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Editors' Note—Volume 42, Number 3, 2008
FINGERPRINTS, BLOOD, AND DEFECTIVE RAILS
Whether you access a computer, enter a secure building, or go on a trip, biometric sensors simplify effective identification. Fingerprinting has a long history of unique identification for individuals; modern scanning equipment eliminates inky fingers and delays in verifying ID. See the article on Page 3 for insights into sensors, feature extraction, pattern matching, and decision making in fingerprint-based equipment.
Blood forms clots to end bleeding at an injured site—a good thing, unless the site is involved in a surgery where blood must keep flowing, as in a heart-lung machine during heart-bypass surgery. In such instances, an anticoagulant is administered during surgery; but the process must be rapidly reversed at the end of the surgery. In controlling the process, it is important to know when coagulation is actually occurring. Coagulation monitoring, see Page 7, uses impedance measurement to provide rapid, automated data—aiding patient safety, workflow, and decision making—and leads to improved outcomes.
Effective, efficient, reliable rail transportation with comfort and safety depends on the soundness of fixed infrastructure, such as rails and roadbeds. This is especially relevant in urban public transportation, with its stresses of rapid acceleration and deceleration. Starting on Page 10, we describe how a new systematic maintenance approach—now going into use in Europe—makes it possible to measure, locate, and fix rail- and tramway defects early on. Key to its effectiveness are mature railway-engineering know how and cutting-edge automated technologies, including Blackfin processors, satellite-based location, detailed record-keeping, and graphical system design techniques.
FOURSCORE
As the 3rd quarter of 2008 ends, we (Dan) have completed another year—our 80th—of breathing Earth’s air, of processing food, beverages, images, sounds, smells, tastes, shapes, temperatures, feelings—and ideas. Coincidentally, as the first quarter of 2009 begins, a two-score stretch (half) of those years, will have been in the service of Analog Devices and the readers of this Journal—and perhaps even their children and/or parents.
We came to ADI after nearly a score of years at George A. Philbrick Researches, Inc. There, originally immersed in analog computing technology and applications, our later publications and products established a market for plug-in operational amplifiers as versatile precision circuit components—a market that in time grew to be dominated by Analog Devices.
Our mission, on joining ADI in 1969—besides the Dialogue, then in its 3rd year (now nearing 42 years in print and 10 online), was to assemble a book that would educate a world of unsuspecting (and some yet unborn) engineers about the nature, applications, pitfalls, and minutiae of analog-to-digital and digital-to-analog converters. The Analog-Digital Conversion Handbook, published in 1972, coincided with a line of converters based on Jim Pastoriza’s precision IC quad current source. That combination sparked a market in which ADI’s data-converter leadership and dominance has grown continuously over the years.
Soon Barrie Gilbert joined us—and Lew Counts—in advocating long-simmering ideas from early Philbrick days about market possibilities for instrumentation circuits with analog computing elements: multiplying, logarithmic, and rms devices. Subsequent publication of the Nonlinear Circuits Handbook led to ADI’s primacy in this somewhat recondite area of analog technology.
Exploiting a fundamental semiconductor property, proportional to absolute temperature (PTAT), led to the introduction of precision temperature-measuring ICs (and their corollary: temperature-insensitive voltage references) and inspired publication of the Transducer Interfacing Handbook.
The watershed books mentioned above are out of print (but perhaps yet available via Amazon.com). ADI’s applications engineers continue to produce timely books in support of our technologies. You can find them at analog.com/analogdialogue; click on “Potpourri,” and then on “Books.” And watch for possibly new books to promote seminal technologies that, as in the past, introduce unanticipated useful tools.
Dan Sheingold [dan.sheingold@analog.com]
ANALOG ICs POWER DIGITAL TVs
At midnight on February 17, 2009, most commercial analog TV broadcasts—long the U.S. standard—will cease, leaving the more flexible and efficient digital television (DTV) broadcasts to rule the video airwaves. Bandwidth will be freed for new telecommunications applications, including ultrafast wireless broadband, mobile TV, and public safety/emergency communication systems.
Don’t confuse digital television with high-definition television (HDTV). DTV refers to the transmission technology, which can carry high definition, standard definition, or data; whereas, HDTV refers to broadcasts of high-resolution pictures. Digital technology and error correction techniques enable reception of crystal-clear pictures and sound, without ghosts, snow, or other artifacts, if the signal level is adequate; otherwise, the error frequency will increase beyond the correction threshold, and the picture will be lost entirely—an all-or-nothing proposition.
Broadcasts from DTV stations using multicasting can replace a single analog channel by up to four channels of programming. They can deliver data services that analog technology can’t provide, including program information and the latest news, weather, sports scores, and traffic updates. Future interactive video services will enable viewers to play additional media elements embedded in the main program.
How will this transition affect you? 85% of all TV viewers— subscribers to cable, satellite, or other pay services—will be essentially unaffected. But free over-the-air broadcasts will no longer be available to those with older analog TVs using standard antennas. Three basic choices are available: connect to cable, satellite, or other pay service (with its set-top box); purchase a new digital TV receiver; or add a converter box to the existing analog TV system (the latter’s $40 to $60 cost may be partially subsidized by $40 coupons from the U.S. government).
Many see the digital television transition as burdensome, but for some, free DTV can replace expensive pay TV. If viewers are satisfied by the broadcast programming from ABC, CBS, CW, FOX, ION, NBC, PBS, and independent stations, they will be able to receive free high-definition broadcasts on their HD television sets or standard-definition pictures on their converter-box-equipped analog TVs. Multicasting will increase the number of digital programs that can be received. In Boston’s suburbs, for example, more than 40 channels are available with a modest antenna and an HDTV or converter box.i
Although analog TV broadcasts are ending and analog TV sets are no longer being manufactured, analog circuitry is far from dead. Contrary to popular belief, more analog content is found in a modern “digital” high-definition TV than in older analog TV sets. As the figure shows,ii Analog Devices makes a variety of video amplifiers, decoders, encoders, and filters to convert legacy analog RGB, composite video, S-Video, and component video signals from analog to digital and back again. HDMI™ buffers, multiplexers, receivers, and transmitters support the use of long cables, allowing multiple components, such as audio-video receivers (AVR), Blu-ray Disc® players, and video games to be interconnected with the TV. Display drivers provide the high-voltage drive signals, control clocks, gamma correction, and other circuitry required to interface with the LCD display panel. RF splitters enable the use of multiple tuners for picture-in-picture and digital video recorder (DVR) functions. Audio processors and Class-D amplifiers provide multichannel surround sound; and audio amplifiers, ADCs, and DACs provide support for legacy system components. Up to 20 power supplies can be found in a state-of-the-art LCD HDTV, so low-dropout regulators and analog power management, monitoring, and sequencing devices are required. In addition, Analog Devices Blackfin® and SHARC® digital signal processors handle much of the real-time signal processing and control in today’s HDTVs.
Advanced television systems demand the highest-performance signal processing solutions in an extremely cost-sensitive market. From RF to baseband video to audio to power management, building on a framework of industry-leading core technologies, Analog Devices Advantiv® advanced television solutions enable lifelike audio and video, offering the widest range of analog, digital, and mixed-signal solutions to solve the most difficult multiformat advanced television challenges.iii
ii Advanced Television Signal Chain
iii Advantiv Advanced Television Solutions
Scott Wayne [scott.wayne@analog.com]
Copyright 1995- Analog Devices, Inc. All rights reserved.