PM vs phase modulation

PM and phase modulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
PM	Yes	No	No	No
phase modulation	Yes	No	No	No

As nouns, PM and phase modulation are synonyms defined as:

PM (noun)	phase modulation (noun)
an examination and dissection of a dead body to determine cause of death or the changes produced by disease	modulation of the phase of the carrier wave
modulation of the phase of the carrier wave
the person who holds the position of head of the government in the United Kingdom