Gravity Expeditions at Sea

This week one of the major milestones of the Vening Meinesz project is a fact. The website is online, where you can follow the adventure of professor Vening Meinesz onboard the submarine K-XVIII! He sailed from Den Helder, Netherlands to Surabaya, Indonesia via a large detour, visiting ports on several continents. Along the way he measured the gravity field of the Earth with extreme precision. He did this with a pendulum apparatus onboard a moving vessel. A great achievement done by a great scientist. Please explore the website and tell me what you think of it.

Enter here!

Oh, for none Dutch speakers, just skip the introduction of the main app, the expedition of Vening Meinesz is written in English. Yet, if you can read Dutch, please check my interview in the TU Delta (University paper) about the project, here (page 18).

The captain and crew of the K-XVIII with the professor among them.

Reacties

Een reactie posten

Populaire posts van deze blog

Measuring the geoid. What is the geoid?

Afbeelding
During my weekly fitness session with one of my friends, we started discussing gravity (yes, also my friends are geeks (in the good way)). We discussed the measurements done by Vening Meinesz in the K18. He used I pendulum device, that directly measures the downward gravity attraction in the location of the device, plus all the motions of the device itself. On land, these motion are negligible, but on sea the device swings a lot due the ocean waves. Therefore, Vening Meinesz used a submarine to reduce the motions of the measurement device (waves are dampened underwater). Furthermore, he used three pendulums instead of one, which he ingeniously used to separate the motions of the device and the gravity attraction. Explaining this all to my friend, he remarked that it sounded very complicated and asked me if this could be done more easy. "Yes, this is possible", I replied, "with a GPS receiver". "How is it possible to measure Earth's gravity field with a GPS...
Meer lezen

How to make a spectrogram or waterfall plot

Afbeelding
In a few blogpost ago, I showed you several figures of a satellites transmission. You know, those beautiful S-curve plots with all the colours.  Those are called spectrograms or we like to call them waterfall plots, because the radio transmissions streams up in time like a reversed waterfall. To see such a waterfall plot live in action, the University of Twente opened their antennas for you to listen and see (see link ). Yet, how to make such a figure? To start with you need a recorded radio transmission. When the website of the TUDelft tracking station is up and running you can download some data there. However, (Start NerdAlert!) you can also buy your own little USB stick that acts like a software defined radio (SDR) receiver like the Logilink DVB-T . For only 20 euros you have your own satellite tracking station. NOTE: Beware! You need the RTL2832U chip version, because a lot of open software is written for that device. It is almost plug and play, you need some software, b...
Meer lezen

Interacting of the SDR with Matlab during my classroom tutorial

Afbeelding
This year was the second time I gave my tutorial with an SDR dongle. The idea behind this tutorial is to simulate ground-station-to-satellite interaction in the radiowave spectrum. The ground station is replaced by the SDR dongle and the student's computer. For the satellite, I use a radio beacon designed and built by a colleague of mine. The device transmits an FSK modulated signal at a certain frequency. During the tutorial, the students learn to develope software that interacts with the SDR, such that they can process the digital stream observed by the SDR. I made a small video of the signal with GQRX software, such that you can see the signal in the frequency spectrum and listen to the FSK modulation. Last year, I was using an open-source software package "gnuradio" for the signal processing part, but I found out that this introduced a lot of trouble-shouting in the first few hours, because of students having: different operating systems and versions (every s...
Meer lezen