August 4th, 2009
A radio scanner is a device which helps in tuning or scanning automatically two or more frequencies at a time. The scanning stops when it finds any frequency and after that continues to scan for other frequencies as the initial transmission moves on. This term radio scanner is generally used for communications which is intended for Very High Frequency and Ultra High Frequency in landline mobile radio systems and this kind of receiver is used to monitor international shortwave transmission. Also these scanners can tune into various modulation such as AM, FM, WFM, etc., all these kind of modulations are useful in many applications such as radio transmission, mobile transmission.
These scanners used to be slow, expensive and huge. It had very small number of users. But due to the advancement made in communication technology the VHF radio scanners are made available to public usage for much lower prices. This is mainly because of the use of microprocessors which allows the scanner to store thousands of channels and also it can monitor hundreds of channel at the same time. The VHF radio scanner is one of those scanners used to intrude into the airwaves consisting of very high frequencies.
The range of VHF ranges from 30 MHZ to 300 MHZ which is used for FM radio broadcast, television broadcast, land mobile stations for the purposes of emergency, military and business , Amateur Radio, marine communications, air traffic control communications and air navigation systems. The characteristics of VHF propagation are perfect for short-distance terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter. The ionosphere does not usually reflect VHF radio whereas HF is usually reflected and Thus restricting the transmission to a very small area helping short distance communications. The effects that atmospheric noise and interference from electrical equipment have on VHF are much lesser when compared to lower frequencies.
This vhf radio scanner is used in many fields which use airwave spectrum of 30 MHZ to 300 MHZ. The vhf scanners of today are equipped with many IF band passes. The VHF radio scanner uses a receiver with very narrow a bandwidth that produces pictures saturated in blacks and whites. This kind of vhf radio scanners are also used in walkie-talkie. These scanners have become portable and affordable to be used by the public which makes it more and more popular opening up a huge market especially in the countries like US.
