How is FM wave generated?
FM signals can be generated using either direct or indirect frequency modulation: Direct FM modulation can be achieved by directly feeding the message into the input of a voltage-controlled oscillator. For indirect FM modulation, the message signal is integrated to generate a phase-modulated signal.
What is FM generation?
In direct FM generation, the instantaneous frequency of the carrier is changed directly in proportion with the message signal. For this, a device called voltage controlled oscillator (VCO) is used. A VCO can be implemented by using a sinusoidal oscillator with a tuned circuit having a high value of Q.
What is modulation in communication PPT?
What is Modulation? • Operation of varying amplitude, frequency or phase of carrier signal accordingly with the instantaneous amplitude of the message signal is called modulation • Modulation = Adding information to a carrier signal.
Which method is used for FM generation?
The alternative method is to use the indirect method called as the Armstrong method of FM generation. In this method, the FM is obtained through phase modulation. A crystal oscillator can be used hence the frequency stability is very high and this method is widely used in practice.
What are two methods for generating FM waves?
The following two methods generate WBFM wave.
- Direct method.
- Indirect method.
What are the applications of FM?
The applications of frequency modulation include FM radio broadcasting, radar, seismic prospecting, telemetry, & observing infants for seizure through EEG, music synthesis, two-way radio systems, magnetic tape recording systems, video broadcast systems, etc.
What are the two methods of FM generation?
This method is called as the Direct Method because we are generating a wide band FM wave directly. In this method, Voltage Controlled Oscillator (VCO) is used to generate WBFM. VCO produces an output signal, whose frequency is proportional to the input signal voltage. This is similar to the definition of FM wave.
Why is modulation necessary PPT?
Need for modulation ECE-3050-02 5 ➢ The main reason is the disturbance of noise. ➢ After transmitting, our message signal can be attacked by unwanted signals in the channel. ➢ Message signal can be modified into unwanted signal by noise. ➢ Because of noise, modulation must be done before transmitting.
What are types of FM?
There are different types of FM demodulators including: Slope Detector. Foster-Seeley Discriminator. Ratio Detector.
What are the advantages of FM?
The main advantages of FM over AM are:
- Improved signal to noise ratio (about 25dB) w.r.t. to man made interference.
- Smaller geographical interference between neighboring stations.
- Less radiated power.
- Well defined service areas for given transmitter power.
What is the range of FM?
87.5 to 108.0 MHz
Broadcast bands Throughout the world, the FM broadcast band falls within the VHF part of the radio spectrum. Usually 87.5 to 108.0 MHz is used, or some portion thereof, with few exceptions: In the former Soviet republics, and some former Eastern Bloc countries, the older 65.8–74 MHz band is also used.
Why is modulation necessary?
Modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. It is necessary because of following reasons: Reduction in the height of antenna. Avoids mixing of signals.
What is the importance of modulation?
Modulation allows us to send a signal over a bandpass frequency range. If every signal gets its own frequency range, then we can transmit multiple signals simultaneously over a single channel, all using different frequency ranges. Another reason to modulate a signal is to allow the use of a smaller antenna.
What is FM radio and characteristics?
FM radio uses frequency modulation, of course. The frequency band for FM radio is about 88 to 108 MHz. The information signal is music and voice which falls in the audio spectrum. The full audio spectrum ranges form 20 to 20,000 Hz, but FM radio limits the upper modulating frequency to 15 kHz (cf.
What are the advantages and limitations of FM?
Advantages and Disadvantages of Frequency Modulation
| Advantages | Disadvantages |
|---|---|
| Power Consumption is less as compared to AM. | More complicated receiver and transmitter |
| Adjacent FM channels are separated by guard bands. | The antennas for FM systems should be kept close for better communication. |
How many types of modulation are there?
Modulation techniques are roughly divided into four types: Analog modulation, Digital modulation, Pulse modulation , and Spread spectrum method. Analog modulation is typically used for AM, FM radio, and short-wave broadcasting.
Where is modulation used?
radio communications
In radio communications, modulation is needed in the transmission systems to transfer the message into the available high frequency radio channel. Modulation is also used in e.g. voice-band modems where digital data modulate the carrier frequencies inside the voice frequency band.