3 ms·
The key feature of this approach that many other commenters seem to be missing: They are not harvesting power from ambient RF and using it to power a second tr
by chockablock 13y ago
The key feature of this approach that many other commenters seem to be missing:
They are not harvesting power from ambient RF and using it to power a second transmitter. Instead, they are using that harvested power to communicate with other nodes by modulating their device's reflection of ambient RF, a process that they claim is ~100x more power efficient.
Not an RF engineer, can't judge novelty, but this seems really, really clever.
EDIT: added text in italics above to make my post clearer.
- StandardFuture 13y agoSorry, but that is wrong. Figure 3 explains everything. EDIT: I should say that yes the technique is using analog conditioning circuitry to get the job done without storing power in a battery.
- chockablock 13y agoThere is indeed a block in that diagram labeled 'Transmitter', but it is not a transmitter in the colloquial sense of converting onboard power into RF energy. Instead, the 'transmitter' modulates the amount of ambient RF energy that is backscattered, by modulating the antenna impedance. This appears to be the major innovation in the paper. As lots of commenters have pointed out, harvesting power from ambient RF is nothing new (whether or not a battery is involved). (Section 3.2): "By modulating the electrical impedance at the port of the antenna one can modulate the amount of incident RF energy that is scattered, hence enabling information to be transmitted." (Section 8a): "backscatter communication is two orders of magnitude more power-efficient than state-of-the-art radio communication")
- StandardFuture 13y agoYeah, it's a cool technique. But it still has no room to scale as far as I can tell. At least not for transmitting inside licensed frequencies ... maybe they should try it out on 2.4 GHz or 3.5 GHz??