

A pink $16 pocket spectrum analyzer - gourneau
http://ossmann.blogspot.com/2010/03/16-pocket-spectrum-analyzer.html

======
jules
What you can do with spectrum analyzers is pretty awesome. In my first year in
a lab I built a program that scrapes the NIST spectral database, reads the
data from a spectrum analyzer attached to the computer, and figures out which
types of atoms the thing the spectrum analyzer is looking at contains. This is
harder than it sounds. Essentially you're trying to match tens of thousands of
sets of spectral lines of varying strength to a noisy spectrum measurement
(something like this but noisier:
[http://upload.wikimedia.org/wikipedia/en/thumb/5/5d/Spectra-...](http://upload.wikimedia.org/wikipedia/en/thumb/5/5d/Spectra-
Philips_32T8_natural_sunshine_fluorescent_light.png/800px-Spectra-
Philips_32T8_natural_sunshine_fluorescent_light.png)).

The problem is that one element, say natrium, has many spectral lines of
varying strength. You're trying to find a set of elements that best explains
the measured spectrum. If you plotted all spectral lines from all elements on
a spectrum, it would be completely black because there are so many. In the end
it only worked well for fluorescent tubes, but it could tell you what's in
them, even things a human would have a very hard time discovering by looking
at the spectrum and manually comparing it to the NIST database (the university
has all kinds of weird lamps like natrium lamps, blacklights, and fluorescent
tubes in many colors all containing different stuff, and looking at computer
monitor pixels is fun too).

My program output an element X who's name I forgot for many of the lamps, but
when I plotted its spectral lines over the spectra I couldn't see the match
clearly, so I added a parameter to the algorithm so that it would be more
restrictive on the number of different elements returned. In the presentations
of the lab the prof commented "many of these tubes also contain element X, but
you can't see it with the spectrum analyzer you used, you need a higher
quality one". Bummer.

~~~
kens
The original posting describes a spectrum analyzer that shows the strength of
radio-frequency signals. It's built by reprogramming a toy that uses the Texas
Instruments CC1110F32 RF system-on-a-chip
(<http://focus.ti.com/docs/prod/folders/print/cc1110f32.html>)

You (jules) are discussing a spectrometer, that shows the strength of optical
spectral lines to identify materials
(<http://en.wikipedia.org/wiki/Spectrometer>). These are two totally different
things - radio-frequency vs optical. (Just want to keep the discussion from
getting totally confused.) Also, Natrium == Sodium (Na)

~~~
jules
You are completely right. Now that I'm reading it again they are repeating
"radio" a lot of times and there are a ton of clues that this is radio
frequency, but the picture of the device on the yellow peppers just triggered
"oh they are measuring the light spectrum of yellow peppers". Sorry for the
confusion.

------
JonnieCache
Someone reversed the USB transceiver dongle too:
[http://blog.hodgepig.org/2010/10/22/im-me-usb-dongle-
hacking...](http://blog.hodgepig.org/2010/10/22/im-me-usb-dongle-hacking/)

Of course not forgetting the GPL drivers for the same: <http://im-
megpldrivers.sourceforge.net/>

Also, $16? I paid £0.99 for mine on ebay :)

------
Zaak
> The frequency ranges supported by my device are 281 - 361, 378 - 481, and
> 749 - 962 MHz. This is about 50% more than the chip is advertised to support
> and covers quite a bit of interesting activity in the US including ISM, LMR,
> television, amateur bands, pagers, and mobile phones.

Do hackers of this device risk running afoul of laws against intercepting
mobile phone transmissions?

~~~
JonnieCache
Quite possibly, but you would likely not get prosecuted. If you actually want
to do online GSM decryption you need a lot fancier software radio than this
thing, because GSM involves a lot of algorithmic frequency
hopping/multiplexing.

Also there is no realistic practical way to passively detect a passive
detector. Plus how would they distinguish you from someone on a normal mobile
phone?

~~~
anamax
> Also there is no realistic practical way to passively detect a passive
> detector.

Is that true? I heard that the BBC license police used "receiver detectors" to
find unlicensed TVs.

~~~
JonnieCache
This is well known to be a a lie. The vans are fake. It's basically just
extortion.

Just think of it as part of our eccentric british ways.

EDIT: just to add, I pay my license fee, happily, even though I dont have to
because its not required to watch the iPlayer streaming service, which is how
I watch almost all my TV. The fee is pretty cheap considering the sheer
breadth of services the BBC provides. The UK would essentially fall apart
without it culturally.

~~~
blackguardx
It may be fake, but it is possible. All televisions have a number of local
oscillators for super-heterodyne reception. With sensitive equipment, the
radiation from these oscillators can be detected because they are not well-
shielded.

~~~
JonnieCache
This is the case, but this technique will not allow you to distinguish between
my television which I have paid for, and that of my nonpaying neighbour which
is 12" away on the other side of an internal wall, on the 20th floor of a
towerblock with hundreds of televisions in it, from the street. Which is what
the Television Licensing Authority (the BBC dont actually have any involvement
in collection or enforcement) claim they can do.

------
sofuture
Travis Goodspeed gave a talk at HOPE about the RFID badges, and touched on his
work with the IM-ME. Smart (and neighborly!) guy.

------
commieneko
For some reason this reminds me of ... <http://megatokyo.com/strip/1107>
(towards the bottom of the page)

Very cool mod, though.

------
Jun8
How do you get them so cheap? Amazon lists them for $29.99.

~~~
sasvari
quote:

 _I found mine for $15.99 and free shipping on eBay._

------
J3L2404
Where's my iPhone spectrometer!!!

But this is a frequency analyzer for finding overtones to determine broadcast
frequency at close distance.

------
J3L2404
Why pink?

EDIT: I didn't see that the keys were alphanumeric and thought that was its
intended purpose. I thought maybe they were going for the "science girl"
demographic, which would have been cool.

~~~
PostOnce
It's a toy for little girls. It just happens to be easily hackable for other
uses. Which is neat.

