About OptiJam technology in “Perseus”® bomb jammers.

The problem of jamming radio controlled improvised explosive devices (RCIEDs) is of high priority for protecting convoys, VIPs and public places.

Company „ARLI SPETSTECHNIKA” manufactures wide range of bomb (RCIED) jammers under the trademark „Perseus” ®. The devices differ in power, frequency ranges, application, constructional design and control circuit. Many original technical solutions and technologies have been utilized in „Perseus” devices. The most important feature is OptiJam technology.

As it is known the emitted integral output power of a jammer depends on the power supply of this jammer. For instance, we are allowed to take 240 W from vehicle onboard network for jammer feeding (at voltage 12V the current will be 20A). We know that real average efficiency coefficient for jamming systems is 25%, thus the optimal output power of jammer, which can be installed in this vehicle will be:

Рoptimal.= 0,25 Рsupply, thus it will be 60 W in our case.

For instance, we need to block frequency range 20...520 MHz (so the bandwidth is 500 MHz)

Radio detonating fuse has the bandwidth 10 kHz and the output power of terrorist transmitter is 1W. Given that the distance between terrorist’s transmitter and receiver connected to bomb equals to distance between receiver at the bomb and the bomb jammer (for instance 100 m).

The receiver with 10kHz bandwidth will receive the signal from the transmitter with spectral density 0,1 W/kHz , and at the same time it will receive the jamming signal from the bomb jammer with spectral density 60W/500 MHz = 0,00012 W/kHz, thus we can see that the jamming signal is much weaker and the receiver at the bomb will not be jammed.

Surely in real conditions the distance between the receiver at the bomb and the jammer will be

5-10 times less, but all the same this will slightly improve the result.

But we know that terrorists RCIEDs are not spread smoothly along the frequency range 20...520 MHz; terrorists try to make their job easier and they use all handy devices: walkie-talkie, wireless toys etc. There are statistics from police and special services regarding frequencies used for RCIEDs. It is possible to calculate the probability of applying RCIEDs in one or another frequency range. For instance, in given full frequency range 20...520 MHz, which we analyze now, the most dangerous sectors (in Afghanistan, for instance), will be the bandwidths 146...155 MHz and 430...450 MHz. So we will concentrate maximum power of jammer on these particular sectors:

and the curve of power distribution will look like above diagram. And this principle will be applied to all range 20...500 MHz.

As can be seen from above the OptiJam technology allows optimization of power distribution along the frequency range and its application increases many times the fighting efficiency of a jammer.

Bomb jammers „Perseus” ® have been working for protecting human life and health all over the world.