实验十五（国外英文资料）.docVIP

实验十五（国外英文资料） The individual arranges, feel very good, go up to the library to share with everybody Experiment 15 BPSK/DPSK modulation demodulation [experimental content] Second phase BPSK modulation demodulation experiment DPSK modulation demodulation experiment The PSK unmodulated carrier extract experiment 【 experiment 】 Master the working principle and circuit of two phase BPSK (DPSK) modulation demodulation Understand the production methods of carrier frequency signals Master two phase absolute and relative code transformation methods [experimental environment] Group 1: one group or one person Equipment: computer, double channel digital storage oscilloscope, communication principle experiment platform Software: digital storage oscilloscope related software 【 experimental principle 】 (1) modulation experiment: Modulation experiment, the absolute phase shift keying (PSK) is the direct phase modulation method is adopted to realize, also is the input of the baseband directly has control of carrier phase change to realize the phase shift keying. Figure 9-1 is the two-phase PSK (DPSK) modulator circuit diagram Figure 9-2 is its electrical schematic Figure 9-3 is the PSK DPSK encoded waveform diagram PSK modulation is a very important modulation in digital communication system Its anti-interference noise performance and the utilization rate of the bandband are preferred over the ASK shift keying Therefore, PSK technology is widely used in the medium and high-speed data transmission The circuit in figure 9-2 is analyzed The carrier inverter Analog signals of the inverter are usually make inverter using op-amp, circuit is composed of U304 etc, from 1.024 MHz carrier signal input to the inverting input U304 2 feet, in the input can be a negative phase of the carrier signal, namely Pi carrier signal In order for the zero phase carrier to be equal to the amplitude of the Pi phase carrier, we added the potentiometer W302 in the circuit Figure 9-3 PSK DPSK encoding waveform T