A few days ago we started a contest to identify the frequencies used in the multibeam and the chirp. After what can only be called an unprecedented number of responses I am very happy to announce that Matt Crowne is our winner. Matt used a program called Audacity (a very cool open source program for playing around with audio) to generate a power spectrum from the MP3 I uploaded and select the correct frequencies. Matt picked 3.7 kHz for the chirp and 11.6 kHz for the multibeam. The “official” values are 3.5 kHz and 12 kHz respectively.
Do you want to win a tee shirt too? We’ll be starting a tee shirt design contest soon, so check back often!
As Joyce pointed out in her post the sounds of the multibeam and chirp system can be heard in most places on the ship and are now are constant companions. I was able to record the sounds in a relatively quite passageway on the ship (using my cell phone believe it or not).
This image shows part of the waveform of the audio I recorded. There are three pulses, the first and last are the Knudsen chirp and the middle pulse is the EM122 multibeam.
Below is the full audio, 3 chirps with the multibeam between chirps 1 and 2.
The multibeam can be tough to hear because it operates at a higher frequency than the chirp, so I slowed it down by 4x.
Here is the chirp, also slowed down 4x, just because it sounds cool.
And now for a challenge: Take the mp3 with the chirp and multibeam pulses from above and figure out what frequencies the chirp and multibeam operate at. The source is noisy so lets say that you need to be within 20% to get the answer right. First one to post the correct answer wins a tee-shirt.
Fine print: If you already know the answer then you can’t play. You need to use the sound file to get the answer don’t look up the specs. Also I’m in international waters so I don’t have to comply with any of those annoying rules that ‘man’ wants me to.
One of the things about life on board a ship is that no surface stays horizontal for long. If you are a landlubber like me this means paying special attention to where you put a pen, or worse your coffee cup.
The ship and the crew, however, are well used to life at sea, and have modified their world to account for when gravity doesn’t point “down”. All the chairs in mess, the labs and around the ship are heavy and have no-slip rubber feet attached to the legs. Shelves and desks have raised edges to prevent things form sliding off. There are a few other techniques for keeping things in their place when they would otherwise be thrown to the floor. Continue reading →