[aprssig] HackRF as SDR for ham use?

John Gorkos jgorkos at gmail.com
Sat Aug 2 23:19:52 CDT 2014


So, the max rx bandwidth on the HackRF is 20Mhz, or 20MSps delivered via
USB.  Since an 802.11b or g channel is 20Mhz, you can pull that off.
The N channels are 40MHz wide and the AC channels are (I think) up to
80Mhz+, so those are outside the capability.  The limiting factor (to my
knowledge) is the bandwidth of the USB connection.  There are several
scripts out there to incrementally snapshot fairly large swaths of
spectrum (i.e. sample 20MHz for 10 seconds, FFT, write to disk, move up
20Mhz, repeat ad nauseum).  Doing that, you get a pretty good picture of
regular, repeating signals fairly quickly.
Many of my classmates are interested in either bluetooth work, or
Z-Wave, and probably some Zigbee stuff in there.  This thing can even
decode ATSC OTA signals in real time.

Gqrx is a pretty slick piece of software that's cross platform, and SDR#
is supposedly the cat's meow in the Windows world.  Since I haven't run
Windows since Windows ME, I can't really comment on that.
The in-class exercise that we're working on is intercepting, decoding,
and eventually spoofing an RF-based PC security system that uses
low-powered 905 MHz transmitters to tell a USB device plugged into a
workstation when an authorized user is in the vicinity.  I suspect there
are some other cool exercises that Mike has up his sleeve for later on.
 Again, I'll have a full report tomorrow night.  Right now, I'm 3 hours
off between clock time and body-clock time, two beers in, and full of
steak.  I'm probably not spelling half the words in this email
correctly... :)

John Gorkos
AB0OO



On 8/3/14, 12:00 AM, Greg D wrote:
> Hi John,
> 
> Non-Ham related question...  Professionally, I work in the Wi-Fi area,
> and was also interested in being able to use the HackRF for capturing
> and decoding Wi-Fi traffic, as well as getting a better look at the RF
> environment (spectrum analysis).  Can this be done with the available
> (free) software?
> 
> Sounds like a really interesting and fun conference!
> 
> Greg KO6TH
> 
> 
> John Gorkos wrote:
>> I'm at BlackHat right now, and just finished the first day of classes,
>> hands on, with Michael Ossmann and the HackRF.  I've barely had any time
>> with it at all.  It has extremely low transmit power, and is classified
>> as "test equipment" to avoid all of the FCC legalities for type
>> certification.  I can tell you I've gotten 20MHz of bandwidth samples
>> out of it, into a Linux VM on my MacBook pro, and it seems to be pretty
>> slick.  Tomorrow will be more hands on with the device, and a LOT of
>> time in GnuRadio.  Obviously, based on the fact that we're at BlackHat,
>> most of the concentration is on security and penetration.  Things like
>> finding unknown signal types in a very large chunk of spectrum, then
>> locating and identifying those signals.
>>
>> BTW, Michael is a real genius at explaining SDR techniques and the math
>> behind them.  At the beginning of the class, he passed out little green
>> plastic slinkys with his company logo on them.  Today, about halfway
>> through the afternoon session, he used the slinkys to explain how a sine
>> wave and cosine wave look the same, depending on whether you're looking
>> at them from the imaginary or real number point of view, and that the
>> slinky represents the longitudinal axis of time extending out of the
>> paper, as you plot complex numbers on a two axis system.  Freaking
>> brilliant.   If you ever get the opportunity to go to one of his
>> classes, you'd be a fool to decline.
>>
>> I'll try to provide more info about the device tomorrow.  I'm mentally
>> and physically drained after a day of complex math.
>>
>> John Gorkos
>> AB0OO
>>
>>
>> On 8/2/14, 6:13 PM, Greg D wrote:
>>> Hi folks,
>>>
>>> I see there's a new SDR receiver being built for the "hacker"
>>> community:  http://hakshop.myshopify.com/products/hackrf
>>>
>>> They claim it's compatible with SDR#, so I wonder how well it will work
>>> for the variety of digital ham radio purposes?  It's a little pricy, but
>>> claims to cover 10mhz to 6 ghz, so that would cover through our
>>> 5.65-5.925ghz allocation.  I don't know what the bandwidth is.
>>>
>>> Useful?
>>>
>>> Thanks,
>>>
>>> Greg  KO6TH
>>>
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