Help! Seems OK but not doing the business!

[soram]

Ok. I have built the thing and over many months should be there with the final result.

I posted previously about the PWM test but I have overcome that. Now I am stuck. I have got my hands on a 3GHz spectrum analyser and the output looks like everything is functioning. I get a spike around the required tuning frequencies for both VCOs. There is also some other higher frequency stuff happening but not sure what that is.

However, I can 'mate' my iPhone with wavebubble but it has absolutely no affect on the reception. I suppose the only issue now could be the power but this is outside my expertise.

Attached is a pic of the spectrum and the build. Any help, suggestions mightily appreciated. I only have the analyser for the weekend!

[TheFallen]

The aim of a jammer is to raise the noise floor in a defined band. It looks like you've got peaks at 900MHz, 1.7GHz and 2.6GHz. The first two are mobile phone bands, the 3rd is just a bit higher than Bluetooth/WiFi.

What are the programs and their tuning settings? If you print them out of the terminal then copy and paste them into here (between code tags) please. Also, what VCOs have you soldered in there?

Now what do you mean by "mate" ? A wavebubble will jam a phone if it's done in the proper manner: 1. Set the wavebubble up, use this to help you use the frequencies, also ensure you're on the correct program. 2. Now the WB is on, and on the correct program, make a call with your phone. It should drop out and you will get some sort of no service message.

Hope that helps.

[soram]

Thanks for the reply.

Yes, I have a peak around 900MHz. As you can see below I tuned the low range VCO for 850-950MHz so this should be right. I believe the other lower peaks are harmonics. Michtronics' graphs also seem to have such harmonics.

By 'mate' I mean the phone can't get any closer to the Wavebubble. It is physically on top of it! But I still get nearly full bar reception and it doesn't drop any calls.
So it looks to me like the PLL and VCO is actually working but perhaps I have no power for some reason - though I would have expected at least some phone signal degradation at such close proximity.

The VCOs are the ROS 1700 and 2500 as specced in the original design.



Program #1 of 1

VCO 1: 1800 -> 1900 (0, 0)
VCO 2: 850 -> 950 (0, 0)
---------------------------------
PLL for RF freq 1850MHz & prescaler 8: B=231 A=2

midpoint @78

bandwidth tuning...
PLL for RF freq 1800MHz & prescaler 8: B=225 A=0
26 done!
PLL for RF freq 900MHz & prescaler 8: B=112 A=4
midpoint @62

bandwidth tuning...
PLL for RF freq 850MHz & prescaler 8: B=106 A=2
48 done!

[Mictronics]

The harmonics are normal since there is no output filter installed.

With the cell phone I had same experience. I'm not able to jam my Nokia phone.
But this might be related to the fact that these phone are dual or three band types. So maybe the phone changes to another GSM band if one is blocked.

Try with GPS and WLAN, works good for me.

[soram]

Hmmmmmmm

The phone may switch between 900 and 1800 but not any others as I don't think they are available here.

I sort of figured out what the analyser is telling me and it appears I am getting about 20 dBm in the 900GHz range and 12 dBm in the 1800 range. That doesn't seem terribly bad and I would have thought enough to jam the iPhone if the theory was correct.

I will try to jam my local WiFi signal when I get a chance later to see if I am indeed radiating but I would be let down if after it all I can't jam the cellphone!

Am I missing something here?

Cheers

[TheFallen]

Phones typically expect signals in the -60 to -100dBm range. My HTC Desire S actually tells be what it's getting and it sez: -99dBm.

I think the most important question I have is, have you got antennas on? I mean, when you're trying to jam your phone you do have antennas on the RP-SMA connectors? (I've got 2 5dBi WiFi antennas, terrible I know...) If instead your not jamming anything when you have no antennas, or have attached it via 50ohm co-axial cable to your SA then you won't get much of a signal in the first case, and none in the second case. Make sure to stick an antenna on, even if it's the worst antenna ever (say a 4GHz antenna on the 600MHz output) it's still an antenna.

[TheFallen]

ALSO: A lot of phones will let you set the phone to a specific band, say GSM or/and WCDMA etc...

[soram]

Yep, I have antennae on. I'll post a pic later but I have a quad band antenna on both outputs on an sma connector. I screwed the spectrum analyser on the sma connector to measure it so at that point there was no antenna.

So I'm kinda stuck. And now I'm kinda disillusioned!Does this thing work or not? Hands up how many have it working?

I have done all the tests and my analyser says it is performing as designed - I think - but it doesn't do what I want and now Michtronics says he can't interfere with his Nokia even with the non plus ultra new design!

What's the story?

[TheFallen]

Some phones are quad band, i.e. 4. This is a 2 band jammer. Some phones can work around it, others can't. When I've been playing around with it it is possible to jam most phones whilst they're in the middle of a call.

Right, just tested mine:

Code: Select all

Program #1 of 1

VCO 1: 1805 -> 1880 (30, 254)
VCO 2: 925 -> 960 (30, 254)

(Think mine's having problems, no way 1880MHz is 254, it would be more like 2500MHz...)
Now I'm in the UK so those are the UK bands for GSM/WCDMA and I just made a call to 1234 (speaking clock), connected fine, then I turn the jammer on, and the call is dropped. I've got a modern smart phone which is quad band so despite that, it definitely works (although I'm a bit worried about those values of 254 ).

Note the "non plus ultra new design" is purely a streamlining of the old WB design wit ha few little tweaks (VCOpower select, more common parts etc)

[soram]

I still don't understand why the 2 bands should not be enough even if the phone is a quad. In the UK the operators will only be on 900/1800 so even if the phone switches to 800 it wouldn't find a base station.

My tuning for the same frequencies is:

Program #1 of 1

VCO 1: 1805 -> 1880 (86, 16)
VCO 2: 925 -> 960 (76,22)

I have verified with the analyser that I am indeed getting the correct output too!

I also tried 2400-2400 for 802.11b and that does indeed whack my wireless network to a range of about 10 feet so it is working some way.

Do you have to turn the jammer on to drop the call? I would have hoped I could leave it on and any phone that then came within range would experience a loss in signal. Are 3G phones different?

[TheFallen]

Just tried having the jammer on then making a call.MY phone switched to 3G, made the call connected, ot about 2 secs of times then it became unintelligible but still connected.

[soram]

OK I did the Google thing and found another band 3G apparently uses in Europe.

http://en.wikipedia.org/wiki/UMTS_frequency_bands

There is the 2100 from 2110 to 2170MHz. I put this in and hey presto it kills my iPhone 3GS at short range! But not the Nokia 3G

Well at least I know it actually works and can try to fine tune it from here.

Watch this space

[soram]

I've done a few tests with various frequencies. At very close range I can knock out the 3GS. Close being about 3 feet. Sometimes it gets knocked out but seems to find a signal somewhere else that seems more difficult to hit.

It would be great if I knew what channel the phone was working on so I could correlate that with the jammer. Anybody experience with IOS and where to read the frequency? I can do a basic app myself to display it if I knew where to grab the channel info. If indeed that was possible!

Secondly, I reckon power is a problem. I am only getting 10dBm in the high frequency range and have to open up it quite big to hit both the 1800 and the 2100 bands. I can get 20dBm from the lower VCO. Might it be possible to get some serious gain for short period bursts? I have no RF experience so wouldn't know what to do here but would it be possible to build an add on that would give some more power? As it is it is a nice toy but with the limited range it is not as useful as I would like it to be.

[TheFallen]

I'd google around for the iOS frequency settings, but I haven't a clue about iOS (closed source overpriced cultist-ware tat grumble...).

I get 4 feet with a Desire S and 2 5dBi 2.45GHz antennas, a.k.a. worst antennas possible to use.

Power-wise the problem you have is that finding an amplifier that can provide +20dBm over ~1GHz is just about manageable, anything greater is impossible. For example WiFi has a bandwidth of 100MHz, phones are about ~70MHz, we want a bandwidth of 1000MHz. Sure we're satisfied with a spotty power vs bandwidth curve but that only helps us so far. If we want say 30dBm (1Watt) we'd need to construct a multi-band amplifier unit. This involves multiple filters and amplifiers, and BLAM we've just doubled the wavebubbles size (and quartered its battery life).

Just had a mad through, those Quad band antennas, are they SMA or RP-SMA? Links to websites/manufactures/datasheet would be splendiferous!

[soram]

http://www.farnell.com/datasheets/492002.pdf

The above is a link to the antennae datasheet. I have the OS-GSMQB-00-C which is a very stubby one. I have two identical - one on each output. They are SMA i.e. not reverse.

I'm thinking I need the penta band one (IR-GSMPB-02-C) for the higher frequency output now that I know I need to go to 2100MHz. What sort of improvement can I expect with swapping out the antenna? Will it be very noticeable? Will I get 3dBm?

The thing is I screw the analyser on to the SMA connector in place of the antenna and get 20dBm from the low range VCO and 10dBM from the high range. I guess that is degraded more with the wrong antenna? Anything to boost this band would be helpful. I reckon from 1800-2200MHz