Handheld GPS jammer locator

Handheld device determines the strength and direction of a jamming signal

Military Technology Electronics Sensors

Navy engineers have developed a handheld GPS jammer locator device for determining the strength of an L1 GPS frequency jamming signal and the direction of the jamming signal. The handheld GPS jammer locator has two modes of operation, an amplitude mode for determining signal strength, and a difference mode for determining direction. The technology can be acquired for commercial development by licensing the patent from the Navy.

According to the patent, the device consists of two small antennas separated by a half wavelength of a GPS carrier frequency. The radio signals from the antennas are then combined in a 3 dB quadrature coupler. The two RF signals output from the coupler represent two displaced antenna beams. An RF switch sequentially selects the two RF signals and then supplies the selected RF signal to a receiver, terminating the coupler output not selected during a particular time period. The RF signals are reduced in frequency from the L1 GPS frequency of 1575.42 MHZ to an IF (intermediate frequency) signal of 70 MHZ by the receiver which includes a low noise amplifier, an RF amplifier, and a balanced mixer.

A log amplifier utilizes signal compression to provide a log transfer function covering IF signals within a power level range of +10 dBm to -70 dBm. The log amplifier then provides a one-volt to five-volt signal which represents the power level range of +10 dBm to -70 dBm for the 70 MHz IF signal. The output of the log amplifier is sequentially switched by an integrated switch with the sample and hold circuits in synchronization with the RF signal Switching by the RF switch. The output signals from the sample and hold circuits are Summed to determine signal strength which is an indication of the approximate distance to the jammer source and differenced to indicate the azimuth direction of arrival of the jamming signal.

The prototype was built within a plastic housing and is powered by a 9-volt battery. Contact TechLink now to find out more about licensing this invention.

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