What is the middle frequency?
Medium frequency (IF) is a replica of the received signal, but with a frequency that usually moves below the frequency of the radio receiver. The use of medium frequency is the result of an effort to build a receiver capable of a wide range of receiver frequencies. If it is often used to increase signal processing or converting frequencies to common for processing. The amplifiers increase the signal level, which means that the antenna signal must be fed to a very sensitive first phase, amplified and sent to the second phase and so on for further amplification. The first radio receivers built were the radio frequency receivers (TRF), which had the RF phases that were tuned to the frequency of the receiver. TRF receivers are best suited for accepting only one frequency. For tuning on a wide range of frequencies, TRF receivers may not be practical, with the exception of special applications that can be received about 580 to 1600 kiloherz (KHz). When debugging with a resonant circuit, usually tuned frequency transformer capacityItant, is reduced to tune in to higher frequencies. At some point, the perimeter ends with a complicated multi-controller with a ganged-tunation with four separate capacitors. Another problem is the undesirable signal binding at the fourth degree output and you can find the first phase input. All of them lead to the noisy output of the speaker.
Other TRF receivers are a complicated design of inductance and capacity needed in tuned circuits. The solution is to replace most of the IF RF stages with fixed frequency -tuned transformers. These medium frequency transformers have primary windings and secondary wound windings on the adjustable core.
IF strategy should shift the frequency of RF received so that it is determined at the IF. For example, for receiving 580 kHz, the receiver generates a local frequency of 1,035 kHz. The difference of the local frequency and frequency of the receiver is 455 kHz, which is the middle FreKvence. The same process is duplicated at various local frequencies, which means that debugging on a wide range of receiving frequencies is simplified when using IF.
The transient frequency amplifier is tuned only once in the factory. A device that is already tuned to a specific if it is called a transition frequency filter. Most of these filters are controlled quartz or pre -cut crystals tuned to IF. Medium frequency is used for almost all radio receivers categorized as heterodyne or super-heterodyne receivers.