The working frequency range of GPS jammer can be adjusted manually

The U.S. Department of Transportation will host an afternoon seminar on December 3 on the topic of GPS interference and deception in the marine environment. Speakers include Diana Fuchtlot, Assistant Assistant Secretary of Research and Technology, Captain of Maersk Line; and representatives from the National Security Council, Maritime Administration, and the US Coast Guard.

Although gps jammer and spoofing are a problem in many transportation and critical infrastructure areas, they are usually most obvious in maritime transportation. This is because the automatic identification system (AIS) used for collision avoidance and traffic management of large ships transmits location data based on GPS input. These transmissions are received by coastal networks and satellite systems. AIS data is usually provided free of charge or easily accessible to the public.

Ships in Russian waters were faked as inland airports, ships in Chinese ports were reported to be inland and hovering in government buildings, ships in parts of the world broadcast their location circles thousands of miles away in the oceans of Northern California. Three of the highest cases provided in recent years. In 2019, the US Coast Guard raised GPS signal interference as an “emergency issue” of the International Maritime Organization. In February, President Trump issued an executive order on the responsible use of positioning, navigation, and timing. The seminar is part of the federal government’s efforts and an important part of educating the public, which involves loopholes related to excessive reliance on the GPA. The seminar is free, but participants must register. Pre-registration is possible.

The component labeled 13BA A041 is clearly the star of the show. What is that? Although I cannot find a data sheet for this particular model, it is a voltage controlled microwave oscillator (VCO). The visible top plate is actually a metal shielding layer. With a little convincing situation, we can look inward and see that the number of components packed into the 9mm x 7mm area is amazing.

The basic working principle here is that the control pin of the VCO (marked as VC on the silk screen) is connected to the output of the 555 timer on the other side of the board. The signal from 555 modulates the output of the VCO and generates noise, which is concentrated on the GPS frequency of 1,575 MHz.

After connecting the oscilloscope to the VC pin, we can see that the 555 timer generates a sawtooth signal of 133KHz. Adjusting this signal allows you to change the frequency range of the GPS jammer. However, without the VCO’s data sheet, it is difficult to tell how far you can move it. But since these may be the cheapest components available, they may not be far away.

It is worth looking at the small four-pin device marked Q6 on the top of the motherboard. When the high-frequency signal goes from the VCO to the center pin of the antenna connector, it is in the path of the high-frequency signal, which will be a reasonable place to place the amplifier. But it can also be a diode to protect electronic equipment from all objects picked up by the antenna.