EE Times Under the Hood - June 23, 2008 - (Page U10)

UTH0623pg4-10.qxd 6/13/08 5:57 PM Page 10 under the hood: FEATURE www.eetimes.com • www.techonline.com PIC16F690 simple,” he said. Bible suspects it will increase in popularity now that it can be done digitally, rather than in analog. Other additions to SuitSat-2 include a more-complex band plan, as more bandwidth is available, along with more temperature sensors to better understand the overall thermal environment. Engineers being engineers While the SuitSat project presented its share of headaches and demanded patience as the Microchip team dealt with NASA’s requirements and waited for the launch (they’re still waiting for a launch date for SuitSat-2), Bible said they’d do it all again—and he’d recommend it as the type of project engineering companies should encourage. While little of what was learned from the experience is Power controller board The SuitSat-2 design team at Microchip (from left to right): John Charais, principal engineer, Enrique Aleman, senior applications engineer, Joseph Julicher, engineering manager, Sunil Fernandes, applications engineer, Jerry Zdenek, senior applications engineer, Tim Moffat, intern, and Steven Bible, engineering manager. tion to shut down portions of the circuit if it’s not meeting the current budget, as well as six individual circuits to monitor each panel separately. These are based on PIC16F690 microcontrollers. On the radio end, SuitSat-2 will have much more capability than its predecessor. For starters, it will be softwaredefined. “It uses one of our dsPICs [dsPIC33F] to do the modulation and demodulation, and to control a regular audio codec that’s running at 48 kHz, sampling,” said Bible. The downlink is 145 MHz and the uplink, 437 MHz (amateur satellite service frequencies). “We’ll convert these to a 10.7-MHz intermediate frequency, and that will get digitized to that 48-kHz bandwidth,” he said. ‘And then the DSP does its processing on it.” An FM signal will be stored in an SD card and sent to the dsPIC over an SPI line, then sent down. An outstanding feature of the radio’s design is the use of a quadrature sampling detector instead of a mixer. “This allows you to downconvert from 10.7 MHz to audio, with better dynamic range and performance for less power,” said Bible. It’s not a demanding circuit, he said, and is basically a quad switch that’s switching in quadrature (I and Q). Capacitors reside at the input to these switches; the whole thing is just an integrator, he said. “So long as you’re switching in a certain order [vector], then you basically get the I and Q at output: incredibly dsPIC33F Software-defined transponder board directly applicable to his job at Microchip, the intangibles are valuable, he said. For one, there’s the group experience itself. “Microchip has many product groups, but they don’t work together. [The SuitSat team members] have been learning a lot about each other’s products and about each other,” he said. Bible said he has also seen the work translate into better customer interactions. For himself, he said, SuitSat appealed to the very core of what he’s done all his life, from building bottle rockets as a kid right through his career at Microchip. It was simply an extension of who he is: an engineer. ■ 10 Electronic Engineering Times, TechOnline | June 23, 2008 http://www.eetimes.com http://www.techonline.com

Table of Contents Feed for the Digital Edition of Under the Hood - June 23, 2008

Under the Hood - June 23, 2008 Extreme Design: SuitSat Pushes Desigers' Limits Evolution of the Smart Phone Mature Devices get Rolly Rocking GPS: Garmin Nuvi 750 vs. HP iPaq 310 Inside the Sony OLED TV Multizone Dgital Audio Flip Ultra Camcorder - An Ode to Clean Design Robot Guitar Tunes Itself E-book is a Sight for Sore Eyes Scientific Calculator Boils Down to Two ICs $100 BOM Eludes First OLPC Laptop 45 nm: What Intel Didn't Tell You Next Step in NAND Flash Evolution Surveillance on a Shoestring Hot 3G Phone Owes Debt to Analog SecurID Fob: Single-Chip Safety Net

Under the Hood - June 23, 2008

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