RFDefence®

Warranty

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FAQ

Warranty

Equipment and modules enjoy 1 and 1.5 years warranty respectively when the damage is not from faulty operation or vandalism by the user.

Warranty void when the following circumstance occurred:

For internal module:

1- Disassemble the module without authorization from the factory;

2- Module’s input power is exceeding the safe value, which is specified in the user manual. If without any claim, input power should not exceed 15dBm;

3- Leave the RF output open/without load for a long time when the module is working; Or be shorted when working at high power;

4- Exposing under the rain or soak in the water;

5- Long term operation without heat dissipation system;

6- Working voltage is out the range of 24-30VDC.


For equipment:

1- Disassemble the equipment without authorization from the factory;

2- The power supply is out of the equipment’s tolerance - rate voltage: ±15%;

3- Use a non-manufacturer charger;

4- Operating by the battery when the equipment is charging;

5- Exposing under the sunlight with long term work.


Our company will assist the user in confirming the problem and providing technical support. Once the problem is ensured by non-human or faulty operation mentioned above, depending on the actual situation, our company will assist with simple guidance for repair or provide replacements free of charge.

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Specification Sheet
Name Introduction Size Downloads Update DOWNLOAD
HL-B647B 6x50W Cell Phone Jammer - Portable 539.82KB 18 2021-03-01 DOWNLOAD
HL-B347B 3x50W Drone Jammer - Portable 441KB 1 2021-08-13 DOWNLOAD
FAQ
FAQ Category

Genral information about signal jammer

1. What are "Jammers"?

Generally, “jammers”- which are also commonly called signal blockers, GPS jammers,  cell phone jammers, text blockers, etc. - are radio frequency transmitters that are designed to block, jam, or otherwise interfere with authorized radio communications.  


2. How do jammers work? 

Jamming technology generally does not discriminate between desirable and undesirable communications. A jammer can block all radio communications on any device that operates on radio frequencies within its range (i.e., within a certain radius of the jammer)  by emitting radiofrequency waves that prevent the targeted device from establishing or maintaining a connection.  For example, jammers can:  

  • prevent your cell phone from making or receiving calls, text messages, and  emails; 

  • prevent your Wi-Fi enabled device from connecting to the Internet;  

  • prevent your GPS unit from receiving correct positioning signals.


3. What customer we are serving?

Our products are aiming at the public enforcement department, security department, or any agency or people who have legal licences that can prove the equipment will get proper use after sell.

The basic theory of jamming systems

The basic theory of jamming system is that when the target receiver(handset devices, walkie talkie, IED, drone, etc.) receives an "effective interference signal" more than "original signal" 6dB to 20dB in the target channel and location, at this time, target receiver can be jammed.


The following is a general estimating formula for signal level from Jammer.

Rg=10lg [Pg/(Wg/Ch)] +Ag – Lg  (1)

Lg=32.4+lg(FD) + Lf          (2)

Rg: The received output power from Jammer unit to target channel (dBm)

Pg: The full output power of Jammer (W)

Wg: The bandwidth of jamming band (MHz)

Ch: The channel bandwidth of jamming target (MHz)

Ag: The comprehensive gain of antenna (dB), including the gain of the antenna and the loss from the cable.

Lg: The path loss between antenna and jamming target (dB)

F: Center Frequency (MHz); i.e.: 1842.5MHz of 1805-1880MHz

D: Distance between antenna and jamming target (km)

Lf: The frequency compensation from the loss (for example, the Lf of the DCS system is 6dB)


100W DCS jammer for instance:

The frequency range of the DCS system from 1805 to 1880MHz with 0.2MHz channel width and 100 watts output power. When the comprehensive gain of an antenna is 0dB, Theoretically, the "effective interference signal" to 100 meters jamming distance should be:

10*lg(100*1000*100/0.2)+5dB-(32.4+20*logFD )=-50dBm


The factors that influence the jamming effect

1.1 Jamming technology 

The main factor of interfering effect is the source technology. 

The different radio system has different coding, modulating network organization and channel bandwidth. the best interfering technology is different for the different radio systems, but they have complicated technology, long developing period and high price. VCO is a popular and low-cost choice, but also with an effective result for most radio systems. 


For instance, if the VCO interference system is a pickup truck, it can carry people and goods, also can climb the mountain, even do some racing. However, although it can suit for the varying environment, still, when the user is aiming to a specific area with specific effect, they will need a customized system - a big truck for the goods, car for the people, SUV for the mountain and an auto racing for the competition.

 

1.2 Antenna selection of a signal jammer

Omni antenna: With 360 degrees horizontal angle, and the vertical angle normally has 10 degrees. Normally, gain increased by every 3dB will double the length of the antenna.

Panel antenna: Normally with 90 to 180 degrees horizontal angle and 10 degrees vertical angle. The gain of the panel antenna is 5dB higher than the Omni antenna at the same length.

Yagi-antenna: Have 30 degrees vertical and horizontal angle, at the same size, the gain of the Yagi antenna is 3 dB higher than the Omni antenna.


You can find the coverage estimate diagram of a signal jammer in our product details.

 

1.3 Frequency choose

The wider bandwidth, the worse jamming effect it has.


1.4 Relative position of the test

To some extent, the jamming effect is determined by the relative position of the signal source, the jammed target, and the jammer.


1.5 Free space loss of different Frequency

Jamming effect - Free space loss of different Frequency

Q: A jammer to cover the full bands

Actually, there is no right answer about what is the standard of the full bands. We need the information which is quantitative but not qualitative. For instance, when you describe a building as a “massive” one, it will not give us an exact concept about how big it is. We need more details!


BTW, the power amplifier's property is determined by the performance of the transistor, and which had fixed its ability to work in a specific range. We cannot create the device but only what it can achieve.


So, when you need a Jammer, please confirm your target bands frequencies first. Basically, we will jam only the downlink, whereas it is illegal in some countries that if we intercept the uplink frequencies, to which, it will influence your local BTS.


Q: I want to shield the drone.

First of all, you should know the main parameters of the Jammer are consist of target jamming frequencies and the output power. 

Then, when your application aims to intercept the drone, you should clear what frequency your drones are using. We had concluded the following bands for generally drone application, but some brands(drone) might use others. So when you want to buy a signal jammer, you’d better check your target frequencies first.


SystemFrequency
Wi-Fi2.4GHz
Wi-Fi5.8GHz
GPS1.6GHz


Q: What’s the effect range of our signal jammer?

As mentioned in the above article, the main specification of a jammer is composed of frequency and output power. Without a doubt, more powerful can impact on a longer range. But there is another issue that influences the jamming range, and that is your local signal strength. For instance:


When your target site is near to local BTS and which means the jammer is receiving a very strong signal, the jamming radium will be shorter than a location where receive a bad signal. Besides that, there still many factors, such as the weather, obstacles, terrain and so forth, those factors will also change the signal condition and have an impact on jamming effect as well.


More information please find in the typical jamming coverage model.


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