We see you without your knowledge and aproval, don't ever forget that. We can also park a misil in your garage.... The Black Spot - GPS Jammer with 3.4W EQP
Some of you will be very upset because of this project.
You will probably claim that it is destructive and immorally to present.
I believe it is a constructive project and educationally in many ways.
All knowledge can be used in a good way or a bad way.
It is up to you to use this knowledge with high moral and responsibility.

Weather it is legal or not to use, is also up to you to find out.
I take no legal responsibility for any use of the product.

The construction is extremely simple and the unit is very small.
This project comes in a KIT version, se more details below.
All contribution to this page are most welcome!

This project has been updated, please visit : The Black Spot II - GPS Jammer with 7.2W EQP

Nowadays people has very high believe in technical machines and electronic devices.
Electricity and electronic is implemented in all our products and we trust it with our lives.
People travel deep into unknown forests and sail far out on the open sea trusting the electronic to guide the way.
What will happen when the electronic fails?
Maybe this project will open your mind and make you think twice before you put your life into electronic machines.

Gerardus Mercator was born in 1512.
He was an intellectual, a mathematician, and an innovator. He went on to become the great Renaissance mapmaker.
He gave us the Mercator projection. He published a world map in that projection in 1569. For centuries, navigators and explorers have searched the heavens for a system that would enable them to locate their position on the globe with the accuracy.

On June 26, 1993, however, the answer became as simple as the question. On that date, the U.S. Air Force launched the 24th Navstar satellite into orbit, completing a network of 24 satellites known as the Global Positioning System, or GPS. In the same year it is also definitely decided to authorise the world wide civilian use free of charge.
With a GPS receiver that costs less than a few hundred dollars you can instantly learn your location on the planet--your latitude, longitude, and even altitude--to within a few hundred feet.
Today we have GPS system running all around us. In our, cars, boats, aeroplane and in many other transportation units.

This is a typical GPS tracking on the market. An upcoming range of devices are GPS trackers as GPS Vehicle Tracking and Person Monitoring Tracking.
Booth of these two systems can be used in a very good way but all too often they are used in bad way.
These tracker units monitor the exact location of you, and then deliver that information to a second part.

These devices are so small that they can fit into your hand easy. Imagine then how easy it is to hide a tracker in your car, bag…clothes…
This project describes a RF unit that will take care of that.

The PCB has the same size as a standard 9V battery.
  • High accuracy RF system using PLL controlled VCO
  • High output power, equivalent power = 3.4 W
  • Long Jamming range 1000-2000 feets
  • Small zise 1" X 1.8" (25 mm x 46 mm)
  • 7-12 V DC power supply, 9V battery is default
  • LED flash indication of operation.
  • Low current consumption.
  • Blocks all known GPS and trackers on the market today.
  • Simple to build and tune.

  • Click on rhe picture to enlarge. Hardware and schematic
    The Main part of this project is a VCO, PIC16F870 and a PLL LMX2322.
    The PIC control the PLL through LE, Data and clock input and set the PLL to lock the VCO to the GPS frequency 1.57542 GHz.
    A feedback system of R4 and C7 feed the PLL with RF frequency. X1 is a VCTCXO oscillator which acts as reference frequency.
    It feed both the PLL and the PIC. A pot P1 is added to fine tune the output frequency. X1 is a very stable and exact oscillator.
    You will achieve best performance from the jammer if X1 is calibrated with a frequency counter.
    Still, the VCTCXO is so exact that the jammer will work even if X1 is not tuned.

    The PIC will control the VCO with a tuning voltage at pin 2. The voltage is built up from the PLL filter R6, C3 and C12.
    You can measure the voltage over C3 or directly at pin 5 PLL to monitor the tuning voltage.
    The voltage should be around 0.5 to 1.5V in a locked system. If the voltage is 0V or +5V, something is wrong.

    At pin 13 of the PIC you have an output that generate the jamming signal. It is feed to the VCO through C6.
    The output of the VCO is directly connected to a MMIC IC3. This IC amplify the RF signal and feed it to the antenna. The power to the MMIC is feed from R3 and L1.

    You should monitor the current though R3. Easiest way is to measure the voltage over R3 and divide it with 20. The current should be around 40 - 60mA.
    You can lower this current by increasing the R3. You can also increase the current by lowering the value of R3.
    Although I advice you to stay around 50 mA since you can blow the MMIC with to much current. The more current the higher gain and more output jamming power.

    A diode D1 is added to indicate that the PIC is alive and kicking.
    The routing and type of PCB will affect the system very much with stray inductance's and capacitance's.

    The antenna is a whip of 45 mm. The gain is 0dbB and it has been the reference of my measurements.
    You can of course you a better antenna with much more gain and thereby get much better performances and longer jamming range.
    Some antenna links: Homebrew GPS antenna

    PCB and KIT
    I will not present the PCB for this project, because the system works at 1.5 GHz which require a double side factory made PCB.
    The PCB is double side and have many via holes. A factory made PCB also makes the soldering so much easier.
    If you wish to buy a complete KIT with a factory made PCB, you can go down to section named "KIT" a bit down. Click here to jump down!

    Click on rhe picture to enlarge. Assembly
    The assembly of this KIT is very simple. I will guide you through the assembly and I will also explain how to verify that the unit is working properly.
    Click on the picture at right to see all details.
    The picture show you both side of the PCB. We will start with the Top_side.

    Soldering Top_side
    Start by mounting IC2 LMX2322.
    Here comes the big challenge but since we have a factory made PCB you will handle it with no problems.
    The circuit is a fine pitch SO-IC circuit and this little bug can make your life miserable.
    Don't worry I will explain how to handle it. I use very thin solder lead and I always use a clean soldering tool.
    (Thin solder lead and wick will be added in the KIT)

    I start by fixate one leg on each side of the circuit and makes sure it is correct placed.
    Then I solder all other legs and I don't care if there will be any lead bridges.
    After that it is time to clean up and for that I use a "wick".

    The desoldering wick is a flattened, braided copper sheath looking for all the world like shielding on phone cord (except that the shielding is tinned) without the cord.
    I impregnate the wick with some rosin and place it over the legs and bridges of the circuit. The wick is then heated by the soldering iron, and the molten solder flows up the braid by capillary action.
    After that, all bridges will be gone and the circuit looks perfect. Click here to see photo and read how to solder SOIC and smd components.
    You can find wick and rosin at my component page http://www.rfcandy.com.
    Front side of the GPS transmitter
    Mount X1, VCO, P1, IC2, IC3 and L1.
    (When you mount VCO, you must try to place it as centred as possible in the white fram on the PCB.
    In this way you will be sure to get good solder connection at its sides.

    Mount D1 which is a LED diode. This diode must be placed in correct direction.
    It has a green mark fot the cathode and at the bottom you also find a marking.
    Click on the schematic above for more details.
    Mount 28 pin IC socket for PIC16F870, V1, J1 and J2.

    Soldering Bottom_side
    Mount C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 and C12.
    Mount R1, R2, R3, R4, R5, R6 and R7.

    Mount the antenna.

    Assembly Details
    Mount X1 16.8 MHz Reference crystal
    Solder as picture show.
    Mount VCO 1575.42 MHz Voltage control oscillator
    Try to center VCO in as good as possible.
    Mount P1 Pot to tune the reference crystal
    Solder as picture show.
    IC2 LMX2322 PLL Synthesizer
    Solder as picture show.
    IC3 MMIC MAR-3 power amplifier
    The leg with 45 degree cut, is the input.
    Note the text M5 is up side down.
    L1 inductor Inductor to provide current to amplifier
    Solder as picture show.
    D1 Led
    Led diode
    Green Marking to the right.
    Mount 28 pin IC socket for PIC16F870, V1, J1 and J2 Top layer
    Solder the hole mounted parts as picture show.
    C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, R1, R2, R3, R4, R5, R6 and R7 Bottom Layer
    Solder the smd mounted parts as picture show.

    Testing and tuning
    The testing of this unit is pretty simple.
    Mount the PIC16F870 and power it up. You should now see that the LED diode blinks.
    If the LED is not blinking, something is wrong. (see trouble section below)
    The blinking LED indicates that the PIC is alive and kicking.

    Now, we must make sure that the PLL system is working and the easiest way is to measure the PLL voltage over capacitor C3 or at pin 5 of the PLL. (see schematic)
    The voltage here should be a stable voltage of 0.5 to 1.5V DC. The voltage can vary from VCO to VCO.
    If the voltage is 0V or +5V, something is wrong. (see trouble section below)

    The reference oscillator frequency can be found at pin 3 of the 16.8MHz VCTCXO. You can also find it at C8 and C10.
    Since the 16.8 MHz VCTCXO is very exact in frequency, you will get good functionality even if it is not tuned correct.
    Although, the more exact reference frequency you have, the better jamming you will get.
    The best way to tune the unit is to connect a frequency counter and tune P1 till you get 1.57542 GHz

    Remember that the output of the MMIC has a DC voltage of +5V!
    If you connect any instrument to this output, you MUST add a serial capacitor, 47pF will work good.

    GPS Jammer with 3.4W EQP KIT KIT Assembled in protective box
    Black Spot jammer assembled into a protective box with with battery cover. A button for switch ON/OFF and LED indicator.
    Black Spot jammer assembled into a protective box with  button for switch ON/OFF.

    Download PIC16F870 program (INHX8M format)
    s_gpsjam.zip GPS software (the hex file is zipped!).

    Demonstration VIDEO
    Here you can download and look at a demonstration video during a test with U-blox GPS receiver module.
    The module is connected to a computer running U-blox evaluation software. The jammer is placed 100 feet from the GPS receiver.
    jammer.avi download video (4.5 Meg).

    I have put together an educational KIT with a factory made PCB.
    You can also buy an assembled KIT which is tested, tuned and ready to use. (More info below)
    All components, PCB, VCO and PIC16F870 are included in the KIT (Click here to download component list.txt).
    Order a KIT
    which will include all parts listed below
    Factory produced PCB

    Click on the picture to see larger
    Click on the picture to see larger photo.
    The PCB is blue and factory made.
    1 pcs
  • Red PCB factory produced - See photo at right
  • 1 pcs
  • PIC16F870 PIC16F870 pre-programmed with software (DIP)
  • 1 pcs
  • 28 pin IC socket for PIC16F870 DIP (IC1)
  • 1 pcs
  • PLL LMX2322 smd (IC2)
  • 1 pcs
  • VCO Modco 1.57542 GHz smd
  • 1 pcs
  • MMIC MAR-3 smd (IC3)
  • 1 pcs
  • VCTCXO 16.800MHz smd high performance (X1)
  • 1 pcs
  • 78L05 + 5 VOLT REGULATOR (V1)
  • 1 pcs
  • 68nH smd (L1)
  • 1 pcs
  • Capacitor 10pF smd (C7, C11)
  • 5 pcs
  • Capacitor 1nF smd (C4, C5, C6, C8, C10)
  • 3 pcs
  • Capacitor 100nF smd (C2, C9, C12)
  • 2 pcs
  • Capacitor 2.2uF smd (C1, C3)
  • 1 pcs
  • Resistor 20 smd (R3)
  • Download assembly maual

    Click on the picture to see larger
    Click on the picture or on pdf to download.
    1 pcs
  • Resistors 100 smd (R6)
  • 1 pcs
  • Resistors 330 smd (R4)
  • 2 pcs
  • Resistors 3.3k smd (R1, R2)
  • 1 pcs
  • Resistors 10k smd (R5)
  • 1 pcs
  • Variable resistor 20k smd (P1)
  • 1 pcs
  • Resistors 100k ohm smd (R7)
  • 1 pcs
  • LED blue smd (D1)
  • 1 pcs
  • 1 pin header (J1)
  • 1 pcs
  • 2 pin header (J2)
  • 1 pcs
  • soldering lead (Extra thin)
  • 1 pcs
  • Cleaning wick (to clean up bad soldering)

  • Order here

  • Blocks all known GPS and trackers on the market.
  • High accuracy RF PLL system using PLL control
  • High output power, equivalent power = 3.4 W
  • Long Jamming range 1000-2000 feets (300m)
  • Small zise 1" X 1.8" (25 mm x 46 mm)
  • 7-12 V DC power supply, 9V battery is default
  • LED flash indication of operation
  • Low current consumption.
  • Easy to build (one evening project)

  • Trouble Shooting section
    If you get a problem with your unit, you might find this section helpful.

  • My PIC16F870 is not working and I get no blink from the diode D1!

  • Make sure you have placed the PIC in correct way.
    Make sure you have + 5V to pin 20 of the PIC.
    You should test that the Reset (pin 1) goes high when power is turned on.
    Make sure you have 16.8MHz oscillation on pin 10.
    (You can check this with an oscilloscope)
    Check that the diode is placed in correct way.

    I often use a small speaker or piezo element and listen to the signals at pin 12, 14, 15.
    You should hear clicking sound or beeping tone once per second.

  • I get 0V or +5V over capacitor C3 !

  • Your PLL system is probably not locking.
    Make sure you have placed IC2 correct and that you have proper soldering.
    Measure that you have reference frequency on pin 1 IC2.
    Make sure you have placed VCO correct and solder it well.
    Check all other parts involving the PLL filter.
    If you have a frequency counter, you can connect it to VCO output or the MMIC output and
    apply a DC voltage to pin 2 of the VCO.
    The VCO should then change frequency when the voltage changes.

  • I have no voltage over R3!

  • This means that you have no current running through the MMIC.
    Make sure you have placed it in the correct way.
    One leg is cut diagonal to indicate the input.

    Final word
    I hope you have had a fun time assembly this KIT.
    The project may be a small one, but still it is a very powerful unit.
    Thanks for your time…

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    Copyright © Last modified on 28 Okt 2008.