Forums

2.4Ghz Oscillator

Started by Cursitor Doom October 20, 2018
On Monday, 22 October 2018 02:22:46 UTC+1, Jeff Liebermann  wrote:
> On Sun, 21 Oct 2018 17:57:06 -0700 (PDT), tabbypurr wrote: > >On Monday, 22 October 2018 01:34:03 UTC+1, Jeff Liebermann wrote: > (...)
> >> The problems is that WiFi uses spread spectrum modulation, which is > >> largely immune to interference from an unmodulated carrier. A simple > >> oscillator, without any modulation, will not work. Even the same > > >I suspect it'd work well enough if P_out were say 800W :) > >NT > > Yep. There are many ways to break a system. You can starve it for > data, overload it, or choke it garbage. 800 watts or overload will > work because the dynamic range of the typical WiFi receiver is fairly > small (about 50dB) allowing any strong signal to cause the front end > to rectify the RF and shut it down. This is called "blocking".
IME it blocks the target receiver by turning it to charcoal.
> However, such brute force methods are not considered very elegant and > should be avoided if possible.
heh, probably true NT
On Sun, 21 Oct 2018 20:14:53 -0700 (PDT), tabbypurr@gmail.com wrote:

>On Monday, 22 October 2018 02:22:46 UTC+1, Jeff Liebermann wrote: >> On Sun, 21 Oct 2018 17:57:06 -0700 (PDT), tabbypurr wrote: >> >On Monday, 22 October 2018 01:34:03 UTC+1, Jeff Liebermann wrote: >> (...) > >> >> The problems is that WiFi uses spread spectrum modulation, which is >> >> largely immune to interference from an unmodulated carrier. A simple >> >> oscillator, without any modulation, will not work. Even the same >> >> >I suspect it'd work well enough if P_out were say 800W :) >> >NT >> >> Yep. There are many ways to break a system. You can starve it for >> data, overload it, or choke it garbage. 800 watts or overload will >> work because the dynamic range of the typical WiFi receiver is fairly >> small (about 50dB) allowing any strong signal to cause the front end >> to rectify the RF and shut it down. This is called "blocking".
>IME it blocks the target receiver by turning it to charcoal.
Not charcoal. In order to produce charcoal, one heats wood to remove water and volatiles in the absense of oxygen. That would be difficult to do outside of an enclosed air tight stove, oven, shed, or mound.
>> However, such brute force methods are not considered very elegant and >> should be avoided if possible. > >heh, probably true
Most definately true. At the short range needed to be effective, 800 watts at 2.4GHz into presumably a 0dBi isotropic radiator is well above the FCC RF safety guidelines. Anything that will vaporize silicon can probably do the same to brain cells. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Sun, 21 Oct 2018 17:33:59 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sat, 20 Oct 2018 15:05:42 -0000 (UTC), Cursitor Doom ><curd@notformail.com> wrote: > >>Has anyone got any ideas for a simple, low-power (milliWatt level) VCO >>for the WIFI band? Something with a minimal range of just a few feet? I >>just want to ensure my phone can't access my home network WIFI unless I >>expressly allow it. > >What type of cell phone or smartphone are you using? If your >unspecified carrier supports Voice over WiFi, Advanced Calling, or >other trademarked name for using WiFi for making phone calls, your >question makes some sense. > >If you don't want your phone to suddenly become self-aware by >connecting to the outside world without your permission, the easiest >fix is to turn off the WiFi feature in your smartphone. However, if >you're worried that the mind control division of your government >communications authority might take control of your phone and use it >to spy on your evil and nefarious activities, then some manner of WiFi >jammer might be appropriate. > >The problems is that WiFi uses spread spectrum modulation, which is >largely immune to interference from an unmodulated carrier. A simple >oscillator, without any modulation, will not work. Even the same >style of DSSS (direct sequence spread spectrum) modulation will not >produce adequate interference unless it uses the same PN (pseudo >noise) spreading code. At best, it might reduce the receiver >sensitivity somewhat. > >For your paranoid scheme to work, you need either the same type of >modulation, as found in a proper WiFi jammer, or a similar but >incompatible PN modulation scheme, such as FHSS (frequency hopping >spread spectrum). WiFi jammers are commonly available: ><https://www.google.com/search?q=wifi+jammer> >Most are based on an EPS8266 module. ><https://www.ebay.com/itm/ESP8266-Module-WiFi-Jammer-V3-With-Full-Support-Development-Hacking-Tool-Attacks-/123053804050> ><https://hacks.today/build-wifi-jammer/> >You can also build one using a Raspberry Pi board: ><https://www.google.com/search?q=build+wifi+jammer+raspberry+pi> >Using any one of these, you should have little difficulty trashing >WiFi for yourself and anyone within range and put you on the road to >global WiFi domination. > >Another method is to modulate with FHSS instead of DSSS. Direct >sequence is fairly immune to interference from other DSSS sources, but >FHSS will usually cause your WiFi to go comatose. A higher power >BlueGoof transmitter will do the trick. This might help: >"Jamming and Anti-jamming Techniques in Wireless Networks: A Survey" ><https://www.cs.montana.edu/yang/paper/jamming.pdf>
I guess one of these jammers would pretty much take one of the Simply Safe alarm systems right out. I will pass one one of these alarm systems then. I see the jammers run about 260 bux or so, just cost of business for burglars.
On Monday, 22 October 2018 05:10:05 UTC+1, Jeff Liebermann  wrote:
> On Sun, 21 Oct 2018 20:14:53 -0700 (PDT), tabbypurr wrote: > >On Monday, 22 October 2018 02:22:46 UTC+1, Jeff Liebermann wrote: > >> On Sun, 21 Oct 2018 17:57:06 -0700 (PDT), tabbypurr wrote: > >> >On Monday, 22 October 2018 01:34:03 UTC+1, Jeff Liebermann wrote: > >> (...) > > > >> >> The problems is that WiFi uses spread spectrum modulation, which is > >> >> largely immune to interference from an unmodulated carrier. A simple > >> >> oscillator, without any modulation, will not work. Even the same > >> > >> >I suspect it'd work well enough if P_out were say 800W :) > >> >NT > >> > >> Yep. There are many ways to break a system. You can starve it for > >> data, overload it, or choke it garbage. 800 watts or overload will > >> work because the dynamic range of the typical WiFi receiver is fairly > >> small (about 50dB) allowing any strong signal to cause the front end > >> to rectify the RF and shut it down. This is called "blocking". > > >IME it blocks the target receiver by turning it to charcoal. > > Not charcoal. In order to produce charcoal, one heats wood to remove > water and volatiles in the absense of oxygen. That would be difficult > to do outside of an enclosed air tight stove, oven, shed, or mound.
I've done it, it works. If you want to try it, stick some food in a microwave oven on full for 30 minutes. Do it somewhere a fire would not cause danger. Yes, technically it's charelectronics, charplastic, charfood etc. Impure carbon anyway.
> >> However, such brute force methods are not considered very elegant and > >> should be avoided if possible. > > > >heh, probably true > > Most definately true. At the short range needed to be effective, 800 > watts at 2.4GHz into presumably a 0dBi isotropic radiator is well > above the FCC RF safety guidelines. Anything that will vaporize > silicon can probably do the same to brain cells.
Orders of magnitude above any sane guidelines. Do you need guidelines to tell you to not incinerate things in a pile of sparks? NT
On Mon, 22 Oct 2018 06:11:05 -0700 (PDT), tabbypurr@gmail.com wrote:

>On Monday, 22 October 2018 05:10:05 UTC+1, Jeff Liebermann wrote: >> Not charcoal. In order to produce charcoal, one heats wood to remove >> water and volatiles in the absense of oxygen. That would be difficult >> to do outside of an enclosed air tight stove, oven, shed, or mound.
>I've done it, it works. If you want to try it, stick some food in a >microwave oven on full for 30 minutes. Do it somewhere a fire would >not cause danger.
I've already done it. About 15+ minutes for a yam, instead of 5 minutes at 1300 watts: <http://www.learnbydestroying.com/jeffl/pics/drivel/slides/burned-yam.html> The yam was glowing red on the inside and belching smog from every hole. It coated the inside of the microwave oven with a permanent layer of orange something. The oven now looks disgusting, but works normally after I tore it apart and cleaned the electronics. However, the burned smell lingered for several weeks.
>Yes, technically it's charelectronics, charplastic, charfood etc. >Impure carbon anyway.
Yep. I'm not sure what to call it. I threw it outside while it was still burning. Even the dogs and the local critters wouldn't eat it. Anyway, it's not charcoal.
>> >> However, such brute force methods are not considered very elegant and >> >> should be avoided if possible. >> > >> >heh, probably true >> >> Most definately true. At the short range needed to be effective, 800 >> watts at 2.4GHz into presumably a 0dBi isotropic radiator is well >> above the FCC RF safety guidelines. Anything that will vaporize >> silicon can probably do the same to brain cells.
>Orders of magnitude above any sane guidelines. Do you need guidelines >to tell you to not incinerate things in a pile of sparks?
It won't produce sparks unless I throw in some steel wool. <https://www.youtube.com/watch?v=oiWZYdr9Zvo> However, you don't really need a microwave oven to burn steel wool: <https://www.youtube.com/watch?v=5MDH92VxPEQ> Guidelines are probably a good idea, so that I know what to ignore. Having made all the basic mistakes, I believe that I have a fair understanding of how RF works. However, that isn't quite universal as there are plans for various microwave oven guns all over the internet: <https://www.youtube.com/results?search_query=microwave+oven+gun> I suppose any of these will be adequate for interfering with a smartphone wireless internet connection by destroying every semiconductor junction within range. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Monday, 22 October 2018 17:41:06 UTC+1, Jeff Liebermann  wrote:
> On Mon, 22 Oct 2018 06:11:05 -0700 (PDT), tabbypurr wrote: > >On Monday, 22 October 2018 05:10:05 UTC+1, Jeff Liebermann wrote: > >> Not charcoal. In order to produce charcoal, one heats wood to remove > >> water and volatiles in the absense of oxygen. That would be difficult > >> to do outside of an enclosed air tight stove, oven, shed, or mound. > > >I've done it, it works. If you want to try it, stick some food in a > >microwave oven on full for 30 minutes. Do it somewhere a fire would > >not cause danger. > > I've already done it. About 15+ minutes for a yam, instead of 5 > minutes at 1300 watts: > <http://www.learnbydestroying.com/jeffl/pics/drivel/slides/burned-yam.html> > The yam was glowing red on the inside and belching smog from every > hole. It coated the inside of the microwave oven with a permanent > layer of orange something. The oven now looks disgusting, but works > normally after I tore it apart and cleaned the electronics. However, > the burned smell lingered for several weeks. > > >Yes, technically it's charelectronics, charplastic, charfood etc. > >Impure carbon anyway. > > Yep. I'm not sure what to call it. I threw it outside while it was > still burning. Even the dogs and the local critters wouldn't eat it. > Anyway, it's not charcoal. > > >> >> However, such brute force methods are not considered very elegant and > >> >> should be avoided if possible. > >> > > >> >heh, probably true > >> > >> Most definately true. At the short range needed to be effective, 800 > >> watts at 2.4GHz into presumably a 0dBi isotropic radiator is well > >> above the FCC RF safety guidelines. Anything that will vaporize > >> silicon can probably do the same to brain cells. > > >Orders of magnitude above any sane guidelines. Do you need guidelines > >to tell you to not incinerate things in a pile of sparks? > > It won't produce sparks unless I throw in some steel wool. > <https://www.youtube.com/watch?v=oiWZYdr9Zvo> > However, you don't really need a microwave oven to burn steel wool: > <https://www.youtube.com/watch?v=5MDH92VxPEQ> > > Guidelines are probably a good idea, so that I know what to ignore. > > Having made all the basic mistakes, I believe that I have a fair > understanding of how RF works. However, that isn't quite universal as > there are plans for various microwave oven guns all over the internet: > <https://www.youtube.com/results?search_query=microwave+oven+gun> > I suppose any of these will be adequate for interfering with a > smartphone wireless internet connection by destroying every > semiconductor junction within range.
A mobile phone in a nuke produces plenty of sparks. And charphone. NT
On Mon, 22 Oct 2018 10:29:35 -0700 (PDT), tabbypurr@gmail.com wrote:

>A mobile phone in a nuke produces plenty of sparks. And charphone. >NT
Nope. There isn't enough RF voltage across the air gap to produce a visible spark. The steel wool in the microwave oven works because steel is a mediocre RF conductor. The RF causes the steel to heat up sufficiently to melt the ends of the wires. The produces a cloud of iron ions sufficient to propagate the heating to adjacent strands. The initial burning may look like a spark, but it's not. I could probably calculate what it takes to produce a visible spark, but I'm late for lunch. Figure on a breakdown voltage in dry air of about 3 million volts per meter. This might help: "How strong is the electrical field inside a microwave oven?" <https://electronics.stackexchange.com/questions/339481/how-strong-is-the-electrical-field-inside-a-microwave-oven> Destroying a phone with a microwave oven is too obvious, not very imaginative, and much too easy. My Samsung S6 has a wireless charging feature, which is depressingly slow at charging the battery. I'm wondering if putting it on an induction cooker or stove might speed things up. Try it and let me know what happens (or what remains after the test). Learn by Destroying(tm). -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Sun, 21 Oct 2018 17:33:59 -0700, Jeff Liebermann wrote:
[snip]

> The problems is that WiFi uses spread spectrum modulation, which is > largely immune to interference from an unmodulated carrier. A simple > oscillator, without any modulation, will not work. Even the same style > of DSSS (direct sequence spread spectrum) modulation will not produce > adequate interference unless it uses the same PN (pseudo noise) > spreading code. At best, it might reduce the receiver sensitivity > somewhat.
This is why I suggested a VCO for the job. The control voltage could be a sine wave that causes the oscillator's output to wander over the applicable frequency range and maybe a bit of modulation of that same sine wave just to "thicken" the signal up a bit. [snip loads of links] Thanks, Jeff. Loads of info there in those links. I am going to have fun doing this! :-D -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.
Am 22.10.18 um 23:54 schrieb Cursitor Doom:
> On Sun, 21 Oct 2018 17:33:59 -0700, Jeff Liebermann wrote: > [snip] > >> The problems is that WiFi uses spread spectrum modulation, which is >> largely immune to interference from an unmodulated carrier. A simple >> oscillator, without any modulation, will not work. Even the same style >> of DSSS (direct sequence spread spectrum) modulation will not produce >> adequate interference unless it uses the same PN (pseudo noise) >> spreading code. At best, it might reduce the receiver sensitivity >> somewhat.
Actually, a clean _unlocked_ carrier exactly on the (suppressed) nominal carrier frequency of the PM of a DSSS system is the most efficient way to kill it. The problem is only to find the frequency. It dwarfes whatever the carrier recovery tries to average out of the noise. See Dixon, Spread Spectrum Systems. Good book. Cheers, Gerhard (who tried to build a squaring loop with excessive filtering a long time ago; that completely destroyed the performance. When someone says he has experience, that usually means bad experience :-) )
On 10/22/18 6:27 PM, Gerhard Hoffmann wrote:
> Am 22.10.18 um 23:54 schrieb Cursitor Doom: >> On Sun, 21 Oct 2018 17:33:59 -0700, Jeff Liebermann wrote: >> [snip] >> >>> The problems is that WiFi uses spread spectrum modulation, which is >>> largely immune to interference from an unmodulated carrier.&nbsp; A simple >>> oscillator, without any modulation, will not work.&nbsp; Even the same style >>> of DSSS (direct sequence spread spectrum) modulation will not produce >>> adequate interference unless it uses the same PN (pseudo noise) >>> spreading code.&nbsp; At best, it might reduce the receiver sensitivity >>> somewhat. > > Actually, a clean _unlocked_ carrier exactly on the (suppressed) nominal > carrier frequency of the PM of a DSSS system is the most efficient way > to kill it. The problem is only to find the frequency. > It dwarfes whatever the carrier recovery tries to average out of the noise. > > See Dixon, Spread Spectrum Systems. Good book. > > > Cheers, Gerhard > > (who tried to build a squaring loop with excessive filtering a long > time ago; that completely destroyed the performance. When someone > says he has experience, that usually means bad experience :-)&nbsp;&nbsp;&nbsp; )
Squaring loops led to a lot of that sort of thing. Costas loops were easier to get working. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com