Relatively simple QPSK demodulator, that uses substantially all digital circuitry and an internally generated symbol clock, and circuitry for use therein

Granted: Oct 11, 1994 Filed: Jun 24, 1993

This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.