Re:Is Am Radio Dead?
by cannonpr on Tuesday January 31, 2023 @07:35PM
(#34604546)
Not to be pedantic, receiving is actually traceable to a motivated enough agent with sufficiently expensive equipment, especially if your receiver is home made or poorly built, due to oscillator leak back, there are a few other effects that can be used such as shadow casting.
This gives a light idea of what’s possible: https://ham.stackexchange.com/questions/2160/is-there-a-way-...
I simply mention this because in some regimes and some situations, it’s best to understand what’s possible.
[ Parent
| on HN ]
I'm sure you're right that a "motivated enough agent" might trace a receiver but the two replies in the ham.stackexchange.com answer seem pretty clear that it's very difficult to do in the real world.
I appreciate technology may have changed but in the cold war many East Germans listened to the BBC East German service, in particular a programme called "Letters Without Signatures" [0] which relied on East Germans writing letters to the BBC . The programme ran for many years and clearly had a significant audience, I think if the Stasi had been able to detect reception they would have done so.
[0] https://www.bbc.co.uk/blogs/bbchistoryresearch/entries/9a651...
Odds of being tracked down that way are near-nil given that your oscillator could for anything. Also you can build a crummy AM receiver without one: https://www.buildcircuit.com/how-to-make-a-batteryless-cryst...
Re:Is Am Radio Dead?
by smackeyacky on Wednesday February 01, 2023 @01:38AM
(#34607234)
I had a "bionic man" doll when I was a kid that had a crystal radio built into his back (although on reflection it might have been the 3 faced robot guy).
Seemed like magic at the time, got me into simple electronics.
Re:Is Am Radio Dead?
by JasonFruit on Tuesday January 31, 2023 @10:37PM
(#34606027)
> not to be pedantic
(proceeds to be extremely pedantic)
Same goes for Tor. If you're one of 3 using Tor in your entire city, it won't be difficult to target you. This kind of stuff only works well when its used en mass, making the government have too many targets to bother.
Re:Is Am Radio Dead?
by userbinator on Wednesday February 01, 2023 @12:18AM
(#34606720)
You don't need a local oscillator to receive AM.
However, a nonlinear junction detector will still find a receiver (among other things).
AFAIK only if you are using a het-design receiver, a DSP receiver should be immune to that tracing?
Re:Is Am Radio Dead?
by BenjiWiebe on Wednesday February 01, 2023 @02:13PM
(#34615950)
It would need to sample baseband. If you are using an LO to down-convert or up-convert that would be detectable.