It is a piece of cake to grab the entire 200 to 425 MHz chunk of the
spectrum and mathematically extract a covert transmission even if the
signal is hopping all over the place or is using Direct Sequence modulation.
-jma
At 04:51 PM 5/11/2007, coderman wrote:
>i've intended to write this for a little while. intrigued both by
>JMA's desire for more automation in spectrum sweeps and Kondrak's cost
>estimate for flexible wideband gear.
>
>not long ago it used to be exceedingly expensive to inspect and
>process RF spectrum in detail, and the tools for such were both
>cumbersome and limited.
>
>i've been watching this trend change drastically over the last half
>decade, fueled by a combination of pervasive high speed digital
>networks and the DSP workhorses they require (OFDM is a computational
>pig), and the general surge in interest around wireless communications
>for commodity / broadband use.
>
>to address the cost issue of intercepting and processing FHSS/DSSS in
>the 900Mhz band, let me simply point to the GNU Radio USRP [0]. the
>cost has gone up a bit from the original prototypes, but ~$600 for the
>board and 900Mhz front ends is fairly cheap. this can intercept and
>process FHSS/DSSS phone conversations with ease. #include
><std_disclaimer> : THIS IS ILLEGAL FOR YOU TO DO IN MOST SITUATIONS.
>
>moving on toward the few thousand dollar price point you get to
>nallatech gear, like their Virtex-4 Quad ADC unit [1] which combines
>an FPGA for signal processing with FOUR very high rate 12-bit 250MSPS
>ADC on board. you can get these boards on PCI/PCI-X [2] motherboards
>for easy integration into a host system.
>
>given the hardware above, GNU Radio and OpenCores.org [3] fill much of
>the remaining work to utilize these systems for various purposes.
>while a lot of this is "roll your own", it seems likely that the
>market for integrated solutions built with flexible software defined
>radios, and commodity signal processing components will be large.
>(how much would you pay for an RF sweep unit that used a number of the
>nallatech boards to scan in parallel what used to take dozens of
>iterative setup/inspect/teardown steps? and had the software smarts to
>discern irrelevant signals and highlight suspicious ones?)
>
>i believe this will have some interesting and profound implications,
>with hints of some of what is to come reflected in the open GSM
>project and 802.11 work in GNU Radio.
>
>a few years back active GSM interception and man-in-the-middle would
>cost $50,000 in hardware. this price point is now down to a few
>thousand dollars. it won't be long until effective privacy over
>wireless (be it cordless phones, cell phones, wifi voip phones, etc)
>requires strong ciphers and no less. some might argue we're at that
>point already.
>
>best regards,
>
>0. GNU Radio Universal Software Radio Peripheral
> http://www.comsec.com/wiki?UniversalSoftwareRadioPeripheral
>
>1. Nallatech Virtex-4 Quad ADC DIME-II Module
> http://www.nallatech.com/?node_id=1.2.2&id=31
>
>2. PCI FPGA Computing Card w DIME Slot
> http://www.nallatech.com/?node_id=1.2.2&id=6&tab=2
>
>3. Open Cores Categories (see DSP, ECC, etc)
> http://www.opencores.org/browse.cgi/by_category
>
>
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Received on Sat Mar 02 2024 - 00:57:16 CST