Mixing
How exactly DOES AM/FM carry both pitch and loudness of voice? Why does nobody ask this question?
Clash Royale CLAN TAG#URR8PPP
up vote
1
down vote
favorite
I do have a primary EE question, #1 at the end and described as follows, so please bear with my rant. I've always been boggled by this, and in the hundreds of explanations, YouTube videos, and radio tutorials I have seen, nobody addresses what to me is the most obvious, glaring question, to which I haven't found a satisfactory answer, making me feel a little paranoid like everyone knows something I don't.
Almost every tutorial on AM/FM modulation shows the modulating signal as something like a simple tone or continuous sine wave. Now that's easy, and for AM you just superimpose the modulating signal over the carrier wave as an envelope, and voila, and for FM you continuously and consistently vary the frequency. but no one seems to point out the obvious problem... Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams. No tutorial nor explanation I have seen then takes the next, glaringly necessary step, to explain how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, i.e.
amplitude for AM or frequency for FM.
I primarily asking here, specifically, how it is done, of course. But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
TL;DR:
How does AM or FM modulation, each of which only have one modulatable variable, carry both the pitch and loudness of voice, which are at least two distinct analog streams of data?
Why does absolutely nobody seems to address this glaring question in any tutorials/video/write-up on radio modulation?
modulation fm amplitude-modulation
edited 39 mins ago
Dave Tweed♦
109k9131235
asked 52 mins ago
aAaa aAaa
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
1
down vote
favorite
I do have a primary EE question, #1 at the end and described as follows, so please bear with my rant. I've always been boggled by this, and in the hundreds of explanations, YouTube videos, and radio tutorials I have seen, nobody addresses what to me is the most obvious, glaring question, to which I haven't found a satisfactory answer, making me feel a little paranoid like everyone knows something I don't.
Almost every tutorial on AM/FM modulation shows the modulating signal as something like a simple tone or continuous sine wave. Now that's easy, and for AM you just superimpose the modulating signal over the carrier wave as an envelope, and voila, and for FM you continuously and consistently vary the frequency. but no one seems to point out the obvious problem... Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams. No tutorial nor explanation I have seen then takes the next, glaringly necessary step, to explain how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, i.e.
amplitude for AM or frequency for FM.
I primarily asking here, specifically, how it is done, of course. But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
TL;DR:
How does AM or FM modulation, each of which only have one modulatable variable, carry both the pitch and loudness of voice, which are at least two distinct analog streams of data?
Why does absolutely nobody seems to address this glaring question in any tutorials/video/write-up on radio modulation?
modulation fm amplitude-modulation
edited 39 mins ago
Dave Tweed♦
109k9131235
asked 52 mins ago
aAaa aAaa
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
You understand how a signal is modulated, right? So it has the frequency, which is a pitch (roughly speaking), and amplitude - which is the "loudness". These are not different streams. These are parts of the same "wave", which is the "envelope" of ,say AM-modulated signal..
– Eugene Sh.
50 mins ago
Both modulation schemes modulate the carrier amplitude or frequency with all aspects of the audio signal, though stations do use compression of the audio to avoid over modulation which leads to severe distortion and side-band noise.
– Sparky256
44 mins ago
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I do have a primary EE question, #1 at the end and described as follows, so please bear with my rant. I've always been boggled by this, and in the hundreds of explanations, YouTube videos, and radio tutorials I have seen, nobody addresses what to me is the most obvious, glaring question, to which I haven't found a satisfactory answer, making me feel a little paranoid like everyone knows something I don't.
Almost every tutorial on AM/FM modulation shows the modulating signal as something like a simple tone or continuous sine wave. Now that's easy, and for AM you just superimpose the modulating signal over the carrier wave as an envelope, and voila, and for FM you continuously and consistently vary the frequency. but no one seems to point out the obvious problem... Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams. No tutorial nor explanation I have seen then takes the next, glaringly necessary step, to explain how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, i.e.
amplitude for AM or frequency for FM.
I primarily asking here, specifically, how it is done, of course. But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
TL;DR:
How does AM or FM modulation, each of which only have one modulatable variable, carry both the pitch and loudness of voice, which are at least two distinct analog streams of data?
Why does absolutely nobody seems to address this glaring question in any tutorials/video/write-up on radio modulation?
modulation fm amplitude-modulation
edited 39 mins ago
Dave Tweed♦
109k9131235
asked 52 mins ago
aAaa aAaa
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I do have a primary EE question, #1 at the end and described as follows, so please bear with my rant. I've always been boggled by this, and in the hundreds of explanations, YouTube videos, and radio tutorials I have seen, nobody addresses what to me is the most obvious, glaring question, to which I haven't found a satisfactory answer, making me feel a little paranoid like everyone knows something I don't.
Almost every tutorial on AM/FM modulation shows the modulating signal as something like a simple tone or continuous sine wave. Now that's easy, and for AM you just superimpose the modulating signal over the carrier wave as an envelope, and voila, and for FM you continuously and consistently vary the frequency. but no one seems to point out the obvious problem... Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams. No tutorial nor explanation I have seen then takes the next, glaringly necessary step, to explain how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, i.e.
amplitude for AM or frequency for FM.
I primarily asking here, specifically, how it is done, of course. But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
TL;DR:
How does AM or FM modulation, each of which only have one modulatable variable, carry both the pitch and loudness of voice, which are at least two distinct analog streams of data?
Why does absolutely nobody seems to address this glaring question in any tutorials/video/write-up on radio modulation?
modulation fm amplitude-modulation
modulation fm amplitude-modulation
edited 39 mins ago
Dave Tweed♦
109k9131235
asked 52 mins ago
aAaa aAaa
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 39 mins ago
Dave Tweed♦
109k9131235
asked 52 mins ago
aAaa aAaa
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 39 mins ago
Dave Tweed♦
109k9131235
edited 39 mins ago
Dave Tweed♦
109k9131235
edited 39 mins ago
Dave Tweed♦
109k9131235
109k9131235
asked 52 mins ago
aAaa aAaa
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 52 mins ago
aAaa aAaa
62
asked 52 mins ago
aAaa aAaa
62
62
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
aAaa aAaa is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
You understand how a signal is modulated, right? So it has the frequency, which is a pitch (roughly speaking), and amplitude - which is the "loudness". These are not different streams. These are parts of the same "wave", which is the "envelope" of ,say AM-modulated signal..
– Eugene Sh.
50 mins ago
Both modulation schemes modulate the carrier amplitude or frequency with all aspects of the audio signal, though stations do use compression of the audio to avoid over modulation which leads to severe distortion and side-band noise.
– Sparky256
44 mins ago
add a comment |Â
1
You understand how a signal is modulated, right? So it has the frequency, which is a pitch (roughly speaking), and amplitude - which is the "loudness". These are not different streams. These are parts of the same "wave", which is the "envelope" of ,say AM-modulated signal..
– Eugene Sh.
50 mins ago
Both modulation schemes modulate the carrier amplitude or frequency with all aspects of the audio signal, though stations do use compression of the audio to avoid over modulation which leads to severe distortion and side-band noise.
– Sparky256
44 mins ago
1
1
You understand how a signal is modulated, right? So it has the frequency, which is a pitch (roughly speaking), and amplitude - which is the "loudness". These are not different streams. These are parts of the same "wave", which is the "envelope" of ,say AM-modulated signal..
– Eugene Sh.
50 mins ago
You understand how a signal is modulated, right? So it has the frequency, which is a pitch (roughly speaking), and amplitude - which is the "loudness". These are not different streams. These are parts of the same "wave", which is the "envelope" of ,say AM-modulated signal..
– Eugene Sh.
50 mins ago
Both modulation schemes modulate the carrier amplitude or frequency with all aspects of the audio signal, though stations do use compression of the audio to avoid over modulation which leads to severe distortion and side-band noise.
– Sparky256
44 mins ago
Both modulation schemes modulate the carrier amplitude or frequency with all aspects of the audio signal, though stations do use compression of the audio to avoid over modulation which leads to severe distortion and side-band noise.
– Sparky256
44 mins ago
add a comment |Â
4 Answers
4
active
oldest
votes
up vote
4
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
No. Voice is transmitted initially as one analog 'stream' of sound pressure waves in which the air pressure variation amplitude corresponds to the volume (at that instant) and the rate of change gives the pitch.
No tutorial ... explain[s] how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, ...
The AM and FM modulation schemes are analog and are called analog because the modulation is analagous (adjective, comparable in certain respects, typically in a way which makes clearer the nature of the things compared) to the original signal - voice or music.
But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
Maybe there's an opportunity for you there when you figure it out.
The tutorials demonstrate the results with sinusoidal signals because otherwise it would be impossible to see the modulation of a complex signal on a reasonable scale on a diagram.
Figure 1. The Simplified analysis of standard AM from Wikipedia goes a little bit of the way to describe what you are asking.
Notice in the illustration that the waveform is not sinusoidal but is an arbitrary waveform. Notice also that the amplitude modulation just follows the signal waveform. There's not much more to it. The microphone will convert the voice into an analog electrical signal and the modulator will modulate the carrier analogously too.
answered 42 mins ago
Transistor
73.5k570158
1
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
add a comment |Â
up vote
1
down vote
Forget about radio — how do you think voice is transmitted over a wire, which only has "voltage" — again, a single variable?
The point is, "pitch" and "amplitude" are abstract parameters of a single-valued function of time. In fact, you can superimpose many different signals at different frequencies on a single wire. Each component of such a complex waveform has its own frequency, phase and amplitude, yet we can still tell them apart.
It is possible to convert voltage to amplitude in an AM transmitter, and convert it to frequency in an FM transmitter. In both cases, the signal can be converted by the receiver back into a replica of the same voltage waveform that created the modulation in the first place.
So if you believe that voice (and music, for that matter) can be transmitted over a wire, it's a simple extension to transmit it as a radio signal.
answered 33 mins ago
Dave Tweed♦
109k9131235
add a comment |Â
up vote
0
down vote
In a simple AM system, the transmitted signal is something like
$$x(t) = Aleft(1+m(t)right) sinomega_c t$$
and $m(t)$ is called the message signal.
In an AM radio, the message signal basically just says how hard to push the speaker cone at each instant in time. If the audio signal is a single tone, $m(t)$ will itself be a sinusoid.
If you want a louder tone, you increase the amplitude of $m(t)$. If you want a higher frequency tone, you increase the frequency of $m(t)$.
And if you want a musical audio signal, you sum together multiple tones with different frequencies and amplitudes, and vary them in a melodic way.
answered 43 mins ago
The Photon
79.7k394189
add a comment |Â
up vote
0
down vote
Sound is just a single-dimensional time-varying signal. Microphones essentially continuously track variations in air pressure. At any point in time, this is a single value. This value is what gets 'modulated' onto the carrier.
This single-dimensional time-varying signal carries both the loudness and pitch information. It can actually contain the loudness and pitch information for many different voices at the same time, or many musical instruments at the same time, etc. in this single time-varying value.
answered 34 mins ago
alex.forencich
31.3k14682
add a comment |Â
4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
No. Voice is transmitted initially as one analog 'stream' of sound pressure waves in which the air pressure variation amplitude corresponds to the volume (at that instant) and the rate of change gives the pitch.
No tutorial ... explain[s] how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, ...
The AM and FM modulation schemes are analog and are called analog because the modulation is analagous (adjective, comparable in certain respects, typically in a way which makes clearer the nature of the things compared) to the original signal - voice or music.
But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
Maybe there's an opportunity for you there when you figure it out.
The tutorials demonstrate the results with sinusoidal signals because otherwise it would be impossible to see the modulation of a complex signal on a reasonable scale on a diagram.
Figure 1. The Simplified analysis of standard AM from Wikipedia goes a little bit of the way to describe what you are asking.
Notice in the illustration that the waveform is not sinusoidal but is an arbitrary waveform. Notice also that the amplitude modulation just follows the signal waveform. There's not much more to it. The microphone will convert the voice into an analog electrical signal and the modulator will modulate the carrier analogously too.
answered 42 mins ago
Transistor
73.5k570158
1
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
add a comment |Â
up vote
4
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
No. Voice is transmitted initially as one analog 'stream' of sound pressure waves in which the air pressure variation amplitude corresponds to the volume (at that instant) and the rate of change gives the pitch.
No tutorial ... explain[s] how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, ...
The AM and FM modulation schemes are analog and are called analog because the modulation is analagous (adjective, comparable in certain respects, typically in a way which makes clearer the nature of the things compared) to the original signal - voice or music.
But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
Maybe there's an opportunity for you there when you figure it out.
The tutorials demonstrate the results with sinusoidal signals because otherwise it would be impossible to see the modulation of a complex signal on a reasonable scale on a diagram.
Figure 1. The Simplified analysis of standard AM from Wikipedia goes a little bit of the way to describe what you are asking.
Notice in the illustration that the waveform is not sinusoidal but is an arbitrary waveform. Notice also that the amplitude modulation just follows the signal waveform. There's not much more to it. The microphone will convert the voice into an analog electrical signal and the modulator will modulate the carrier analogously too.
answered 42 mins ago
Transistor
73.5k570158
1
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
add a comment |Â
up vote
4
down vote
up vote
4
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
No. Voice is transmitted initially as one analog 'stream' of sound pressure waves in which the air pressure variation amplitude corresponds to the volume (at that instant) and the rate of change gives the pitch.
No tutorial ... explain[s] how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, ...
The AM and FM modulation schemes are analog and are called analog because the modulation is analagous (adjective, comparable in certain respects, typically in a way which makes clearer the nature of the things compared) to the original signal - voice or music.
But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
Maybe there's an opportunity for you there when you figure it out.
The tutorials demonstrate the results with sinusoidal signals because otherwise it would be impossible to see the modulation of a complex signal on a reasonable scale on a diagram.
Figure 1. The Simplified analysis of standard AM from Wikipedia goes a little bit of the way to describe what you are asking.
Notice in the illustration that the waveform is not sinusoidal but is an arbitrary waveform. Notice also that the amplitude modulation just follows the signal waveform. There's not much more to it. The microphone will convert the voice into an analog electrical signal and the modulator will modulate the carrier analogously too.
answered 42 mins ago
Transistor
73.5k570158
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
No. Voice is transmitted initially as one analog 'stream' of sound pressure waves in which the air pressure variation amplitude corresponds to the volume (at that instant) and the rate of change gives the pitch.
No tutorial ... explain[s] how both aspects are transmitted over radio schemes that apparently can only take one degree of variation, ...
The AM and FM modulation schemes are analog and are called analog because the modulation is analagous (adjective, comparable in certain respects, typically in a way which makes clearer the nature of the things compared) to the original signal - voice or music.
But I am also curious as to why this next obvious question that never seems to arise to the people making these tutorials and explanations, nor is the answer easily found out there, as I've been fruitlessly searching.
Maybe there's an opportunity for you there when you figure it out.
The tutorials demonstrate the results with sinusoidal signals because otherwise it would be impossible to see the modulation of a complex signal on a reasonable scale on a diagram.
Figure 1. The Simplified analysis of standard AM from Wikipedia goes a little bit of the way to describe what you are asking.
Notice in the illustration that the waveform is not sinusoidal but is an arbitrary waveform. Notice also that the amplitude modulation just follows the signal waveform. There's not much more to it. The microphone will convert the voice into an analog electrical signal and the modulator will modulate the carrier analogously too.
answered 42 mins ago
Transistor
73.5k570158
edited 29 mins ago
answered 42 mins ago
Transistor
73.5k570158
answered 42 mins ago
Transistor
73.5k570158
answered 42 mins ago
Transistor
73.5k570158
73.5k570158
1
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
add a comment |Â
1
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
1
1
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Aaaah. I got it now. I feel kinda dumb...although, certainly, no tutorial I have seen addresses the second part, showing how it works with complex waves, but I totally missed the part about the instantaneous amplitude of versus the rate of change of the amplitude being the actual frequency change. Darn it. And all these years I didn't get it.
– aAaa aAaa
39 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
32 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
@aAaaaAaa. No need to feel 'dumb'. AM radio has been around since the 1950's and basic FM since the late 1960's. We grew up with it for so long that the details drifted our way over time. It worked so we did not ask for more details.
– Sparky256
30 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
AM radio was around much earlier than the 1950s - Wiki says widespread broadcasting started in the 1920s. FM was invented in 1933 with experimental broadcasts in 1934.
– Peter Bennett
2 mins ago
add a comment |Â
up vote
1
down vote
Forget about radio — how do you think voice is transmitted over a wire, which only has "voltage" — again, a single variable?
The point is, "pitch" and "amplitude" are abstract parameters of a single-valued function of time. In fact, you can superimpose many different signals at different frequencies on a single wire. Each component of such a complex waveform has its own frequency, phase and amplitude, yet we can still tell them apart.
It is possible to convert voltage to amplitude in an AM transmitter, and convert it to frequency in an FM transmitter. In both cases, the signal can be converted by the receiver back into a replica of the same voltage waveform that created the modulation in the first place.
So if you believe that voice (and music, for that matter) can be transmitted over a wire, it's a simple extension to transmit it as a radio signal.
answered 33 mins ago
Dave Tweed♦
109k9131235
add a comment |Â
up vote
1
down vote
Forget about radio — how do you think voice is transmitted over a wire, which only has "voltage" — again, a single variable?
The point is, "pitch" and "amplitude" are abstract parameters of a single-valued function of time. In fact, you can superimpose many different signals at different frequencies on a single wire. Each component of such a complex waveform has its own frequency, phase and amplitude, yet we can still tell them apart.
It is possible to convert voltage to amplitude in an AM transmitter, and convert it to frequency in an FM transmitter. In both cases, the signal can be converted by the receiver back into a replica of the same voltage waveform that created the modulation in the first place.
So if you believe that voice (and music, for that matter) can be transmitted over a wire, it's a simple extension to transmit it as a radio signal.
answered 33 mins ago
Dave Tweed♦
109k9131235
add a comment |Â
up vote
1
down vote
up vote
1
down vote
Forget about radio — how do you think voice is transmitted over a wire, which only has "voltage" — again, a single variable?
The point is, "pitch" and "amplitude" are abstract parameters of a single-valued function of time. In fact, you can superimpose many different signals at different frequencies on a single wire. Each component of such a complex waveform has its own frequency, phase and amplitude, yet we can still tell them apart.
It is possible to convert voltage to amplitude in an AM transmitter, and convert it to frequency in an FM transmitter. In both cases, the signal can be converted by the receiver back into a replica of the same voltage waveform that created the modulation in the first place.
So if you believe that voice (and music, for that matter) can be transmitted over a wire, it's a simple extension to transmit it as a radio signal.
answered 33 mins ago
Dave Tweed♦
109k9131235
Forget about radio — how do you think voice is transmitted over a wire, which only has "voltage" — again, a single variable?
The point is, "pitch" and "amplitude" are abstract parameters of a single-valued function of time. In fact, you can superimpose many different signals at different frequencies on a single wire. Each component of such a complex waveform has its own frequency, phase and amplitude, yet we can still tell them apart.
It is possible to convert voltage to amplitude in an AM transmitter, and convert it to frequency in an FM transmitter. In both cases, the signal can be converted by the receiver back into a replica of the same voltage waveform that created the modulation in the first place.
So if you believe that voice (and music, for that matter) can be transmitted over a wire, it's a simple extension to transmit it as a radio signal.
answered 33 mins ago
Dave Tweed♦
109k9131235
edited 16 mins ago
answered 33 mins ago
Dave Tweed♦
109k9131235
answered 33 mins ago
Dave Tweed♦
109k9131235
answered 33 mins ago
Dave Tweed♦
109k9131235
109k9131235
add a comment |Â
add a comment |Â
up vote
0
down vote
In a simple AM system, the transmitted signal is something like
$$x(t) = Aleft(1+m(t)right) sinomega_c t$$
and $m(t)$ is called the message signal.
In an AM radio, the message signal basically just says how hard to push the speaker cone at each instant in time. If the audio signal is a single tone, $m(t)$ will itself be a sinusoid.
If you want a louder tone, you increase the amplitude of $m(t)$. If you want a higher frequency tone, you increase the frequency of $m(t)$.
And if you want a musical audio signal, you sum together multiple tones with different frequencies and amplitudes, and vary them in a melodic way.
answered 43 mins ago
The Photon
79.7k394189
add a comment |Â
up vote
0
down vote
In a simple AM system, the transmitted signal is something like
$$x(t) = Aleft(1+m(t)right) sinomega_c t$$
and $m(t)$ is called the message signal.
In an AM radio, the message signal basically just says how hard to push the speaker cone at each instant in time. If the audio signal is a single tone, $m(t)$ will itself be a sinusoid.
If you want a louder tone, you increase the amplitude of $m(t)$. If you want a higher frequency tone, you increase the frequency of $m(t)$.
And if you want a musical audio signal, you sum together multiple tones with different frequencies and amplitudes, and vary them in a melodic way.
answered 43 mins ago
The Photon
79.7k394189
add a comment |Â
up vote
0
down vote
up vote
0
down vote
In a simple AM system, the transmitted signal is something like
$$x(t) = Aleft(1+m(t)right) sinomega_c t$$
and $m(t)$ is called the message signal.
In an AM radio, the message signal basically just says how hard to push the speaker cone at each instant in time. If the audio signal is a single tone, $m(t)$ will itself be a sinusoid.
If you want a louder tone, you increase the amplitude of $m(t)$. If you want a higher frequency tone, you increase the frequency of $m(t)$.
And if you want a musical audio signal, you sum together multiple tones with different frequencies and amplitudes, and vary them in a melodic way.
answered 43 mins ago
The Photon
79.7k394189
In a simple AM system, the transmitted signal is something like
$$x(t) = Aleft(1+m(t)right) sinomega_c t$$
and $m(t)$ is called the message signal.
In an AM radio, the message signal basically just says how hard to push the speaker cone at each instant in time. If the audio signal is a single tone, $m(t)$ will itself be a sinusoid.
If you want a louder tone, you increase the amplitude of $m(t)$. If you want a higher frequency tone, you increase the frequency of $m(t)$.
And if you want a musical audio signal, you sum together multiple tones with different frequencies and amplitudes, and vary them in a melodic way.
answered 43 mins ago
The Photon
79.7k394189
answered 43 mins ago
The Photon
79.7k394189
answered 43 mins ago
The Photon
79.7k394189
answered 43 mins ago
The Photon
79.7k394189
79.7k394189
add a comment |Â
add a comment |Â
up vote
0
down vote
Sound is just a single-dimensional time-varying signal. Microphones essentially continuously track variations in air pressure. At any point in time, this is a single value. This value is what gets 'modulated' onto the carrier.
This single-dimensional time-varying signal carries both the loudness and pitch information. It can actually contain the loudness and pitch information for many different voices at the same time, or many musical instruments at the same time, etc. in this single time-varying value.
answered 34 mins ago
alex.forencich
31.3k14682
add a comment |Â
up vote
0
down vote
Sound is just a single-dimensional time-varying signal. Microphones essentially continuously track variations in air pressure. At any point in time, this is a single value. This value is what gets 'modulated' onto the carrier.
This single-dimensional time-varying signal carries both the loudness and pitch information. It can actually contain the loudness and pitch information for many different voices at the same time, or many musical instruments at the same time, etc. in this single time-varying value.
answered 34 mins ago
alex.forencich
31.3k14682
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Sound is just a single-dimensional time-varying signal. Microphones essentially continuously track variations in air pressure. At any point in time, this is a single value. This value is what gets 'modulated' onto the carrier.
This single-dimensional time-varying signal carries both the loudness and pitch information. It can actually contain the loudness and pitch information for many different voices at the same time, or many musical instruments at the same time, etc. in this single time-varying value.
answered 34 mins ago
alex.forencich
31.3k14682
Sound is just a single-dimensional time-varying signal. Microphones essentially continuously track variations in air pressure. At any point in time, this is a single value. This value is what gets 'modulated' onto the carrier.
This single-dimensional time-varying signal carries both the loudness and pitch information. It can actually contain the loudness and pitch information for many different voices at the same time, or many musical instruments at the same time, etc. in this single time-varying value.
answered 34 mins ago
alex.forencich
31.3k14682
answered 34 mins ago
alex.forencich
31.3k14682
answered 34 mins ago
alex.forencich
31.3k14682
answered 34 mins ago
alex.forencich
31.3k14682
31.3k14682
add a comment |Â
add a comment |Â
aAaa aAaa is a new contributor. Be nice, and check out our Code of Conduct.
aAaa aAaa is a new contributor. Be nice, and check out our Code of Conduct.
aAaa aAaa is a new contributor. Be nice, and check out our Code of Conduct.
aAaa aAaa is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f397112%2fhow-exactly-does-am-fm-carry-both-pitch-and-loudness-of-voice-why-does-nobody-a%23new-answer', 'question_page');
);
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
1
You understand how a signal is modulated, right? So it has the frequency, which is a pitch (roughly speaking), and amplitude - which is the "loudness". These are not different streams. These are parts of the same "wave", which is the "envelope" of ,say AM-modulated signal..
– Eugene Sh.
50 mins ago
Both modulation schemes modulate the carrier amplitude or frequency with all aspects of the audio signal, though stations do use compression of the audio to avoid over modulation which leads to severe distortion and side-band noise.
– Sparky256
44 mins ago