brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell

30Mar/090

Updated WSPR Map

I've gotten a couple of additional sporadic spots from DX locations, so I thought I'd update my WSPR map again. This shows my reception from the Russian station RA6AS, Canadian VE1VDM (of Big Ears fame, and my most distant North American spot) as well as the LITCHFIELD station in Northern Australia. I'm still at 37 states. All spots with a path length of greater than 3000 miles are marked with a line showing the great circle path.

world1

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29Mar/090

Funny, but somewhat uncourteous image on 30m

I was scanning back through my log of all the pictures from my QRSS grabber over the past few days, and found this rather funny image in its midst:

smile

It wasn't particularly courteous to take up the entire band, but as near as I can tell, the transmission didn't repeat, so it wasn't all that evil, and gave me a chuckle that broke up my morning coffee.

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27Mar/090

Computing the Square Root of Two

I was dusting off some of my old code for computing pi to many decimal places, and was reminded that I'd never written similar code for computing a more basic value: the square root of two.

The usual way to do this would be to use Newton's iteration to solve x2 - 2 = 0. If you apply this, you get the following
iteration formula:

         x
          n    1
x      = -- + --
 n + 1    2   x
               n

There's a problem with this, you have to implement reciprocals (or long division) to let the Newton's iteration work. If instead you try to solve 1/x^2 - 1/2 = 0, you get an easier iteration that also works:

                 3
         3 x    x
            n    n
x      = ---- - --
 n + 1     2     4

Here are some digits. It appears to work.

1.
4142135623 7309504880 1688724209 6980785696 7187537694
8073176679 7379907324 7846210703 8850387534 3276415727
3501384623 0912297024 9248360558 5073721264 4121497099
9358314132 2266592750 5592755799 9505011527 8206057147
0109559971 6059702745 3459686201 4728517418 6408891986
0955232923 0484308714 3214508397 6260362799 5251407989
6872533965 4633180882 9640620615 2583523950 5474575028
7759961729 8355752203 3753185701 1354374603 4084988471
6038689997 0699004815 0305440277 9031645424 7823068492
9369186215 8057846311 1596668713 0130156185 6898723723


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25Mar/090

Nifty kits from K5BCQ

In the comments to one of my postings about the K1EL, Tom, K9AC mentioned that I might want to look at K5BCQ's list of kits. Indeed, they seem really cool, and very reasonably priced. I am particularly interested in their Si570 controller, and their Morse controller, but there are lots of other nifty little gadgets there too. Bookmarked for the future.

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25Mar/093

NavSpaSur Lunar Imaging by DF6NM

While recovering from my brief outpatient procedure yesterday, I was surfing around, looking for the ChirpHell and ChirpPix programs that some people mentioned in the context of creating the Hellschreiber IDs that I saw yesterday. A bit of Googling revealed that they were written by DF6NM, so I did some more websearching, and as soon as I found this page:

NavSpaSur Lunar Imaging by DF6NM

I forgot entirely about ChirpPix. This page is all about using the reflections from the NavSpaSpur radar fence to generate actual pictures of the moon. Very, very neat. I should think about this, it seems like a very nifty project.

He also seems to have done some interesting work in the LF spectrum.

24Mar/090

Some nice signals this evening…

Regardez!

big1

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24Mar/090

Ouch.

For all my close friends who I've chatted with about today's adventure: I'm home, and doing fine. But seriously, ouch.

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24Mar/090

Feature Column from the AMS

I've been using StumbleUpon to find new webpages on a variety of subjects when I am bored, and as you might have seen from other blog postings (although not so many recently), mathematics is one of those things that I actually find kind of interesting to think about. While scanning around this morning, I found a link to the Feature Column from the AMS, which has many interesting articles on a wide variety of mathematical topics. I found the December 2008 article on the mathematics of clock making to be particularly interesting.

Filed under: Math No Comments
23Mar/091

aamath

Suppose you wanted to format a nifty math equation for insertion into plain old ordinary email, or maybe as a comment in your C program. For instance, something reasonably complex like this rendition of the series used in the BBP algorithm to compute hexidecimal digits of pi:


      oo
     =====
__   \     /   4         2         1         1   \   -n
|| =  >    |------- - ------- - ------- - -------| 16
     /     \8 n + 1   8 n + 4   8 n + 5   8 n + 6/
     =====
     n = 0

It would be pretty tedious, right? Well, perhaps you could use this linke to aamath, a nifty command line program for rendering ascii art versions of math formulas.

Filed under: Math 1 Comment
22Mar/090

TEST appears on 30m…

Reveal yourself! 🙂

test1

test2

Addendum: Voila!

kc6stj

And I'm not the only one listening!

wy7usa

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22Mar/091

More WSPR/MEPT developments…

This morning I was scanning my WSPR logs and my MEPT screenshots for the night. It seemed to be pretty good. I had quite a number of spots into Australia overnight: both from VK6DI (who is nearing the end of his time in VK6 land, we hope to see you again back on the eastern side of Australia) and from a newcomer: VK2DAG. Checking back through my MEPT screenshots, I was hoping to get some nice shots from VK2ZAY, but he was pretty marginal, and there was very definitely some spreading in frequency. But I was pleased to find a few nice beacon messages from Eric, WY7USA, running at 500mw:

scr00038

Addendum: A couple of hours later....

w7usa

Thanks Eric!

21Mar/094

Too much caffeine == shaky soldering

I'm glad I didn't try my hand at my second Softrock today. Instead, I decided to wire up all the programmable message buttons on my K1EL keyer (I had mounted them, but didn't bother connecting them the last time I hooked them up). Man, my hands were jittery, I guess those two Diet Cokes really got too me. Still, finished it all, buttoned it up, and now I've got the keyer completely done. When my oscillator project gets completed, I'll be able to go immediately to beaconing.

Oh, and I got my cheesecake baked for tomorrow's brunch.

Filed under: General 4 Comments
21Mar/092

Genius! Extreme Sheep LED Art


httpv://www.youtube.com/watch?v=D2FX9rviEhw

19Mar/090

X Prize? How about the N-Prize?

The Official Site for the N-Prize

The N-Prize offers two cash Prizes, each of £9,999.99 (nine thousand, nine hundred and ninety-nine pounds and ninety-nine pence, sterling).

The prizes will be awarded to the first persons or groups to put into orbit around the Earth a satellite with a mass of between 9.99 and 19.99 grams, and to prove that it has completed at least 9 orbits.

One prize (the "single-spend-to-orbit", or "SSO" Prize) will be awarded to the first entrant to complete the challenge using a non-reusable launch system. The other prize (the "reusable vehicle" or "RV" Prize) will be awarded to the first entrant to complete the challenge using a partially or wholly reusable launch system. Both prizes carry equal status.

The cost of the launch, but not ground facilities, must fall within a budget of £999.99. Entrants for the RV Prize may exceed this budget, but must demonstrate recovery of hardware such that the per-launch cost remains within £999.99.

Imaginative use of string and chewing gum is encouraged. Entrants are responsible for everything, organisers are responsible for nothing.

17Mar/090

Signals crossing the Mighty Pacific…

David, VK6DI has his grabber running, and WB3ANQ, WA5DJJ and even NM5DV can be made out in not only my grabber, but in his as well.

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