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Humans can be tracked with unique 'fingerprint' based on how their bodies block Wi-Fi signals
(www.theregister.com)
This is a most excellent place for technology news and articles.
Cat tracker
Put an airtag on the collar. Done.
Why do you need to identify specific cats over merely the presence of movement or cats in general?
Because I want to know which cat is getting up to shit they shouldn't :P