Access technologies : DSL and cable by James H. Green

By James H. Green

Show description

Read or Download Access technologies : DSL and cable PDF

Best professional books

Case Studies in Emergency Medicine

A case-based ebook geared up by way of the pinnacle 10 universal lawsuits of sufferers proposing to emergency departments. This procedure permits the reader to benefit the pathophysiology of the main illnesses, and research every one case in a fashion that extra heavily approximates the scientific perform of drugs; no longer realizing which organ process is broken or compromised ahead of interpreting the sufferer.

Core Clinical Cases in Paediatrics: A Problem-Solving Approach

Center medical situations courses you to consider the sufferer as a complete, instead of as a series of unconnected indicators. With its functional method strongly associated with underlying concept, the sequence integrates your wisdom with the realities of coping with scientific difficulties, and gives a foundation for constructing problem-solving talents.

Kaplan Medical USMLE Flashcards: The 200 Diagnostic Tests You Need to Know For Steps 2 & 3

This robust learn device includes:4-color flashcards in laminated five x 7 formatPictures or vignettes with questions about one aspect, with solutions at the backCrucial info for making right diagnosesThe most often visible diagnoses that seem at the USMLE Steps 2 and 3 examsAdditional on-line Author Podcast

The iPad Book Vol. 5

No matter if you personal an iPad, iPad Air or iPad mini, the hot quantity of The iPad e-book is the fitting significant other. it's going to advisor you thru the entire inbuilt apps, exploring the main easy features and the extra complex positive factors in easy-to-follow tutorials. We actually have a entire advisor to iOS eight, Apples most recent working method.

Extra resources for Access technologies : DSL and cable

Sample text

Voice can be compressed to 8 kbps with only a small loss of intelligibility. The quality is equivalent to a solid cell phone connection. The protocols add some overhead, so the number of channels is less than a straight multiple of the compressor output, but the voicecarrying capacity is substantial. Note, however, that faxes and modems require an uncompressed channel. The amount of bandwidth the voice channel occupies depends on the protocol used. ATM is the most common protocol. With 5 bytes of header per cell, the overhead is approximately 10 percent.

Telephone Electrical Concepts To understand why access technologies behave as they do, it is necessary to have some appreciation of electrical terms. Any circuit, such as a twisted-wire cable pair or a coaxial cable, has inherent electrical characteristics such as resistance and impedance. Direct current flows in a predictable manner in response to Ohm’s law, which states that the amount of Telephone Local Loop Characteristics 41 current flow is directly proportional to the voltage or electrical pressure and inversely proportional to the resistance.

Any UHF channels in the area were applied to a vacant VHF channel on the cable. Gradually, however, cable systems were expanded to the Cable Access Technology 65 point that the typical system today has a bandwidth of 1 GHz, of which the top 250 MHz is reserved for future applications, leaving room for about 100 channels. An analog cable system could amplify signals to extend the range almost indefinitely, except for the problems of noise and distortion, which limit the serving radius of 80channel CATV to about 8 km from the headend.

Download PDF sample

Rated 4.22 of 5 – based on 16 votes