On the fabulous Bali the snow fell or how easy to fool a GPS

Good day, judging by the photos, Bali snowed! How did it happen?

Crying

the last time I have to deal with the design and manufacture of satellite navigation antennas, antenna arrays and receivers (RPU). It should be noted that these RPU is preobrazovateli the navigation signal to the form convenient for further processing, and not the navigation receivers, which give the solution to the navigation problem and which are embedded in your gadgets.

When testing antennas, especially their new designs, in the usual city room have problems with good radio visibility of satellites. Roughly speaking, it is difficult to understand the new antenna is better or worse than the old one, changed the scheme of approval of RPU antenna gave or no improvement in system sensitivity. About antenna arrays in General can not speak. Besides, personally, in my case, there is some obstacle which prevents. Is to move away from the window and the receiver loses the satellites, although direct visibility of a quarter of the sky is preserved.

in Summer, the dacha becomes the salvation. There is almost free the sky and there is no interference. But there you need either to go with all the equipment, either to keep him there an extra set. There are still comrades from past work that give to work in an anechoic chamber. Don't know why, but there is happiness.

In General, a hard fraction of the developer.

Luck

Recently I was lucky enough to get close to solving this problem. I always knew about the simulator navigation signals, but they were dear to me. Here there is a few happy events.

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1. One comrade from Moscow at the meeting spoke about the GPS simulator, published by Professor Ebinuma in the source texts.

   
   
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2. I was already familiar with the Professor's correspondence and I had confidence in him and his development. You can start work, relying on the advice of the Professor.

   
   
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3. I Have long been overlooked fee USRP B210, and it was listed among the supported cards.

it was Thought that it would be cool to be able to test the antenna and RPU is stable and predictable.

And then, I think, because of our almost traditional Russian fun — cheat GPS. I remembered how he was recently rejected information from Tretyakovskaya to the airport Vnukovo. And you can even do something like dolls — start at the Tretyakov false signal like I'm at the Tretyakov.

Illusion, but it can help soothe many troubled people, especially in the spring. How is it in Russian, dammit!

if they , we why not? But it is noteworthy to mention that the launch of the simulator was carried out on minimal power 10 kW and even without connecting the antenna fell all the hair on his head. Ask all experiments to be accurate and wear a tin foil hat to not to destroy the navigation space of other people and specialservices. Also it is worth mentioning that ignorance of the law is no excuse. And that in Russia we have decided not to renounce not only of the amount.

All down with philosophy! To business! Fewer letters, more pictures!

How to run

To start your global positioning system before we would need the orbital group of satellites, ground stations, etc. Now everything is easier.

We need:

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1. Computer operating system type Windoz or Linux and preferably with a USB 3.0 port. On the 2.0 port I have not tested, but should work.

   
   
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2. the Fee USRP b210 (other options).

   
   
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3. the Generated file with the signal, or the program for its generation GPS-SDR-SIM from Professor Ebinuma.

   
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4. Blog Professor (little-Russian)
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5. Source simulator

installation Procedure

To run all this stuff on the computer more slowly and carefully to install from the card manufacturer recruitment software. Although, it may not be necessary. But let it be. When installing under windoz it sometimes complains that it can not add itself to PATH, but that does not stop, because of all this stuff I only need a utility uhd_find_devices.exe that allowed us to understand a General system that fee. Find the utility at:

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C:/UHD/bin/uhd_find_devices.exe

Then stick charge and open device Manager. Where can I find that driver under the device machine not established. What – happens. Manually using the programs zadig choose the system that under the charge it is necessary to use the libusb driver, i.e. winusb.

After the system picked up the default driver that you can run uhd_find_devices from the set of software from the manufacturer of the Board. This utility must find the fee and to reprogram its controller (there is FX3 from Cypress). It seems, then the device will change its PID and will have to tell the system (using zadig), and for this device, you can use the standard driver winusb.

of Course it is the first attempt does not work. And of course it can be cured by disconnecting the motherboard and connecting it back. Here detailed instructions.

you Must install gnuradio, which within itself contains the Python-Python. I took here the latest version under AVX2 processors.

I was too lazy to configure properly the environment, so I used the script included: C:/GNURadio-3.7/bin/run_gr.bat

Through him I will run a script to send generated file to the Board a b210.

For convenience, the path to that script must be added to the PATH environment variable.

generated signal

the Source code to take here. That was a pleasant surprise is the ease and simplicity of Assembly. No dependencies, no further action. All would be well.

Build under Linux

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$ gcc gpssim.c -lm-O3 -o gps-sdr-sim

building windus

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1. Start Visual Studio. To start the Studio (I used 2015)

   
   
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2. Create an empty project for a console application. To create an empty console project. That is empty!

   
   
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3. On the Solution Explorer at right, add "gpssim.c and getopt.c" to the Souce Files folder. Add two serznyh file to the project.

   
   
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4. Select "Release" in the Solution Configurations drop-down list. Change the build type to the release version, select x86 / amd64.

   
   
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5. Build the solution. In fact, to collect.

I'm under Linux is not collected, because there was a need to run on a particular machine, and on it stood a dozen.

a Detailed description of the generator settings are in the README. For starters, you can not to understand, and very easy to do, to generate signal as follows:

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gps-sdr-sim.exe -e brdc3540.14n -s 2500000 -l 30.286502,120.032669,100-b 8 -d 300-v-o sim.bin

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• gps-sdr-sim.exe is a file that you collected.

  
  
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• brdc3540.14n is a file with the ephemeris data of the satellites.

  
  
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• 2500000 is the sampling frequency

  
  
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• 30.286502,120.032669 — coordinates

  
  
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• 100 height

  
  
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• 8 is the length of numbers in the output file (one reference is IQ, two numbers).

  
  
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• 300 is the duration in seconds.

  
  
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• -v — is that more wrote in the log

  
  
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• sim.bin — the name of the output file.

You can take the line from the README, but it will generate a signal with RR=2.6 MHz, then b210 needs to be configured on the same CD (sampling frequency). If you could generate a single frequency, and the cost issue with another, that, of course, nothing will work.

the Signal for a fee, I was served with this command:

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run_gr.bat gps-sdr-sim-uhd.py -t sim.bin -s 2500000 -x 40

For the b210, the value of BH must evenly divide the frequency of the internal generator, and it there seems to be 40 MHz.

Run

And now the fun part.

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1. Disable is a cost.

   
   
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2. the Connected cost.

   
   
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3. Run uhd_find_devices

   
   
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4. If not defined, then goto 1.

   
   
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5. Run transmit.bat, watching the log.

   
   
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6. At some point the Board will light up the second diode, that would mean that everything has already begun to emit.

If the log continuously displays the letter U, it means that your system does not have time to put data in charge. You should check if something in the background and not specifying a very high BH.

after some time (up to 3 minutes) all devices will start to identify the location as specified. But before that, they suddenly lose the current position.

Carefully read the user manual to the program Professor Ebinuma you can understand how to generate a file with a changing location, how to use dates and so on.

Insights

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1. There is a proven way to get the most out of inexpensive means of simulator the GPS signal. It is a great joy for developers. Thank you to Professor Ebinuma!

   
   
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2. Not all receivers are influenced by simulation interference. Some have protection.

   
   
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3. There is a danger that such a simulator will be used or is being used by criminal elements for their own purposes. We already have receivers with the function of protection against spoofing signal. Need to test this function and to use such receivers in critical applications.

   
   
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4. it Is likely that in the future people will have small-sized and inexpensive device for spoofing the navigation signal, which they will use for their nearly household needs, ranging from cheating spouses and ending with deception geogr type PokemonGO. Receivers that find themselves in the neighborhood will have to cope with the large number of such simulation of interference.

And for the last two paragraphs — thanks to Professor Ebinuma! Developers will have something to do on both sides of the fence.

I will Soon tell about trying to get rid of the noise and came out of it.

Article based on information from habrahabr.ru