09.03.2013 Views

BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...

BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...

BLOCKING READER: DESIGN AND IMPLEMENTATION OF A ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

4.3.2.7 Frequency-Hopping Spread-Spectrum (FHSS)<br />

The FHSS signaling of the Reader shall comply on the FCC regulations. It shall<br />

comply on the RF envelope shown in the Figure 4.2. So it is important to consider<br />

these regulation in the reader design.<br />

4.3.3 Tag-to-Reader (T⇒R) communications<br />

4.3.3.1 Modulation<br />

- 3.3.2.3.<br />

Modulation shall be same as reader, as explained earlier in the sections 3.3.2.1<br />

4.3.3.2 Data encoding<br />

The backscattered data from the Tag shall be encoded by FM0 baseband or<br />

Miller modulation of a subcarrier at the data rate.<br />

• FM0 baseband:<br />

FM0 encoding or the bi-phase space is as shown in the Figure 4.5. The FM0<br />

basis functions showing the data-0 and data-1. And the FM0 generator state<br />

diagram labels, S1-S4, indicating four possible FM0-encoded symbols.<br />

• Miller-modulated subcarrier<br />

Miller encoding is as shown in the Figure 4.6. The FM0 basis functions showing<br />

the data-0 and data-1. And the FM0 generator state diagram labels, S1-S4,<br />

indicating four possible Miller-modulated subcarrier symbols. In this encoding<br />

the duty cycle of the symbols is measured at output and is between 45% to<br />

55%. A Miller encoding signaling shall end with a ”dummy” data-1 bit at the<br />

end of signal transmission.<br />

35

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!