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RF jammer

hxhl95

Jul 7, 2011
2
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Jul 7, 2011
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Hi everyone,

Just a quick question about RF jamming.

From what I understand, the concept is just to send out high power waves at the same frequency as the device being jammed. So a sawtooth wave fed into a VCO should sweep out a certain frequency band and, with an amp and good antenna, jam most of the signals within the range.

In particular I've been examining LadyAda's Wave Bubble project, a "self-tuning portable RF jammer" (self-tuning?)

However, from what I've read online, a PLL is apparently also necessary. Why? Technically it shouldn't do much because the band is sweeped, so precise frequencies are not necessary.

Thanks in advance for your help.
 

davenn

Moderator
Sep 5, 2009
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The PLL is used because you can program freqs into it. The synth/pll will be controlled by some sort of uPC a PIC chip etc. it will set the freq range or a specific freq within the range of the VCO that you want to jam. After all you dont want to upset other legit spectrum users by your blatant disregard for their activities.

What it doesnt tell you is that the overall freq range will still be governed by the VCO that is used
So for your statement....
From what I understand, the concept is just to send out high power waves at the same frequency as the device being jammed. So a sawtooth wave fed into a VCO should sweep out a certain frequency band and, with an amp and good antenna, jam most of the signals within the range

that is totally ok for an uncontrolled jammer that will just transmit over the range of the VCO. for no option of specific freq jamming.

cheers
Dave
 
Last edited:

hxhl95

Jul 7, 2011
2
Joined
Jul 7, 2011
Messages
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Would it be easier to adjust the sawtooth wave so it only covers part of the range of the VCO to limit the bandwidth, and adjust the DC bias to change the frequency band being jammed? Is this approach (using digital pots controlled by a uPC) easier than using a PLL?

So lets say I wanted to jam 600-800 and my VCO is from 400-800 with a V range of 0 to 20. I could just set my sawtooth wave to have 10V peak-to-peak and a DC offset of 15V to sweep 600-800 on my VCO, right?

I'm asking this because it seems to me that using a PLL would require many more components, whereas I already need to have components to adjust peak-to-peak voltage and DC bias of my sawtooth wave.

Thanks :)
 
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