Showing posts with label Phone. Show all posts
Showing posts with label Phone. Show all posts

Sunday, 10 July 2011

Build Homemade Cell Phone Jammer

Not so long ago I was in a deep search for quality instructions about how to make this thing. It took a lot of time and no real results were found. But I did not stopped my searches and at last found what I have looked for, and all this thanks to guys from manufacturing team of Jammer Store Inc.

Their blog post with nice explanations and many pictures and schemes is just awesome! After reading it many things about making signal jammer and how it operates were clean to me as never before. So I used my new knowledge and managed to build my own mobile phone jammer.

Have a look at it and maybe you will build your own too.

Technical Details

Many cell phones use GSM800 mobile standard to operate, thus my VCO (sweeping oscillator) is tuned to the 800MHz frequency range. It may be quite difficult to make this one to work properly without some skills and good testing tools, but in result you will have the efficient VCO.

I used clock oscillator for 45MHz as the noise generator for this jammer. It drives the local oscillator port which is located at the mixer. The signal is going out from the local oscillator and passes through the impedance matching network along its way. This helps equate the impedance of 45MHz clock oscillator with the impedance of the mixer's port.

This port acts like RF input of the signal jammer. The RF output signal passes through the amplifier on the mini-circuit. The output power is increased by additional 15-16dbm in this way. Then the output signal goes to the RF output antenna. RF input has the antenna too.

Jammer Operating

Why I chose 45MHz clock oscillator? Because GSM800 band transmitted and received signals are always separated by the exact number of frequency and it is that 45MHz. Now picture this: cell phone user dial someone and signal goes off. RF input antenna catches it and jammer modifies this signal and lets it go. This signal have a frequency of cell phone's received signal, so cell phone user would hear his or her own voice in a phone! :)

I should also mention that this particular cell phone jammer might be used to block the signal of the cell-based car tracking device which records your GPS data and sends it to some bad guys. And it probably can even jam some IED signals if they are controlled by cell phone GSM800 band.

But I hope that there be no situation in this life when that feature will be needed by me, or you, or anyone else.

Photos And Some Notes

Used mixer was originally made for 600MHz but I modified it a little and it works perfectly for 800MHz.

The amplifier makes fantastic thing with output power. Despite it draws additional power supply, it is worth it.

Jammer case was made from old aluminium box and UHF connectors I took from my old Motorola phone.

Those connectors must be soldered to the mini-circuit to work properly.

To supply this little signal jammer the nine volts battery with voltage regulator is enough. I have separated it from other electronic components with foam plastic.

Don't forget to make a power switch for your new creation. Oh, and attach antennas to the UHF connectors.

So it is ready! Use it wisely ;)

Jammer Scheme


This page was last modified 09:20, 8 July 2011 by beargrills.

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Friday, 24 June 2011

Video Chat on Your Android Phone

Sometimes, the expressions on a person's face can mean much more than what they say. To help you stay in touch with your friends and family, we’re launching Google Talk with video and voice chat for Android phones.



You can now video or voice chat with your friends, family and colleagues right from your Android phone, whether they’re on their compatible Android tablet or phone, or using Gmail with Google Talk on their computer. You can make calls over a 3G or 4G data network (if your carrier supports it) or over Wi-Fi.





  


















































In your Google Talk friends list, a video or voice chat button will appear next to your contacts and you can simply touch the button to connect with them. Any text chats from the person you’re talking with will be overlaid on your phone’s screen so you can read them without having to leave the video. And, if you need to check something else, the video pauses automatically so you can go back to your phone’s home screen or another app. The audio will keep going even though the video has paused. Check out how this works:









Google Talk with video and voice chat will gradually roll out to Nexus S devices in the next few weeks as part of the Android 2.3.4 over-the-air update and will launch on other Android 2.3+ devices in the future. To learn more about using video and voice chat, check out our Help Center.





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