Car Shortwave Receivers

Car Shortwave Receivers

A Decade in RF Jamming

Historically, broadband jammers have been used by the US and other countries' militaries during warfare to prevent their enemies from being able to communicate with one another. Ireland used frequency jamming to prevent citizens from listening to the pirate radio stations such as Radio Nova. The UK also used RF technology to jam Radio North Sea International, a sea-based pirate operation off the coast of Britain, in the '70s.

Since the turn of the millennium, radio jamming technology has seen more use outside of wartime efforts. China has been using radio jamming technology to block out foreign radio stations broadcasting into it's borders, as do several countries in the Middle East. North and South Korea still regularly jam each other's radio stations. Pakistan stated it's intention to start jamming Taliban-operated radio stations. Jammers are also used to prevent terrorist organizations from communicating.

The radio jamming technology has been advanced to create bomb jammers (also called RF jammers or IED jammers). IEDs (Improvised Explosive Devices) and RC-IEDs (Radio Controlled Improvised Explosive Devices) are remotely activated by transmitting an RF signal to a receiver attached to the bomb. The jammer technology transmits a signal at the same frequency as the RF signal, but it uses a random noise so as not to set off the bomb.

Though the bomb jamming technology has been around for around 30 years, the conflicts and rise in IEDs and RC-IEDs have drawn a lot of attention to it, and spurred more development in the area of electronics jamming.

Companies such as SESP, Security Intelligence Technology, Comp Nine and Netline have been actively developing smaller, more portable bomb jammers that can be carried in briefcases. Jammers can also block surveillance devices such as hidden cameras and eavesdropping devices. These jammers are becoming more common for ambassadors, heads of state and US troops to carry around as the technology to make them advances. RF jammers include mine clearance teams, VIP security forces, oil executives, government contractors and government agencies. Other types of bomb jammers are bigger and stronger, designed to sit in armored vehicles or in helicopters. These vehicles, once outfitted with the IED-jamming devices, accompany convoys and ensure that bombs cannot go off while in range.

In this day and age, when everyone has a cell phone, new threats have been created. Bombs are sometimes set off by cell phone frequencies. Some RF jammers are also capable of jamming cell phone communications, and there are stand-alone mobile phone jammers as well. Cell phones operate by transmitting to the nearest cellular tower. Though cell phones operate on two different frequencies (both incoming and outgoing), jamming just one of the frequencies "tricks" the cell phone into thinking there is no service from the tower, and effectively jams both incoming and outgoing communication. It also prevents any phones within a 30-500 meter range from sending frequencies to detonate bombs.

The past decade has seen leaps and bounds in jamming technology. From shortwave radio jammers to bomb jammers the size of cars to jammers small enough to fit in a briefcase that also block cell phones, the electronic security industry has come very far in keeping people safe. As new threats come up, they will have to continue finding ways to block dangerous communication.

About the Author

Learn more about SESP’s revolutionary and professional developments in RCIED jammers and convoy protection systems. SESP has been designing and manufacturing electronic security equipment for the security market since 1986.


Car Shortwave Receivers


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Frequently Asked Questions...

Physics Electromagnetic Waves help please.?

1. Why does the radio reception fade in the receiver of your car when you enter a tunnel?

2. Shortwave radio waves are reflected by the ionosphere of the Earth; this makes them very useful for a long- range communications. Explain.

3. Suppose that the sensitivity of your eye were constant over the entire interval of wavelengths. How would this alter your visual perception of some of the things you see in your everyday life?

Thank you.

Answer:

1. radio waves get absorbed and/or reflected by material so magnitude of the signal reaching antenna is lower.

2. radio waves behave more or less like light and travel nearly is straight line. this is more pronounced with higher frequencies. this is why you cannot receive FM station from place that is far away (there is no line of sight due curvature of the planet). at short frequencies however, this behavior is not so pronounced and signal can get reflected of the ionosphere (which acts like a 'mirror'). multiple reflections are also possible allowing signal to travel around the planet. this way one can get signal to opposite side of the planet (huge mass of the planet would completely block any line of sight signal).

3. some colors would become more vivid compared to what we perceive now.

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