Browsing all articles from July, 2012

This is just an update on the Arduino watering system, everything seems to be going well whilst I am away (I am away for ~a month, till the end of Blackhat / Defcon). In winter the plants don’t require nearly as much water and it seems that after 8 days the water level has dropped only 11.5cm in a reservoir ( read orange bucket ) that is about 60cm across.  The orange container is smaller at the bottom, probably around 45cm so an guestimated average of say 50cm for the diameter.

At this stage I was going to do the math to work out how much water had be consumed minus that of evaporation, but I’m too lazy right now.

At this rate that container should keep the 4 plants near it (tomato, chilli, orange, peppers) as well as the palm and the 2 trays as well as the random flower going for about 6 weeks!

 

Having a look at the stats everything seems pretty stable with the 4 plants :)

-AM

A few weeks ago (I’ve been meaning to do this post for ages, few weeks ago is give or take 2 months) there was a post on reddit regarding a new software defined radio that cost around $20. After reading a few topics on the discussion (now all avail at http://www.reddit.com/r/RTLSDR now http://rtlsdr.reddit.com) my interest was peaked. RF was a whole new world of WTF for me. I think it offers the same awe and wonder that I had putting a tape into my very first tape into my vomit brown fischer-price tape player:

The basic gist of how it all works is as follows:

* There is a common chip found in video cards known as an RTL2832U
* This chip is commonly used for specific frequencies used for Television signals (and then software decodes this so you could watch TV on your pc)
* A bunch of cool guys ™ found a way to read the data coming into the card directly with drivers
* These cards also offered some tuners that allowed tuning beyond the basic TV ranges

So there are 2 basic sections:
* RTL2832U chips – reading data
* Tuner (E4K,other) – allows changing frequencies to various ranges

With such I started hunting around in Centurion for a Video card that had these options, after phoning a few places (read 5/6) I eventually found a TV card known as a Compro VisionMate U650F. It costs around R250 from pcpalace in centurion which offers a RTL2832U as well as the E4K tuner (the best one at this stage). *update* the cheaper visionmates (without remote) go for about R100 less than this!

This meant:

* I can tune to frequencies from around 55MHz to 1800Mhz
* For R250!

This was super, ordered my card and a few days later it arrived!

Following some _really_ easy guides for installing a few tools in windows:
* HDSDR, WRPlus, ExtIO, zadig ( http://spench.net/ has all the info but at time of writing was having some issues, try one of these: http://rtlsdr.org/ http://rtlsdr.reddit.com)

And on linux:
* GnuRadio (install guide: http://gnuradio.org/redmine/projects/gnuradio/wiki/InstallingGR)
* gr-osmodr
* rtl-sdr

Off the bat I loaded up HDSDR (after all the config and setup – zadig for drivers, extIO copied) and immediately got that sinking feeling of ‘I know absolutely nothing’:

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