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LoRa Backscatter [pdf]

homes.cs.washington.edu

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Re: LoRa Backscatter [pdf]

#11

Post by j_s »

LoRaWAN packet received at record distance of 702 km | https://news.ycombinator.com/item?id=15201692 | (5 days ago, 178 points, 50 comments)

> animats: Wow. Both the receiving and transmitting antennas were omnidirectional

> vvanders: I regularly see APRS packets of 120mi+, although probably at a lot more power.

> superkuh: I run two ubiquiti nanostation M900 at home on a 10m pole and in my car through the sunroof for a mobile data link.

> aw3c2: From a balloon in almost 40km altitude.

Re: LoRa Backscatter [pdf]

#12

Post by baccredited »

stickfigure wrote: post #6
NZSmartie wrote: post #2

Got a mirror? Website imposes a article viewing limit...

Disable Javascript for that site and it reads normally. I've found that most news sites become much more readable (and chew through far less of my CPU, and stop autoplaying loud videos, and skip paywalls) with JS disabled. The Chrome plugin I'm using (Quick Javascript Switcher) disables on a per-domain basis and remembers the setting for each. I'm a huge fan of SPAs and JS in the browser and yet I'm quickly blocking…

YesScript worked for me on Firefox. Thanks for the idea. https://addons.mozilla.org/en-US/firefox/addon/yesscript/dev...

Re: LoRa Backscatter [pdf]

#13

Post by junkcollector »

anfractuosity wrote: post #10

It says regarding CSS "That makes even faint LoRa signals easy to distinguish from background noise, which fluctuates randomly". Is CSS better than FSK than in this respect or..? Edit: http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20... Says "Spreading codes does not improve sensitivity over FSK systems, for usable datarates you get similar sensitivity using standard FSK modulation"

CSS is an analog (continuous frequency function) modulation where the CSS standard specifies that only linear encoding be used while FSK is a digital modulation that can employ pseudo-random keying and operates at discrete frequency keys. Without these restriction imposed by standards, FSK would be a special case of CSS, at least mathematically.

Re: LoRa Backscatter [pdf]

#14

Post by junkcollector »

wonderous wrote: post #7

Anyone know of any notable related research on real world use of this tech? Best I was able to find was "An Investigation of Fading on a Short Range 900MHz radio link": https://mentor.ieee.org/802.11/dcn/10/11-10-1355-00-00ah-fad...

You might have more luck looking at Active RFID. The same technology in any meaningful sense.

Re: LoRa Backscatter [pdf]

#20

Post by miekw »

Here's the paper: https://homes.cs.washington.edu/~gshyam/Papers/loRaBackscatt...

Tech like this already exists (look up "UHF RFID") and the picture they've got looks very similar to existing tags (image search for "alien rfid tag").

The interesting thing here is managing to implement LoRa's modulation scheme in a passive tag.

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