QPSKC Family

A form of digital modulation which can use a C4FM FM transmitter or a CQPSK AM transmitter with a Compatible Frequency Discriminator Detection (CFDD) compatible receiver. This modulation method is a blend of 4level Frequency Shift Keying (FSK) and p/4 DQPSK, which allows operation using either a transmitter with a frequency modulator using a class C power amplifier or a transmitter with an AM modulator using a linear class AB power amplifier. The CFDD compatible receiver is used for either transmitter.