Phase and amplitude modulated modem

摘要: A method and apparatus for generating phase amplitude modulated signals to be transmitted demodulating the with improved reliability accuracy is disclosed. modulator at transmitter adapted continuously group digital data into multibit words of equal length. The responsive predetermined subgroups within each word differentially modulate a carrier signal during successive modulation periods. further remaining bits demodulator provided receiver. differential detection portion reconstitutes subgroup encoded modulator. variable gain amplifier receiver varies received in accordance derived selection commands. commands are from an also provides output indicative originally encoded. vary cause levels accurately correspond levels. corresponded insure correct