Generation of different waveforms within a continuous a continuous broad range of frequency band (assuming high stability and resolution of frequency for each waveform) using traditional methods, needs a bank of crystals. This solution is neither feasible nor cost effective, especially when new efficient methods are available.
The aim of this project was to study the DDS (Direct Digital Synthesis) technique and to investigate the use of DDS for the generation of signals with arbitrary wave from and frequency (high resolution frequency) by using of just one crystal.
In the final stage of this project a DDS function generator was designed and implemented with the following features:
1. Sine and square waveforms: 0.5 Hz to 3.1 MHz with 0.5 resolution.
2. Triangle and saw-tooth waveforms and black & T.V. pattern: 0.5 Hz to 300 kHz with 0.5 Hz resolution.
3. Manual programmable attenuator with ranges: 0.1 dB, 1 dB and 10 dB.
4. Microprocessor based control system for various settings including these selections: frequency, waveform, sweep-range and sweep- time.
5. Maximum output voltages: 20 Vpp.
6. output impedance: 50 Ohms.