Talk:Modulation

Spelling

Please be consistent about "Analogue" vs "Analog". As wikipedia redirects all "Analogue" articles to "analog" I changed the spelling here to be consistent. - Xeo 14:43, 12 October 2005 (UTC)

Diagrams

Would one or more simple diagrams of some of these concepts help? I am able to make some new (high quality) graphics, or 'refactor' existing ones. Any ideas or requests? At the very least, I think a few graphs illustrating the carrier and signal like the one over at Amplitude modulation ? --Aidan 10:52, 20 February 2006 (UTC)

I don't think we need to replicate the content of other articles here, no. That's why we have the other articles! We could use a system diagram or something generic and high-level like that. One that doesn't deal with a particular modulation scheme but has, you know "data source"->"modulator" -> etc (with a little bit more detail, perhaps). But then that might live better in a general communications article. -Splash^talk 19:18, 12 February 2006 (UTC)

Mmm, I totally agree about replicating graphics. The main reason I suggest this is I think 'Modulation' is a relatively broad/high-level topic. Including image(s) in this article could help demonstrate this idea. Also, from a usability perspective, it can instantly make it clear that this article is definately not about musical modulation (some people don't read). But yeah, now that I think about it, just because an article's 'child' articles have images, doesn't mean it should. (Also, useless images are just that...) Thoughts? --Aidan 10:52, 20 February 2006 (UTC)

Error(s)?

Kindly justify the points u think are errors. That touched my heart. --Electron Kid 16:27, 18 December 2005 (UTC)

Several things

1. There was no reason to drop the whole section on "why modulation", since it contains perfectly correct, standard reasons for modulation.
2. The section it was replaced with focuses entirely on antenna length; well yes, modulation has an effect on that by allowing us to shift up in frequency, but it's not the principal reason. It should be mentioned, but an approximate calculation of antenna length doesn't really have a lot to do with modulation: that info belongs elsewhere, and the text already mentioned "smaller...antennas". Plus, the example was a bit peculiar: why would we ever try to transmit at 20kHz?
3. I didn't understand "Logical Reason" at all. We don't transmit signals at that frequency, but I'm not sure with what they would get superimposed, apart from human speech. It's an odd point to make, and again not directly related to the topic of modulation. (And why is this 'reason' logical?)
4. "Redundancy" has nothing to do with modulation. Modulation doesn't introduce or require redundancy. I think you must be thinking of coding, where redundancy is key. Then the text in that section seemed to have nothing to do with redundancy, but did seem to be an unusual statement of the means of modulation — which is already present in clearer, cleaner language right at the top of the article.
5. The musical use of modulation belongs at the top of the article, because that's how we do things like that in lots of other pages.
6. Modulation seems odd in Category:Electronics and Category:Encodings, since the article doesn't talk, or need to talk about electronics (it would belong in the individual schemes' articles) and modulation isn't an encoding.
7. The other categories you added were sensible but we usually only put articles in their most specific subcategories, otherwise the categorization scheme overlaps a lot. So I will put it in Category:Radio modulation modes and Category:Communication theory. overlapping nature of those category names does reveal the mess that the various parts of the comms categorisation scheme is in. -Splash^talk 05:45, 19 December 2005 (UTC)
8. As u stated in ur point no. 1, all the reasons are perfectly sound. It must be explained why modulation theory was developed. This also removes the disambiguation. --Electron Kid 18:22, 23 December 2005 (UTC)
9. I am new, and I took out this part: "There are several reasons to modulate a signal before transmission in a medium. These include the ability of different users sharing a medium (multiple access), and making the signal properties physically compatible with the propagation medium." It didn't make sense. That is because without modulation, it would be impossible to use a signal to carry information. So modulation to allow multiple users to share the medium, or to match the physical properties of the medium, only apply to specific modulation techniques designed to do so, and do not relate to the general property that is modulation.
10. Again, I took out the following part for the same reason as number 9: "Modulation is generally performed to overcome signal transmission issues such as to allow Easy (low loss, low dispersion) propagation as electromagnetic waves Multiplexing — the transmission of multiple data signals in one frequency band, on different carrier frequencies. Smaller, more directional antennas Carrier signals are usually high frequency electromagnetic waves."
11. This is regarding #9 and #10. I understand these changes have been made before, and been undone. I suggest review by a professional before putting the lines back in. I am the second person who thinks it didn't make sense for them to be there.
12. Frequency modulation (FM) (here the frequency of the carrier signal is varied in accordance to the instantaneous frequency of the modulating signal) and Phase modulation (PM) (here the phase shift of the carrier signal is varied in accordance to the instantaneous phase of the modulating signal)

should read Frequency modulation (FM) (here the frequency of the carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal) and Phase modulation (PM) (here the phase shift of the carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal)

Kindly justify the points u think are errors. That touched my heart. --Electron Kid 16:27, 18 December 2005 (UTC)

I don't think that it is right that redundancy has nothing to do with modulation. One of the two sidebands in AM is redundant, which is part of the way AM works. Also, digital modulation techniques often are described as coding. Most commonly, Manchester coding is a specific form of synchronous phase modulation. Others also have multiple names. Gah4 (talk) 05:52, 27 September 2019 (UTC)

what are the modulation techniques used in mobile networks ????

In mobile communication systems, usually a combination of modulation techniques are used. The most common being NB-FM (for GSM), TDMA (now obsolete), FDMA, CDMA, etc.. Elaborate ur quesy/suggestion in the body with only the main theme in the title region. --Electron Kid 04:03, 22 January 2006 (UTC)

I have no idea what you are asking, sorry. -Splash^talk 04:23, 22 January 2006 (UTC)

GSM uses GMSK, I've no idea what "NB-FM" is. TDMA, FDMA and CDMA are multiple access schemes, not modulation schemes. TDMA is not obsolete - it's used in GSM, for instance (GSM also uses FDMA). Oli Filth 11:33, 23 August 2006 (UTC)

Too much jargon

A quick look around this bundle of articles is not very enlightening for an outsider. It's all incredibly difficult to penetrate. Is there a suitable entry point? Omphaloscope talk 18:42, 1 September 2006 (UTC)

I have added some metaphores from music and numerical examples, in an attempt to give the article a popular scientific touch. But we need lots of illustrations! Mange01 01:45, 27 November 2006 (UTC)

It still sucks. I'm going to make the entry strike home more. Something about modulation as being a variant of the more generally understood modification.

+ I really don't think it's unreasonable to expect and accept that some people will simply not have the level of education in the subject matter required to understand the article. That definitely doesn't mean the article should be dumbed-down. Then it would help ultimately no one. — Preceding unsigned comment added by 206.208.32.2 (talk) 17:28, 13 May 2021 (UTC)

Polarization Modulation

Somebody can explain modulation formats in a wireless/wireline agnostic way. --பராசக்தி 21:35, 23 November 2006 (UTC)

Why?

The article doesn't explain why waves would be modulated. It doesn't explain why you would want to have a modulated wave, why an information wave is not suitable for long-range transmissions, etc. Titoxd^{(?!? - cool stuff)} 07:36, 6 April 2007 (UTC)

There are a few different reasons, partly depending on what the source signal is. Audio frequencies don't go through the air well as electromagnetic waves. They do go down wires, but even in that case, modulation allows more than one signal on the same wire. Video signals on magnetic tape are FM, as the wide frequency range is otherwise too difficult to record with required linearity. Gah4 (talk) 06:00, 27 September 2019 (UTC)

digital modulation techniques

There is two list of the digital modulation techniques. I think this section should be revised. —Preceding unsigned comment added by 189.27.3.193 (talk) 17:20, 12 December 2007 (UTC)

I believe this chapter contradicts itself as it mentions digital modulation is ultimately analog (as it is), But the last (uncited) source claims it is not. — Preceding unsigned comment added by 187.189.247.68 (talk) 01:41, 27 September 2019 (UTC)

I suppose I am not surprised that there might be contradictions, as it isn't so obvious. Since wires hold voltages and currents, but not ones and zeros, it is somewhat obvious that, in the end, they must be treated as analog. One could, however, do modulation or demodulation in the digital domain, separate from the D/A or A/D conversion. This applies for both analog and digital sources. Consider a radio station broadcasting from a CD. Normally, one converts the CD digital data to an analog audio signal, and then applies that to an analog modulator. One could, though, using digital electronics, generate a digital representation of a modulated AM or FM carrier, convert that to analog, amplify as appropriate, and feed the transmitter. Similarly, one could, in the digital domain, generate the PAM waveform from a digital source, or demodulate one converted to digital. This process is most often included in Software-defined_radio. (Even though most often it is done using programmable hardware.) Gah4 (talk) 17:18, 27 September 2019 (UTC)

Survey: bit/s/Hz, (bit/s)/Hz, bps/Hz or bit·s⁻¹·Hz⁻¹ as Spectral efficiency unit?

Please vote at Talk:Eb/N0#Survey on which unit that should be used at Wikipedia for measuring Spectral efficiency. For background, see the discussion at Talk:Spectral_efficiency#Bit/s/Hz and at Talk:Eb/N0#Bit/s/Hz. Mange01 (talk) 07:21, 16 April 2008 (UTC)

Suggestion: Format

The article shows Analog, Digital, and Spread Spectrum as three types of modulation. Analog and Digital are summarized in the article, but Spread Spectrum is not. The article for Spread Spectrum should be summarized here to highlight the important details of that type of modulation. Also modulation in music is mentioned in the opening paragraph, but modulation in telecommunications is the subject of the article. A link or a brief explanation of how it is used in music should be shown. (RobPSL (talk) 02:50, 5 June 2008 (UTC))

There is a link to Modulation (music) in the sentence you are referring to. Oli Filth^(talk) 08:03, 5 June 2008 (UTC)

Merge?

It seems to me this article is very similar or identical in purpose and scope to the Amplitude modulation article. Could/should they be merged? --166.70.188.26 (talk) 17:45, 30 June 2008 (UTC)

Amplitude modulation is a specific case, this article is the general case. I believe that there is enough reason to keep both. For some rare modulation methods, it might not be worth a separate article. Gah4 (talk) 00:07, 6 December 2015 (UTC)

Too many animations

See discussion at Talk:Frequency modulation#Too many animations

Needed - History of Modulation

The main article could be improved with a couple paragraphs on the history of modulation. Did it really start with telegraph wires that were turned into telephones? How did it differ in the later years, when radio broadcasting came to be the norm?

The main article contains the following sentence:

"Often a high-frequency sinusoid waveform is used as carrier signal to convey a lower frequency signal."

but doesn't explain the history or mathematics behind it. Why does the waveform have to be sinusoidal? Was that the easiest waveform to generate? What happens when some other waveform is used? Was there a spectacular failure or difficulty encountered by some early pioneer who tried a different waveform? Dexter Nextnumber (talk) 03:08, 17 December 2009 (UTC)

The first radio transmitters were spark-gap transmitter because an impulse sequence is the easiest waveform to generate. However, it is hard to detect. Transmitters generating sinusoid waveforms made it possible to build tuned receiver side filters. The tuner improves the signal-to-noise ratio and makes multiplexing possible (dividing the radio spectrum into channels). A sinusoid signal is easy to detect if the reception conditions are poor. Just like you can hear someone blowing a tone in a wistle allthough the weather may be windy, while a noisy and wide bandwidth signal is hard to detect.Mange01 (talk) 14:40, 17 December 2009 (UTC)

Do you mean gaps like in automobile spark plugs, or distributor point gaps? A spark of that nature would be a momentary all bands broadcast, wouldn't it? Dexter Nextnumber (talk) 23:24, 17 December 2009 (UTC)

See Spark-gap transmitter. I don't know how much it resembled these. And yes, it wold momentary affect large portions of the spectrum. The idea of sending impulse sequences over large portions of the spectrum is kind of reinvented in some of today's UWB proposals. Mange01 (talk) 12:06, 18 December 2009 (UTC)

Power requirements in the 1920s and 1930s

Were there significant differences in the consumption of power between AM and FM in the 1920s and 1930s? I am curious about the expenses an early station director would have had to consider, to decide which kind of modulation he would have to authorize in order to run his business. Dexter Nextnumber (talk) 03:16, 17 December 2009 (UTC)

Interesting question. In the 1920's, when vacuum tube amplifiers were new, getting to 100MHz at high power wasn't so easy. On the other hand, there is a lot of electrical noise around the 1MHz of the AM band, so you don't need as much power to be heard. Also, high gain antennas are easier to build (smaller) at FM frequencies than AM frequencies. Between those, I have no idea how the costs would be for transmitters or receivers. In the beginning, there weren't as many FM receivers, until it got popular enough. That is an additional consideration. Gah4 (talk) 00:23, 6 December 2015 (UTC)

Why the DSB-SC illustration?

Simple example of amplitude modulation.

I tried to remove the above illustration, but the removal was reverted. I don't see any motivatation of the illustration. It is hard to understand and shows DSB-SC AM, something not used in any application today. The carrier frequency should be much higher to make the illustration comprehensible, but anyway, DSB-SC is too academic and theoretical for this article. DSB-UC is the most common form of AM, and is already clearly illustrated in this article. Other common forms are QAM and SSB, but let's leave those for the AM article.

However, we need simple illustrations of the most common digital modulation schemes. Mange01 (talk) 21:28, 21 March 2011 (UTC)

First, a moan: per WP:BRD you should not make your edit a second time until after the discussion (and please don't mark an edit as minor when removing an image).

I had hoped that my edit summary ("while problematic, it is ok and needed for preceding para") would provide an alert that the paragraph preceding the image belongs to that image. To resolve the issue (I agree the image is problematic), I have removed the paragraph.

While doing that, I was tempted to change "in accordance to the instantaneous amplitude of the modulating signal" because "amplitude" is not really the right word. Perhaps "value"? Johnuniq (talk) 03:27, 22 March 2011 (UTC)

I'm sorry that I did not wait longer for your reply before I removed the illustration, and that I did not check the preceeding paragraph. That para was also incorrect. The modulated DSB-SC AM signal is the product of the carrier and the message signal, not the sum! In case of ordinary DSB-UC AM, you could say that you add the carrier wave once again after the multiplication, (or that you multiply the carrier signal by 1+the message signal.). Thanks for handling this is in a good way.

"Instantaneous amplitude" is okay, but I think "instantaenous value", "instantaneous level" or "instantaneous signal level" would be better. (My edits are default marked as minor, and I forgot to remove that. Sorry.) Mange01 (talk) 12:24, 22 March 2011 (UTC)

DSB-SC is used for the stereo subcarrier in FM stereo, so it seems to me that it is widely used. It has the special feature that the output is zero when the (modulating) input is zero, which is often convenient. On the other hand, it requires the receiver to have another way to regenerate the carrier. Seems to be enough reason to keep it, unless it should have its own article. Gah4 (talk) 00:11, 6 December 2015 (UTC)

Also, the figure isn't DSB-SC, where the output goes to zero when either the carrier or input goes to zero. That is, a four quadrant multiplier. And DSC-SC is often used with the modulation frequency close to the carrier frequency, specifically with the almost 19kHz audio and 38kHz subcarrier for FM stereo. Gah4 (talk) 00:29, 6 December 2015 (UTC)

What is "multiplication"?

What does it mean to multiply two waves? 188.58.66.46 (talk) 09:39, 5 March 2012 (UTC)

If you consider, for example the voltage in a wave on a wire, or the pressure difference for a sound wave, you multiply the values from two waves. This makes it easiest to connect the theory to practice. Gah4 (talk) 00:14, 6 December 2015 (UTC)

More specifically, in the case of DSB-SC (double sideband suppressed carrier) the output is (proportional to) the product of the carrier and modulation input voltages. It is suppressed carrier such that the output goes to zero when there is no signal input. Gah4 (talk) 00:32, 6 December 2015 (UTC)

Two definitions in introduction

The two leading paragraphs in the introduction give the impression that there are two different definitions of modulation in telecommunications and electronics. Are there? If true, it should be sourced. If not, maybe the two paragraphs should be edited to emphasize that these are just different ways of viewing the modulation process. --Chetvorno^TALK 15:05, 8 February 2014 (UTC)

Tiny problem

There is a tiny problem in the following sentence (shown in bold):

"In telecommunications, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted."

The sentence implies that "analog audio signal" can not be transmitted physically, and therefore needs to be carried in the carrier signal. However, analog audio signal is already a continuous-time signal (i.e. analog) which can be readily transmitted.

If what is meant by "analog audio signal" is sampled and quantized analog audio signal, then it isn't analog anymore, it is digital, i.e. the same as the first example; a digital bit stream.

A more clearer sentence would be:

Modulation is the process of conveying a message signal inside another signal that will be transmitted. The modulating signal (i.e. the message signal) can be a digital bit stream or an analog signal (e.g. analog audio signal), and depending on whether it is analog or digital, analog modulation or digital modulation is applied for transmission.

78.162.13.181 (talk) 13:00, 17 April 2014 (UTC)

Is that change really needed? Two people can shout to each across a street, so an analog audio signal can be transmitted physically, but they could also flash lights to communicate digitally. The point is that if you want, for example, to send an audio signal from a radio transmitter to a receiver a considerable distance away, the plain audio signal (even in electrical form) cannot be physically transmitted between the two points, while the carrier can. Johnuniq (talk) 23:54, 17 April 2014 (UTC)

well I think it is necessary, because plain audio signals can be, and indeed is everyday, transmitted via a microphone cable or a coaxial cable between two points without modulation (and therefore without a carrier signal). The analog audio signal is actually a modulated pressure wave when its outside, and a modulated electron wave when its inside. The points is, if you have an analog signal, it is already being transmitted physically regardless of whether a modulation will be done or not. An analog signal is a real-world signal in this sense.

There is nothing majorly wrong really, that's why I just dropped a line here. It's just that when you say that audio signals needed a carrier signal to be transmitted physically to a solid state physicist (I am not one), I think s/he would be bothered.

Also for the section "Digital Modulation Methods":

Digital modulation methods can be considered as digital-to-analog conversion (DAC), and the corresponding demodulation or detection as analog-to-digital conversion (ADC). However, there are two opposing definitions that classify the transmission (or the signal transmitted with digital modulation process) as either analog transmission (or analog signal) or digital transmission (or digital signal). According to one definition, the modulated signal is a digital signal, and according to another definition,the modulation is a form of digital-to-analog conversion (DAC). Most textbooks would consider digital modulation schemes as a form of digital transmission, very few would consider it as analog transmission: Data transmission, digital transmission, or digital communications is the physical transfer of data (a digital bit stream) over a point-to-point or point-to-multipoint communication channel. But it should be noted that apart from the nature of the message signal (analog or digital), the transmitted signal itself is always analog (i.e. continuous-time signal); every real signal, wired or wireless, is analog.

78.162.13.181 (talk) 02:00, 18 April 2014 (UTC)

I don't see the problem; that can be physically transmitted does not imply that the original signal cannot also be physically transmitted. Dicklyon (talk) 03:11, 18 April 2014 (UTC)

Comments and questions

1. Under "List of common analog modulation techniques", should "frequency modulation" and "phase modulation" be listed at the same level with "amplitude modulation" or they are actually a type of "angle modulation" technique?

2. "According to one definition of digital signal, the modulated signal is a digital signal. According to another definition, the modulation is a form of digital-to-analog conversion. Most textbooks would consider digital modulation schemes as a form of digital transmission, synonymous to data transmission; very few would consider it as analog transmission."

I'm not sure what this means and what is the relevance.

3. Should "Modulator and detector principles of operation" be "Modulator and demodulator principles of operation"?

4. "Non-coherent modulation methods do not require a receiver reference clock signal that is phase synchronized with the sender carrier wave. In this case, modulation symbols (rather than bits, characters, or data packets) are asynchronously transferred. The opposite is coherent modulation."

I'm not sure what the relevance of the above information with the section.

5. Should "OOK" be listed under "ASK" in the "List of common digital modulation techniques"?

6. "MSK is a particular case of the sub-family of CPM known as continuous-phase frequency-shift keying (CPFSK)".

If that is the case, "MSK" should be listed under "CPFSK".

7. "Pulse-width modulation (PWM) and Pulse-depth modulation (PDM)"

Why aren't they split on two lines?

8. Under "Analog-over-digital methods", shouldn't "ADPCM" be indented under "DCPM"?

ICE77 (talk) 06:59, 14 June 2015 (UTC)

This is similar to the technique used by dialup modems as opposed to DSL modems.

After explaining audio tones and modems for telephones, it seems to suggest that this is different for DSL, but doesn't say why it is different. The frequencies are different, and the modulation method may be different, but otherwise they are similar enough, both being modulated in some way. Gah4 (talk) 00:19, 6 December 2015 (UTC)

Use of pulse modulation with the microwave auditory effect

Since I'm not sure if the below techniques fall under articles for 'Pulse Position Modulation' (if analog waveforms can be considered encoded data, with a clock/sample rate), or (Pulsed) 'Frequency Modulation', could pulse modulating voice using microwave transmitters possibly be included under the 'Miscellaneous modulation techniques' header?
http://en.wiki.x.io/wiki/Modulation#Miscellaneous_modulation_techniques

"Over the years, some have expressed concerns about the capability of communicating directly with humans by pulsed microwaves. In fact, earlier while studying microwave-induced auditory effects in human subjects, it was noticed that in addition to zip, click and knock sounds from exposure to single pulses of microwave radiation, short trains of rectangular microwave pulses are heard as chirps with tones corresponding to the pulse repetition frequencies [Guy et al., 1973, 1975]. It was also found that when the pulse generator was keyed manually such that each closing and opening of a push-button switch resulted in emitting a short rectangular pulse of microwave energy-transmitted digital codes (Morse code) were received and accurately interpreted by the targeted subject [Lin, 1978].
Also, soon after a system was setup for exploring the microwave auditory effect at the Walter Reed Army Institute of Research (WRAIR) [Sharp, et al., 1974], two of the principal investigators were able to demonstrate direct communication of simple speech via appropriate modulation of microwave energy [Justesen, 1975]. They tape-recorded each of the single-syllable words for digits between one and ten. The speech waveforms of each word were then converted to digital signals in such a fashion that each time an analog speech wave crossed the zero reference in the negative direction, a short pulse of microwave energy was emitted from the transmitter. By subjecting themselves to the exposure of 'speech modulated' microwave energy, the investigators reported the ability to hear, identify, and distinguish the word transmitted."

"Frey and Messenger (1973) demonstrated and Guy, Chou, Lin, and Christensen (1975) confirmed that a microwave pulse with a slow rise time is ineffective in producing an auditory response; only if the rise time is short, resulting in effect in a square wave with respect to the leading edge of the envelope of radiated radio-frequency energy, does the auditory response occur. Thus, the rate of change (the first derivative) of the wave form of the pulse is a critical factor in perception. Given a thermodynamic interpretation, it would follow the information can be encoded in the energy and 'communicated' to the 'listener'. Communication has in fact been demonstrated. A.Guy (Note 1), a skilled telegrapher, arranged for his father, a retired railroad telegrapher, to operate a key, each closure and opening of which resulted in radiation of a pulse of microwave energy. By directing the radiations as his own head, complex messages via the Continental Morse Code were readily received by Guy. Sharp and Grove (Note 2) found that appropriate modulation of microwave energy can result in direct 'wireless' and 'receiverless' communication of speech. They recorded by voice on tape each of the single-syllable words for digits between 1 and 10. The electrical sine-wave analogs of each word were then processed so that each time a sine wave crossed zero reference in the negative direction, a brief pulse of microwave energy was triggered. By radiating themselves with these 'voice modulated' microwaves, Sharp and Grove mere readily able to hear, identify, and distinguish among the 9 words."

References:

RrabEkim (talk) 03:18, 6 October 2021 (UTC)

I added the following bullet point and sentence to the article, under the 'Miscellaneous modulation techniques' header:

• The microwave auditory effect has been pulse modulated with audio waveforms to evoke understandable spoken numbers.
  

RrabEkim (talk) 04:44, 1 November 2021 (UTC)

Include Pulse-Frequency Modulation (PFM) under pulse modulation methods

The 'Pulse modulation methods' section:
http://en.wiki.x.io/wiki/Modulation#Pulse_modulation_methods
Does not currently include:
http://en.wiki.x.io/wiki/Pulse-frequency_modulation
RrabEkim (talk) 20:50, 7 October 2021 (UTC)

I've added Pulse-frequency modulation (PFM) to the 'Pulse modulation methods' section.
RrabEkim (talk) 20:59, 7 October 2021 (UTC)

Should there be a new article for "Modulators"?

Should a new article be created describing modulators, different types of modulators and modulator circuits? Or should that information be added under this article only. Alacris (talk) 13:05, 21 March 2023 (UTC)

I suppose so. I started a discussion in Talk:Modulator, which seems to me where it should go. The actual article is a redirect. Gah4 (talk) 17:53, 21 March 2023 (UTC)

What about "modulation" as the term is used in audio synthesis?

Hello! Musician (and amateur DSP nerd) here. In the world of electronic music, signals are often modulated. Typically, the "carrier" is an audio signal, which is not necessarily periodic (though in many cases it would be), or it can be any other parameter in the synthesizer (amplitude envelope parameters, delay time, filter cutoff/resonance, reverb size, pan position, distortion drive amount, compressor threshold, waveshaping curve, stereo width, bitcrusher sample rate, EQ band frequency, etc.). Typically, the modulator signal might be a low-frequency oscillator, or might be a physical control manipulated by a musician (knob or slider or aftertouch or expression pedal), or an automation curve in a DAW, or could in principle be any number of other data sources. I put the word "carrier" in quotation marks because that's not the term that would be used.

The modulating signal might be used to vary the frequency of the audio signal, in which case if the modulation signal has a low frequency you'll get a vibrato effect, and if it is at audio frequency then you'll get complex harmonics and metallic tones (as in FM synthesis). Or it might be used to vary the amplitude, in which case if the modulating signal is low-frequency you'll get a tremolo effect, or if it's audio rates you'll get sidebands and harmonics. And then there's pulse-width modulation, which creates movement in the harmonic content and can be used to create classic "fat" synth string sounds. And ring modulation, which creates bell-like, metallic, or inharmonic sounds and is often used for robotic voice effects.

The article on Subtractive synthesis links here, and much of what appears in this article applies in that situation, however anyone from the electronic music world who is trying to understand modulation as it applies to audio synthesis probably won't find this article useful at all. I haven't found an article that summarizes all of this. I would volunteer to write a new section on this topic, or perhaps a new article, titled "Modulation in audio synthesis", but I'll await the comments of this community before doing so.

Note that although this is a music topic, it is not related to the concept of "modulation" in music theory, which has nothing to do with signals. Solomon Douglas (talk) 09:40, 28 October 2024 (UTC)

The article does lack and Applications section where we could discuss modulation in music, radio, telecommunications, etc. Please go ahead and start one. ~Kvng (talk) 14:30, 31 October 2024 (UTC)