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Help! Seems OK but not doing the business!
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Re: Help! Seems OK but not doing the business!

by soram on Tue Jul 05, 2011 7:31 am

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
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Re: Help! Seems OK but not doing the business!

by Mictronics on Tue Jul 05, 2011 10:25 am

The only solution for more power is a third board with amplifier for each VCO. Requires an additional power supply as well.

Or another redesign of the WB with integrated preamplifier's.
/Michael
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Re: Help! Seems OK but not doing the business!

by TheFallen on Tue Jul 05, 2011 5:10 pm

The initial WB parts list calls for RP-SMA connectors, you're using SMA connectors on your antennas and aerials So unless you've destroyed your RP-SMA connectors that means you've got SMA connectors soldered onto your wavebubble.
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Re: Help! Seems OK but not doing the business!

by soram on Tue Jul 05, 2011 5:24 pm

I have indeed. I had the RP-SMAs but got antennae that didn't fit so ordered SMAs for the board.
I looked it up at the time and it seemed that the only reason for RP-SMA was to stop cross use between some professional and commercial usage so I figured it wasn't a technical issue. Was I wrong? I can't imagine there to be too much (any) difference.
The finishing stage design lists both types of antenna. Rest assured I do have a a male and female antenna / connector combination though!

I have ordered the Penta antenna to try out but I don't expect it to double my output so I'm still looking for a solution to that in the 1800-2100MHz range. The original had a third board with nothing on it. Could that house extra power for those that want it? Even just for the high frequency VCO? The existing power switch could then be used to modulate the output to an acceptable duty cycle.
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Re: Help! Seems OK but not doing the business!

by soram on Thu Jul 07, 2011 6:03 pm

Update....

Well I got the Penta antenna and it is a definite improvement in the 2100 MHz range. The bigger quad antenna however is no noticeable improvement over the stubby quad on the analyser.

The 1800 MHz band is way less powerful than the 800 Mhz so I'm going to play with the attenuator as it is in the higher band I need the power. I'm not sure I understand where the losses are as both VCOs are supposed to deliver between 7 and 8 dBm.

With an antenna on the input to the analyser for kicks I can see the iPhone sends out spikes way in excess of the power the jammer does when trying to connect to base.

I have used the resistor values for the T from the original design. Any comments on that? The low range VCO runs noticeably cooler than the high range one!
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Re: Help! Seems OK but not doing the business!

by lcstyle on Wed Jul 20, 2011 1:05 pm

soram wrote: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.



Have you verified that the vco input is a sweeping sawtooth wave ? Jamming is impossible without noise.

Also, you might want to read through the original thesis paper here and reflect on what may or may not be right with your build:
http://www.ladyada.net/media/pub/thesis.pdf
Let’s put a smile on that face!

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Re: Help! Seems OK but not doing the business!

by TheFallen on Wed Jul 20, 2011 7:20 pm

In fact without the sweeping sawtooth wave it would be impossible to get any output at all. However that is not the problem. He can jam, just not with to the desired distance. As for Lady Ada's thesis, it's definitely interesting reading, but doesn't focus on debugging a lack of range.

Excuse me being a bastard, but did you read this thread, or just the title, before commenting in it?
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Re: Help! Seems OK but not doing the business!

by lcstyle on Wed Jul 20, 2011 7:48 pm

TheFallen wrote:In fact without the sweeping sawtooth wave it would be impossible to get any output at all. However that is not the problem. He can jam, just not with to the desired distance. As for Lady Ada's thesis, it's definitely interesting reading, but doesn't focus on debugging a lack of range.

Excuse me being a bastard, but did you read this thread, or just the title, before commenting in it?


You are right I obviously have no idea what I'm talking about.
Let’s put a smile on that face!

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