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From: Thomas Shaddack <tsc..._at_shaddack.mauriceward.com>
To: tscm-l2006_at_googlegroups.com
Subject: Software defined radios
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For the benefit of the locals, a list of currently available
software-defined radio hardware:
http://www.rtl-sdr.com/roundup-software-defined-radios/
Note that some units can simultaneously transmit and receive (some
half-duplex, a few full-duplex), and there are even those with two
simultaneous channels. Many tricks can be done with those, from radars to
NLJDs to TDR units, with some minimal added electronics.
There is also a mod for the RTL-SDR dongle that allows chaining two (and
possibly more) units together, in a coherent way (use one unit as a
crystal clock source, feed it to the other unit with crystal removed -
voila, clock-accurate synchronization). Some Finns use it for ionospheric
research, and it turned out it is a passive radar too.
http://kaira.sgo.fi/2013/09/passive-radar-with-16-dual-coherent.html
And many of the devices are opensource, with available schematics and
firmware, so they can be modded to the limits of your RF and FPGA skills,
for any desired purpose. For the non-Amerians, there are also no hassles
with US export paperwork as this equipment is too generic for that and the
magic is only in fairly uncontrollable software. Which itself can be
fairly generic and downloadable internationally; see the Crypto Wars era.
This also has the potential of significantly simplifying traveling; the
low cost of the specialized hardware as a bonus lowers the risk of losing
the equipment to "natural causes" damage, aka baggage handlers.
The low cost of some of the units allows leaving a multiple of them at the
target premises, leisurely scanning the spectrum with patience of a zen
spider and and automagically looking for threats.
I believe the future of the trade will go this way, of the marriage of
computers, fast ADCs and RF frontends. (Correct me please if I am wrong.)
But no development is only good. There is the Internet Of Things spectre
looming above our heads (oh the good old times when it was just lurking
above the horizon...). Increasingly the spectrum is swamped with toys and
gadgets singing and shrieking their messages; the times when an active
transmitter was something out of ordinary are long gone, now even a light
switch can be expected to have one. And everything is "smart". For some
purposes it is good, but the threat environment becomes rather
"target-rich". And more threat models are emerging, as with some devices a
mere software modification can be the only difference between a friend and
a foe; the best screwdriver and mirror and portable xray machine won't
show you that there is a problem. With the security (or lack of, when did
you update the firmware in your printer server adapter?) characteristic
for embedded computers, gaining and leveraging the necessary access does
not seem to be a significant problem for the adversaries.
Thoughts, opinions, comments, usage scenarios?
Received on Sat Mar 02 2024 - 00:57:23 CST