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Showing posts from January, 2009

### NASA Seeks Ham Operators For Sun Data Capture

I just saw a link to this article come across the HAMRADIOHELPGROUP. NASA will be collecting data from two observer satellites on either side of the sun and would like the help of ham radio operators to collect the data on 10m. Anyone with a 10m dish antenna is welcome.

"St. Cyr notes that experienced ham radio operators can participate in this historic mission by helping NASA capture STEREO's images. The busy Deep Space Network downloads data from STEREO only three hours a day. That's plenty of time to capture all of the previous day's data, but NASA would like to monitor the transmissions around the clock.

"So we're putting together a 'mini-Deep Space Network' to stay in constant contact with STEREO," says Bill Thompson, director of the STEREO Science Center at Goddard.

The two spacecraft beam their data back to Earth via an X-band radio beacon. Anyone with a 10-meter dish antenna and a suitable receiver can pick up the signals. The data rate is…

### Experimenting with Piezoelectric Crystals of Rochelle Salt

Photo Credit

I'm exploring piezoelectric cyrstals, (crystals that produce a small electric potential when mechanically strained). I stumbled across a great concise history[pdf]. The outline is shown below. I also found an interesting summary of another amateur's experiments

### Notes on Working with Schrodinger's Equation

I got a quick lesson on the importance of graphing my work this afternoon. After diligently calculating the expectation position of a particle as predicted by the Schrodinger equation:

I came up with the value 1/2λ.

After a little bit of thought, it occurred to me that the Schrodinger equation was symmetric about 0 and that if I was guessing the expectation, or average, value for the position of a particle predicted by the equation, I'd guess zero. So, I graphed the Schrodinger equation for the potential. Just for good measure, I went ahead and graphed the integrand of the expectation integral as well. Sure enough, the Schrodinger equation is symmetric about 0 and the areas under the expectation integrand curve to the left and right of (x=0) cancel out.

Upon checking my work I realized that I was missing a factor of x in my original integration. I multiplied the x back in and everything worked out just like the graph said it should! Not bad for taking a 20 year break between qu…

### Compton Scattering Paper Mislabeled? It's Obvious... Not

This installment of “It’s Obvious. Not!” looks at:

Periodical: “Physical Review” Volume: 21 Page: 483, 486
Title: "A Quantum Theory of the Scattering of X-Rays by Light Elements"
Author: Arthur H. Compton

Excerpt from page 486:

In the above excerpt, Compton discusses how to calculate the momentum of an electron that caused x-ray or gamma scattering. The momentum added to the electron is the momentum of the incident photon minus the momentum of the scattered photon.

Problem: The angle of scattering, (theta), appears to be mislabeled in the above figure vs. the usage of the angle in formula 1.

In formula 1, Compton calculates the magnitude of the electron momentum as the vector difference of the momentum of the incident and scattered photons. To subtract two vectors, you place their tails together, the resulting vector that points from the head of the second to the head of the first is the difference vector as shown below and described in this Wikipedia article.

To get the magni…

### Ham in a Day in Los Altos, CA

If you're interested in becoming a ham radio operator and you're going to be in the Silicon Valley area on January 24th, you should check out the

Ham Radio Training and Testing in a Day