Intercept receivers (was Re: Hackers Remotely Kill a Jeep on the Highway)

-------- Original Message -------- From: Peter Gutmann 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 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