[HN Gopher] Using low-cost wireless sensors in the unlicensed bands ___________________________________________________________________ Using low-cost wireless sensors in the unlicensed bands Author : signa11 Score : 31 points Date : 2023-02-10 07:17 UTC (1 days ago) (HTM) web link (lwn.net) (TXT) w3m dump (lwn.net) | VLM wrote: | This is "older" tech so the installed base is (was?) large. | | In the past I found out if you use "level" in the format string | it will output signal strength type data that you can analyze. It | is not rocket surgery to store a DB row consisting of timestamp, | id, and signal strength of all RX'd packets, then make a | dashboard of how many unique IDs you hear over a ten minute | period or whatever. | | My hope was to detect 70 cm ham radio band openings (tropo ducts | and the like) Wow did that never work. It was a good idea and fun | but did not work at all. I repurposed the hardware into something | else and moved on. Its possible that with different antennas or | longer term project or something, who knows. The software, as in | the article's link, worked fine however. | | If you'd like to try another frustrating IoT experiment, try | monitoring all the tire pressure monitor systems that drive by | your house using roughly the same hardware and similar software. | IIRC I ran out of patience with that one. Sounded like fun after | I saw a YT video on the topic... The good news is each tire on | the road (by 2023 anyway) has a unique 32 bit ID, IIRC anyway, | the bad news is the range was scarcely better than "a car length" | away. If you've ever driven your car over the machine with the | hoses the DOT puts out to count cars along a road for planning | purposes, I thought I could replicate that kind of data by | sniffing and analyzing TPMS data, but the range is WAY too low | for the low repetition rate of the transmissions. I guess you | could just gather data wirelessly for years at a time, but ... | Maybe you could make parking meters really smart by listening for | the tires parked at the meter, or track super expensive private | parking, or an electric charger could pre-load the new user by | sniffing the new user's tire transmitters. Or my garage door | could automatically open if and only if my car is at the door. | However the transmission rate is too low for most door opener | level of patience. | hummus_bae wrote: | Dumb question, but do you have ID of your house on the chip? | You could at least have a high and low threshold for your house | and compare it to other houses. | timerol wrote: | The opening of this article is confusing. It contrasts relatively | expensive Zigbee and Z-Wave devices with cheap sensors emitting | radio signals in the unlicensed ISM bands. But Zigbee and Z-Wave | both operate in ISM bands, so the distinction isn't a difference. | | It's more like the difference between building and hosting a | static website with Squarespace vs. AWS. One of them is more | expensive with more bells and whistles, but both accomplish | similar goals by communicating with the browser in similar ways. ___________________________________________________________________ (page generated 2023-02-11 23:00 UTC)