LearningMeasure.tv

Episode 45 - How cold is it?

admin — Wed, 24 Feb 2010 04:27:44 +0000

This episode is about temperature. We are planning this being the first of a short series on the subject. A broad overview of the subject is given in this episode, with some of the history of temperature scales. The “zeroth” law of thermodynamics is described, as well as some of the basic concepts associated with temperature measurements.

Episode 43 - Black Bodies - Take Two

admin — Sun, 17 Jan 2010 19:17:43 +0000

I just realized the wrong file was pointed to for episode 43, it actually pointed to episode 9. Sorry about that. Here is episode 43 again, with the correct file. I am currently shooting Episode 44, so look for that soon.

Episode 43 - Blackbodies

admin — Thu, 17 Dec 2009 15:16:09 +0000

Example Blackbody Source - Image via Wikipedia

In this episode the topic of blackbody or thermal radiation is discussed. This is a connection between radiometry and photometry and temperature measurement. Discussed are blackbodies and what are called greybodies (blackbodies with emissivities < 0.99) Blackbody and greybody sources are used in the calibration of radiometric devices. The sun, stars, and the whole universe emit spectra consistent with a blackbody spectrum, as does every body at finite temperature. This is why one can measure temperature approximately by observing the electromagnetic radiation emitted from matter.

The spectral radiance (power radiated per unit area per unit solid angle per unit wavelength) of a blackbody is goverened by what is called Planck’s law:

This can be integrated to give the total radiant exitance (power radiated per unit area) F=σT⁴.

Episode 42 - Life, the Universe, and Radiometry?

admin — Thu, 12 Nov 2009 04:11:05 +0000

This is our latest podcast on the subject of Radiometry. It has been awhile since our last podcast, and in this podcast I explain what is going on. I recorded this twice, and used footage from both attempts, but I am not perfectly happy with the result, but it has been awhile so I decided to put it up anyway.

The first two volumes of our measurement series have just been published:

These are the first two books in a series of eight books that we are planning to publish, built primarily from our online material.

Episode 41 - S-parameter Measurements

admin — Fri, 11 Sep 2009 14:05:27 +0000

In this episode we go over some basics S-parameter measurement. These include a description of a type of directional coupler, the basic concept of how to represent a reflectometer as a two-port device, and finally how to calibrate the associated model parameters using an open short and load. The measurements of a two-port device are then briefly discussed, by adding a through measurement to the calibration. Isolation terms in the calibration are not discussed.

This episode has a few mistakes in it, but those were basically corrected by putting notations on the video. I didn’t want to reshoot a third time to correct them. This episode is heavy on the mathematics of reflectometer calibration, and gives approximate calibration equations that one could use if they wanted to construct their own reflectometer. What is not covered is that there are some problems that need to be considered. The main idea shown here is that it is possible to compensate for errors in a reflectometer or network analyzer with some simple measurements of an open, short, and load.

The following course has been added to the course catalog

MEAS463 - Introduction to MIL-STD-461 RS Measurements

This is the fourth of a series of four courses on MIL-STD-461 measurements. The topic of this course is radiated susceptibility, or RS measurements.

Episode 40 - S-parameters

admin — Sat, 25 Jul 2009 18:25:18 +0000

This is the first in a series of podcasts on the subject of RF and microwave measurement. In this episode we reintroduce S-parameters, and give some of the basic equations for cascading a two-port and a one-port or two-port. S-parameters come from a concept that was borrowed from particle physics by electrical engineers to solve the problem of propagation of RF signals through a network. A network is anything that has ports where signals can be input and output, if there are N of these ports, there are N² of these S-parameters.

If there is an wave amplitude input at port n of a_n, and and output of wave amplitude b_m at port m, then

S_mn = b_m / a_n

There were several courses introduced into the LearningMeasure.com course catalog since the last podcast. These are

If these, or any of the other courses in our course catalog, interest you, please register as a student and subscribe. It is your subscriptions that keep this podcast going!

As always, let us know if there is any topic you want to see covered on the podcast, or if there is any course you would like to see developed.

Episode 39 - Louis Parker

admin — Wed, 01 Jul 2009 02:17:42 +0000

In this episode we do something a little different. We did our first interview using the Mac software iChat to do the interview remotely.

Louis Parker, the person interviewed in this podcast, is a member of the LearningMeasure.com consultant network, and is owner of Test & Measurement Consulting, LLC.

Louis has 20+ years in RF/Wireless with an emphasis on designing and testing short range wireless devices (RFID, Bluetooth, WiFi), RADAR and SATCOM transceivers. 6 years training engineers and account managers on RF technology and measurement (metrology) fundamentals as well as presentation, public speaking and sales skills.

This podcast has three sections, first a short interview with Louis, followed by a technical talk on the real behavior of circuit elements often thought as ideal, and finally some elaboration on the subject of oscilloscope probing.

If you would like to utilize Louis Parker’s services as a consultant or for training, contact him through his website, or you can contact us here at learningmeasure.com and we will forward your request.
If you want to join our consultant network, register as a student, and then fill out a consultant profile. If you want to be on the podcast, email me at vendors@learningmeasure.tv.

Episode 38 - Gravity Waves

admin — Fri, 12 Jun 2009 17:45:16 +0000

This is an episode about gravity waves and the Laser Interferometer Gravitational Wave Observatory or LIGO experiment. This was something requested by one of you, and here it is! I am also trying to get someone on the podcast who has something to do with this experiment in a future episode. So if you want me to cover some topic, let me know. This topic is a little out of my areas of expertise, but I hope this provides some sort of basic explanation for what is involved.

We also announce a new course CLP101 - Calibration Intervals. This is one of many courses that we plan to add in the Cal Lab Practice section of courses.

We need more feedback! Let us know if there is any topic you would like to see covered in the podcast, let us know. Also if there are any courses in particular you would like to see us to develop to meet your needs, that information would be appreciated.

Episode 37 - About Us

admin — Fri, 22 May 2009 13:50:47 +0000

There have been a lot of changes to the LearningMeasure.com website since Episode 0, so it seemed that this might be a good time to do a screencast to tour the site. We are trying to work on some new ideas for the podcast, so it has been awhile, but we will be doing some new podcasts soon.

Episode 36 - Mixing up the meter

admin — Tue, 24 Mar 2009 09:55:21 +0000

In this episode, we discus how one might realize the meter electromagnetically. I will be at the Measurement Science Conference this week, and hope to meet any of you who might be there.