Hey everyone,
I'm a little bit confused with signals and I was hoping someone could clarify a few things for me. I would be very grateful.
First of all, signals consist of a frequency and an amplitude. They travel through the air as fast as the speed of light towards all directions (based on the type of antenna used) and eventually get captured by another antenna. Now here's the list of my questions:
1) Sound also consists of a frequency and an amplitude, such as our voice. This led me to the assumption that signals are basically sounds. Now if this is true, then why can't we 'hear' the signals? Is it because their frequency is usually too high so our ears can't hear them? Also if signals are sounds, then how come they travel at the speed of light and not at the speed of sound? Finally, if signals are sounds, does that mean that all sounds have an electric current?
2) If signals are not sounds, what's the difference between a signal and a sound wave?
3) When you turn on the radio and you listen to a frequency at which nothing is broadcast, the radio still captures noise. Why? If the noise is from the sound of the air around the room, doesn't that mean that if you would make a sound at the same frequency the radio would play it back?
4) Sounds cannot travel through empty space since they travel through the air. If signals also travel through the air, why can they travel through empty space?
I know that somewhere (or everywhere) I am wrong since it doesn't make sense. I would be very grateful if someone could simplify things.
Thank you very much,
Orestis
I'm a little bit confused with signals and I was hoping someone could clarify a few things for me. I would be very grateful.
First of all, signals consist of a frequency and an amplitude. They travel through the air as fast as the speed of light towards all directions (based on the type of antenna used) and eventually get captured by another antenna. Now here's the list of my questions:
1) Sound also consists of a frequency and an amplitude, such as our voice. This led me to the assumption that signals are basically sounds. Now if this is true, then why can't we 'hear' the signals? Is it because their frequency is usually too high so our ears can't hear them? Also if signals are sounds, then how come they travel at the speed of light and not at the speed of sound? Finally, if signals are sounds, does that mean that all sounds have an electric current?
2) If signals are not sounds, what's the difference between a signal and a sound wave?
3) When you turn on the radio and you listen to a frequency at which nothing is broadcast, the radio still captures noise. Why? If the noise is from the sound of the air around the room, doesn't that mean that if you would make a sound at the same frequency the radio would play it back?
4) Sounds cannot travel through empty space since they travel through the air. If signals also travel through the air, why can they travel through empty space?
I know that somewhere (or everywhere) I am wrong since it doesn't make sense. I would be very grateful if someone could simplify things.
Thank you very much,
Orestis
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First, your premise is wrong. While frequency and amplitude can be characteristics of a signal, a signal is any change from an at-rest state that carries information. The mathematics of signal processing is the theory of how to put information onto and extract information out of signals. Signals can be in the form of a sound, but they can also ride electromagnetic waves, heat, or (as is the case of my job) statistical blips in how a process works.
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