Many arbitrary waveform generators provide frequency scanning function, generally can achieve "linear sweep frequency", "logarithmic sweep frequency", a few arbitrary waveform generators can also achieve "step sweep frequency" function. "Linear sweep" refers to the output frequency at a constant number of Hertz per second "change," logarithmic sweep "refers to the output frequency at a constant change" octave per second ", "step frequency sweep" refers to a certain frequency interval from start frequency to the end frequency step by step, at the same time in each step point can be set to stay.
However, in the actual electronic development, engineers often have a variety of needs for sweep types, which are not limited to the above three sweep types.So, is there a solution that meets all the sweep needs of engineers? The answer is yes. At present, many arbitrary waveform generators provide the function of frequency modulation. As long as the frequency modulation parameters are properly configured and the arbitrary wave editing function of arbitrary waveform generator is utilized, the frequency scanning of any type can be realized.
We know that the general mathematical expression for A sine wave is as follows: F(t)=A Sin(2 2πf×t+θ) where A is the amplitude of the sine signal, F is the frequency of the sine signal, and r is the initial phase of the sine signal. The current output frequency of the sinusoidal signal is only related to f. Assuming that f is a time-dependent dynamic function, the frequency of the sinusoidal signal will change with the change of the dynamic function, so as to realize frequency scanning. The mathematical expression is as follows: F(t)=A×Sin(2π×Fmod(t)×t+θ), where Fmod(t) is a time-dependent dynamic function.
Looking at the expression, it can be found that the formula is actually the mathematical expression of frequency modulation.When we change the shape of the modulated wave in the frequency modulated mode, we are actually changing Fmod(t).
What we know as linear sweep is Fmod(t) frequency modulation of the sawtooth wave, and logarithmic sweep is Fmod(t) frequency modulation of the logarithmic function. Therefore, as long as we can define any modulation waveform, then we can achieve any type of frequency scanning. Fortunately, the general arbitrary waveform generator provides a very convenient arbitrary wave editing function, as long as the use of arbitrary wave editing function to edit the desired arbitrary waveform, and then select the arbitrary wave as a frequency modulation mode modulation wave, so that any type of frequency scanning can be achieved.