A carrier wave recovery apparatus of the decision feedback type having analog multipliers of lower dynamic range. The modulated signal is phase detected by comparison with a VCO signal. The analog multipliers receive a signal derived by subtraction of the phase detected signal from the same phase detected signal compared with a reference. That signal is multiplied in an analog multiplier by the phase detected signal or by the signal produced from comparing the phase detected signal with a reference.

For a pair of detection signals derived by coherent quadrature detection from an amplitude-and-phase modulated signal, a demodulator comprises a pair of quantizer sections each of which produces a quantized signal serving as a part of a regenerated data signal, a quantization error signal, and a "first path" signal given by that portion of the quantized signal which indicates one and the other of the plus and the minus sides of the signal reference plane known in the art. The signals produced by the quantizer sections are used to control a voltage controlled oscillator for reproducing a carrier signal for use in the coherent detection. Each quantizer section may comprise at least one quantization circuit and at least one quantization error deriving subtractor. Alternatively, the quantization may be carried out in a space or a time division fashion.

In a TDMA burst preamble, the phase is varied between .+-..pi./4 radians, and carrier synchronization is achieved by averaging the phase over a given interval. Symbol timing synchronization is achieved by filtering the upper sideband of a conventional delay-and-multiply circuit and demodulating the filtered upper sideband with a coherent carrier available by the end of the preamble. After the preamble, modulation removal is used to obtain the unmodulated carrier.

A phase acquisition and tracking apparatus in which a phase difference between a reference signal and a signal to be acquired is rotated within a negative feedback loop so that such phase difference disappears is disclosed. In another embodiment, a baseband signal which is influenced by such a phase difference is rotated within a negative feedback loop so that the phase difference disappears. The phase rotated signal serves as an output signal from the phase acquisition and tracking apparatus, and this output signal faithfully and rapidly reproduces the input signal regardless of any particular value of such phase difference. Since a negative feedback loop is used to control the amount of phase rotation, non-linearities and other errors produced by multipliers, summing devices and combining circuits are automatically compensated for through the feedback.

The present invention is directed to circuitry for achieving concurrent synchronization of carrier phase and clock timing in double-sideband, suppressed carrier transmissions systems. A phase-lock loop (PLL) is used in the respective carrier and clock recovery networks. The carrier recovery loop is similar to the conventional "Costas Loop". The PLLs are cross coupled in an interdependent recovery structure to enable a more effective clock and carrier regeneration.