celtic folklore and traditions that have helped shaped the way our family operates and lives. One aspect of folklore that has helped shape my family dynamic is the Celtic cross—both its background and what role it has played in our lives

Julia Margaret Cameron

1406 words - 6 pages At a time when women were looked upon as being homemakers, wives, mothers and such the late 1850's presented a change in pace for one woman in specific. Photography was discovered in 1826 and soon after the phenomenon of photography was being experimented with and in turn brought new and different ways of photo taking not only as documenting real time, but also conceptualizing a scene in which an image would be taken. Julia Margaret Cameron will

Evaluation of School Improvement

1403 words - 6 pages The evaluation process should be progressive to incorporate overall planning, implement changes, which contribute to success. In order to focus on school climate and norms, the evaluation design must include the students, instructions, and outcomes to improve communication and building-level concerns to be address in this response. School Climate and Social Norms The school principal, other staff leaders, and personnel set the tone and the

Case Study: The Benefits of Animal Testing

1757 words - 7 pages Nine year old Amy has already had a rough start in life. She was born with an abnormal heart that hinders her everyday activities. Amy is unable to keep up with kids her own age because she often tires out easily. As a consequence, she has very little friends and is often alone. Amy is forced to take different medications everyday just to survive. Amy’s life consists of medicine, doctors, and constant hospital visits. However, Amy is due for a

Myth and Magic: Realism in "One Hundred Years of Solitude"

1531 words - 6 pages “He enjoyed his grandmother's unique way of telling stories. No matter how fantastic or improbable her statements, she always delivered them as if they were the irrefutable truth” (Wikipedia, 2011). Experiences are particular instances of one personally encountering or undergoing something and in these moments of time life changes for the best or the worst and memories are formed. These recollections such as riding your first bicycle, going to

Adiponectin: a Novel Indicator of Malnutrition and Inflammation in Hemodialysis Patients

2384 words - 10 pages Objective Protein-Energy malnutrition (PEM) and inflammation are common and overlapping conditions in hemodialysis patients which are associated with increased risk of morbidity and mortality. Adiponectin is an adipocytokine which is exclusively produced by adipose tissue. Few studies in hemodialysis patients have demonstrated that serum levels of adiponectin were significantly higher in malnourished patients compared to well-nourished ones. The

The Congo Free State: A Legacy of Apathy, Exploitation and Brutality

2298 words - 9 pages Between 1885 and 1908, Belgium’s Leopold II ruled Congo, a region in central Africa, as his personal colony, exploiting the resources and inhabitants for his own gain. Leopold allowed and encouraged Europeans and other Westerners to enter Congo and set up companies whose primary purpose was to gather rubber, which was abundant but difficult to get to in the Congo, using the Congolese as the laborers for the Europeans. Rubber gathering in Congo

Selective Exposition in The Lottery, by Shirley Jackson

1073 words - 4 pages Usually when someone hears the word “lottery” the first thing that comes to mind is a large sum of cash that people compete against highly impractical odds to win. Shirley Jackson’s story The Lottery might imply a similar conception based on the title alone, but the story is filled with unknowns never revealing exactly when and where the story takes place, or why the lottery exists; even what the lottery is isn’t revealed until the very end. Yet

Similar Essays

Convolutional Coding Essay

1374 words - 5 pages : As mentioned earlier, convolutional codes only transmit parity bits which are later decoded by the recipient. Above shows an example that illustrates the use of parity equations, but now we will go over what governs parity bit equations as well as why it’s called convolutional coding. The example above uses the equations below. All Additions are modulo(2) Above are the parity bits for a code with a rate of ½. To help illustrate parity bit

Analysis Of A Transmission Model

657 words - 3 pages . III. Space-Time Trellis Codes Space–time trellis codes (STTCs) are a type of space–time code employed in multiple-antenna wireless communications. This scheme transmits multiple, redundant copies of a trellis (or convolutional) code distributed over time & a number of antennas ('space'). These multiple, 'diverse' copies of the data are employed by the receiver to attempt to reconstruct the actual transmitted data. For an STC to be employed

When The Bubble Burst Essay

1539 words - 6 pages By the time I arrived state side from my second tour in the Middle East the housing bubble had already burst. I noticed a drastic change in the way that many of my friends and family were living. Several of my friends that worked in real estate had sold their boats and seconds houses. My own stock portfolio had lost a third of its value. My sister and her husband had defaulted on their home mortgage leaving them scrambling for a place to live. I

Phase Diagram Essay

4456 words - 18 pages Introduction: Chemical equilibrium is a crucial topic in Chemistry. To represent and model equilibrium, the thermodynamic concept of Free energy is usually used. For a multi-component system the Gibbs free energy is a function of Pressure, Temperature and quantity (mass, moles) of each component. If one of these parameters is changed, a state change to a more energetically favorable state will occur. This state has the lowest free energy