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 cell phone jammer source and differenced to indicate the azimuth direction of arrival of the jamming signal.
Enemy jamming of US and allied communications is a growing concern, especially given DoD’s widespread reliance on legacy radios and datalinks. Protecting communications from jamming usually requires the use of complex waveforms, frequency hopping (either pre-planned or rapidly improvised by “cognitive” software), higher power levels, and/or directional beams. DoD will implement improvements to Link-16 in 2019 that incorporate some or all of these features. The most fundamental way to avoid being signal jammer, however, is to keep the enemy from detecting your communications in the first place. That requires LPI/LPD communication systems, which are growing in importance beyond niche capabilities and are increasingly becoming the assumed baseline communication network for new DoD systems and operational concepts.
Even if they can avoid enemy jamming and passive detection, U.S. forces will still need to obscure and confuse adversaries’ radars and disrupt enemy communications. With the advent of adaptive, frequency-agile radars and radios among U.S. competitors, jamming increasingly will require systems able to operate across wider swaths of the RF spectrum that can detect and disrupt adversary transmissions with the help of cognitive and machine learning algorithms.
The electronic war was on display from the start of the Russian incursion into Crimea in the spring of 2014. Not long after Russian EW equipment began rolling into the region, Ukrainian troops began to find that their radios and phones were unusable for hours at a time. Meanwhile, the Organization for Security and Co-operation in Europe, an international conflict-monitoring group, has consistently reported that its drones watching the conflict in eastern Ukraine have been “subject to military-grade GPS jamming,” forcing monitors to scrub missions taking stock of the war below.
GPS jamming is extremely common on the battlefield as well. The real difficulty would be inertial navigation, or terrain following cameras. Luckily inertial navigation is not only expensive, but it’s difficult to get right, and can’t update it’s mission on the fly if it’s being RF jammed.