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Mark-Space Ratio

03/22/2016 8:26 PM

Hi if I had the ratio of 4:1 and the frequency of 10Khz how would I go about finding the time, if anyone could help me with this question it would be great!

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#1

Re: Mark-Space Ratio

03/22/2016 8:31 PM

Look at a clock.

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#2

Re: Mark-Space Ratio

03/22/2016 8:52 PM

First, you don't mean the time of day, right?

Do you mean duty cycle?

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#3
In reply to #2

Re: Mark-Space Ratio

03/22/2016 8:55 PM

Hi, no I dont mean the time of day!, I know what mark-space ratio is, I just dont know how to figure the question above out

I did do t=1/F

Which is 1/10,000=100 microseconds

would this be correct?

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#7
In reply to #3

Re: Mark-Space Ratio

03/23/2016 5:43 AM

Your answer is correct, you can prove it with the following expansion.

For a 4:1 ratio, a full cycle of one mark and one space will occupy 5 time periods - 4 for the mark and 1 for the space.

Therefore, in every second of a 10kHz pulsing signal you must accommodate 10,000 X 5 time periods.

So 1 second divided by 50,000 equals 20 micro seconds.

Therefore, the duration of your mark will be 80 micro seconds, and of your space will be 20 micro seconds, total duration of 1 cycle is 100 micro seconds.

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#4

Re: Mark-Space Ratio

03/23/2016 12:50 AM

"A duty cycle is the percentage of one period in which a signal or system is active.[1][2][3] A period is the time it takes for a signal to complete an on-and-off cycle. As a formula, a duty cycle may be expressed as:

[2]

where is the duty cycle, is the time the signal is active, and is the total period of the signal. Thus, a 60% duty cycle means the signal is on 60% of the time but off 40% of the time. The "on time" for a 60% duty cycle could be a fraction of a second, a day, or even a week, depending on the length of the period.

Duty cycles can be used to describe the percent time of an active signal in an electrical device such as the power switch in a switching power supply or the firing of action potentials by a living system such as a neuron.[4][5]

The duty factor for periodic signal expresses the same notion, but is usually scaled to a maximum of one rather than 100%.[6]

The duty cycle is defined as the ratio between the pulse duration () and the period () of a rectangular waveform

https://en.wikipedia.org/wiki/Duty_cycle

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#5
In reply to #4

Re: Mark-Space Ratio

03/23/2016 1:17 AM

First you have to determine your mark to space ratio which you have as 4 to 1...then you need your duty cycle? so you would be on 4 off 1....?

Example...

  • "Use the timer to determine the length of time the machine is switched on. Take a note of this value. For example, a refrigerator pump may be on for approximately 30 minutes.
  • Time the period in which the machine is switched off. Take a note of this value. Following the example, a refrigerator pump may be off for approximately 10 minutes.

Calculate the duty cycle using the following formula:

Duty Cycle = 100 * (Time on ) / (Time on + Time off)

Following the example leads to a duty cycle of:

Duty Cycle = (30 minutes) / (30 + 10 minutes) = 30/40 = 75 %

The bandwidth of a digital signal, in kilohertz, is related to the data speed in bits per second. In general, the greater the data speed, the larger the bandwidth. Data speed is not, however, the same thing as bandwidth. A modem operating at a speed of 28,800 bps has, in a certain sense, a nominal frequency of 28.8 kHz. But the bandwidth is generally much smaller, because it depends on variations in the individual data characters, not on the number of data bits per unit time.

The engineer's society, IEEE, and most other sources prefer "kHz" to "KHz." This apparently makes it less likely that users will confuse "kilo" (decimal 1,000) with the computer "K" (1,024).

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#6
In reply to #5

Re: Mark-Space Ratio

03/23/2016 1:39 AM
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