Just seen the neatest gadget... it looked like a cigar tube and about the size of one... when the guy turned it on took out all the cell phones in the wallmart we were in... I should have asked him more about it... anyone else seen one of these or construction details?
Warmest regards, John
-- Watching the cutting edge of yesterday replay--in virtual reality, right before my eyes--in real time!
I was kicking around the design, a voltage controlled oscillator swept though a freq range and modulated with white noise should do it--and sending the output though a buffer and amp... really should be a simple thing to slap together...
John
An extremely handy gadget when a relative of yours had a heart attack and a pedestrian tries to call the ambulance with a mobile phone. Make sure that you really inherit before activating the jammer.
Rene
.... naaa, jamming there might be a problem, I was thinking more of localized areas where people are just an annoyance with their cell phones... like turn it on in the theatre you are watching a movie in--or the library...
John
Why would you want to jam cell phones when you can go out to the airport and jamming commercial aircrafts GPS's and transponders? I don't think the FCC or FAA really minds at all.
Ben:
I was certainly noticing that the vco with a a buffer and amp would probably do the job!
John
"John Smith" wrote in news:ewlqe.44$ snipped-for-privacy@news.sisna.com:
Or when an idiot driver is driving dangerously/negligently while yakking on their phone.
-- Jim Yanik jyanik
Is this what prompted the "VCO Design" and "VCO Design Considerations" posts? I'm not sure of the exact range of cell phone frequencies, but it seems suspicious to me.
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Rich The Newsgroup Wacko wrote in news: snipped-for-privacy@example.com:
Why would you want to *murder* them,instead of just blocking their calls,a non-violent approach?
-- Jim Yanik jyanik
gesus... that would probably take out the am broadcast band on up... heck, it might even "jam" sensitive audio amps... now that is going to cause some real problems...
... not to even mention how in-efficient it is and the power you would need to generate enough power to block even one small set of frequencies--you certainly would start going thorough batteries quickly... might be best to hook it up to 220V mains!
John
Yes, were would one find the cell handshaking protocol... should be able to program a pic to run the handshake...
John
"John Smith" wrote in news:9wtqe.4538$ snipped-for-privacy@news.sisna.com:
Why not just a diode-based,band-limited white noise fed to an amp? You would need one for each cellphone band.
-- Jim Yanik jyanik
.... oh, I think it would, you certainly are not going to concentrate on making the vco very narrow bandwidth... low Q tank circuit would be excellent for this case... and of course if the vco's bandwidth is wide enough--you would not even have to sweep... .... I was thinking of a "white noise audio generator" as might keep the phone so confused would not be able to pull out digital signals...
I don't know--never checked at what range of freqs you would have to cover to catch all phones... but sweep if vco is not wide enough--don't if it is...
.... however, if you sweep, you would sweep at a very high speed... the object does not even have to be to completely block the cell signal--just cause enough havoc to make it unusable...
John
Well, your question already makes me think of taking an easier way into this...
... however, just guessing, I am sure there is a "hold" protocol where the tower can hold the phone in a static state--promising to get back to it--just queue new cell signals and keeps sending each a hold signal...
... but you are right, a more simplistic approach just to make the signal unusable to cells in range would be best...
John
The better jammers mimic a cell tower. The cell phone latches onto the cell tower mimicker and of course, gets nowhere... clever, without pumping out a lot of white noise.
But you have the frequencies wrong, (and it's not in my interest to tell you the correct ones).
Mark Zenier snipped-for-privacy@eskimo.com Washington State resident
He did use the word "band limited". I was once surprised when a student of mine built a noise diode source using a 300mW zener (but really its an avalanche process) diode. The noise was detectable at 2.2GHz - the limit of the spectrum analyser.
The problem with amplifying noise is that you need big amps, since the power/Hz might be small, but if the bandwidth is large, the total power is high.
Kill the jammers? Maybe! I'm not a fan of public use of cell phones, but they *are* a PITA is many places. In fact I think I've come around to the anti-driving-while-chatting law side.
...and yes, I do have a cell phone (and no land-line).
-- Keith
keith wrote in news: snipped-for-privacy@att.bizzzz:
No,he meant to murder the annoying or unsafe CP users.
Yes,but that still does not condone murdering them.
Funny,but my experience with last years 3 Hurricanes in Florida shows that having a land-line is a good thing.That's the only phone that worked after Charlie.CPs were out of service,and many cells were down due to loss of electric power or damage.
-- Jim Yanik jyanik
Dave wrote in news:42ab3040@212.67.96.135:
Cellphone(CP) bandwidth is fairly small.And with the low power levels at the hand-held CP,a great amount of power is not needed,all you need is a noise floor high enough to cover the received signal at the CP,-not at the cell site.Breaking one side of the 2-way link is all you need. You need broadband for CP because of the spread-spectrum methods of modulation. Sweeping a VCO is not going to affect spread-spectrum transmissions.
-- Jim Yanik jyanik
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