In telecommunication, a ternary signal is a signal that can assume, at any given instant, one of three significant conditions, such as power level, phase position, pulse duration, or frequency.

Note: Examples of ternary signals are (a) a pulse that can have a positive, zero, or negative voltage value at any given instant (PAM-3), (b) a sine wave that can assume phases of 0°, 120°, or 240° relative to a clock pulse (3-PSK), and (c) a carrier wave that can assume any one of three different frequencies depending on three different modulation signal significant conditions (3-FM).

Modulation techniques
Analog modulation
AM · SSB  · QAM  · FM · PM · SM  · VM
Digital modulation
FSK · ASK · OOK · PSK · QAM MSK · CPM · PPM · TCM OFDM · SC-FDE
Spread spectrum
CSS  · DSSS  · FHSS  · THSS
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See also: Demodulation, modem

Some examples of PAM-3 line codes that use ternary signals are:

• hybrid ternary code
• bipolar encoding
• MLT-3 encoding used in 100BASE-TX Ethernet
• B3ZS
• 4B3T used in some ISDN basic rate interface
• 8B6T used in 100BASE-T4 Ethernet
• return-to-zero
• SOQPSK-TG uses ternary continuous phase modulation[1]

3-PSK can be seen as falling between "binary phase-shift keying" (BPSK) which uses two phases, and "quadrature phase-shift keying" (QPSK) which uses four phases.

[edit] References

•  This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C".

[edit] See also

• balanced ternary
• digital signal
• Fast Ethernet#100BASE-T2 uses PAM-5, which, like ternary, is one of the few modulation schemes that does not use a power-of-two number of symbols.
• three-phase electric power, like 3-PSK, uses 3 phases at a single frequency and amplitude.

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