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Modular RF for Embedded System

Modular RF for Embedded System. EE 281 November 25, 2002 Ying-zong Huang. Special Embedded Needs. Portable Self-contained Small Real-time remote operation.  Wireless data transfer (also portable power…). RF: Not Trivial. Modular RF. Faster TTM for systems with a radio component

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Modular RF for Embedded System

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  1. Modular RF for Embedded System EE 281 November 25, 2002 Ying-zong Huang

  2. Special Embedded Needs • Portable • Self-contained • Small • Real-time remote operation Wireless data transfer (also portable power…)

  3. RF: Not Trivial

  4. Modular RF • Faster TTM for systems with a radio component • Cordless telephone • Baby monitors • OEM’s • Bluetooth-enabled • 802.11-enabled

  5. Modular RF • No (or very very few) external components • Linx Technologies: • http://www.linxtechnologies.com • Module + Antenna = Wireless • RF modules (miniboards) • LC Series (SAW, 315, 418, 433 MHz) • KH Series (with Encoder/Decoder) • HP-2 Series (FM/FSK, Multi-channel, 900 MHz)

  6. Linx LC Series - Transmitter • 2.7V–5.2 VDC • Direct Serial Interface • (Digital) data rates up to 5 Kbps • Up to 300 feet

  7. Linx LC Series - Receiver • Similar features as Transmitter

  8. Linx LC Series - Modulation • Carrier Present/Carrier Absent modulation • Saves power when sending ‘0’ • Takes advantage of FCC rules • Easy to understand • Encoding not provided by LC Series: Add your own protocol (By way of Pascal Stang: http://www.procyonengineering.com/hardware/linxrf.html)

  9. Linx LC Series - Radiation • Short wire or matched transmission line to antenna • Antenna mounting • Antenna (nominal) length • Quarter wave: L [inches] = 234 / F [MHz] • Antenna Styles: • Whip • Helical • Loop • Stub • Just a wire

  10. Linx LC Series - Other Issues • VSWR – voltage standing wave ratio, ideal form: • Rho is the reflection coefficient (RC) going into the antenna:

  11. Modular RF - Other Issues • More radiation, more reliable link • Ground plane • Clean power supply • But maybe not too much • Note EMI/FCC issues ♦

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