Jamming involves pumping out RF in the frequency range they are using enough to overpower their own signals. So, you need power and you need to know the frequency range. Since RF drops off as the square of the distance, unless you can aim it very carefully, you have to be close or have lots of power. They don’t really publish exactly where it is you need to point, so go with needing lots of power.
In principle, yes. But modern frequency-hopping technology makes it very difficult, because the cell phone jammer can’t predict what frequency will be used from one moment to the next. The only practical approach is a broad-band assault on the entire frequency range, which requires a very large amount of power.
The North Koreans are believed to possess a mix of old Soviet jammers, purchased roughly 10 years ago, and their own homemade equipment. These signal jammer on wheels are positioned in Kaesong province hilltops around the border for maximum reach, Last said.
A new generations of jammers were introduced too, they could cover a broad range of frequencies and perform specific “set-on” jamming which mean that “rather than confuse a receiver with a modified version of its own signal, Duke had a series of built-in jamming responses, designed to fool very specific devices.” And as jammers got better, the insurgents in Iraq largely abandoned the use of IEDs and deaths from IEDs dropped.
In the field of mobile communications, a jammer is a device that blocks transmissions by creating interference. The jammer emits signals in the same frequency range that cell phones uses, and within the range of a jammer a cellphone user may lose their signal.
Jammers are usually undetectable, and users may experience minimal effects such as poor signal reception. Jamming devices may be used in any location but are typically deployed where cellphone use may be disruptive, such as in libraries and restaurants.