TC-PAM is an acronym for Trellis

Trellis modulation

In telecommunication, trellis modulation is a modulation scheme which allows highly efficient transmission of information over band-limited channels such as telephone lines...

 Coded Pulse

Pulse

In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...

 Amplitude Modulation

Amplitude modulation

Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...

. It is the modulation

Modulation

In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...

 format that is used in both HDSL2

HDSL2

HDSL2 is the 2nd generation of HDSL with a 6dB Noise Margin, put simply it is another way to provision a T-1 line, only this technology relies on fewer wires - two instead of four - and therefore costs less to set up....

 and SHDSL, and provides vigorous presentation over an assortment of loop circumstances. SHDSL uses TC-PAM to give a rate/reach adaptive potential offering improved performance and enhanced spectral compatibility with ADSL when compared to today's traditional 2B1Q

2B1Q

Two-binary, one-quaternary is a physical layer encoding used for Integrated Services Digital Network Basic Rate Interface implementations...

 SDSL

SDSL

SDSL may refer to:*Symmetric digital subscriber line*Site-directed spin labeling...

 offerings.

TC-PAM is also known as 4B1H, because it uses 16 levels to represents a 4 digit binary, 4 Binary

Binary code

A binary code is a way of representing text or computer processor instructions by the use of the binary number system's two-binary digits 0 and 1. This is accomplished by assigning a bit string to each particular symbol or instruction...

 1 Hexadecimal

Hexadecimal

In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...

.