What is Frequency Modulation FM. FM explained

FM or frequency modulation is a mean of modulating carrier with information or base signal in radio technology so that the RF or radio frequency can be propagated to distance receiver from a transmitter. There are three basic methods of modulation for radio frequency. They are CW or continuous wave, AM or amplitude modulation and FM or frequency modulation. CW or continuous wave was used in older days for Morse code transmission in the way that a fixed frequency and fixed amplitude signal wave was switched on and off and transmitted. this on and off signal was carrying Morse code information to the other side of receiver. In amplitude modulation a fixed frequency wave is used whose amplitude is varied according to the base frequency or information. Or in other words the base information is overlay of the carrier frequency signal. The next type is FM or frequency modulation in which the amplitude of the carrier signal is kept fixed and the base information is used to change the frequency of the carrier signal to take the information.

Different methods of modulation

The time of CW had passed. There in no more use of Morse anywhere. But still the amplitude modulation and frequency modulation is in use. Amplitude modulation are affected much from external disturbances where the FM or frequency modulation is affected very less. This is the reason we hear very clear ad beautiful music and voice at FM whereas at AM band this is not possible. The other reason for clarity is the frequency modulated signal provides much wider band for modulation of base signal or information which is up to 75Khz whereas the AM or amplitude modulation provides only 5Khz of bandwidth. Modren days FM or frequency modulation signal can even modulate stereo audio signal as base frequency which can be received by a stereo receiver are receiving end. Sure stereo audio signal is way better and natural compared to mono audio signal.

Frequency modulation can also use the concept of pre-emphasis and de-emphasis. In this system the FM signal is much more amplified at transmitting end and is then attenuated with the same ratio at receiving end. In this method the unwanted signals injection is also reduced and we receive a very clear signal at receiving end.

Modern days FM receivers are using one single chip IC which is responsible for doing all the required tasks and functions. Receivers are comparatively simple for FM. FM is using high frequency band and that frequency the need of the antenna is less. A small size antenna can effectively transmit and can receive the signal. One disadvantage of FM is the signal is highly direction or it uses line of sight. In normal conditions the transmission limit is 25Km circle for an FM signal.

Comments

Post a Comment

Popular posts from this blog

Microwave oven front panel keypad repair and modification

Image
Here is the video on youtube. You must watch it if you are a Urdu to Hindi viewer: Here is the video on youtube. You must watch it if you are an English viewer: The microwave oven is a useful machine to preheat or cook food. The microwave oven is working reliably but now a days Chinese microwave oven have big front panel keypad failure. The keypad is breaking down in one year of less time. The repair is not easy and sometimes the replacement parts are not readily available then it becomes another problem. The solution to such a problem is a modification with existing easily available parts and some wire connections to the main board. The modification is a very robust an reliable work so that will never break down or if breaks down, the repair would be way easy and low cost. Here is a little detail with images is included for such a modification work. Most of the images are from the video associated with this blog post. Anyhow it will further explain the important
Read more

Sandwich maker or sandwich grill repair and maintenance

Image
Here is a youtube video covering all these details in video: Sandwich maker or sandwich grill is a common house hold electrical appliance used in every house and every facility. They are daily use electrical appliances. They are of different make and model. One thing is common in all of them is the heating element and a sort of temperature controlling switch operated on some preset or selectable temperature range. The heating element are heated by line power and are switched off when the desired temperature is reached. By that way the grill or heating plate is heated and the toast put there is also grilled or heated by that temperature. Sandwich makers or sandwich grill are reliable equipment but some times they develop troubles. The result is no heating grill or heating plates. Normally there are electrical connection problem or temperature controlling switch problem. The heating element failure is also possible but that is a rare fault. So if a grill or sandwich
Read more

TP4056 li-ion 3.7v battery 18650 Charging Module Detail, Pinout and datasheet

Image
 In this text I will discuss about the famous TP4056 charging module which is a 3.70V  Li-ion battery 18650 in detail. The pinout, characteristics, setup and calibration for battery value will be covered in this text. TP4056 charger module is a very tiny size module to charge li ion batteries that it can fit anywhere inside any electronic equipment or instrument. TP4056 module consists of a single chip IC TP5640  and a few other supporting components which makes high quality and precision charging module which gives complete solution to automatically charge li-ion batteries of any small size. Using TP4056 module to charge the li-ion battery, it provides full battery life and effective charging to prolong battery life with great efficiency. Using TP4056 battery charging module you can make the line powered equipment less power consuming and the old equipment using dry cell can be converted to rechargeable battery solution. TP4056 Charger or charging module TP4056 Charging Module Charact
Read more