how to make my device resistant to jamming

Go To Last Post
24 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi, I'm designing an anti-theft GPS car tracker that uses gsm as well with sim808. I recently found out that with a jammer the gsm signal can be destroyed. how can I make my device resistant to jammers? i searched and found on a site that "you can build antennas with steerable nulls so that your antenna is quite insensitive only in the direction of the jammer.  Techniques that permit communications in spite of jamming include spread spectrum systems such as “direct sequence” and “frequency hopping” systems." how can I apply these theories to my device.      

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Why not simply jam the GPS?  That is simple to do & you simply won't know where the car is?

Who is going to "destroy" the gsm signal?  Sone standing on the sidewalk?  Someone riding in the car?

 

"you can build antennas with steerable nulls so that your antenna is quite insensitive only in the direction of the jammer.

If you are aiming at the car riding with the jammer inside, directionality against picking up the jammer sound like a losing proposition! 

 

spite of jamming include spread spectrum systems such as “direct sequence” and “frequency hopping” systems." how can I apply these theories to my device.

They are already part of such systems, since signal to noise levels are very weak.

your question bring back memories

 

https://www.youtube.com/watch?v=...

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Thu. Jan 13, 2022 - 06:23 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

No solution to your question, just some high-level thoughts to consider while you are working on your system.

 

Frequency hopping is an effective way of reducing congestion and interference in radio link networks, and in military and law enforcement scenarios using concealed hopping seeding and frequency tables that are not released to the public, is effective at reducing the chances of people being able to listen in on your transmissions. However, given that the SIM808 operates on the quad bands (850/900/1800/1900MHz) all that is required to circumvent frequency hopping to jam a signal is to build a broad spectrum jammer that covers those frequency bands which if strong and close enough will drown out the signal you are trying to get out. The SIM808 puts out about 2W maximum so any close signal generated at a sufficiently higher output than that will interfere or drown out the SIM808 altogether. Data transmissions by their nature are susceptible to interference, and even though they employ various methods of redundancy and error checking, such conditions will make data transmission very difficult.

 

Quote:

General features

  • Compliant to GSM phase 2/2+
    • Class 4 (2 W @ 850/900MHz)
    • Class 1 (1 W @ 1800/1900MHz)

 

It is more complex to build a jammer that transmits a constant blanketing broad band signal than it is to build a jammer that rapidly oscillates across specific frequencies within the broad band you are trying to jam. Take for example the GSM-900 band, you have your uplink at 890Mhz to 915Mhz and your downlink from 935Mhz to 960Mhz with a channel spacing of 200khz and a duplex spacing of 45Mhz. You only need to disrupt one side of the conversation to prevent the device from communicating with the network so let's say you are trying to jam the uplink side between 890Mhz and 915Mhz to stop your device from getting a message out. You build a device that rapidly oscillates in 200khz steps from 890Mhz to 915Mhz and then returns to 890Mhz and starts again. At 200khz this is 124 steps. If this oscillation is fast enough it will interfere with enough of your signal to disrupt data transmissions. 124 steps is not a lot in the greater scheme of things and assuming a 1000ms cycle time for the oscillations and depending on how efficient the jammer is will result in roughly 8ms of each 1000ms (1 second) being jammed. This method does leave some leeway to circumvent the jamming but that depends on how the method is employed, how fast the oscillations between 890Mhz and 915Mhz occur and how fast the data transmission from the SIM808 is.

 

 

Quote:

GSM-900 and GSM-1800 are used in most of the world.
GSM-900 uses 890 - 915 MHz to send information from the Mobile Station
to the Base Transceiver Station (BTS) (This is the “uplink”) and 935 - 960
MHz for the other direction (downlink), providing 124 RF channels spaced
at 200 kHz. Duplex spacing of 45 MHz is used.

Sorry to add to your headaches but I thought this may help you try and figure out ways to circumvent the problems.

 

EDIT: Also note that the frequency hopping used in cell communications is determined by the towers not the end devices, and the hopping sequence is made known to the device by the tower otherwise the device could not follow the tower's hopping. This makes it a method of improving the signal to noise ratio as avrcandles said rather than a method of securing your transmission.

 

  •  

Wayne

East London
South Africa

 

  • No, I am not an Electronics Engineer, just a 54 year old hobbyist/enthusiast
  • Yes, I am using Proteus to learn more about circuit design and electronics
  • No, I do not own a licensed copy of Proteus, I am evaluating it legitimately
  • No, I do not believe in software or intellectual property piracy or theft
Last Edited: Thu. Jan 13, 2022 - 07:06 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

how can I apply these theories to my device

WayneZA had some good background that shows the jamster has things for & against him:

 

   If the jammer is in the car, antenna directionality discrimination to pick up only from the direction of the car is rather meaningless. 

   The trasmitters already use some form of SS/FH means so that makes it harder for someone to Jam, regardless of where they are.  

It is not something you are likely to  "add on" to the module, especially if it already uses it.  And then you would have broadcast license worries if you modified the RF performance

 

Even if you could use both of the above, anyone can very easily disrupt the GPS location signal (which is quite illegal, so never try to do so).

anti-theft GPS car tracker

What does that mean compared to a GPS car tracker??  If you want anti-theft, you might be better off with some smart disabling device (until it is loaded on a trailer)

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0


broadfire2014 wrote:
I recently found out that with a jammer the gsm signal can be destroyed.

This is true of any radio signal - including, as already mentioned, the GPS.

 

how can I make my device resistant to jammers?

Practically, you can't.

 

You are using an off-the-shelf commercial module: https://www.simcom.com/product/SIM808.html - its radio operation is fixed by the manufacturer.

 

i searched and found on a site that "you can build antennas with steerable nulls so that your antenna is quite insensitive only in the direction of the jammer.

That would require that you could locate the jammer, and re-position your antenna to put that jammer into a null. That's not going to be practical.

 

Techniques that permit communications in spite of jamming include spread spectrum systems such as “direct sequence” and “frequency hopping” systems." how can I apply these theories to my device.      

You can't,  because that would break the GSM operation; GSM is already using those techniques for its own purposes.

 

 

The thing to remember about jamming is that it's illegal and indiscriminate. If someone turns on a GSM jammer, it's going to jam all GSM in the area - and that will soon be noticed.

Similarly with GPS.

 

So, as avrcandies suggests, you're stuck with having to live with the fact that jamming is a possibility.

 

So you need to design your system to mitigate that; eg,

  • if your GPS and/or GSM unexpectedly loses signal, you might regard that as suspicious;
  • have other means to detect that the vehicle is moving (eg, accelerometer); if that indicates that the vehicle is moving, when the GPS and/or GSM indicates  it's stationary - flag that as suspicious
  • if your central "server" unexpectedly loses contact with the tracker, flag that as suspicious.

 

Check with the module manufacturer (SIMCOM)[1] whether the module has any special features to detect and/or mitigate jamming, or any recommendations they have.

 

anti-theft GPS car tracker

How, exactly, will a tracker prevent theft?

 

Surely, all it can actually do is to detect theft, and then help to locate the stolen vehicle, as an aid to recovery?

 

 

EDIT

 

[1] SIMCOM support:

 

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
Last Edited: Thu. Jan 13, 2022 - 10:25 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

broadfire2014 wrote:
I'm designing an anti-theft GPS car tracker that uses gsm as well with sim808

This one: https://www.avrfreaks.net/forum/how-get-speed-limit-latitude-and-longitude-using-microcontroller-0 ?

 

Did you manage to work out how to get your local speed limit data?

 

Please add a conclusion to that thread, and mark the solution ...

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

awneil wrote:

The thing to remember about jamming is that it's illegal and indiscriminate. If someone turns on a GSM jammer, it's going to jam all GSM in the area - and that will soon be noticed.

Similarly with GPS.

 

Being slightly pedantic but that first statement is not true. I sometimes work in highly secure and sensitive locations where jamming technology is deployed by state agencies. I've also worked on projects that involved supplying such technology to state agencies in other countries.

 

The bottom line for the OP is that there is nothing they can do, using commercially available technology, that can prevent jamming.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Brian Fairchild wrote:
I sometimes work in highly secure and sensitive locations where jamming technology is deployed by state agencies. I've also worked on projects that involved supplying such technology to state agencies in other countries.

When "State Agencies" are involved, jamming is going to be the least of your worries ...

 

surprise

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

awneil wrote:

Brian Fairchild wrote:
I sometimes work in highly secure and sensitive locations where jamming technology is deployed by state agencies. I've also worked on projects that involved supplying such technology to state agencies in other countries.

When "State Agencies" are involved, jamming is going to be the least of your worries ...

 

It's always good to make sure the snipers know who you are and that you have permission to be there.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I sometimes work in highly secure and sensitive locations where jamming technology is deployed by state agencies

Some prisons here have been court-battling to do so for cell phone signals.  Hopefully you are not making license plates! cheeky  

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Probably a more significant issue is the fact that both GPS and GSM signals (again, like all radio signals) are naturally subject to interference and blocking.

 

So your system needs to be designed to cope with the cases where you will just have no GPS and/or no GSM signal - without any jamming or other nefarious activity.

 

eg, in a multi-storey car park or, especially, an underground car park ...

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

avrcandies wrote:

your question bring back memories

 

https://www.youtube.com/watch?v=...

Banger.  yeswink

“Everyone knows that debugging is twice as hard as writing a program in the first place. So if you're as clever as you can be when you write it, how will you ever debug it?” - Brian W. Kernighan
“Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.” - Antoine de Saint-Exupery

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

broadfire2014 wrote:
hi, I'm designing an anti-theft GPS car tracker that uses gsm as well with sim808. I recently found out that with a jammer the gsm signal can be destroyed.
Another source of destruction is the automobile thief themself as he/she is educated, trained, mentored, and practiced in antenna removal.

 

"Dare to be naïve." - Buckminster Fuller

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

Don't all cars these days already have GPS tracking? 

 

 

Keys to wealth:

Invest for cash flow, not capital gains!

Wealth is attracted, not chased! 

Income is proportional to how many you serve!

If you want something you've never had...

...you must be willing to do something you've never done!

Lets go Brandon!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

how to make my device resistant to jamming

You can't unless you are a United Kingdom Type 45 Destroyer Europe Umbrella

 

Each civil apparatus must be designed to accept interference.

Last Edited: Thu. Jan 13, 2022 - 03:58 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Once Radar had become widely used in military applications, they started to make things to interfere with the opponent's radar - called Electronic Counter Measures, ECM.

 

https://en.wikipedia.org/wiki/Electronic_countermeasure

 

Of course, once ECM became widely used, they then started on Electronic Counter-Countermeasures, ECCM

 

and so it goes on and on - nowadays, they just call it Electronic Warfare, EW.

 

https://en.wikipedia.org/wiki/Electronic_warfare

 

But that's military - not the kind of thing you can do in consumer products!

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

If your position report (posit) requires a two way comm to have a successful transfer of data, then your scheme will fail as any local jammer will desensitize your receiver and prevent it from hearing its partner, however if your posit can be sent without an ack from the receiving comm partner, (ie. a one way comm) then the jammer is of no use!   Perhaps that is one solution to your purposed problem....

Good luck

 

Jim

 

 

Keys to wealth:

Invest for cash flow, not capital gains!

Wealth is attracted, not chased! 

Income is proportional to how many you serve!

If you want something you've never had...

...you must be willing to do something you've never done!

Lets go Brandon!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

awneil wrote:

But that's military - not the kind of thing you can do in consumer products!

Sometimes ideas of products came from Military applied and some Military ideas came from civilian products. Depend of countries with their rules about cell phone frequencies.

www.tokopedia.com/madagang for cheap electronics and manuscript

Last Edited: Sat. Jan 15, 2022 - 10:12 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

ki0bk wrote:

If your position report (posit) requires a two way comm to have a successful transfer of data, then your scheme will fail as any local jammer will desensitize your receiver and prevent it from hearing its partner, however if your posit can be sent without an ack from the receiving comm partner, (ie. a one way comm) then the jammer is of no use!   Perhaps that is one solution to your purposed problem....

Good luck

 

Jim

 

thanks can you elaborate on that? how can I apply this method to sim808? I found an at command for jamming detection is there an at command for one-way communication? 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

How about building in a EMP generate to take out the jammer? Then you just need to harden the tracker and auto against the EMP.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

balisong42 wrote:

Then you just need to harden the tracker and auto against the EMP.

 

And every other device in a several km radius.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

ki0bk wrote:
however if your posit can be sent without an ack from the receiving comm partner, (ie. a one way comm) then the jammer is of no use!

 

But surely this will only work if an adequate "jammer" is not running on the TX frequency of the one-way communication? If it is sufficiently swamping out the frequencies the TX is using to get the one-way communication out then it will never get there?

 

Wayne

East London
South Africa

 

  • No, I am not an Electronics Engineer, just a 54 year old hobbyist/enthusiast
  • Yes, I am using Proteus to learn more about circuit design and electronics
  • No, I do not own a licensed copy of Proteus, I am evaluating it legitimately
  • No, I do not believe in software or intellectual property piracy or theft
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Spend more time preventing the theft...that's the real winner.

If the car move 2 inches without proper authorization, it locks the driver inside and cranks up Spandau Ballet songs.

They'll never steal again.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

broadfire2014 wrote:
how can I apply this method to sim808?

You're going about it the wrong way.

 

You need to set your requirements first, and then make a design & choose parts which can meet those requirements.

 

I found an at command for jamming detection is there an at command for one-way communication? 

You'd need to ask SIMCOM that.

 

But GSM is inherently 2-way ...

 

Perhaps you've chosen the wrong comms solution ... ?

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...