Mixing
How exactly does AM/FM carry both pitch and loudness of voice?
Clash Royale CLAN TAG#URR8PPP
up vote
4
down vote
favorite
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.
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 10 mins ago
user71659
2757
asked 10 hours ago
aAaa aAaa
333
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
4
down vote
favorite
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.
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 10 mins ago
user71659
2757
asked 10 hours ago
aAaa aAaa
333
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.
10
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.
10 hours 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
10 hours ago
5
frequency, and loudness, which are two separate analog data streams... that is incorrect .... it is only one analog data stream
– jsotola
5 hours ago
add a comment |Â
up vote
4
down vote
favorite
up vote
4
down vote
favorite
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.
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 10 mins ago
user71659
2757
asked 10 hours ago
aAaa aAaa
333
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.
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.
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 10 mins ago
user71659
2757
asked 10 hours ago
aAaa aAaa
333
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 10 mins ago
user71659
2757
asked 10 hours ago
aAaa aAaa
333
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 10 mins ago
user71659
2757
edited 10 mins ago
user71659
2757
edited 10 mins ago
user71659
2757
2757
asked 10 hours ago
aAaa aAaa
333
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 10 hours ago
aAaa aAaa
333
asked 10 hours ago
aAaa aAaa
333
333
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.
10
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.
10 hours 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
10 hours ago
5
frequency, and loudness, which are two separate analog data streams... that is incorrect .... it is only one analog data stream
– jsotola
5 hours ago
add a comment |Â
10
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.
10 hours 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
10 hours ago
5
frequency, and loudness, which are two separate analog data streams... that is incorrect .... it is only one analog data stream
– jsotola
5 hours ago
10
10
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.
10 hours 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.
10 hours 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
10 hours 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
10 hours ago
5
5
frequency, and loudness, which are two separate analog data streams ... that is incorrect .... it is only one analog data stream– jsotola
5 hours ago
frequency, and loudness, which are two separate analog data streams ... that is incorrect .... it is only one analog data stream– jsotola
5 hours ago
add a comment |Â
6 Answers
6
active
oldest
votes
up vote
16
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 10 hours ago
Transistor
73.8k570159
5
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
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours 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
9 hours ago
1
@Sparky256: 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
9 hours ago
3
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
 |Â
show 4 more comments
up vote
13
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 10 hours ago
Dave Tweed♦
109k9131236
add a comment |Â
up vote
6
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 10 hours ago
alex.forencich
31.4k14682
add a comment |Â
up vote
2
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 10 hours ago
The Photon
79.7k394189
add a comment |Â
up vote
0
down vote
It's been pointed out that the instantaneous signal level is just a one-dimensional time-varying variable. So why bother with sine signals? Because both AM and FM are used for transmitting a band-limited signal through a higher-frequency carrier signal, and the simplest band-limited signal is a sine signal as it has only a single frequency. AM is pretty straightforward regarding its frequency spread (and you can double the capacity by using sideband modulation) whereas FM is quite more fuzzy and involves Rice distributions, with the frequency spread partly depending on modulation depth.
Either way, the simplest signal for analysing the combination of a carrier frequency and a band-limited signal remains a sine signal.
add a comment |Â
up vote
0
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
There's more than two, depending entirely on how you perceive/analyze it, and what else is going on, on the track. There could be hundreds in a My Bloody Valentine song, the streams have streams and they go to 11.
What if we forced them all to fit onto one data stream?
Because that is exactly what happens when those things all enter the medium of air, which is the innate medium for all sounds. It can only handle one data stream, so the compression is forced.
When we stick a microphone in that air and get a waveform, we are getting the one data stream. Separating Bilinda Butcher's breathy trill in the chorus from what her MP-41 Phase Compressor (particularly) did to her guitar amongst the 16 other effects pedals in the stack... It's impossible. Because so much uniqueness has been lost in the compression into that single stream.
And yet, that's what music is, and we love it.
This one microphonable stream is the thing that gets encoded on AM or FM. That's what you have been missing.
I'm ignoring stereo, that's a deal of its own.
answered 1 hour ago
Harper
5,206622
add a comment |Â
6 Answers
6
active
oldest
votes
6 Answers
6
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
16
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 10 hours ago
Transistor
73.8k570159
5
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
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours 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
9 hours ago
1
@Sparky256: 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
9 hours ago
3
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
 |Â
show 4 more comments
up vote
16
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 10 hours ago
Transistor
73.8k570159
5
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
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours 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
9 hours ago
1
@Sparky256: 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
9 hours ago
3
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
 |Â
show 4 more comments
up vote
16
down vote
up vote
16
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 10 hours ago
Transistor
73.8k570159
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 10 hours ago
Transistor
73.8k570159
edited 9 hours ago
answered 10 hours ago
Transistor
73.8k570159
answered 10 hours ago
Transistor
73.8k570159
answered 10 hours ago
Transistor
73.8k570159
73.8k570159
5
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
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours 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
9 hours ago
1
@Sparky256: 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
9 hours ago
3
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
 |Â
show 4 more comments
5
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
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours 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
9 hours ago
1
@Sparky256: 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
9 hours ago
3
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
5
5
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
10 hours 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
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours ago
Have a look at the update. I found what you were looking for on Wikipedia.
– Transistor
10 hours 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
9 hours 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
9 hours ago
1
1
@Sparky256: 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
9 hours ago
@Sparky256: 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
9 hours ago
3
3
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
@bits: One of the things that surprised me as I aged was the realisation that some of the AM frequencies weren't all that high. The European LW (longwave) band starts at 148.5 kHz which is roughly only ten times the highest audio frequencies it will transmit. (Maybe you can't even transmit 10 kHz audio on LW radio?)
– Transistor
9 hours ago
 |Â
show 4 more comments
up vote
13
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 10 hours ago
Dave Tweed♦
109k9131236
add a comment |Â
up vote
13
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 10 hours ago
Dave Tweed♦
109k9131236
add a comment |Â
up vote
13
down vote
up vote
13
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 10 hours ago
Dave Tweed♦
109k9131236
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 10 hours ago
Dave Tweed♦
109k9131236
edited 9 hours ago
answered 10 hours ago
Dave Tweed♦
109k9131236
answered 10 hours ago
Dave Tweed♦
109k9131236
answered 10 hours ago
Dave Tweed♦
109k9131236
109k9131236
add a comment |Â
add a comment |Â
up vote
6
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 10 hours ago
alex.forencich
31.4k14682
add a comment |Â
up vote
6
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 10 hours ago
alex.forencich
31.4k14682
add a comment |Â
up vote
6
down vote
up vote
6
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 10 hours ago
alex.forencich
31.4k14682
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 10 hours ago
alex.forencich
31.4k14682
answered 10 hours ago
alex.forencich
31.4k14682
answered 10 hours ago
alex.forencich
31.4k14682
answered 10 hours ago
alex.forencich
31.4k14682
31.4k14682
add a comment |Â
add a comment |Â
up vote
2
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 10 hours ago
The Photon
79.7k394189
add a comment |Â
up vote
2
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 10 hours ago
The Photon
79.7k394189
add a comment |Â
up vote
2
down vote
up vote
2
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 10 hours 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 10 hours ago
The Photon
79.7k394189
answered 10 hours ago
The Photon
79.7k394189
answered 10 hours ago
The Photon
79.7k394189
answered 10 hours ago
The Photon
79.7k394189
79.7k394189
add a comment |Â
add a comment |Â
up vote
0
down vote
It's been pointed out that the instantaneous signal level is just a one-dimensional time-varying variable. So why bother with sine signals? Because both AM and FM are used for transmitting a band-limited signal through a higher-frequency carrier signal, and the simplest band-limited signal is a sine signal as it has only a single frequency. AM is pretty straightforward regarding its frequency spread (and you can double the capacity by using sideband modulation) whereas FM is quite more fuzzy and involves Rice distributions, with the frequency spread partly depending on modulation depth.
Either way, the simplest signal for analysing the combination of a carrier frequency and a band-limited signal remains a sine signal.
add a comment |Â
up vote
0
down vote
It's been pointed out that the instantaneous signal level is just a one-dimensional time-varying variable. So why bother with sine signals? Because both AM and FM are used for transmitting a band-limited signal through a higher-frequency carrier signal, and the simplest band-limited signal is a sine signal as it has only a single frequency. AM is pretty straightforward regarding its frequency spread (and you can double the capacity by using sideband modulation) whereas FM is quite more fuzzy and involves Rice distributions, with the frequency spread partly depending on modulation depth.
Either way, the simplest signal for analysing the combination of a carrier frequency and a band-limited signal remains a sine signal.
add a comment |Â
up vote
0
down vote
up vote
0
down vote
It's been pointed out that the instantaneous signal level is just a one-dimensional time-varying variable. So why bother with sine signals? Because both AM and FM are used for transmitting a band-limited signal through a higher-frequency carrier signal, and the simplest band-limited signal is a sine signal as it has only a single frequency. AM is pretty straightforward regarding its frequency spread (and you can double the capacity by using sideband modulation) whereas FM is quite more fuzzy and involves Rice distributions, with the frequency spread partly depending on modulation depth.
Either way, the simplest signal for analysing the combination of a carrier frequency and a band-limited signal remains a sine signal.
It's been pointed out that the instantaneous signal level is just a one-dimensional time-varying variable. So why bother with sine signals? Because both AM and FM are used for transmitting a band-limited signal through a higher-frequency carrier signal, and the simplest band-limited signal is a sine signal as it has only a single frequency. AM is pretty straightforward regarding its frequency spread (and you can double the capacity by using sideband modulation) whereas FM is quite more fuzzy and involves Rice distributions, with the frequency spread partly depending on modulation depth.
Either way, the simplest signal for analysing the combination of a carrier frequency and a band-limited signal remains a sine signal.
answered 5 hours ago
user199066
add a comment |Â
add a comment |Â
up vote
0
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
There's more than two, depending entirely on how you perceive/analyze it, and what else is going on, on the track. There could be hundreds in a My Bloody Valentine song, the streams have streams and they go to 11.
What if we forced them all to fit onto one data stream?
Because that is exactly what happens when those things all enter the medium of air, which is the innate medium for all sounds. It can only handle one data stream, so the compression is forced.
When we stick a microphone in that air and get a waveform, we are getting the one data stream. Separating Bilinda Butcher's breathy trill in the chorus from what her MP-41 Phase Compressor (particularly) did to her guitar amongst the 16 other effects pedals in the stack... It's impossible. Because so much uniqueness has been lost in the compression into that single stream.
And yet, that's what music is, and we love it.
This one microphonable stream is the thing that gets encoded on AM or FM. That's what you have been missing.
I'm ignoring stereo, that's a deal of its own.
answered 1 hour ago
Harper
5,206622
add a comment |Â
up vote
0
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
There's more than two, depending entirely on how you perceive/analyze it, and what else is going on, on the track. There could be hundreds in a My Bloody Valentine song, the streams have streams and they go to 11.
What if we forced them all to fit onto one data stream?
Because that is exactly what happens when those things all enter the medium of air, which is the innate medium for all sounds. It can only handle one data stream, so the compression is forced.
When we stick a microphone in that air and get a waveform, we are getting the one data stream. Separating Bilinda Butcher's breathy trill in the chorus from what her MP-41 Phase Compressor (particularly) did to her guitar amongst the 16 other effects pedals in the stack... It's impossible. Because so much uniqueness has been lost in the compression into that single stream.
And yet, that's what music is, and we love it.
This one microphonable stream is the thing that gets encoded on AM or FM. That's what you have been missing.
I'm ignoring stereo, that's a deal of its own.
answered 1 hour ago
Harper
5,206622
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
There's more than two, depending entirely on how you perceive/analyze it, and what else is going on, on the track. There could be hundreds in a My Bloody Valentine song, the streams have streams and they go to 11.
What if we forced them all to fit onto one data stream?
Because that is exactly what happens when those things all enter the medium of air, which is the innate medium for all sounds. It can only handle one data stream, so the compression is forced.
When we stick a microphone in that air and get a waveform, we are getting the one data stream. Separating Bilinda Butcher's breathy trill in the chorus from what her MP-41 Phase Compressor (particularly) did to her guitar amongst the 16 other effects pedals in the stack... It's impossible. Because so much uniqueness has been lost in the compression into that single stream.
And yet, that's what music is, and we love it.
This one microphonable stream is the thing that gets encoded on AM or FM. That's what you have been missing.
I'm ignoring stereo, that's a deal of its own.
answered 1 hour ago
Harper
5,206622
Voice has both pitch, i.e. frequency, and loudness, which are two separate analog data streams.
There's more than two, depending entirely on how you perceive/analyze it, and what else is going on, on the track. There could be hundreds in a My Bloody Valentine song, the streams have streams and they go to 11.
What if we forced them all to fit onto one data stream?
Because that is exactly what happens when those things all enter the medium of air, which is the innate medium for all sounds. It can only handle one data stream, so the compression is forced.
When we stick a microphone in that air and get a waveform, we are getting the one data stream. Separating Bilinda Butcher's breathy trill in the chorus from what her MP-41 Phase Compressor (particularly) did to her guitar amongst the 16 other effects pedals in the stack... It's impossible. Because so much uniqueness has been lost in the compression into that single stream.
And yet, that's what music is, and we love it.
This one microphonable stream is the thing that gets encoded on AM or FM. That's what you have been missing.
I'm ignoring stereo, that's a deal of its own.
answered 1 hour ago
Harper
5,206622
answered 1 hour ago
Harper
5,206622
answered 1 hour ago
Harper
5,206622
answered 1 hour ago
Harper
5,206622
5,206622
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%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
10
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.
10 hours 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
10 hours ago
5
frequency, and loudness, which are two separate analog data streams... that is incorrect .... it is only one analog data stream– jsotola
5 hours ago