Archive for December, 2009

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The anatomy of a modern audio-video amplifier

Wednesday, December 30th, 2009

A modern Audio-Video amplifier/receiver (AVR) is an exceedingly complex piece of consumer electronics, requiring expertise in many aspects of analogue and digital audio and high definition video, plus considerable software skills. ‘The anatomy of a modern audio-video amplifier’ lecture by John Dawson from Arcam for Audio Engineering Society UK is an interesting talk on engineering related to home theater amplifiers. This lecture takes a look inside the Arcam AVR600 (one of the few such units developed outside of the large Japanese consumer electronics companies) and will discuss some of the design choices made in order to try to ensure a good chance of commercial success. You can download the lecture in MP3 format.

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The main points in talk are that designing a home theater amplifier is a paradox. The amplifier should be cheap to sell well. On the other hand it should be expensive to be well made (it is a very complex device). The amplifier should be designed quickly (so that it is not outdated when comes to quickly changing markets) but the design should be free of bugs. The amplifier should have all the newest features in it, but it should also be as simple as possible to sound good and be easy to use.

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Image source: Arcam AVR600 web page

Posted in Audio and Video, Electronics Design, Products | 46 Comments »

Happy Birthday, Linus

Monday, December 28th, 2009

Happy Birthday, Linus article tells that today December 28th is the birthday of Linus Torvalds, the creator of Linux operating system kernel. The article tells that the birthday has an interesting historical link to the creation of the Linux kernel, too. Some of the funds for buying the Linus’s first PC arrived in the form of birthday presents. The specification of that year 1991 PC were rather sobering: 386, DX33, 4 Megs of RAM, no co-processor, 40 Megs hard disc. Somewhere around March-91, Linus had a 386 system running Minix-386. He then started to write his own software that evolved to Linux. Thank you for Ari Lemmke for creating pub/OS/Linux subdirectory at nic, and thus also gave the system it’s name.

It’s truly extraordinary to contemplate that Linus’s “glorified “Hello world” program” is now running nearly 90% of the world’s top supercomputers and increasing number of smart-phones. Indeed, it is difficult to imagine what the world would be like today had Linus not bought that PC in 1991 with his Christmas and birthday money.

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Posted in Computers | 16 Comments »

Blu-ray 3D specification

Monday, December 28th, 2009

The Blu-ray Disc Association has completed its specification for 3D video. The specification was completed just few days before Christmas. It standardises the inclusion of stereoscopic 3D content on Blue-ray Disk. According to BDA the 3D video system doesn’t depend on any specific 3D technology – active-shutter or polarised lens – or display type. The material will be presented in resolutions up to and including 1080p.

The BDA’s spec mandates encoding 3D video using the Multiview Video Coding (MVC) codec, an extension to the H.264 Advanced Video Coding (AVC) codec currently supported by all Blu-ray Disc players. This codec will need around 50% more data rate / storage space for 3D video compared to 2D video. MPEG4-MVC compresses both left and right eye views with a typical 50% overhead compared to equivalent 2D content, and can provide full 1080p resolution backward compatibility with current 2D Blu-ray Disc players.

The specification provides a way for existing Blue-ray players can take the new 3D content and display it in 2D form at 1080p. This will allow Hollywood to release 3D movies in place of 2D version without pissing off the installed base – assuming it doesn’t charge an unreasonable premium for the material, of course. Maybe just wishful thinking keeping in mind the history of Hollywood pissing off with paying customers with DRM and other artificial restrictions…

There is also some existing Blue-ray players that work with 3D system. The Blu-ray 3D specification is designed so that it allows Sony PS3 game consoles to play back Blu-ray 3D content in 3D.

This kind of 3D as used in 3D Blue-ray is not like a hologram, it is more like a viewmaster. I have seen many 3D video systems and played with 3D technologies in the 1990’s, and everything I have seen didn’t really feel like I was looking at the real world, but something “artificial”. I am still waiting to be amazed by 3D video some day.. I was really amazed by some 3D photos and computer graphics around 15 years ago when I saw then first time and had possibility to play with them. Nowadays 3D video seems to be mostly recycling the same old ideas and same limitations. 3D can be entertaining and look cool on special uses where the presented video content is designed in such way that the limitations of the technology can be hidden… My quess is that 3D will not overtake the traditional 2D video anytime soon…

Posted in Audio and Video, Entertainment Technology | 227 Comments »

Macy’s Holiday Light Show Technology

Monday, December 28th, 2009

Control Geek blog posting Backstage at the Macy’s (Wanamaker’s) Light Show shows you what technology is used to run one large commercial light show.

Posted in Audio and Video, Entertainment Technology | 23 Comments »

Cool Computer Keyboards

Monday, December 21st, 2009

Computer keyboards are peripherals partially modeled after the typewriter and designed both for the input of text and characters and also to control the operation of a computer. Keyboards can arrive in many shapes or sizes. 14 Cool Computer Keyboards for Geeks shows you a set of extraordinary and interesting computer keyboard designs currently available in the market.

Posted in Computers, Products | 24 Comments »

Christmas-tree light testing

Friday, December 18th, 2009

Simple tester checks Christmas-tree lights article gives you ideas how to test mains powered Christmas lights. The article presents a simple test circuit. Some more testing ideas can be found at Christmas Lights and How to Fix Them web page.

LED lights are becoming more and more popular for common in Christmas lights for many good reasons. They consume considerably less energy than traditional light bulbs and fail much less often. If you LED lights fail, you can find ideas how to fix then at LED Christmas Lights and How to Fix Them web page.

Posted in Entertainment Technology, diy | 100 Comments »

Christmas Light Hero

Wednesday, December 16th, 2009

What do you get when you mix a Christmas Light show with Guitar Hero? Christmas Light Hero! A real game you play with a wii wireless guitar controller. Christmas Light Hero video shows an amazing Christmas Light show with Guitar Hero.

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Posted in Entertainment Technology | 8 Comments »

Computerized christmas lights

Sunday, December 13th, 2009

Do It Yourself Computerizing web page gives idea how to control christmas lights using PC. This web page presents several different technologies to use computer to control lights. If you are interested in the topic after this, it is a good idea to go to ePanorama.net Home Automation forum and read the articles archive there.

Posted in Computers, Entertainment Technology, diy | 8 Comments »

How an expensive Blue-Ray player is made

Friday, December 11th, 2009

AV Science Forum has an interesting posting on Ayre DX-5 blueray player. The article claims that Ayre DX-5 bluray player is a modified Oppo BDP-83 blueray player and even describes the modifications made to the device. Interesting article indeed to read, although I am a pretty skeptic would those modifications be worth of all of the money they cost (from $500 to $10000). Maybe for someone, or maybe not…

Some picks from article:
“Well, first of all you have to remember that we don’t have to pay $500 for the unit.”
“Then to make it an Ayre, we dismantle it completely and recycle everything except the main PCB (with the video decoder, ABT scaler chip, and HDMI transmitter), the transport mechanism, the VFD display, and the remote control handset.”
“All of the supplies are replaced with pure linear supplies with analog regulators.”
“Next, we replace the low-quality master video clock with a VCXO.”

End comment: “If you want a great Blu-Ray player for an incredible price, buy the Oppo. If you want the best picture and sound quality in the world for your home theater and price is not a concern, check out the Ayre. And no, it will not be available in November, sorry. Early next year will be a better guess.”

Another article on the same topic is Ayre DX-5 at $10,000 is a rebadged $500 OPPO.

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Posted in Audio and Video, Products | 208 Comments »

Ground Loops and Returns in instrumentation

Tuesday, December 8th, 2009

Proper ground configuration is essential for a good data acquisition system. Most measurement systems such as data acquisition devices allow for many different types of ground configurations depending on the type of signal being acquired or measured. This flexibility is the source of confusion when deciding which configuration to use in each specific situation.

National Instruments tutorial Ground Loops and Returns teaches you to select the right configuration to use. Here is the material from the document related to ground loop problems in condensed format:

A grounded signal source is one in which the voltage signals are referenced to a system ground, such as earth or building ground. The most common examples of grounded signal sources are devices, such as power supplies, oscilloscopes, and signal generators that plug into the building ground through a wall outlet. The difference in ground potential between two instruments connected to the same building ground system is typically 10mV to 200mV, or even more (up to several volts at normal use and tens of volts during short circuit surges).

Single ended is the “default” configuration for most data acquisition devices, modular instruments, and stand-alone devices. Single-ended systems are very susceptible to ground loops. There are essentially two main types of Single-Ended measurement systems: Ground Referenced Single Ended (GRSE) and Non-Referenced Single-Ended (NRSE).

An ideal differential measurement system reads only the potential difference between the positive and negative terminals of the amplifier and thus it completely rejects common-mode voltages. However, practical devices are limited in their ability to reject common-mode voltage.

A grounded signal source is best measured with a differential or non-referenced measurement system.

The pitfall of using a ground-referenced measurement system to measure a grounded signal source is that grounding potential difference between signal source and measuring system causes a current called ground loop current to flow in the interconnection which can greatly affect measurements causing offset errors, especially when measuring low level signals from sensors.

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Image source: http://zone.ni.com/devzone/cda/tut/p/id/3394

Posted in Groundloop | 12 Comments »

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