In the context of RF, one can think it in two ways:Įncoding a baseband message on a carrier frequency signal.įrequency shift the baseband signal to radio frequency signal. Modulation: Modulation means encoding a message. IQ signals is the building block of modern digital modulation and demodulation scheme. Quadrature I/Q Components: two components I (in phase signal) and Q (out of phase signal) are 90 degrees out of phase. Quadrature: Orthogonal relationship (i.e 90 degrees) between two vectors. Improved selectivity: easier filter design with sharper rolloff can be constructed at lower frequencies. Two main reasons for using low BW baseband signal are:Ĭome within sampling range of ADC/DAC : sampling rate are limited on ADC/DAC mixed signal hardware which is needed for pre/post digital signal processing. It's a low bandwidth analog signal containing data the such as voice and data typically found after downconverting from RF to DC before analog to digital converter (ADC) in radio receiver or right after digital to analog converter (DAC) in radio transmitter.

The reason is that due to miniaturization of consumer electronics, high RF carrier signal is needed for efficient electromagnetic radiation using small antenna in transmission and reception of wireless network. It's a high frequency signal that 'carries' the lower bandwidth of 'real' information signal such voice and data In modern cellular standard LTE, the low band roughly starts at 600 MHz and extends to 6000 MHz (refer ) B46 is the last LTE band in frequency. A signal frequency with greater than 300 MHz is considered RF.

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