Signal modulation

Process of varying one or more properties of a periodic waveform Passband modulation Analog modulation AM SM SSB Angle modulation FM PM QAM Digital modulation ASK APSK CPM FSK MFSK MSK OOK PPM PSK QAM SC-FDE TCM TC-PAM WDM Hierarchical modulation QAM WDM Spread spectrum CSS DSSS FHSS THSS See also Capacity-approaching codes Demodulation Line coding Modem AnM PoM PAM PCM PDM PWM ΔΣM OFDM FDM Multiplexing vte Categorization for signal modulation based on data and carrier types Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in the form of a message signal modulated onto a carrier signal to be transmitted. For example, the message signal might be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing a sequence of binary digits, a bitstream from a computer. Carrier waves are necessary when the frequency of the message is too low to practically transmit. Generally, receiving a radio wave requires a radio antenna with a length that is one