sophiecentaur said:
So far, despite having posted a number of screen shots, you haven't yet said what you mean by noise floor.
In Audacity, I was taught days after this thread was started that I could add noises in Audacity and see how they mixed up. So I was able to visualize the earlier question why 50Hz has more jagged edge vs 900Hz. .
This is 50Hz signal with 1000Hz noise.
This is 900Hz signal with 1000Hz noise.
Before I used the 1000 Hz software low pass filter in Audacity on the following 30,000 Hz signal. I didn't know what would happen. I thought if you didn't put any low pass filter on the hardware itself (like a 2nd order Butterworth filter). The noises would overwhelm the lower frequency increasing its noise. After I ran it. It became clear to me what it means the frequency spectrum of white noise is flat. And how white noise is characterized by a flat spectrum, i.e. the variance is approximately the same at all frequencies. And it is retained even after passing via an ADC. That's why you can do digital filtering like brick wall
And with your descriptions in the following. How can I not understand Noise Floor already. Of course Noise Floor doesn't mean there is a floor at the circuit where noise collects. It's like Sky is the Ceiling. There is no actual ceiling.
"The Noise we are discussing is a totally random fluctuation of a signal. Forget the sine wave ideas - that's just Maths and comes later. There is nothing in a hot resistor (or a transistor etc.) that consists of a sine wave oscillator there's just random fluctuations of charge carriers in there. When you look at a signal on a wire with an oscilloscope you will see a fuzz around the wanted signal that fuzz / grass is at a level that depends on the bandwidth that's been admitted by the input filter. "
sophiecentaur said:
What does that mean in grown up language?
In grown up language. It means ordinarily, dark matter (we who tried to detect it call it the dark sector) shouldn't interact with ordinary matter, even down to the photons. But the Big Bang should logically produce some kind of relics that can bind them together, sort of a coupler (restoring higher symmetry state lower than the electroweak plasma). In the past. They tried to find equations that could produce all the constants of nature, but couldn't. So the universe is more complicated than simple minded idea of it. And the idea is just slowing coming around the corner, and CERN is still transitioning to the idea the universe is more complicated than their rigid ideas as Sabine Hossenfelder kept saying.
Some of us believe ordinary and dark matter can be glued together. And we tried to detect it. No harm trying to detect it too for us civilians. But remember CERN are also composed of Civilians too, and very human.
