If you have ever watched a football game on television, you have likely seen a parabolic microphone on the sideline. Parabolic microphones are highly directional microphones that are commonly used for sporting broadcasts and by nature enthusiasts. A DIY parabolic microphone will allow you to test out and experience the directional power of a parabolic mic.
The type of microphone used in a parabolic mic will greatly affect the quality of the sound. The most common type of microphone used in parabolic mics is the condenser. A condenser microphone is more sensitive than a dynamic microphone and will pickup a better range of frequencies more clearly than a dynamic. The specific choice of microphone you use for your parabolic microphone is up to you. You can spend a lot of money, but this is not necessary. A basic condenser element will likely be enough for a homemade parabolic microphone. Due to the design of parabolic microphones, low frequencies are not picked up well, so your microphone does not need great low frequency response.
The Parabolic Reflector
The purpose of the parabolic reflector is to reflect sound to a centralised point, which is where the microphone element is located. This is similar to the way a satellite dish works. The parabolic reflector should be shaped like a satellite dish, and as such an old satellite dish makes a great reflector for a DIY parabolic microphone. Other materials that can be used include cooking bowls or umbrellas. These shapes may not be true parabolas, but they will function in a similar manner. If you would like to use a true parabola for the reflector, you can purchase a parabolic reflector from a speciality company like Telinga. When you have chosen your parabolic reflector, you need to attach the microphone to it. The mic can be attached from the edges, or you can drill a small hole in the reflector and attach the microphone to a dowel rod.
The FBI appears to have begun using a novel form
The FBI appears to have begun using a novel form of electronic surveillance in criminal investigations: remotely activating a mobile phone\\\'s microphone and using it to eavesdrop on nearby conversations.
The technique is called a \\\"roving bug,\\\" and was approved by top U.S. Department of Justice officials for use against members of a New York organized crime family who were wary of conventional surveillance techniques such as tailing a suspect or wiretapping himthe eavesdropping technique \\\"functioned whether the phone was powered on or off.\\\" Some handsets can\\\'t be fully powered down without removing the battery; for instance, some Nokia models will wake up when turned off if an alarm is set