By this, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a Fourier transform. Would I see the same thing with sunlight?

It's my understanding that no, sunlight is essentially a DC source. Is it? If not, what frequencies would one observe if they were to look at the Fourier transform of a sun-exposed photodiode's time series?

Some edits for clarification: suppose I put a $10 silicon photodiode outside on a sunny day and hooked up an A/D system that samples at 64kHz and gives me a spectrum from an FFT every second. Assume normal solar activity, no clouds, no passing aircraft, and that the sun doesn't go behind trees to create shade. Assume that the photodiode signal doesn't clip, either. Would I see any regular, consistent features in the FFT?

By frequency, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a Fourier transform. Would I see the same thing with sunlight?

It's my understanding that no, sunlight is essentially a DC source. Is it? If not, what frequencies would one observe if they were to look at the Fourier transform of a sun-exposed photodiode's time series?

Some edits for clarification: suppose I put a $10 silicon photodiode outside on a sunny day and hooked up an A/D system that samples at 64kHz and gives me a spectrum from an FFT every second. Assume normal solar activity, no clouds, no passing aircraft, and that the sun doesn't go behind trees to create shade. Assume that the photodiode signal doesn't clip, either. Would I see any regular, consistent features in the FFT?

By this, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a Fourier transform. Would I see the same thing with sunlight?

It's my understanding that no, sunlight is essentially a DC source. Is it? If not, what frequencies would one observe if they were to look at the Fourier transform of a sun-exposed photodiode's time series?

Some edits for clarification: suppose I put a $10 silicon photodiode outside on a sunny day and hooked up an A/D system that samples at 64kHz and gives me a spectrum from an FFT every second. Assume normal solar activity, no clouds, no passing aircraft, and that the sun doesn't go behind trees to create shade. Would I see any regular, consistent features in the FFT?

By this, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a Fourier transform. Would I see the same thing with sunlight?

It's my understanding that no, sunlight is essentially a DC source. Is it? If not, what frequencies would one observe if they were to look at the Fourier transform of a sun-exposed photodiode's time series?

Some edits for clarification: suppose I put a $10 silicon photodiode outside on a sunny day and hooked up an A/D system that samples at 64kHz and gives me a spectrum from an FFT every second. Assume normal solar activity, no clouds, no passing aircraft, and that the sun doesn't go behind trees to create shade. Assume that the photodiode signal doesn't clip, either. Would I see any regular, consistent features in the FFT?

By this, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a Fourier transform. Would I see the same thing with sunlight?

It's my understanding that no, sunlight is essentially a DC source. Is it? If not, what frequencies would one observe if they were to look at the Fourier transform of a sun-exposed photodiode's time series?

By this, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a Fourier transform. Would I see the same thing with sunlight?

It's my understanding that no, sunlight is essentially a DC source. Is it? If not, what frequencies would one observe if they were to look at the Fourier transform of a sun-exposed photodiode's time series?

Some edits for clarification: suppose I put a $10 silicon photodiode outside on a sunny day and hooked up an A/D system that samples at 64kHz and gives me a spectrum from an FFT every second. Assume normal solar activity, no clouds, no passing aircraft, and that the sun doesn't go behind trees to create shade. Would I see any regular, consistent features in the FFT?