Digital TV does not live up to Analog broadcast.

February 21st, 2009

Well, this isn’t such a big surprise to me, but there’s a very insightful article on EDN, about the new DTV system, which does not live up to the hype, and largely fails to serve the public interest: Digital TV, close but no cigar.

A couple of salient points from the article:

- DTV signals do not propagate well, as they are not robust against signal degradation. Analog TV signals degrade gracefully as signal strength weakens – the critical parts of the signal are strong, so the broadcast remains usable even with very poor reception. DTV on the other hand is all-or-nothing. If signal quality is insufficient to permit recovery of the data stream without errors, it cannot be decoded at all, so both audio and video cease to function. In addition, maximum transmit power will decrease, further reducing the effective range of DTV stations. The result, compounded by poorly conceived / deliberately biased propagation studies, is that actual broadcast coverage will seriously decline relative to the existing analog system. Poor DTV reception will force many people to give up and switch to (non-free) cable or satellite.

- DTV is not backward compatible with older technologies, rendering useless a lot of existing equipment, and more disturbingly, part of our society’s emergency communication infrastructure (portable TV sets used during natural disasters, etc).

- Simple, public-domain technology can no longer be used to receive a TV signal. Instead, complex digital ASICs encumbered with an array of patent and licensing issues are required. This serves only the interests of the patent holders (the “Grand Alliance”), whom the FCC foolishly put in charge of creating the new system.

- The newly cleared spectrum has not been retained for public use, but instead sold off for exclusive commercial use, arguably constituting a hidden tax.

The article goes on to summarize the major grievances. “In short everybody wins, except the public.”

From my perspective, perhaps the only (partially) good thing to come out of this will be unlicensed use of TV band “white space”. The scheme involves a good deal of unnecessary complication to manage authorized frequencies by geographic location, and will likely suffer significant interference difficulties anyway. I’d much rather see the creation of a dedicated swath of spectrum for unlicensed use.

Samuel Groner’s Analogue Audio Design Website

February 20th, 2009

SG-Acoustics. Chock full of great stuff. Especially his paper on op-amp distortion!

Scrounging – how to get good stuff!

February 7th, 2009

One post every three months?  Oh well, I suppose it could be worse…

Something every analog circuits junkie knows (or should know!) is how to scrounge. Yes, it’s possible to build a hobby around 100% new parts and equipment, bought at retail. But you won’t get much for your dollar, and boy, you’re missing a huge world of opportunity! There is so much great stuff available surplus, it’s ridiculous – with some careful scrounging, the average person can afford truly top-notch test equipment and the very best quality electronic parts, including plenty of stuff that is either no longer produced, or has no contemporary equivalent.

While the inexorable march of technological progress continues to bring us fantastic new capabilities, it has not always meant continual improvement. Rather, the world of technology is driven by commercial interests – many of the best technologies can no longer be produced, simply because it is not profitable in today’s globalized, consumer-driven economy. In decades past, very different competitive pressures (including a huge military industry fueled by cost-no-object cold war spending) and a smaller scale of production meant component parts and entire systems were often engineered to perfection, and finely crafted. A slower rate of change meant things were built to last. Yet despite tremendous advances in the underlying science, the dawn of the digital age and decimation of domestic manufacturing have forever changed the market for precision analog technologies. Much of it has been supplanted by mass-produced, cheap devices which are “good enough”, while digital sophistication enables designers to work around the limitations of low grade components – quality flaws can now be calibrated out with ease.

Fortunately for the hobbyist, this means that now you can find an array of top-quality surplus parts at a fraction of the original cost. “Obsolete” yet perfectly serviceable test equipment from first-class brands like HP and Tektronix can be had for near scrap prices. Combining the best technology of the past with modern computing power and digital techniques opens a vast world of possibilities for the hobbyist.

I could go on, explaining all of the ins and outs of scrounging for tech surplus, but I’d be hard pressed to do any better than Bruce Lane’s excellent website: So you want to be a Scrounger… and The Wonderful World of Scrounging!

Hello world!

November 16th, 2008

Well, here it is – the inaugural post on my new website. I haven’t maintained a website in years, and probably don’t really have the time for it, but what the heck. I’ve been wanting a place to document and share my hobby for some time now.

There’s not much here yet, but over the coming months, I’ll try and post some permanent pages with useful technical references, and details about the projects I’ve built, or am currently working on.