The differeces between frequency and amplitude modulation does not effect the range. Fundamentally the amplitude modulation system is less efficient in that a carrier is generated, which is modulated. The modulation power is half of the carrier power. The bandwidth required is twice the highest modulating fequency. Because of the small bandwidth required, the Amplitude Modulated band on radios is from 550 Khz to 1500 Khz. Channels are separated by 10 Khz, with actual users usually separated by 2 or three channels minimum. Frequency modulation varys the frequency of the carrier by the audio modulating component. While the frequency deviation can be as low as the audio frequency modulating the carrier, better noise performance is achieved by deviating the carrier by as much as possible. In commercial broadcast operations, the 15 Khz audio signal deviated the carrier by 75 Khz. This presents exceptionally good audio reproduction. It also causes the FM (Frequency Modulated) signal to occupy a band of about 240 Khz for a 15 Khz audio channel. This compares to 30 Khz for an equivalent AM (Amplitude modulated) signal. Because of the larger bandwidth required, the FM broadcast band is moved higher in frequency. This makes the other comments about range etc come into effect. AM signals can be received even when an interfering signal is present. Weak signals can be received in the presence of strong signals. Because of this property, Aviation signals, (Airplane to control tower and tower to plane) are in AM. FM signals have an effect called "capture effect" in which a stronger signal will capture the channel and eliminate interference from the weaker signal. Basically you are trading bandwidth for interference rejection. Because of this, signals from satellites, where the signal strength is extremenly small, used to be sent in FM. Present technology uses digital broadcast techniques.
Talking about digital, because of the ability of digital receivers to process signals of extremely small size, digital signals are being sent along with both AM and FM broadcast signals for either better quality, or supplementary services. Cell phones are all being switched over to digital technology for better reliability and better channel usage.
You must transmit the redundant carrier with the signal.
AM imply amplitude modulation of a carrier signal
amplitude modulating signal
the maximum amplitude of carrier wave varied with respect to instantaneous values of message signal is called amplitude modulation
One disadvantage of the standard amplitude modulation system is that 67% of the power is used for the carrier, but the carrier transmits no information, so it can be considered as wasted power.The 34% remaining power is split between two mirror opposite sidebands so, in effect, you really only have 17% of your power used to carry the signal.
In a analog transmitter the RF carrier have to be modulated with the analog signal either by AM or FM where in digital transmitter the carrier is simply switched on and off a off = a zero and on = a one
In amplitude modulation, modulation depth refers to the ratio of the unmodulated carrier amplitude to the amplitude deviation for which the modulated carrier wave reaches its minimum value. If this minimum value is zero, the modulation depth is 100%.For amplitude modulation,modulation depth = (a-b)/(a+b),wherea is the unmodulated carrier amplitude, andb is the minimum amplitude deviation.The modulation depth ratio is also referred to as the modulation index.
AM imply amplitude modulation of a carrier signal
In amplitude modulation, modulation depth refers to the ratio of the unmodulated carrier amplitude to the amplitude deviation for which the modulated carrier wave reaches its minimum value. If this minimum value is zero, the modulation depth is 100%.For amplitude modulation,modulation depth = (a-b)/(a+b),wherea is the unmodulated carrier amplitude, andb is the minimum amplitude deviation.The modulation depth ratio is also referred to as the modulation index.
low level amplitude modulation occurs when the carrier signal is first modulated and then amplified,whereas in high level modulation,the carrier signal is first amplified and then is modulated.
Amplitude modulation is a method of sending information by modifying the intensity of a carrier wave.
amplitude modulation is where we modulate our signal with a carrier signal amplitude changes but frequency remains constant in amplitude modulation
amplitude modulating signal
the maximum amplitude of carrier wave varied with respect to instantaneous values of message signal is called amplitude modulation
Amplitude of the (high frequency) Carrier signal is varied with respect to low frequency of message signal is called amplitude modulation. Frequency of the carrier signal is varied with respect to low frequency of message signal is called frequency modulation.
One disadvantage of the standard amplitude modulation system is that 67% of the power is used for the carrier, but the carrier transmits no information, so it can be considered as wasted power.The 34% remaining power is split between two mirror opposite sidebands so, in effect, you really only have 17% of your power used to carry the signal.
Amplitude modulation.
In a analog transmitter the RF carrier have to be modulated with the analog signal either by AM or FM where in digital transmitter the carrier is simply switched on and off a off = a zero and on = a one