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Gadget: Software Defined Radio for £12


My lastest toy was bought off eBay for under £12, it’s a DVB-T usb stick which doubles up as an SDR Radio.

For those that don’t know, SDR stands for Software Defined Radio ( What this means that all the usual hardware gubbins of a radio (mixers, filters, amplifiers, modulators/demodulators etc) are replaced with software running on your computer. With this, bug fixes and new features are easily implemented and with the processing power of modern processors we can watch a large bandwidth at once as well as changing mode (AM, FM, Side Band, digital modes, etc.) all done within software!

The guys at osmocom that developed the Open Source GSM stack for Motorola phones, started a new project called OsmoSDR (, and from this an offshoot, RTL-SDR (, project using cheap DVB-T USB receivers came about. The receivers supported by RTL-SDR are based on the RTL2832U chip and E4000 tuner.

This picture shows a 2MHz window of our local FM Radio segment – 2MHz at once! Try and do that with your scanner! On the right, the top window shows the spectrum analyser, and the bottom window shows a waterfall output or the signals in the segment. You can adjust the bandwidth, filters, squelch (for FM). From this picture you can see three strong and one weak radio station. Bonus points to those that can identify them ;)

This picture shows the same spectrum, but with a 3.2MHz window – notice the extra stations.

What can we do with RTL-SDR? Watch segments of radio spectrum (in the range of 64 – 1700 MHz with a gap from approx. 1100 – 1250 MHz) and identify signals. Analyse those signals and even try to decode any content. All done within software. For under £12.

Here’s a couple of youtube videos that help show SDR in use:

FM Radio Test:
Pager reception:
UHF Milsat:


Microsoft SkyDrive updates


If you have an existing SkyDrive account, you might want to login and claim your 25GB before it’s reduced to 7GB as part of “updates”. Any new accounts only get 7GB.

Farset Labs


For those that haven’t heard, Bolster and the guys have managed to get a space started. Follow the story at

Hackerspace, revisited


We’ve been giving a lot of thought to NI’s potential hackerspace and how to get the project moving. TJ came up with a good idea on using the model that uses. Basically a project is setup, with a goal (i.e. the amount of funding needed) and a deadline to meet that goal. This can be weeks/months, whatever. If the goal hasn’t been reached by the deadline, then no money is charged, the project is canned and we go back to sitting by ourselves drinking beer. However, if enough money is pledged before the deadline, then money is charged from these people and the project goes ahead.

To set up this project we have to have an idea of how much is needed each year. If we go on the basis of renting a space in Belfast (we’re assuming this is were the majority of people will use the space) then you are looking at between £250-600 per month, depending on size and location. Then there’s electric, heating (for the winter), internet access, rates (do we get discount for non-profit organisation?), insurance, general maintenance, bog rolls :) We’re basing it on a year as rent/insurance etc all need to be signed up for a year and we dont’ want people bailing out 1/2 way through and leaving the others to cover the costs!

Here’s a rough tally of costs:

Item Cost
Rent 4800 (400 x 12 months)
Electric 600 (50 x 12 months)
Heating 600
Internet 300 (25 x 12 months)
Rates 1200
Insurance 300
General 1000

From this we reckon it’s going to cost £8800 per year to run a space. To generate this sort of money we’re thinking of setting a guide of £300 per year for members. This seems a lot (and it is!) but if you break it down it’s only £25 per month. If we can get 20 people to cough up £300 then that’s a good part of the costs covered (in principle)!

We’ve also thought about going to local tech companies for a “donation” to help fund the space. If we got 10 companies donating £250, that’s a good chunk of the goal met. What to they get for their money? The chance to help local guys meet, come up with ideas, work on project and learn new skills. Skills that they might be able to call upon.

We’d also thought about selling items, t-shirts, recycled hardware etc, but this might be something we have to put on hold until after the “goal” is reached. If you go back to the theory – the goal has to be reached within the time limit, or no money is taken.

So, we’ve started a plan, we need your comments/suggestions/corrections. This is the part where we need your feedback. If we don’t get enough feedback from you guys, we’ll not even bother setting up a project and a goal. If you think the costs are too small/big, let us know. If you think that £300 for the year is WAY to much, let us know. We need your feedback.


TJ & A


Belfast ‘Hackathon’


The guys at the Belfast Hackerspace Working Group are organising a Hackathon on Saturday 23rd October at the QUB Students Union.

If you’re interested in programming, like to take things apart and see what happens if you mess with hardware, or want to know more about some of the the pitfalls of network and computer security (as well as how to prevent them), come along and mess with a group of like minded people

The success of these hackerspace events depends ENTIRELY on your support. If you want Belfast and NI to have a hackerspace, please show your support!

More Ciphers


For those that followed the last Cyber Securitry Challenge cipher, more have been posted at:

Cyber Security Challenge


For those of you stuck on the cyber security challenge: here’s how I did it:

First, the stream of characters is a base64 encoding. When you decode it you get a jpeg image:

If you follow the url you get the original image, but the new one contains something extra… a border. If you look closely a the border you’ll see it’s a stream of blocks…. perhaps binary? The best way to see this is to convert the image to monochrome bitmap, erase the original image, leaving just the border and then cut and paste the borders into one image. The order of the borders is important – read clockwise from top left (i.e. top is as is, right rotates 90 counter-clockwise, bottom rotates 180 and left rotates 90 clockwise). This leaves us with this:

If you view this file in a hex editor you’ll see it contains:

Cyrnfr sbyybj guvf yvax:      uggcf:// uggcf://

which if you ROT13 ( get:

Please follow this link:

Visit this url and you get more cipher to look at:


If you look closely there’s a lot of “04”… perhaps this is a common letter? In fact this sequence “6e04d2042f” makes me think the 04 is a space, and D2 is a letter, perhaps “a”? If we go off the presumption that 04 is space, and lookup the ascii code for space, it’s 32 (0x20 in hex). So how to we convert 0x04 to 0x20? Shift left three times! (Thanks to otaku for the suggestion to use rotate). Use the following hacky perl script to convert the text:

sub conv{
  my $hex = shift;
  my $bin = sprintf "%08b", hex($hex);
  my $bin_rev = substr($bin,3,5) . substr($bin,0,3);
  $new = oct("0b".$bin_rev);
  return chr($new);
my $s = ...encoded_string...
for ($i=0; $i<length($s); $i+=2){
  $x = substr($s, $i, 2);
  my $hex='0x'.$x;
  print conv($hex);
Looking forward to the next challenge!
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