Radio Jamming

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Radio Jamming Anonymous 04/02/15 (Thu) 21:38:00 No.210

Do any of you know about this topic?
From generating waves in order to jam devices to preventing it.
I think it's an interesting topic.

Anonymous 04/08/15 (Wed) 16:12:51 No.238

>>210
it is an interesting topic. from the conventional HAM view it is seen as RFI (radio frequency interference) and nobody would intentionally cause it. it is the subject of great study in order to prevent interference with other transmitted signals. but it is quite easy to use the same knowledge and principles to quite the opposite effect.

>troubleshooting a problem with robotics in a coca-cola bottling plant
>little robots carry pallets all throughout the plant following guidewire buried in concrete floor
>robots suddenly start going nuts when they go near battery charging station
>15 feet between nearest battery charger and guidewire as well as grounded steel wall
>everything well grounded and the system had worked for years until the battery charger software was updated
>turned out that all the protections to prevent interference that they thought were effective over the years weren't
>new charger program included for 1st time frequency sequence that could interfere with robots and it did
>all engineering specified protections were for RFI and conventional electrostatic protections
>batteries were 48v 1400AH forklift units recieving 72v 250A max charging current

the whole problem ended up being magnetic waves produces by the 250 amp current pulses

Anonymous 04/08/15 (Wed) 23:10:02 No.242

>>238
Nice story, thanks for shearing it!
My I ask you a question about it? You seem to be in topic.
How a narrow band Gaussian noise signal behaves with some RF system? (ie signals with the frecuency used for L1 GPS )

Anonymous 04/08/15 (Wed) 23:10:53 No.243

>>242
And how that differs from a simple continuous wave.

Anonymous 04/09/15 (Thu) 02:08:04 No.244

>>242
I'm not quite sure what you are asking. a narrow band gaussian noise signal?

different types of noise will have different distributions of power and frequencies
I have little information about how different types of noise affect different digital systems

I'm sure you can find specifics in various articles that compare modulation schemes to reduce the bit error rate

>>243
>And how that differs from a simple continuous wave.

well for starters the noise signal will be made up of many different frequencies while the simple wave will be only one.

if you are looking at this from the perspective of jamming you have choices.
a pure wave signal on the same frequency as the target frequency to be jammed must be significantly stronger at the receiver in order to overwhelm the information

a properly configured noise signal however will seek to disrupt the digital process by having the noise interfere with the detection of leading and trailing edges of the digital ones and zeros, thus introducing error with a jamming signal that is of a lower level than the signal to be jammed
a noise signal that will