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An AM signal encodes the information into the carrier wave by varying its amplitude in direct sympathy with the analogue signal to be sent. There are two methods used to demodulate AM signals: The envelope detector is a very simple method of demodulation that does not require a coherent demodulator.
Once correctly aligned/recovered, the quadrature signals also successfully demodulate the signal. Costas loop carrier recovery may be used for any M-ary PSK modulation scheme. [ 5 ] One of the Costas Loop's inherent shortcomings is a 360/M degree phase ambiguity present on the demodulated output.
The equation above shows that by multiplying the modulated signal by the carrier signal, the result is a scaled version of the original message signal plus a second term. Since , this second term is much higher in frequency than the original message. Once this signal passes through a low pass filter, the higher frequency component is removed ...
In order to correct this, a small amount of the original carrier signal can be transmitted so that receivers with the necessary circuitry to synchronize with the transmitted carrier can correctly demodulate the audio. This mode of transmission is called reduced-carrier single-sideband.
Such a device is often used to demodulate AM radio signals because the envelope of the modulated signal is equivalent to the baseband signal. To sufficiently attenuate the frequency of the carrier wave frequency f carrier {\displaystyle f_{\text{carrier}}} , the cutoff frequency of the low-pass filter should be well-below the carrier wave's ...
Categorization for signal modulation based on data and carrier types. In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted. [1]
Delta-sigma (ΔΣ; or sigma-delta, ΣΔ) modulation is an oversampling method for encoding signals into low bit depth digital signals at a very high sample-frequency as part of the process of delta-sigma analog-to-digital converters (ADCs) and digital-to-analog converters (DACs).
A signal demodulated with a product detector will have a higher signal-to-noise ratio than the same signal demodulated with an envelope detector. On the other hand, the envelope detector is a simple and relatively inexpensive circuit, and it can provide higher fidelity, since there is no possibility of mistuning the local oscillator.