Non Contact Radar Level Calculation

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Emmanueloj Participant Join Date: Aug 2013 Posts: 4	Non Contact Radar Level Calculation 09/07/2013 3:43 AM
	I am suppose to make a speedsheet that can be use for level calculations of non contact radar instrument. Given the formula D= C.t/2. whereD is the empty distance from the top of the Tank to the liquid.( with know tank dimension, the level of liquid can be calculated)C is the speed of light. (3 x 10⁸ m/s) Maxwell`s theories of electromagnetism confirmed by Heinrich Hertz experiment shows that all electomagnetic radiation travels at the speed of light.Since I want a general calculation that would be applicable to difference frequency variations, do I use C(speed of light) directly? how would the difference in frequency be considered?How do i calculate the time of flight t.????
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#1 Re: Non contact Radar level calculation 09/07/2013 6:23 AM
	DO your own homework.
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JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#2 Re: Non contact Radar level calculation 09/07/2013 6:57 AM
	Search the 'net to find an equation expressing the dependence of the speed of light on frequency. Let us know when you find it. __________________ "Love justice, you who rule the world" - Dante Alighieri
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tonykuphaldt Power-User Join Date: Sep 2011 Location: Bellingham, WA Posts: 191 Good Answers: 46	#3 Re: Non Contact Radar Level Calculation 09/07/2013 10:15 PM
	The speed of light in a vacuum is constant (2.9979 x 10^8 m/s), but electromagnetic waves travel at different velocities through different media. The principal variables here are the dielectric permittivity and magnetic permeability of the substance that wave is traveling through, because these factors influence the electric and magnetic portions of the wave's propagation. For most applications the dielectric permittivity is the most important factor. Calculating the time of flight is a simple matter of computing time given distance and velocity. A simple thought experiment is to imagine calculating how long it would take an automobile to travel a given distance at a given speed. Pick some really easy numerical values (e.g. how long to drive 200 km if the car's speed is 50 km/hour) and then see what mathematical expression works to give you the right answer. The real trick, however, is how to calculate the velocity of the wave given the medium it's traveling through. For this you will need to consult a physics textbook to find a formula relating wave velocity to "c" and to the variables mentioned in the first paragraph. __________________ They call me "lightning" when wielding a hammer, because I never strike twice in the same place
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JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#4 In reply to #3 Re: Non Contact Radar Level Calculation 09/08/2013 7:42 AM
	Since the refractive index of air at STP is about 1.000293, and the OP refers to "... the empty distance from the top of the Tank to the liquid", there is no real trick here. __________________ "Love justice, you who rule the world" - Dante Alighieri
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tonykuphaldt Power-User Join Date: Sep 2011 Location: Bellingham, WA Posts: 191 Good Answers: 46	#5 In reply to #4 Re: Non Contact Radar Level Calculation 09/08/2013 12:58 PM
	"Empty" doesn't necessarily mean air at STP. For all we know the process application is measuring liquid butane level. Besides, the odds are pretty good that this is a homework question, in which case the student needs to have all their assumptions challenged in order to learn the concept thoroughly! __________________ They call me "lightning" when wielding a hammer, because I never strike twice in the same place
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JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#7 In reply to #5 Re: Non Contact Radar Level Calculation 09/10/2013 4:24 AM
	1) If it is homework, he should be asking his tutor (or reading the textbooks); CR4 is not the place to ask. 2) Otherwise, if he's allowed anywhere near a tank of liquid butane, we should all stay as far away as possible. __________________ "Love justice, you who rule the world" - Dante Alighieri
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#6 Re: Non Contact Radar Level Calculation 09/09/2013 3:40 AM
	What a bizarre thread. Most instrument manufacturers have taken care of these things already, meaning that simply programming the instrument correctly in accordance with the user manual will produce a 0-100% signal over the range of level fluctuations. Bizarre. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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