6 ms·

Great explanation! Maybe I'm asking a dumb question but I'll shoot anyway: what is power? I mean, when I change the power of a signal what physical variable am

Great explanation! Maybe I'm asking a dumb question but I'll shoot anyway: what is power? I mean, when I change the power of a signal what physical variable am I playing with? Amplitude, frequency, or wavelength are intuitive to visualize, but power?

vvanders 7y ago
Power roughly correlates to amplitude. On the transmitter side keeping the signal linear means you generally don't see great efficiency in terms of power in -> power radiated.
spapas82 7y ago
Power is how "strong" a signal is. I think it's the easiest one to understand, that's why everybody's talking about dbm! In all electric circuits to change the power a component will consume you either change the voltage you apply to it or change its resistance, based on the P=VI & R=V/I equations.
- rambojazz 7y ago
  I really cannot get my head around it. What is "strong" in a signal? What physical variable is stronger? I assume "strong" or "more power" means that the signal attenuates less over time/distance, but what is causing this lesser attenuation?
  - monadgonad 7y ago
    The amplitude of the wave is bigger to begin with. I think the waves in water analogy is suitable here: drop a stone in water and there'll be very big ripples just around the point where it drops, but they'll get smaller the further out they are. Drop an even bigger stone, you'll get bigger ripples. That's power.
  - spapas82 7y ago
    No, the attenuation is exactly the same no matter the power and is analogous to the square of the distance. So a signal that has power X in a point 10 meters from the source it will have X/100 20 meters from the source. The analogy of the waves that another comment mentioned is a nice one (since we talk about EM waves). Another thing that may help you understand that more power means that the electrical charge to the protons/electrons in the air where the EM field is transmitted will also be more.
    - rambojazz 7y ago
      Thank you.

vvanders 7y ago

Power roughly correlates to amplitude. On the transmitter side keeping the signal linear means you generally don't see great efficiency in terms of power in -> power radiated.

spapas82 7y ago

Power is how "strong" a signal is. I think it's the easiest one to understand, that's why everybody's talking about dbm! In all electric circuits to change the power a component will consume you either change the voltage you apply to it or change its resistance, based on the P=VI & R=V/I equations.

rambojazz 7y ago
I really cannot get my head around it. What is "strong" in a signal? What physical variable is stronger? I assume "strong" or "more power" means that the signal attenuates less over time/distance, but what is causing this lesser attenuation?
- monadgonad 7y ago
  The amplitude of the wave is bigger to begin with. I think the waves in water analogy is suitable here: drop a stone in water and there'll be very big ripples just around the point where it drops, but they'll get smaller the further out they are. Drop an even bigger stone, you'll get bigger ripples. That's power.
- spapas82 7y ago
  No, the attenuation is exactly the same no matter the power and is analogous to the square of the distance. So a signal that has power X in a point 10 meters from the source it will have X/100 20 meters from the source. The analogy of the waves that another comment mentioned is a nice one (since we talk about EM waves). Another thing that may help you understand that more power means that the electrical charge to the protons/electrons in the air where the EM field is transmitted will also be more.
  - rambojazz 7y ago
    Thank you.