Jammer circuit


Posted on Feb 7, 2014

The frequency jammer works by creating interfering RF noise, centered around the 2. 45 GHz carrier. As the power associated with the noise increases, the signal to noise ratio for the wireless communication channel decreases. This increases the bit error rate until it becomes large enough for the wireless device to be no longer operable. The freque


Jammer circuit
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ncy jammer is designed around the voltage controlled oscillator, VCO, which creates the interfering RF signal. While VCO`s can be built using opamps, resistors and capacitors, the low cost, availability and reliability of prefabricated VCO`s make it optimum to just purchase the device. For our proof-of-concept design, we needed to create an interfering signal for the 2. 4 GHz band. We were able to find a VCO from Mini-circuits that met these requirements. The VCO, ZX95-2650, can be tuned from 2. 05 GHz to 2. 70 GHz and is already housed in a case with an SMA connector. The ZX95-2650 was a little more expensive than surface mount VCO`s, but fit within our budget and reduced the time we would need to design a Printed Circuit Board (PCB). The jammer works by applying a triangle wave to the input of the VCO. The voltage range of the triangle wave corresponds to an interfering frequency range of the VCO. Each prefabricated VCO will have a specific voltage range that corresponds to an interfering frequency range. In the case of the ZX95-2650, we decided that a voltage range of 9. 6 V to 12. 5 V would create the desired interfering signal for our project. According to the data sheet of the VCO, this corresponds to the VCO being swept from about 2. 38 GHz to 2. 5 GHz. It is necessary to sweep the VCO from slightly below the 2. 4 GHz band to slightly above 2. 4 GHz in order to ensure the desired jamming takes place. Also note that...




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