PAM (Pulse Amplitude Modulation)

A form of signal modulation in which the amplitude of the dig-

ital pulse carrier is modulated according to the amplitude level of the original signal. PAM samples an incoming analog signal, for example, measures its amplitude, and outputs a digital pulse of a representative amplitude.

The outgoing pulse closely matches the amplitude of the incoming signal, but when digitized in an A-to-D

converter, the digital output is the nearest of a number of standard amplitude values. PAM was used in this manner in early channel banks to interface analog PBXs and central offices (COs) to DS-1 digital circuits.

The PAM-encoded signal subsequently was further encoded using pulse code modulation (PCM) before the signal was placed on the circuit. PAM is considered obsolete in this application, having been replaced by direct

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• PSE (Power Sourcing Equipment)
• pseudonoise (PN)
• pseudoquaternary coding
• pseudorandom noise (PN)
• pseudowire
• pseudowire emulation edge to edge (PWE3)
• pseudowire emulation (PWE)
• PSK (Phase-Shift Keying)
• PSP (Payphone Service Provider)
• PSQM (Perceptual Speech Quality Measurement)
• PSQM+ (Perceptual Speech Quality Measurement plus)
• PSS1 (Private Signaling System No. 1)
• PSTN (Public Switched Telephone Network)
• PSTS (Public Switched Telephone System)
• PTE (Path Terminating Equipment)
• PTI (Payload Type Indicator)
• PTT
• PTT
• public data network (PDN)
• public domain
• public IP address
• public key encryption
• public key infrastructure (PKI)
• Public Safety Access Point (PSAP)
• Public Service Commission (PSC)