tag:blogger.com,1999:blog-257781122011-12-14T19:02:53.021-08:00We talk about really technical things in this blog. This is primarily my personal note when I am studying my subject -- electrical engineering. This cover wide aspect of issues, including signal processing, RF and others. The first topic is image processing -- DCT, sub-band filtering and many others image processing released issue. If you have any thing to share, finding any mistake in my blog, please leave me a message.E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.comBlogger171100tag:blogger.com,1999:blog-25778112.post-1175568439885810502007-04-02T19:44:00.000-07:002007-04-02T19:47:19.886-07:00

It has been almost 6 months since I posted my last Blog. Adsense sent me a PIN code and that reminds me that I had a blog.. well and someone is reading it..I should have been constantly updating this blog so to make the content richer.

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1153726412569214742006-07-24T00:25:00.000-07:002006-07-24T00:33:32.576-07:00

CELP -- a voice compression technology.- 4.8kbps or 2kbps- 2 time-varying linear recursive filter* long-delay with 3 coeff, determined by minimizing the mean-squared prediction error after pitch prediction over a 5ms* short delay with 16 coeff, determined using weighted stabilized covariance method of LPC analysis once every 10ms- Instantaneous quantizer deteriorate at bitrate below 10kbps,

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1150170549003778542006-06-12T20:18:00.000-07:002006-06-12T20:49:31.710-07:00

These information is extracted from http://www.deviceforge.com/articles/AT5096801417.html802.11n- define modifications to the Physical Layer and Medium Access Control Layer (PHY/MAC)- high throughput, 100Mbps throughput at MAC SAP- backward compatibleWireless LAN Throughput by IEEE Standard IEEE WLAN Standard Over-the-Air (OTA) Estimates Media Access Control Layer, Service Access Point (MAC SAP)

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1149136438050638092006-05-31T20:57:00.000-07:002006-05-31T21:33:58.113-07:00

QoS(Quality of Service) issue- Delay caused by echo and talker overlap1) Echo* signal reflection by far end equipment* significant if round-trip delay > 50ms* removed by digital filter2) Talker overlap* significant if one way delay > 250ms* source of delayi) Accumulation delay/Algorithmic delayCaused by need to collect a frame of voice samples to be processed by the voice coderii) Processing

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1148280760407257902006-05-21T22:55:00.000-07:002006-05-21T23:52:40.446-07:00

This article is based on the work of Andreas Tonnesen in University of Oslo. Please visit to OLSR.org for full details and downloadableMANET (Mobile Ah-hoc NETworking)- GSM, WLAN: mobile nodes communicate directly with some centralized access point.- Constrast: multi-hop approach- Multi-hop: nodes can communicate by utilizing other nodes as relays for traffic- Challenge and major different is in

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1147671505293065282006-05-14T21:18:00.000-07:002006-05-14T22:39:39.990-07:00

Fuzzy Logic- provides a simple way to arrive at a definite conclusion based upon vague, ambiguous, imprecise, noisy, or missing input information- rule-based, example of rules is "IF (process is too hot) AND (process is heating rapidly) THEN (cool the process quickly)"- Command-feedback is known as error - Rate-of-change-of-error is known as dot-error- Error and dot-error were modified by the

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1146539835649618212006-05-01T19:55:00.000-07:002006-05-01T20:17:15.656-07:00

Terms and acronymsRM - reference modelIM - Implementation modelPDU - Protocal Data UnitLSAP - Link Service Access PointMSAP - MAC Service Access PointPhSAP - Physical Service Access PointAUI - Attachment Unit InterfacePMA - Physical Medium AttachmentMDI - Medium Dependent InterfacePHY - Physical layerSDE - Secure Data ExchangeMultiple-link service access points provide interface ports to multiple

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1146037975709154952006-04-26T00:24:00.000-07:002006-04-26T00:52:55.720-07:00

This is an interesting question:-Can a wi-fi device communicating with an AP while at the same time communicating with another wi-fi device via adhoc-mode (The two wi-fi devices are not talking via the AP)?I read an article on a technology, known as mesh networks.http://www.fujitsu.com/us/news/pr/fma_20020604-05.htmlhttp://www.wi-fiplanet.com/tutorials/article.php/961951I visited the website

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1145870906104162752006-04-24T01:53:00.000-07:002006-04-24T19:08:34.543-07:00

OSI/RM1.Application layer2.Presentation3.Session4.Transport5.Network6.Data Link7.PhysicalData Link-MAC address* MAC-48 specification, specify a 48-bit address. * An example of a MAC-48 address would be "00-08-74-4C-7F-1D"* MAC addresses are permanently attached to a product and are also known as burned-in addresses(BIA), "Universally Administered Addresses"(UAA) or Physical address* The first

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1145594006651169702006-04-20T21:28:00.000-07:002006-04-24T02:59:46.436-07:00

802.11 defines-the Physical and Data Link layerDate link layer is defined in two sub-layer-Logical Link Control -> 802.2-MAC -> 802.1TermsBSS, Basic Service Set- is 2 or more stations communication with each otherIBSS, Independent BSS or Ad-hoc Network- is a stand alone BSSDS, distribution system- connects 2 more more BSSESS, Extended Service Set- is a system of BSS connected with DSPortals-

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1145593685998207592006-04-20T21:13:00.000-07:002006-04-20T22:37:41.376-07:00

802- IEEE Standard for local and Metropolitan Area Networks- Packet based, transmission in sequence of data octets, length is variable> Contrast to cell, data in shorter, fixed-length unit> Contrast to isochronous, data as a steady stream of octets802.2- LLC, logical link control802.11 (Wi-fi)- Wireless Medium Access Control (MAC) and Physical layer specification802.16 (Wi-Max)802.11a - 5GHz,

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1145438679044693952006-04-19T02:22:00.000-07:002006-04-20T21:13:22.346-07:00

Dear readers,My boss wants me to source some of the wi-fi modules in the market, and if you know any good and cheap wi-fi module or any internet resource regarding to wi-fi, please leave me a message on this blog.Also I will be studying on wi-fi from now on.Thanks.e Duczer.

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1145347492549954562006-04-18T00:25:00.000-07:002006-04-18T01:05:46.586-07:00

- Was adopted in December 1990 for use in the Integrated Services Digital Network by CCITT Study Group XV.- Most of the international video coding standards, MPEG-1, MPEG-2/H.262 and H.264 are based on H.261. - Has a total latency for compression and decompression less than 150ms. - Bitrates are multiple of 64kbps, and is also known as p * 64 compression.In H.261, - Transformation block is 8 * 8

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1144745718665495572006-04-11T01:40:00.000-07:002006-04-11T02:05:46.283-07:00

JPEG- a flexible compression standard- defines a bit stream syntax- configuration of a variety of different buliding blocks- 8 x 8 2D DCT- uniform scalar quantization- Huffman or adaptive arithmetic coding> most implementation only support Huffman coding> conditional coding, i.e. code words and aritimetic probability tables depend upon a context> conditional coding of arithmetic coding is complex

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1144743978200039792006-04-11T01:10:00.000-07:002006-04-11T01:26:18.210-07:00

Predictive Feedback techniques improve the compression performance. - Delta Pulse Code Modulation (DPCM) are completely used feedback strategy. - only sending the difference of current data and some previously stored data via. - the difference in time of current data and previously stored data is know as displacement vector- also known as Conditional Replenishment (CR)- in Motion Compensation (

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1144660683708785382006-04-10T01:53:00.000-07:002006-04-10T02:18:03.716-07:00

The following is usually used to measure the performance of a image compression scheme.1) average bit per pixel, bpp- measure how much compression you can get.2) bit rates, bits per second, bps- important for implementation, higher bit rates require more memory and data transfer in implementation, lower the better.3) distortion- by mean of calculating the mean square error (MSE)4) robustness to

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0tag:blogger.com,1999:blog-25778112.post-1144658200859584502006-04-10T01:33:00.000-07:002006-04-10T02:19:24.380-07:00

We talk about really technical things in this blog. This is primarily my personal note when I am studying my subject -- electrical engineering. This cover wide aspect of issues, including signal processing, RF and others.The first topic is image processing -- DCT, sub-band filtering and many others image processing released issue. If you have any thing to share, please leave me a message.

E Duczerhttp://www.blogger.com/profile/18328140185980624245noreply@blogger.com0