Review and teardown of a cheap GPS Jammer | Hacker News Reader

Review and teardown of a cheap GPS Jammer

phasenoise.livejournal.com

38 pointswolframio10 comments

This part is ... a worry.

> He was working on a job inside the Newark Liberty International Airport when his jamming signal interrupted air traffic control.

Shouldn't it have better protections against a $25 internet purchased jammer? Are such protections possible?

Also, what would happen if you used this while in an Uber?

> Shouldn't it have better protections against a $25 internet purchased jammer? Are such protections possible?

I don't think so. GPS is a purely passive system. If someone is broadcasting a signal in your immediately area that overpowers the GPS satellites, there isn't much you can do.

Along the same lines, I'm surprised there aren't well publicized amateur UAV combat competitions with directional GPS jammers and EMP weapons yet.

> If someone is broadcasting a signal in your immediately area that overpowers the GPS satellites, there isn't much you can do.

directional receivers?

It would be pretty difficult to track 3-12 satellites at a time with a directional antenna, particularly with both the satellites and the plane in motion.

You could employ something like a directional antenna who's radiation pattern will basically look like a half-circle, with the flat part facing down, but, radiation patterns are not black and white, even if 90% of the energy is received from the main side, there is always some signal still received from unwanted directions. With as weak as GPS signals are, it wouldn't take much to drown them out, even on the back side of a directional antenna.

Yes, that's pretty much how military anti-jamming works. You have a steerable (via phase switching, not physically moving) antenna that can form a beam with nulls pointing at the sources of interference/jammers. See https://en.wikipedia.org/wiki/Zero-forcing_precoding for more info.

GPS navigation is generally a good thing. GPS tracking is a slippery thing, seen by some as an invasion of privacy. The vehicle owner should be entitled to know where their property is, but it is none of their business where I go and what I do during the day. Insurance companies would love to hike premiums based on where you park, where you eat, how many mistresses you entertain, or those brief stops in the seedy part of town.

On one hand, GPS tracking can help against theft, or at least facilitate recovery. On the other hand, it opens up a wealth of possibilities for abuse

It's really incredible to be part of the security industry and know how widely used these things are as part of private investigations. At a rough guess I would say at least a third utilise them in some way.

Would the jammer also work against other global navigation systems?

Xiaomi phones, for example, can receive GLONASS and BeiDou signals.

In the future, Galileo may also be an option.

From the chart in the article, this particular model generates a well defined signal between roughly 1550mhz and 1590mhz.

The BeiDou[1] and Galileo[2] system both operate in the same band, but have an additional band around 1250mhz they operate in.

The GLONASS[3] system operates on two bands, one just outside this one (roughly 1598mhz to 1606mhz) and one lower band around 1246mhz.

GLONASS would appear to be the only one completely not susceptible to this particular device, though a device that would be effective on GLONASS is probably available as well.

I don't know the technology well enough to say for certain that the BeiDou and Galileo systems would operate in the presence of this device, but I believe they would.

For the non-RF engineers, scroll down to the tables on each page, they are a bit easier to understand.

[1] http://www.navipedia.net/index.php/BeiDou_Signal_Plan

[2] http://www.navipedia.net/index.php/Galileo_Signal_Plan

[3] http://www.navipedia.net/index.php/GLONASS_Signal_Plan

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