Archive for the ‘Audio and Video’ Category

Cat 5 Cable Modeling

Thursday, September 22nd, 2011

Category 5 (CAT5) cable is a multi-pair (usually 4 pair) cable that consists of twisted pair conductors, used mainly for data transmission. Basic CAT5 cable was designed for characteristics of up to 100 MHz. Newer CAT6 cable is designed form 250 MHz. Nowadays there are applications where those cables is used to carry higher frequencies.

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Cat 5 Cable Modeling for DVI/HDMI links tells how to analyze the cable performance. The behaviour of each twisted pair is determined by the complex three-dimensional
electromagnetic field in the region within and surrounding the cable. For communications link performance verification we require a simplified representation of the cable that is computationally viable and can be included within the circuit verification environment. The model also needs to correctly represent important cable parameters such as delay, near and far end crosstalk and cable losses.

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Cat 5 Cable Modeling for DVI/HDMI links article gives a simple C++ module was written and added to the CppSim behavioural modelling environment. The article also gives a Hspice ‘W’ model.

The combination of field solver and multi-conductor W model in Hspice can be used to simulate all the key signal degradation characteristics such as frequency dependent loss, delay, near and far end coupling and the effect of discontinuities for different UTP cable geometries.

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Video coat

Friday, September 16th, 2011

Friday special: Groovy Video Coat video I found on Internet:

More details on electronics can be found on Groovy Video Coat pictures and this Video Coat Prototype video:

Webkit-based UI for TV devices

Thursday, September 15th, 2011

Netflix’s Webkit-based UI for TV devices article says that Netflix uses WebKit, JavaScript, HTML5, and CSS3 to build user interfaces that are delivered to millions of game consoles, Blu-ray players, Internet-connected TVs, and devices.

Matt McCarthy and Kim Trott, device UI engineering managers at Netflix, have just published 50 presentation slides from their recent talk at OSCON 2011 in which they explained how Netflix develops its Webkit-based user interfaces. The slides are accompanied by detailed speaker notes.

This stuff is interesting because of the challenges of developing the interface for a wide variety of platforms with vastly differing capabilities. Different platforms have different needs and capabilities. In the slideshow, they acknowledge there are differences between platform UI needs, but they seem to try a one-size-fits all approach.

I saw this slide set first mentioned at Inside Netflix’s WebKit-Based UI For TV Devices posting at Slashdot.

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Power Quality Symptoms & Solutions

Monday, September 5th, 2011

Power Quality Symptoms & Solutions e-book is is written from an electronics point of view, rather than a power engineering one. And in so doing, provides the bridge between theory and real life. According to the book introduction more and more lecturers are using this material as a reference in their courses. You can find lots of interesting reading here for many industry fields and links to other resources.

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Weird Voltages in a PoE Camera System

Friday, August 12th, 2011

It seems that there is a trend to convert video systems over from an old, all-analog system to a modern, IP-based system with cameras powered over the Ethernet line using PoE (Power over Ethernet).

Weird AC Voltages in a PoE Camera System post at Control Geek Blog talks about an interesting PoE (Power over Ethernet) issue I found with some IP cameras and some switches.

Weird AC Voltages in a PoE Camera System–Followup gives some more details and analysis of the problem. And if you are really interested in the details check also Interesting PoE problem discussion at The Show Control Mailing List.

Seen at Assembly 2011

Sunday, August 7th, 2011

The stand for Ubuntu Linux also had some Meego people showing that Meego is still going wrong. I got my hands on the Nokia N9 prototype version (I did not get permission to take picture of it). There was also Intel Meego tablet reference platform shown on the stand. The MeeGo people from Nokia were not allowed to tell any interesting details of their MeeGo plans…

I visited the Assembly TV premises to catch up what they are doing this year and meeting the friends there. This year the broadcasting system was almost completely in HDTV format, including the cameras for main broadcast (seminars still used standard definition video). HDTV video editing and playback was done mainly using Apple computers (proven to work in this application better than PC based systems). Technology to transfer video between devices was mainly HD-SDI, DVI (over fiber optics) and Ethernet. Audio connections used RockNet technology. RockNet real-time, low latency audio distribution network using CAT5 cable. RockNet can link up to 99 devices into a single network comprising 160 audio channels. The network is self-healing for single connection failures.

Helsinki Hacklab had an interesting stand with all kinds of robots and electronics hacks. At the same stand there were also Tampere hackerspace 5w and Hacklab Turku. It is good to see that there are forming groups of people who hack things together. This is one robot on the stand. It is based on RC servos connected with servo card and Python program running on PC.

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metku.net stand had also this year some interesting hardware hacks shows. This is one interesting case for a PC.

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I met Kristoffer Lawson at Assembly. He told about his new on-line banking project Holvi. Holvi in essence is a new way to do online banking. With Holvi, small groups are able to tag each payment in certain ways so that a clear overall picture is formed and thus it helps these groups to better understand how their money is spent and received. This should pretty much makes bookkeeping redundant for smaller organizations and groups. Holvi is a great example of a team sticking to their guns and building upon their core expertise. There is much of Scred in there, but the shift in approach.

The main demo competition and 4kilobytes intro competitions were again high quality. You can find the entries at Assembly Archive. Some coders are really making wonders with their code.

New tech fails to drive new TV set sales

Thursday, June 9th, 2011

TV manufacturers try to put in all kind of new technical gimmicks to their products. Top telly tech fails to drive new set sales. The technologies telly makers are promoting in a bid to persuade punters to replace existing TVs are failing to excite consumers: LED backlight technology, internet connectivity and 3D. LED was the strongest driver, followed by internet access and, a very long way from the average, 3D (only four per cent of Q1 telly shipments).

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Entering The Minority Report Era?

Monday, May 16th, 2011

Stephen Spielberg’s Minority Report (released nearly 10 years ago) captured the imagination of many in the technology space. Today we are seeing some things from the movie start to come true right in front of our eyes today. Entering The Minority Report Era: A Video Series article shows some examples of those technologies. The video collection in this article is quite large, so expect to spend some time with this interesting material.

Fractals without a Computer!

Friday, May 13th, 2011

A fractal is a figure with a self-similar pattern. Usually the fractals are calculated with a computer, but is is possible to produce Fractals without a Computer! It’s very cool – partly because it looks neat, but also partly because it shows you something important about fractals.

Optical video feedback is a well-known phenomenon. If you hook a camera up to a TV and then point it at the TV, you get an infinite regression of images. I remember playing with this effect at 1980’s when first time playing with video camera. You can get some interesting effect in this way (was cool at that time, nothing spectacular at today’s standards when computer special effects are widely used in videos).

This video shows that you can use the same feedback phenomenon with multiple displays to make fractals.

Audio, Distortion and Feedback

Monday, April 18th, 2011

Audiophiles seem to revel in minor controversies – vinyl vs CD’s, tubes versus solid state, capacitor, wires, magic dots… and negative feedback. At one extreme (“objectivists” and engineers), the position is that “feedback makes amplifiers perfect”. At the other extreme (“subjectivists”) usually claim that “feedback is a menacing succubus that sucks the life out of the music, leaving a dried husk, devoid of soul”. Accusations are occasionally made that objectivists can’t hear, and conversely that subjectivists hear things that aren’t there.

Audio, Distortion and Feedback document has some some simple tutorial, comments and a discussion of phenomena associated with complexity in distortion created by nonlinear gain stages, negative feedback, and the audio signal. This is good reading for anybody interested in audio and electronics.

Negative feedback is very successful in stabilizing amplifier circuits and lowering distortion to very tiny numbers as measured by distortion analyzers. Feedback needs to be used in the right way to avoid Transient Intermodulation Distortion (TIM), also called slew rate distortion. In high quality modern amplifiers the open loop response is at least 20 kHz, canceling TIM distortion.

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