Oscilloscope and Polymeter
Published 11 Apr 2017
Because of technological advancements, signal voltages can now be seen. Through an electronic test instrument, this has become possible. This instrument shows a 2-D graph with electrical differences and is called “oscilloscope”. Vertical axis represents possible electrical differences. On the other hand, the horizontal axis stands for another voltage, or time (Tomal and Widmer, 1993, p. 119).
While it is true that vertical axis shows the volate through an oscilloscope, other values can also be seen through this tool, like any quantity which can possible be changed into a voltage. Most of the time, an oscilloscope displays events that change at a slow pace, or repeat without a single change. Out of all the electronic instruments out on the market these days, oscilloscope proves to be the most widely-used and the most versatile tool among others (Tomal and Widmer, 1993, p. 119). If an individuals needs to see the exact wave shape of a particular electrical signal, then an oscilloscope is the perfect tool to make this possible. Aside from the electrical signal’s amplitude, this instrument can also measure frequency and display distortion. It can also display the timing of two signals that are related to each other. An oscilloscope can also show the time taking place between two events. An example of these events include pulse rise or pulse width (Tomal and Widmer, 1993, p. 119).
An individual who uses the digital version of this instrument will enjoy the analysis and display the tool can do. The digital version can do both of these to the spectrum of an event the repeatedly happens. Another type of an oscilloscope is the special-purpose type, which is also known as a spectrum analyzer. This type of oscilloscope has inputs which are highly sensitive, and can show spectra into the gigahertz range. Some oscilloscopes can also show spectra in audio range, and at the same time can also accept plug-ins (Tomal and Widmer, 1993, p. 119).
The term “oscilloscope” may be strange to others, especially those who are not well-versed with the terms of medicine, telecommunications and engineering. This tool is widely used in the field of science, especially in industries, telecommunications, engineering and medicine. Some oscilloscopes are general-purpose oscilloscopes, which can be used to maintain laboratory work and electronic equipment. Those with special purpose can be used to display a heartbeat’s wave form. It can also analyze a specific automotive ignition system (Scherz, 2000, p. 441). In the beginning, the oscilloscope was operated by cathode ray tubes. The ray tubes function as the oscilloscope’s display element. Originally, the oscilloscope’s ability to process signals was made possible with the help of linear amplifiers. Today, oscilloscopes can now be easier to use because of LED and LCD screens.
This tool has become a more convenient instrument for its users because it now has fast converters (from analog to digital). Modern oscilloscopes can now be used with digital signal processors (Scherz, 2000, p. 441).
Basically, what one will see through an oscilloscope is a level of a signal. This signal depends on the changes in time. Voltmeters can do the same. Steady levels are measured with the use of a voltmeter. Steady levels include the use of checking the batteries of a flashlight, or test tones. However, when it comes to measuring the instantaneous value of a signal, then a voltmeter cannot do that. A voltmeter is also not capable of identifying a sine or a square wave, which an oscilloscope can do (Scherz, 2000, p. 441).
An electron beam is an important component of an oscilloscope because this is what the tool makes use of to make dots of light just when the phosphor coating, which can be seen inside a CRT or a cathode ray tube, is struck by the beam. What happens to the beam is that is gets swept from one side of the screen to another in a very rapid manner. The speed is enough to see clearly the input waveform’s variations (Scherz, 2000, p. 441). Aside from the CRT, it can be seen that all oscilloscopes have amplifiers, both horizontal and vertical. Connected to the horizontal amplifier is a frequency sawtooth oscillator. The oscillator is present to make recurrent sweep which is the one responsible in tracking down the input signal. Because the CRT creates just one dot to represent light, the tool works only when the dot is constantly sent across the screen – from left to right, specifically, to make it appear that a line exists, and not just a single dot of light. Individuals can now observe what the oscilloscope displays. The signal which a user can see is applied to the input of the oscilloscope’s vertical amplifier. Because of this, the single dot of light is shifted down, and shifted up (Gibilisco, 2002, p. 59).
The horizontal sweep is a very important part of the tool because if not for this, the single dot will be seen as just a single dot in the middle of the monitor. Signal is applied only into the vertical input. An oscilloscope works when both the signal voltages of the horizontal and the vertical inputs are used, because only in this way can the level of vertical deflection is identified. It is also only in this way can the frequency be seen, represented through a horizontal figure. Reading straight from the lines is possible because of this. The calibrated lines are referred to as graticule, which can be seen on the face of the cathode ray tube (Gibilisco, 2002, p. 59). With the help of an oscilloscope, many activities in science and the arts are made possible. Music visualization, for example, becomes possible because the oscilloscope displays what humans can only hear. Today, music is not just heard, but seen, too, through an oscilloscope (Gibilisco, 2002, p. 59). An oscilloscope may also be used to show different characteristics of music, such as polymeter. A polymeter occurs when two metric patterns work against each other (Beck & Reiser, 1998, p. 308). It happens when more than one meter is used simultaneously in an ensemble composition.
In a polymeter, each functioning element of the texture, such as an instrument or a group, shows a unique rhythmic pattern contained in its own metrical frame, seemingly without apparent regard for an overarching coordinating mechanism. A type of metric polyphony or metric dissonance is created when constituent meters fail to merge with each other to create a larger meter, but merely continues in the background. Therefore, in a philosophical point of view, polymeter is similar to coexistence, not really cooperation (Agawu, 2003, p. 79).
A polymeter may occur, for example, when at least four meters are simultaneously unfolding. In an ensemble, imagine a drummer playing his instrument in 5/8. Another person in the ensemble, playing bells and rattles for instance, plays in 6/8. The guy next to him with hand claps is playing in 3/8. Add to that another member who’s playing the guitar in 12/8 or 6/8, and finally, the singer who sings in 6/8 or 3/4. This kind of musical ensemble exhibits a polymeter, and an oscilloscope may show the distinct patterns (Agawu, 2003, p. 79).
Many people are confused between a polymeter and a polyrhythm. To more clearly define polymeter, let us compare it to polyrhythm. Some people tend to interchange these two terms, but a lot of music and sound experts differentiate between the two of them. Some experts understand polyrhythm as the simultaneous use of multiple rhythms that contrast with each other in a musical texture. Polyrhythm is present in many types of music, for instance, in African music, which is well documented by Locke, Ballantine, Jones, and Arom. There are some experts who are not comfortable with the term “polyrhythm” but the phenomenon it describes is recognized by all of them (Agawu, 2003, p. 79-80).
Unlike in polymeter, music in polyrhythm may use different instruments, but all their patterns are coordinated by a single overarching regulative beat or tactus in a meter. For example, in an ensemble, although the music itself is persistently off beat, the drummer is not doing his own thing separate from the activities of the other members (Agawu, 2003, p.80). Many types of African music, like kaganu, exhibit polyrhythm. It is also heard in many types of European music. Passages from the work of Brahms, Beethoven, and Haydn all contain polyrhythm. Repertoires from the twentieth century, including jazz and work by Elliot Carter and Stravinsky also account for the existence of polyrhythm in Europe (Agawu, 2003, p.81). When metric patterns are simultaneously mixed together to form different metric patterns in different time signatures, mixed polymeter is created. This is possible when more than one time signature happens simultaneously in different areas, with neither being dominant nor changing the time signature once it begins. Such an occurrence may be categorized as a matter of alignment. Since a base time signature is nonexistent, each area maintains its own metric characteristics and has its own time signature. Even in this setup though, one element holds all the areas or parts together. Usually, the 8th note is the one that performs this role (Beck & Reiser, 1998, p. 308).
Musicians are not the only ones who are interested in the phenomena of polymeter and polyrhythm. Psychologists who study various stimuli that a person receives from the environment are also very interested in the true nature of polymeter and its perception by human beings. In fact, the production and perception of polyrhythm has been receiving a lot of attention from researchers for a long time (London, 2004, p.49). Researchers have found different ways to study the perception of polyrhythms by humans. One strategy involves asking subjects to attend to a single stream of polyrhythm or polymemter to test their attentional focus. One research of this kind showed that when a person is confronted with complex polyrhythmic stimuli, he tends to use two different metric strategies. He will either get a composite pattern of all rhythmic streams he receives, and then fit it into an appropriate metric framework, or he will focus instead on a single rhythmic stream, fit it into its corresponding meter, and then treat other rhythmic streams as simply noise (London, 2004, p.50).
More scientific research needs to be done on the true nature of polymeter. Musicians, sound engineers, psychologists, and everyone who’s interested in the effect of sounds to human beings will definitely benefit a lot from the findings of such research. Knowledge from such research can be used to invent new useful devices. Oscilloscopes also have to be further developed to aid in this type of research. The device has many potentials, and we may see it being used to more applications in the future.
- Agawu, V.K. (2003). Representing African music: postcolonial notes, queries, positions. New York: Routledge.
- Beck, J., & Reiser, J.C. (1998). Moving notation: a handbook of musical rhythm and elementary labanotation for the dancer. Oxford: Taylor & Francis.
- Gibilisco, S. (2002). Teach Yourself Electricity and Electronics. New York: McGraw-Hill Professional.
- London, J. (2004). Hearing in time: psychological aspects of musical meter. Oxford: Oxford University Press.
- Scherz, P. (2000). Practical Electronics for Inventors. New York: McGraw-Hill Professional.
- Tomal, D., & Widmer, N. (1993). Electronic Troubleshooting. New York: McGraw-Hill Professional.