whitequark changed the topic of #tinyqma to: design of an open hardware DDS-based QMA with a low-voltage dc/rf stage :: http://irclog.whitequark.org/tinyqma
<bofh__>
I am curious if the intermodulation you'd get from using a quadrupole ion trap instead of a Penning ion trap in FTICR would be too strong for this to be viable.
<whitequark>
hm
<whitequark>
not really familiar, alas
<bofh__>
so we already have something capable of generating a quadrupole electric field and the capability of generating relatively precise RF frequencies on demand. that's a homogeneous magnetic field away from also implementing fourier transform induced cyclotron spectroscopy, in theory (with FTICR, the hard part is detection - but again, SDR has improved dramatically over the past few years).
<bofh__>
just a completely random realization, not necessarily useful.
<bofh__>
ugh I cannot wait for these next two weeks to be over (massive project deadline, after which I never have to see this codebase (mix of awful python, terrible fortran and eldritch postgresql stored statements) ever again).
<whitequark>
nice
<whitequark>
doesn't penning trap also use a quadrupole field?
<whitequark>
different electrode configuration, maybe
<whitequark>
though iirc both ion guides and traps work best with hyperbolic electrode surfaces, it's just too much of a pain to machine for ion guides
<bofh__>
it does, the difference between it and a classical quadrupole (or "paul") trap is one varies the electric field over time and the other uses a constant magnetic field to trap the ions radially
<whitequark>
oh
<bofh__>
in both cases axial confinement is done via a quadrupole (or more complicated higher-order expansion) electric field
<bofh__>
and yeah, hyperbolic electrodes are very desirable
<whitequark>
are they really?
<whitequark>
for ion guides, i've seen some papers that claim several sets of rods work just as well
<bofh__>
for ion traps, yes
<whitequark>
ah
<bofh__>
for ion guides I'm not sure, but even most QMAs use hyperbolic rods
<whitequark>
they do?
<whitequark>
pretty much every one I've seen uses circular
<bofh__>
okay the agilent ones do :P
<whitequark>
hm
<bofh__>
that may just be overkill though
<bofh__>
it *is* agilent after all\
<bofh__>
older stuff uses circular, I'm not sure how much of a benefit you get from using hyperbolic rods
<bofh__>
~10MHz propagates really well. It's skywave skip mostly, with decent propagation even during the day.
<whitequark>
huh
<bofh__>
so yeah when you design your radar to on a bad day be able to hit a circle of radius 3000km over EU, when the sunspot cycle is just the least bit favourable you'll be able to pick that up from east coast US unfortunately no problem.
<bofh__>
it's just interesting that they're now building a bunch of these. and apparently iran also has one they're using now, though at a fraction of the propagation range apparently?
<whitequark>
preparing for a wider war
<whitequark>
i wonder when we'll see whether NATO will hold up
<bofh__>
I feel like the military folks are trying to use the fact that satcom is becoming cheap to grab as much of HF as they can for themselves.
<bofh__>
"well nobody uses that anymore really"
<whitequark>
hm
<bofh__>
also OTH radars transmit with obscenely high power (PLUTO apparently is rated at -3dBm, which honestly feels like a typo to me because what), and transmit very simple signal. That's pretty much optimal if you want to annoy people as far away as possible. :P
<whitequark>
I wonder if you can jam one
<bofh__>
getting it to display garbage data is an interesting question that nobody really knows the answers to atm, but it feels like there should be a way to do it.
<bofh__>
on a different note, DDS being cheap means making your own AM transmitter is so simple. that was my intro to DDS actually.
<bofh__>
quadrature demodulating AM with an MC1496 (multiplier) and an LTC1799.
<bofh__>
an NE602 is probably trivial for you to get and is decent for most of the AM band.
<bofh__>
like that's another intereting thing: zero-IF direct-conversion product detectors are now actually really easy.
<bofh__>
interesting*
<whitequark>
i've sort of made one
<whitequark>
well, almost, i need to get it to actually transmit music
<whitequark>
in a. .. nonconventional way
<bofh__>
so if you're just PWMing a GPIO pin on something, just feed it the product of a sinusoid at the carrier freq with the music you want to transmit
<bofh__>
AM is really simple in the fourier domain
<bofh__>
all you're doing is shifting the signal from being centered around zero to being centered around your carrier frequency.
<whitequark>
oooooooo it works
<whitequark>
(not what you suggested quite)
<bofh__>
oh my god
<bofh__>
so when I listened to that video I immediately recognised both the song
<bofh__>
and the keygen you most likely heard it in (nero 6.5 ultimate)
<whitequark>
yes
<whitequark>
well, almost. one is for nero 6.6, another is for nero 7
<whitequark>
the former with chuck norris
<bofh__>
yeah I'm thinking of the norris one
<bofh__>
also I recall nero 7 being total shite too