Intercept receivers (was Re: Hackers Remotely Kill a Jeep on the Highway)
-------- Original Message -------- From: Peter Gutmann <pgut001@cs.auckland.ac.nz> Apparently from: cypherpunks-bounces@cpunks.org To: jdb10987@yahoo.com Cc: cypherpunks@cpunks.org Subject: Re: Hackers Remotely Kill a Jeep on the Highway Date: Sun, 26 Jul 2015 21:42:14 +1200
jim bell <jdb10987@yahoo.com> writes:
There are some rather economical spectrum analyzers being sold today.
You have to be careful with those, the straight USB-dongle ones are going to be SDR-based, typically the RTL820T meant for DVB-T use (and re-purposed by half the hacking world for all manner of other things), then you have the USB- interface ones with more powerful SDRs, and finally you've got purpose-build spectrum analysers. Compared to the real thing, you're going to run into severely limited bandwidth (anything that spreads the signal across a wide spectrum is going to be difficult to impossible to deal with), and not-so- spectacular signal handling (there's a reason why the real thing costs thousands of dollars).
That's not to say that they're no good, just that you need to be aware that you're getting what you pay for. If you've got a specific purpose in mind, check first that whatever you're getting will be able to do the job. There's quite a bit of material out there on this, google something like "sdr spectrum analyzer" to find articles on it.
Peter.
Achieving receivers and spectrum analyzers with wide frequency coverage, high dynamic range and wide bandwidths (with very low noise circuitry, stable local oscillators, etc.) simultaneiously has, up till recently, demanded very high prices. That's why few outside of governments, corporations and well-funded professionals could afford them. However, with the rapid growth and falling prices of SDR this has and is changing. For example, Ettus' USRPs, covering VHF to 6 GHz or so, starting under $1000, that not long ago were in the $10,000s. The HackRF (which some have complained is little more than an IF strip) effectively covering down to below 10 Mhz is only $300 (though its performance, due to only 8-bit ADC, is not in the same league as the 16-bit USRPs). If some hardware hacker were to deliver a 14-16 bit ADC daughter board (there are afforadble chips offering up to 60M samples/sec) for the HackRF (it is provisioned to accept one) it could substantially improve its use. WW
wirelesswarrior@Safe-mail.net <wirelesswarrior@Safe-mail.net> writes:
For example, Ettus' USRPs, covering VHF to 6 GHz or so, starting under $1000, that not long ago were in the $10,000s. The HackRF (which some have complained is little more than an IF strip) effectively covering down to below 10 Mhz is only $300 (though its performance, due to only 8-bit ADC, is not in the same league as the 16-bit USRPs). If some hardware hacker were to deliver a 14-16 bit ADC daughter board (there are afforadble chips offering up to 60M samples/sec) for the HackRF (it is provisioned to accept one) it could substantially improve its use.
The problem with the HackRF (and other USB-based devices) is the bandwidth of the USB connection, it's not that the HackRF hardware can't handle it, it's that you can't get that much data to the PC. (I have a HackRF - I needed a cheap way to track down some odd RFI issues - and it's a pretty cool piece of hardware for the money, but, as I mentioned earlier, you do get what you're paying for. If I could make a wishlist, it'd be nice to have a rev.2 with some work done on the front- end...). Peter.
From: Peter Gutmann <pgut001@cs.auckland.ac.nz> wirelesswarrior@Safe-mail.net <wirelesswarrior@Safe-mail.net> writes:
For example, Ettus' USRPs, covering VHF to 6 GHz or so, starting under $1000, .>>that not long ago were in the $10,000s. The HackRF (which some have complained is little more than an IF strip) effectively covering down to below 10 Mhz is only $300 (though its performance, due to only 8-bit ADC, is not in the same league as the 16-bit USRPs). If some hardware hacker were to deliver a 14-16 bit ADC daughter board (there are afforadble chips offering up to 60M samples/sec) for the HackRF (it is provisioned to accept one) it could substantially improve its use.
The problem with the HackRF (and other USB-based devices) is the bandwidth of the USB connection, it's not that the HackRF hardware can't handle it, it's that you can't get that much data to the PC.
(I have a HackRF - I needed a cheap way to track down some odd RFI issues - and it's a pretty cool piece of hardware for the money, but, as I mentioned earlier, you do get what you're paying for. If I could make a wishlist, it'd be nice to have a rev.2 with some work done on the front- end...).
Here's my idea for a probe for an RF device. The wavelength of a 2.45 GHz signal (WiFi) is about 12 cm. A quarter-wave antenna would be 3 cm. Or, that 3 cm could be in the form of a loop, at the end of a piece of.'hardline', or other coaxial cable. (hardline would be best, I think, because it is a small diameter. ) https://en.wikipedia.org/wiki/Coaxial_cable So, the diameter of the loop would be a bit more than 1 cm diameter, which is appropriate for finding tiny RF sources. One side of the loop would be connected to the center conductor of the coax, and the other side of the loop connected to the shield of the coax. Note: The coax should probably have many dissipative RF beads strung along its length, in order to prevent the cable itself from picking up RF, and delivering to the loop on the end, thereby to be detected. http://www.amidoncorp.com/small-ferrite-beads/ There are many different kinds of materials that such beads are made from; perhaps we can have an RF engineer chime in on the subject. He can also tell us if the loop is too-badly mismatched (RF impedence) to the coax to function well. Jim Bell
From: jim bell <jdb10987@yahoo.com> From: Peter Gutmann <pgut001@cs.auckland.ac.nz> wirelesswarrior@Safe-mail.net <wirelesswarrior@Safe-mail.net> writes:
For example, Ettus' USRPs, covering VHF to 6 GHz or so, starting under $1000, .>>that not long ago were in the $10,000s. The HackRF (which some have complained is little more than an IF strip) effectively covering down to below 10 Mhz is only $300 (though its performance, due to only 8-bit ADC, is not in the same league as the 16-bit USRPs). If some hardware hacker were to deliver a 14-16 bit ADC daughter board (there are afforadble chips offering up to 60M samples/sec) for the HackRF (it is provisioned to accept one) it could substantially improve its use.
The problem with the HackRF (and other USB-based devices) is the bandwidth of the USB connection, it's not that the HackRF hardware can't handle it, it's that you can't get that much data to the PC.
(I have a HackRF - I needed a cheap way to track down some odd RFI issues - and it's a pretty cool piece of hardware for the money, but, as I mentioned earlier, you do get what you're paying for. If I could make a wishlist, it'd be nice to have a rev.2 with some work done on the front- end...). Do you know anything about this model: http://www.triarchytech.com/index.html 4, 6, 8, and 12 GHz units. Jim Bell
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