Vitamin C

Turns out most of my other images were actually images produced from signals that were not NOAA signals, whoops. Here are some images I managed to get here at Caltech. Our good friends at the local NPR station (KPCC 89.3) over at Pasadena Community College as well as all the other radio noise here are not helping the quality of the images. I need to frequently adjust the antenna orientation to try and block out the differently polarized signals and to only get the circularly polarized satelite signal. I'm using a QFH tuned (very roughly tuned) to 137 MHz.

This is part 2 to my adventure into amature radio receiving. I conveyed my intention to receive images from NOAA satellites in the first part. I was unable to replicate the results of the possible image, despite the construction of a 137 MHz V-dipole antenna (albeit probably not the best antenna since I am not experienced in antenna construction). Tomorrow I'll try building the antenna detailed here . Hopefully that will give me sufficient signal intensity to receive visually recognizable images. The other complicating factor is I'm uncertain how to match the default 11.250kHz sampling of the audio input file in wxtoimg with the 44.1kHz sampling of audio by CubicSDR and then the 44.1kHz sampling of the recording program. I did change the wxtoimg sampling to 44.1kHz however any potential image was distorted beyond the ability of wxtoimg to overlay a map upon it. I'll update you tomorrow (I guess whenever I say tomorrow in this post I mean today since it's past midnight)...

This was just a test to see if I could put LaTeX formatted tables into this webpage MathJax example $$\begin{array}{|c | c | c | c | c|} \hline \begin{array}{c}\end{array} & \frac{3}{2} & \frac{1}{2} & -\frac{1}{2} & -\frac{3}{2} \\ \hline 5 & \begin{array}{c}\end{array} & ^{2}H\begin{array}{c}^{2}H(2^+,2^-,1^+)\end{array} & \begin{array}{c}(1^-,2^-,2^+)\end{array} & \begin{array}{c}\end{array} \\ \hline 4 & \begin{array}{c}\end{array} & ^{2}G\begin{array}{c}^{2}H(2^+,2^-,0^+)\\^{2}G(2^+,1^+,1^-)\end{array} & \begin{array}{c}(0^-,2^-,2^+)\\(1^-,2^-,1^+)\end{array} & \begin{array}{c}\end{array} \\ \hline 3 & ^{4}F\begin{array}{c}^{4}F(2^+,1^+,0^+)\end{array} & ^{2}F\begin{array}{c}^{2}H(2^+,2^-,-1^+)\\^{2}G(2^+,1^+,0^-)\\^{4}F(2^+,1^-,0^+)\\^{2}F(2^-,1^+,0^+)\end{array} & \begin{array}{c}(1^-,2^-,0^+)\\(0^-,2^-,1^+)\\(0^-,1^-,2^+)\\(-1^-,2^-,2^+)\end{array} & \begin{array}{c}(0^-...

     I recently began exploring the world of amateur radio by purchasing a software-defined radio (sdr) which allows one to view a wide band spectrum of radio frequencies (RF). Mine goes from 70 MHz to about 2300 MHz. Although this is just shy of being able to see wifi, there is an sdr that has this capability for about 20 times the cost (HackRF One) and is for the time being far too costly given the general uncertainty involved with sdr.      The uncertainty I'm referring to is what happens when you ask for an inexpensive device that can detect a range as wide as 100KHz-6GHz (I think this is the hackrf one range). This is an extremely tall order. In fact most radio devices have rapidly degrading specs when pushed outside of the range they were designed to operate within. I can think of two good reasons for this, the first being cost, it is more cost effective to fabricate a chip designed to operate at a narrow frequency band rather than having...

Now that pretty much all my friends have left to their respective universities, I've had a lot of time to do the very boring yet nonetheless interesting experiments I've not yet had the time to do. One of these is calculating the emissivity of an aluminum heat sink I have on an amplifier. The heat sink dissipates the heat from two large bipolar junction transistors that are used as the second stage of a two stage class A stereo amplifier. The amplifier is only about 20% efficient, consuming about 50 watts and sending a max of only 5 watts to each of the speakers. As a result, the transistors get quite hot. The heat sink is a square piece of aluminum measuring 12.7 cm x 12.7 cm x .635 cm. Over the course of 1 hour I tracked the temperature given by a digital temperature probe every 30 seconds. The probe was resting between the heat sink and the side of the amplifier. Although this disrupts the ability of the heat sink to dissipate heat ideally, it allows for relatively ...

I used the ~43 grams of Salicylic Acid made in a previous post to synthesize methyl salicylate. Methyl salicylate is the ester that gives wintergreen its distinct flavor and odor. The process is known as a fischer esterification. The procedure is simple, and consists of dissolving the salicylic acid in an excess of anhydrous methanol, and then adding 40ml of concentrated sulfuric acid as a catalyst and refluxing for about two hours. After the reflux, around 50% of the methanol is distilled until the oil methyl salicylate precipitates. The mixture is poured into a separatory funnel and the oil layer is isolated. The oil is then washed with saturated sodium bicarbonate solution twice. The oil, cloudy with methanol and water is then dried using calcium chloride. The oil is totally clear and has a very pleasant refractive index. It has a slight yellow color due to dissolved sulfuric acid and contaminants. Depending on its eventual application I may or may not neutralize the acid. It is no...

I am going to attempt to use a base ester hydrolysis to deacetylate acetyl salicylic acid that I collected from aspirin tablets in an earlier post. The conversion to salicylic acid is only a few steps. First, the acetyl salicylic acid is dissolved in a solution containing about equal mass sodium hydroxide. Then it is left to reflux for half an hour and the solution is combined with hydrochloric acid until the pH reaches 1. The salicylic acid precipitates as the pH decreases and it is important to take the pH as far down as possible. The precipitate is then filtered and washed several times with cold water. I then left the product to dry in the buchner funnel with a vacuum being pulled. To further dry it, I left it in an evaporating dish inside an oven.