Submitted by kenda1l t3_10ocwck in explainlikeimfive
I just finished watching the movie You're Next (generic horror movie about people caught in a house with killers trying to get in.) It mentioned the killers using a jammer to keep them from calling for help. My immediate thought was to find a computer and router to connect directly to the internet via an ethernet cable. Then I realized I know nothing about jammers, and my curiosity was piqued.
This is a great analogy! Tbh I just kind of assumed that they somehow blocked the signal from getting through, similar to cutting the electrical wires. This makes much more sense, though.
>Tbh I just kind of assumed that they somehow blocked the signal from getting through
Nope! That is what intuition would say, but in reality, it just overpowers the signal you are trying to receive with noise (think gray static on a tv along with that characteristic hissing noise) that is at a higher power/amplitude/volume than the signal itself
That makes it cooler in my opinion. It also kind of reminds me of Spaceballs, with the raspberry jam.
No, a cell phone jammer wouldn't do anything to a hard wired connection. A jammer just sends very loud noise on various wireless frequencies so something like a phone can't 'hear' or 'be heard' by a tower any more. They're usually very specific on what they jam, so one designed for cell signals might do absolutely nothing to wifi.
But cell phone and wifi are at same frequency band
It may vary with location, but in the USA the lowest wifi frequency is 2.4GHz, and the highest cell frequency is 2.2GHz
>It may vary with location, but in the USA the lowest wifi frequency is 2.4GHz, and the highest cell frequency is 2.2GHz
That is not true. Look at https://en.wikipedia.org/wiki/Cellular_frequencies_in_the_United_States there cellular communication in use at 39GHz.
Welp, that's what I get for thinking phone=voice, and looking at those channels (and even then ignoring that carriers have started using data channels to carry voice).
Those bands still don't intersect any of the Wifi bands. The BRS band comes close to Wifi 2.4GHz band, so a new cell jammer could block old an old wifi router if the jammer was either poorly designed, or designed to block wifi as well
I used to have one. It wrecked my 2G/3G but my wifi was fine. Idk what else to say
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A wireless jammer cannot block a wired connection. So if everything was connected with cables the internet would work. Unless they cut that cable somewhere.
Jammers work by transmitting a strong noise signal on the frequency being jammed. The wider the frequency range the more power the jammer needs to overwhelm the signals. Jammers don't actually block the signal, they just overwhelm it. Kind of like if you are talking with a friend standing next to you. In a quiet room you can hear each other just fine. The jammer acts like a loud rock concert. You are still talking, but the other person can't hear you because the surrounding noise is too loud.
Glad to know that if I ever have crazy killers in animal masks trying to get me, my best chance is to army crawl with my laptop to the router (pretty sure they'd have to get into our basement to cut the cable, or cut it at the router itself, in which case I'm fucked anyway.) Thank you for the explanation!
But how does the internet cable get into your basement?
If your area uses underground cables then they might have to dig to cut your internet; it would take time but they wouldn't have to breach your property to do it. But many places use the existing overhead cable infrastructure to deliver internet, which are far easier to cut in an attack scenario. Or they could just attack the local exchange point, it's not as direct but it's nowhere near your house.
And in any case it may be easier to just cut the power. Your laptop or mobile phone have battery power but your modem or router probably don't.
Sleep tight.
You would be surprised.
Back as a kid I tried to make an FM transmitter and it turned out to be a cable TV jammer instead. Worked at a range of at least 100ft on a 9V battery.
Enough power and that signal will work it's way past the shielding in wired connections. Not nearly as much range though.
Haven't watched the movie, but it came out in 2011, so it's probably relevant: with wifi specifically, it was possible to stop a connection of a device by pretending to be that device and asking the router to stop the connection. Even on an encrypted wifi network, the 'goodbye' signal was not secured. So a jammer device could just spam 'goodbye' to the router, pretending to be everybody else who is trying to broadcast. The router would then stop the connection, and it would take a while for the true device to figure out that it was no longer being listened to.
I assume this no longer works on modern devices, but perhaps it does.
SonicKiwi123 t1_j6du7av wrote
Imagine you are trying to have a private conversation with someone who is standing two feet away from you in a silent room. You can whisper to reach other and you will both have no problem hearing each other. Now imagine you are standing further away. Much further away. You may need to yell now just to hear each other, if you are far enough away. Now imagine again, that you are back to being two feet away from each other, but this time instead of being in a quiet room, you are in a room full of the sound of jackhammers revving chainsaws horrible static sounds and people screaming, alarms blaring, any and every loud noise you can imagine all at once. Good luck trying to hear each other even if you scream back and forth even if you're standing two feet away, let alone further. There is too much interference from the loud noises covering up the actual stuff you are trying to say/hear.
Well, what a jammer does at a basic level, is essentialially create those loud noises to cover up the actual signals sent by the two transceivers trying to communicate, so that they can not "hear" each other.
Something as simple as a leaky microwave oven (as in it does not contain the microwaves within it and they leak out) can cause interference and act as a jammer to 2.4GHz wifi, as a microwave oven uses microwaves that are the same frequency of 2.4GHz. a wired connection works much differently and would be unaffected.