Design and make a sine signal generator.

72,000 words, 82 pages, with design drawings and program codes.

abstract

Using FPGA+DAC to realize DDS. In this way, frequency synthesis is realized in the digital domain through FPGA, and then the signal waveform is formed through DAC. Because the signals are processed by FPGA in the digital domain, FM and AM modulation can be easily realized in the digital domain. All the functions of the modulation circuit are realized by the digital logic circuit in the FPGA chip, which greatly simplifies the circuit design of the whole system. At the same time, digital modulation avoids the error and interference caused by analog modulation, and greatly improves the modulation performance. The software design of hardware circuit greatly simplifies the upgrading and improvement of circuit design. The system consists of FPGA, MCU control module, keyboard, LCD screen, DAC output circuit and final amplification circuit. Direct digital frequency synthesis (DDS) is realized only by single-chip FPGA, which generates a steady-amplitude sine wave, and realizes four modulation signals such as AM, FM, ASK and PSK in digital domain. The modulation signal can be generated internally by FPGA or input externally by users. The whole system has compact structure, simple circuit, powerful function and strong expansibility.

abstract

The system consists of FPGA, MCU controller, keyboard, LCD, DAC and amplification module. DDS, a direct digital frequency synthesizer, is realized by a unique FPGA chip, which can provide a stable sinusoidal signal with digital AM, FM, ASK and PSK modulation. The modulation signal can be provided not only by FPGA receiving user parameters, but also by external input. The system has compact module, simple circuit, powerful function and flexible expansion.

Key words: FPGA, DDS, AM, FM, ASK, PSK, MCU, SPCE06 1A, accumulation register.

catalogue

I. Introduction

Second, the overall design

(1) Overall design.

(2) Theoretical analysis and parameter design.

(3) Design and analysis of main circuit.

1. DDS design based on FPGA

2. The circuit design of M modulation signal.

3. Design of AM signal

4.4 circuit design. PSK sends out an inquiry signal again.

5.5 circuit design. Query signal generation.