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Wavebubble working....kinda
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Please be positive and constructive with your questions and comments.

Wavebubble working....kinda

by san26141 on Sun Aug 02, 2009 1:02 pm

I have been testing my device with multiple cell phones on different carriers and I don't understand what is happening.

1) I can "jam" an iphone both before and during a call.
2) Other carriers I can "jam" while not on a call. If the other cell is already on a call I have difficulty blocking it (roughly 50/50). I have tried both near and far from a cell tower and it behaves the same. I am roughly judging signal strength between the phones by the amount of bars visible in each one. (Which by no means is accurate.)

Any ideas on why a call in progress is more difficult to "disrupt"?
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Re: Wavebubble working....kinda

by sciguy14 on Mon Aug 03, 2009 12:59 pm

I'm having similar problems. I've built 4 wavebubbles, and on all them, GSM phones (like the iphone) jam perfectly, but CDMA phones hardly jam at all...
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Re: Wavebubble working....kinda

by nux on Mon Aug 03, 2009 9:00 pm

sciguy14 wrote:I'm having similar problems. I've built 4 wavebubbles, and on all them, GSM phones (like the iphone) jam perfectly, but CDMA phones hardly jam at all...


Check the frequency that your CDMA operates on, it may be different from the GSM frequencies you are trying to jam. Also, it may not be suited to the antennas that you are using.
Also, CDMA will be harder to jam, it can work at lower SNR's and is more resistant to noise.
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Re: Wavebubble working....kinda

by cmolson on Tue Aug 25, 2009 1:18 pm

I have been able to jam any CDMA phone (yes very close range). When I say any, I mean I tried 3-4 phones at close range (standing next to the person)

One thing to check as mentioned above is the program you put into the wavebubble, ensure it is set to the correct frequencies.

Also another note,

The wider the frequency you are trying to jam the less range you will have. It takes time to sweep through more frequencies so try only programming in the very specific range you want to jam.
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Re: Wavebubble working....kinda

by andyman on Thu Aug 27, 2009 3:57 am

I just completed one of these babies and I am quickly learning that the amp chips can't tolerate much heat from the soldering iron. Fortunetly I have a spectrum analyzer (FSH6 from R&S) and I can see that one amp puts out very little amplitude (maybe 10dBm).. I replaced the amp with a new one soldered the sucker quickly to prevent damage and my signal went up dramatically (30dBm) on the low freq side.

So just because it works doesn't mean it "works".. You should get it tested somehow.


andy
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Re: Wavebubble working....kinda

by cmolson on Thu Aug 27, 2009 8:13 am

andyman wrote:I just completed one of these babies and I am quickly learning that the amp chips can't tolerate much heat from the soldering iron. Fortunetly I have a spectrum analyzer (FSH6 from R&S) and I can see that one amp puts out very little amplitude (maybe 10dBm).. I replaced the amp with a new one soldered the sucker quickly to prevent damage and my signal went up dramatically (30dBm) on the low freq side.

So just because it works doesn't mean it "works".. You should get it tested somehow.


andy




Good point, I haven't really tested mine yet for actual power output. I am familiar enough with electronics to debug the digital side (micro-controller, even power supplies) but RF is a little out of my league. Is there any way to test the output using only an oscilloscope?

When you say soldered "quickly" how much time are we talking, I tacked one pin on, then waited for everything to cool down and soldered the other two pads the same way. I put a bit of solder on the first pad, then heat it up, then move the component onto the heated pad, as soon as I see it has a good connection (shiny) i remove the heat.
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Re: Wavebubble working....kinda

by sciguy14 on Thu Aug 27, 2009 2:53 pm

You can test it with an oscilloscope only if it is super fast. We used a 20GHZ oscilloscope hooked up directly to the SMA connections to get an idea of the amplitude.
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Re: Wavebubble working....kinda

by cmolson on Thu Aug 27, 2009 3:32 pm

My oscilloscope is 2ghz digital agilent. I know to sample a ~2ghz sine wave you need to get 2.5* the frequency If I remember correctly (nyquest?).

Anyways, the scope has a feature which given a repeated wave, will keep sampling, so it is possible to find the maximum amplitude I believe. (It won't be able to find weird glitches or anything, but it kind of acquires samples over more time.

I will try this later once I get it all hooked up again, thanks for the idea.

Once I get the amplitude, how do I find out the power? (I will be googling this as well )

Thanks!
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Re: Wavebubble working....kinda

by sciguy14 on Thu Aug 27, 2009 4:25 pm

The amplitude is pretty much equivalent to the strength of the output.
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Re: Wavebubble working....kinda

by cmolson on Thu Aug 27, 2009 4:35 pm

What kind of amplitude are you getting (in V?)

Thanks,
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Please be positive and constructive with your questions and comments.