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A baseband signal or lowpass signal is a signal that can include frequencies that are very near zero, by comparison with its highest frequency (for example, a sound waveform can be considered as a baseband signal, whereas a radio signal or any other modulated signal is not). [2] A baseband bandwidth is equal to the highest frequency of a signal ...
Baseband bandwidth is equal to the upper cutoff frequency of a low-pass filter or baseband signal, which includes a zero frequency. Bandwidth in hertz is a central concept in many fields, including electronics , information theory , digital communications , radio communications , signal processing , and spectroscopy and is one of the ...
The RF bandwidth of an AM transmission (refer to figure 2, but only considering positive frequencies) is twice the bandwidth of the modulating (or "baseband") signal, since the upper and lower sidebands around the carrier frequency each have a bandwidth as wide as the highest modulating frequency.
Digital baseband modulation changes the characteristics of a baseband signal, i.e., one without a carrier at a higher frequency. This can be used as equivalent signal to be later frequency-converted to a carrier frequency, or for direct communication in baseband.
If digital single-sideband modulation is used, the passband signal with bandwidth W corresponds to a baseband message signal with baseband bandwidth W, resulting in a maximum symbol rate of 2W and an attainable modulation efficiency of 2N (bit/s)/Hz. Example 3: A 16QAM modem has an alphabet size of M = 16 alternative symbols, with N = 4 bit ...
Amplitude modulation produces an output signal the bandwidth of which is twice the maximum frequency of the original baseband signal. Single-sideband modulation avoids this bandwidth increase, and the power wasted on a carrier, at the cost of increased device complexity and more difficult tuning at the receiver.
If the information to be transmitted (i.e., the baseband signal) is () and the sinusoidal carrier is () = (), where f c is the carrier's base frequency, and A c is the carrier's amplitude, the modulator combines the carrier with the baseband data signal to get the transmitted signal: [4] [citation needed]
The fourth graph depicts the spectral result of sampling at the same rate as the baseband function. The rate was chosen by finding the lowest rate that is an integer sub-multiple of A and also satisfies the baseband Nyquist criterion: f s > 2B. Consequently, the bandpass function has effectively been converted to baseband.