Howtosignalprocessing
- How is AM signal generated?
- Is mixer the same as modulation?
- What is the frequency range of audio message signal in AM?
- How is amplitude modulation achieved?
How is AM signal generated?
AM generation involves mixing of a carrier and an information signal. In low level modulation, the message signal and carrier signal are modulated at low power levels and then amplified. The advantage of this technique is that a small audio amplifier is sufficient to amplify the message signal.
Is mixer the same as modulation?
A mixer is a modulator optimized for frequency-translation. Its place in the signal path is usually close to the antenna, where both the wanted and (often large) unwanted signals coexist at its signal input, usually called the RF port.
What is the frequency range of audio message signal in AM?
The frequency band used for AM radio is about 550 to 1720 kHz. This is the range of carrier frequencies available. The information transmitted is music and talk which falls in the audio spectrum.
How is amplitude modulation achieved?
In AM, the voltage or power level of the information signal changes the amplitude of the carrier in proportion (see Fig. 7.7). With no modulation, the AM carrier is transmitted by itself. When the modulating information signal (a sine wave) is applied, the carrier amplitude rises and falls in accordance.
