Ok, so some shit maths: assuming a phone transmits 0.5watts at 1m, inverse squar... | Hacker News

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		KaiserPro on Nov 18, 2023 \| parent \| context \| favorite \| on: Lockheed is now tracking phones and walkie-talkies... Ok, so some shit maths: assuming a phone transmits 0.5watts at 1m, inverse square law[1] says that it will be 0.0000000000125 watts at a distance of 200km. Thats -79dbm, so kinda shitty wifi level of signal. GPS by contrast is -125 dbm. (logarithmic scale) Your phone can pick out a GPS signal reliably with a tiny chip antenna. Imagine having a 4 meter phased antenna array. [1] https://www.omnicalculator.com/physics/inverse-square-law

leoh on Nov 18, 2023 [–]

Yes, sure; but you're leaving out issues of signal fidelity due to noise.

rightbyte on Nov 18, 2023 | [–]

How much power in the carrier spectrum does the tree next to you emit? That just makes it a question of sampling length and statistics.

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