PI/4 SHIFT QPSK MODULATOR AND COMMUNICATION EQUIPMENT EMPLOYING IT

摘要

PURPOSE: To output a waveform corresponding to burst communication in TDMA communication and a test waveform in addition to a usual modulation waveform and to suppress the circuit scale and a ROM capacity by controlling an address of a ROM by a control means. ;CONSTITUTION: An impulse response value, a waveform suppressing spurious radiation at burst rising and fall down at TDMA communication and a waveform of a sine wave, a square wave and a triangle wave required in the test mode are stored in advance to a ROM 21. Then phase information from a mapping circuit 1, a content of a tap counter 8, a content of an oversampling counter 9 are inputted to the ROM 21 by using an output from a register 20 as an address and waveforms corresponding to them are obtained. For example, when a burst rising waveform is outputted, the desired waveform is outputted by using the phase information from the mapping circuit 1, the content of the tap counter 8 and the content of the oversampling counter 9 as addresses by programming the output C1 of the register 20 as 01.;COPYRIGHT: (C)1994,JPO&Japio