[TechView: Analog & Power]
New Power Approaches May Fuel Analog Job Opportunities In Security And Health Applications
Power-over-Ethernet (PoE, or IEEE 802.2af/IEEE802.3at) is one new approach to security power, but shipping container monitoring may benefit from advances in energy harvesting.
Don Tuite
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ED Online ID #20370 |
December 18, 2008
Kirk then described the growing use of Ethernet for parts of industrial control as well as in security. Pan-zoom-tilt (PZT) security cameras represent part of the push for the higher-power capabilities of the IEEE 802.3at (PoE-Plus) standard. When finally approved, the “Plus” standard will enable such cameras or any powered devices to negotiate their current needs with the Ethernet switch when they are plugged into any port.
If you look at recent announcements of “Power-over-Ethernet” ICs, you’ll note that not all of them are standard. That’s because some folks consider the two-event handshake of the “at” version overkill. They figure the cameras will go into dedicated ports that can be powered by bridges, an arrangement that suits legacy Ethernet installations and allows the purchase of cheaper switches in new construction. They’re happy to buy gear with nonconforming “PoE-like” chips. This also lets the chip makers create product differentiation in terms of higher, non-standard power capacity.
I then asked who needs all those PZT cameras. In the United States, most visible cameras are fixed Internet devices for applications like traffic monitoring. Then there are cameras in limited use, like those in the roof garden of the new California Academy of Sciences Museum in Golden Gate Park in San Francisco. Presumably, organizations have a fairly limited budget for that sort of hardware and an even more limited budget to hire and train the personnel who would use it.
Kirk reminded me that there’s a bigger world beyond the U.S. In fact, there’s hardly anyplace you can go in the United Kingdom and not be on camera. And in most of the cities in the U.K., somebody is watching you on those cameras. As some police authorities around the world think that’s a wonderful idea, it seems there’s a big future in PTZ cameras, the systems to power them, and the hardware and software to make it easier to interpret the raw video.
If that aspect of security gives you the creeps, other opportunities may be more appealing. A few months ago, I met with Bob Durstenfeld of RAE Systems, which makes electronics that detect biohazards. A long time back, I wrote some manuals for a couple of pager-size radiation detectors designed to be carried by first responders, cargo screeners, border guards, and other security personnel.
These firefighters, inspectors, or officers would wear the detectors on their utility belts or even carry them in their pockets. When they reported back to base, they would automatically report via a wireless link their total dosage of radiation exposure from gamma rays and/or neutrons. The device itself had a readout as well.
Those detectors were mature products. But Durstenfeld showed me a demo of something more interesting. RAE Systems has a complete, ready-to-go system for shipping containers. To check out the results of a field test, see www.raesystems.com/~raedocs/Securing_the_Supply_Chain_011205.pdf. While that test was several years ago, though, ports continue to be a vulnerable terrorism target worldwide.
One of the more innovative factors in the RAE Systems solution—and for once, the buzzword “solution” is appropriate—is that the individual sensors in the cargo containers communicate via a mesh network. But those units are battery powered, which is a big drawback.
In the last year or so, energy harvesting has begun to mature. It’s almost practical now to use energy-harvesting systems that might use a combination of vibration harvesting from the ship’s engines and photovoltaics to charge a system of thin-film batteries and supercapacitors to replace or supplement the chemical batteries in the current system. (For more, see “The Field Of Energy Harversting Begins To Ripen”).
Beyond that, plenty is happening on the power front to enable new possibilities in analog design. For example, I’m looking forward to a briefing from Advanced Linear Devices about extremely low-voltage energy harvesting for patient monitoring using thermal energy from body heat. That kind of temperature difference produces very low output voltages—below typical semiconductor threshold voltages. ALD’s core technology is based on pre-charged floating gates. (For more, see “Energy-Harvest Modules Provide Predictable Runtimes”). Look for product announcements in the second quarter of 2009.
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