Are GPS Jammers a thing? A multipart question.

We track our buses with a GPS based system that is very accurate most of the time and our supervisors monitor them on iPads and desktops in real time to make service adjustments.  We've been having an ongoing issue with buses "disappearing" off the system unable to be tracked. Some of them have been identified as having hardware problems, and they are being repaired.  Those buses generally never transmit, or drop off randomly.  We've also identified a number of buses that only disappear with certain operators but reappear with different operators, and some operators don't get tracked regardless of what bus they are on.  There is no way for the GPS to be turned off on the bus without breaking security seals in the roof of the bus which does not seem to be the issue but today I was teaching a class of new supervisors and a few were talking about drivers that had GPS jammers.  A quick Google search brings them up but the ads looked kind of hokey like something you'd get in a novelty shop.

1. Are there actual jammers that would work almost always, be small enough to be carried without notice, and self powered as there is no place on the bus to plug them in?

2. If there are what kind of features should I be looking for if we wanted to test one?  

3. Are there devices that would block a GPS jammer or some kind of detector that could identify if one was being used?

I don’t (honestly) have any direct experience with them, but I know they are out there.  So I can’t speak to how well the units found on the internet work.

They are illegal to operate.  Not only would they be in trouble with their employer, they would be in trouble with the FCC if they are caught operating one.

Maybe if the folks are using them, they are using a portable phone charger to power them.  Basically a small case with batteries in it with a usb to plug stuff into.

Here is a short article about them.

Foil, metal or magnet draped over the GPS antenna could make the GPS stop transmitting.  

In reply to paranoid_android :

Good article.  With a range of only 5 to 10 meters, it's unlikely that the FCC will find these things, especially if operated intermittently.  I would assume that operators that consistently went invisible were actively doing something to accomplish that, although that could be difficult to prove.

Wally said:

We've also identified a number of buses that only disappear with certain operators but reappear with different operators, and some operators don't get tracked regardless of what bus they are on. 

This screams something is up to me. Maybe hide a secondary cellphone based gps tracker and camera and see if it keeps happening with the same operators.

10 meters, roughly 30 ft.  I am assuming that the jammer is on the driver's person.  If the GPS antenna was located in the rear, roof of the bus, that distance would be greater than 30 ft from the driver.  

In reply to paranoid_android :

Thank you, that article is much better than what I was finding.  I’m not terribly tech savvy and that will do a better job of explaining to my manager what I was talking about.  

In reply to MrChaos :

I’ve been observing the same handful of guys on my routes that disappeared when they got the bus but then the bus reappears when someone else has it which is what led me to believe it’s not the bus.  The operators that this happens to also frequently like to run either well ahead or behind schedule making it look even less like a coincidence.

In reply to John Welsh :

The antennas are almost directly above the drivers seat so it would be well within range of these gadgets.  

Thanks everyone for helping. Now I don’t seem as crazy.  This morning I got looked at like I was talking about some James Bond nonsense.

If you wanted proof, I bet the FCC would be interested in it. They might be willing to dispatch someone to ride the bus when those operators are on it and see if there's an unexpected signal. The GPS signal is very low level - it's broadcast from a satellite, after all - and I think what the jammers do is just put out noise on the same frequency making it impossible for the GPS on the ground to pick up the satellite signal. It would be trivial for someone with the right equipment to find the jammer in operation and they do take it seriously.

https://www.gps.gov/spectrum/jamming/

Penalties for a first time offense are in the tens of thousands of dollars. Being in NYC, I imagine they would be interfering with a lot of other GPS devices while on their route, too.

One way of determining if the GPS is being masked or covered with foil, a magnet, etc, is to discretely move the GPS antenna to a new location. 

Or better yet, add a new antenna to certain buses. 

If those same buses, under certain drivers, are still going off the map, it might be time to investigate the possibility of a jammer being used. An easy way to tell would be ask someone not associated with the department to try using Google maps, save the area to offline, turn off celluar (so Google Maps is forced to use the devices GPS), GPS turned on, from within the bus of a suspected "masker".

You can also wait and see which drivers are carrying GPS jammers by waiting for their reproductive parts to fall off from the intense RF.

You know, an even better way would be to bring all the drivers in and have a little heart to heart with them. 

"If anyone is tampering with the GPS devices on the buses, or using a jamming device, be aware the using such devices is a Federal Offense, and not only will you be terminated, you will also face the full wrath of the Federal Government." 

You might be surprised to see the buses sudden appear on the map.

According to the geotab website, fines can run six figures and prison time is not out of the question.  I also noticed many of these products plug into an OBD II diagnostic port.  I know buses do not have OBDII ports but perhaps there is something similar and the drivers are sharing location info about the trackers.  They could just be disabling them by unplugging them.

there are 2 things here , the GPS signal and the transmitting signal back to base , 

the GPS unit sends the location to the base , many trackers  just use a sim card and a ESN like a phone would have , does yours use a frequency saved for Public Works  or a simple cell phone frequency.

So you could get a cell  phone jammer  , turn it on in the bus and it will garble the signal to the tracker and back ,  The GPS can still be working but the location being sent back will be garbled.  Some movie theaters have used Jammers but are illegal in the USA.

If they just go after the GPS , its not the same frequency , so the tracker should still get a signal that its connected but no location.

I am not sure how you legally catch them , a working cell phone with tracking software  will do it if they are jamming only the GPS , but if you are using normal cellphone frequency it will jam that too , which will at least tell you that much !

One thing , if they DID use a cell phone jammer you would be getting tons of complaints from the students who could not use their phones !

I would love to know what you find out :)

Could they be simply pulling a fuse when they board, and re-inserting it when they step off?  Maybe the fuses are not behind the security tape.

Sure thing Wally!  I’m glad it helped.  The principal of the jammer is the same as a white noise machine in an office.  Matching frequencies will cancel each other, whatever they are used for.

As a ham radio nerd, I find this stuff completely fascinating.  The process by which a magic box can take a unicorn fart and turn it into invisible waves that fly through the air, then be received by another magic box and turned into something useful is astounding.

But in the context of disrupting the tracking of public transit- in NYC no less- it is a problem that deserves attention.

I wonder if there is a representative from the company that produced your GPS system that would have some insight to share?

I don’t know many of the particulars of our system beyond what I pick up from being nosy and having outlasted a number of vendors but I believe there is some mix of gps and cell signal because our first attempt was strictly gps and it was a failure because the tall buildings blocked the signal.  Physically tampering with the system is pretty much impossible because they’d have to cut security seals and that wouldn’t go unnoticed plus we’d have video of them doing it as the cameras are always rolling.  

The tech seems more likely, I am going to poke around and see if I can find out about phone signal complaints but they go to another dept. In the meantime the person I call tomorrow will contact the techs to look into this and we will start with the easiest fix that can be done in our office, the sternly worded warning to the unions about tampering and federal fines and time. That usually motivates most problems to stop at least for a while and someone whining on Facebook would confirm my hunch that something is being done.

First things first.  As mentioned they are incredibly illegal to possess, sell or manufacture here in the US. I'm not talking a 500 dollar fine either, I'm talking $32,000 - $112,000 dollars expensive and years upon years in prison if harm can be tracked to you. Okay that said...

1. Are there actual jammers that would work almost always, be small enough to be carried without notice, and self powered as there is no place on the bus to plug them in?

Yes. There are a number of jammers on the market that can be fit in a pocket. The multi-spectrum ones can block GPS, WiFi, Bluetooth and a large number cellular bands. Multi-spectrum ones are about the size of a brick Motorola hand held radio. Smaller jammers which block only GPS are a little larger than a 12v plug for a car with a small antenna.

Range varies according to how much power you can pump into them. The common low power ones have a 10m to 15m radius but it's possible to actually jam GPS at 15,000 to 20,000 feet or more if you pump enough power into it (I've seen it done.)

2. If there are what kind of features should I be looking for if we wanted to test one?  

Short answer is I wouldn't. Even the police aren't supposed to possess them. However there's a number of East Asian websites that will sell you a kit. GPS operates on 1575.42 MHz (L1) and 1227.60 MHz (L2) so you'd need a transmitter to override those frequencies.

3. Are there devices that would block a GPS jammer or some kind of detector that could identify if one was being used?

You can't really block a jammer as they're creating enough noise that the GPS signal can't be found or that the telemetry can't be sent back to home. It's one of those design flaws that exists because you trust nothing else will be operating on the same frequency, so the receiver latches on to the strongest broadcasting signal.

There is software which interfaces with the GPS tracking units that allows supervisors to see where and when signal is being lost then tracks where and when the unit comes back online. Better versions of the software supposedly can flag jamming by monitoring for distortions in the GPS signal. "The best" versions of the software claim to still gather telemetry from the vehicle when the interference starts.

I don't have any first hand experience with the software I just know it exists.

Seriously though, don't open yourself up to the legal liability.

In reply to californiamilleghia :

It’s been impressive to see the system come together and everyone involved has been super helpful so if we bring them good questions then can usually find an answer.  Sometimes we just don’t look in the right places or have so much going on that this gets pushed aside. If it remained the original 4-5 problems it would likely go unnoticed but it seems to be spreading but in a fairly obvious pattern.

In reply to The0retical :

Thank you.  I’m curious but I stopped shopping when the word Federal showed up. That’s one group I like to avoid.

there are 2 types of phones , GSM and CDMA , I assume these are pretty old and probably 3G , 

I am not sure if the jammers  work against both types of phones...

When a bus goes missing can you "ping" it to see that a signal is received and sent back ?

not sure if you have LoJack tracking /antitheft  system back there but it used a frequency in the 700mhz range which was not the same as a cell phone, the bad guys knew this and "scanned" cars to make sure they were clean after stealing them......

The word on the street is that the Iranians, possibly with help from those pesky Russians, have been spoofing GPS signals in their airspace and surrounding waters.  That's said to be how they tricked the little Navy patrol boat into wandering into their water so they could be picked up and made fools of, and how we lost some drones.  Note that that is not just jamming, but spoofing, way more difficult than what your bus drivers are doing.

DE NG6Y AR.

In reply to Wally :

It's no joke when the FCC gets involved. We dealt with that a lot in aviation when jammers first started appearing and ended up at the end of runways.

One of my customers does radio and GPS tracker design and installation for public safety, government, and the NFL. It sounds like you have a course of action but if you need something your vendor can't provide I can put you in contact with them.

We've also identified a number of buses that only disappear with certain operators but reappear with different operators, and some operators don't get tracked regardless of what bus they are on. 

If the issue follows certain operators, they are most certainly doing something to interfere with the signal. I would be willing to bet that the GPS vendor can (and would likely be more than willing) to lend some assistance, as it will only serve to improve their future product design to discover what is going on here if their systems are being disabled.

In reply to Dr. Hess :

Yes they exist. The military loads encryption keys into the aircraft and most equipment though to avoid spoofing based on signal alone.

In reply to The0retical :

Right now I’m just looking for info so that we can talk to our equipment people in a way that they understand what we’re looking for. Being old people that recently surrendered our flip phones sometimes I suspect I sound like an old man shouting at clouds. The more I can learn the easier it is to get my question out in a way they can do something about it.