Editing Signal modulation (section)

==Pulse modulation methods==
Pulse modulation schemes aim at transferring a narrowband analog signal over an analog baseband channel as a two-level signal by modulating a [[pulse wave]]. Some pulse modulation schemes also allow the narrowband analog signal to be transferred as a digital signal (i.e., as a [[Quantization (signal processing)|quantized]] [[discrete-time signal]]) with a fixed bit rate, which can be transferred over an underlying digital transmission system, for example, some [[line code]]. These are not modulation schemes in the conventional sense since they are not [[channel coding]] schemes, but should be considered as [[source coding]] schemes, and in some cases analog-to-digital conversion techniques.

;Analog-over-analog methods
* [[Pulse-amplitude modulation]] (PAM)
* [[Pulse-width modulation]] (PWM) and pulse-depth modulation (PDM)
* [[Pulse-frequency modulation]] (PFM)
* [[Pulse-position modulation]] (PPM)

;Analog-over-digital methods
* [[Pulse-code modulation]] (PCM)
** [[Differential PCM]] (DPCM)
*** [[Adaptive DPCM]] (ADPCM)
* [[Delta modulation]] (DM or Δ-modulation)
** [[Delta-sigma modulation]] (ΣΔ)
** [[Continuously variable slope delta modulation]] (CVSDM), also called [[adaptive delta modulation]] (ADM)
* [[Pulse-density modulation]] (PDM)