[Hackrf-dev] Sensitivity

[Paul Jones]

Is there any easy way to check for defective units? I bought a pair of units from the kickstarter which I suspect might have the same problem. Using every and any antenna I've got I can barely pick up fm radio. I live in the suburbs of Sydney so there are plenty of stations around, but the only one I get any sort of reception on is 96.1, which is the strongest. (I'll take a screenshot when I get my laptop, just to check the gain settings are right). I've also tried scanning GSM frequencies but can't see anything unless I make a call on my phone. Wifi I can just make out above the noise.
Is there anything to look for on the PCB that could be reflowed? I've got all the stuff to do everything except BGA.

Paul.

> -----Original Message-----
> From: HackRF-dev [mailto:hackrf-dev-bounces at greatscottgadgets.com] On
> Behalf Of Michael Ossmann
> Sent: Saturday, 24 January 2015 9:24 AM
> To: indy747 at gmail.com
> Cc: hackrf-dev at greatscottgadgets.com
> Subject: Re: [Hackrf-dev] Sensitivity
> 
> I apologize for the lack of response.  I will get a replacement to you right
> away.  Please reply off-list to confirm your shipping address.
> 
> Mike
> 
> 
> On Fri, Jan 23, 2015 at 02:29:05PM -0700, indy747 at gmail.com wrote:
> >
> > Mike,
> >
> > When are you going to respond to those of us who received defective
> > units?  I have sent you a number of emails, and posts here as well,
> > and you have yet to respond.  What's the deal?  Please respond with
> > RMA instructions.
> >
> > On 1/23/2015 2:24 PM, Michael Ossmann wrote:
> > > Could you please share the details of your noise figure test method?
> > >
> > > Thanks,
> > >
> > > Mike
> > >
> > >
> > > On Thu, Jan 22, 2015 at 09:37:10AM +0100, JMG wrote:
> > >> Sensitivity measurements
> > >>
> > >> Test results for the noise figure NF of the HackRF, obtained at a
> > >> frequency of 435MHz:
> > >>
> > >> NF = 22dB               LNA=OFF
> > >> NF = 10.8dB           LNA=ON
> > >> NF =   1.1dB           LNA=ON, additional external LNA  "LNA4ALL"
> > >>
> > >> RTL-SDR, tuner 820T or 820T2
> > >> NF = 3.7dB
> > >>
> > >> The HackRF really is extremely "deaf" when the internal
> > >> preamplifier is turned off. Turning it on and installing a good
> > >> external amplifier brings NF down to a very good value.
> > >> Applying so much gain at the preamplifiers in front of the mixer
> > >> will degrade the intermodulation properties.
> > >> Adding an external LNA will block the transmitter path to the antenna.
> > >>
> > >> The noise figure is the fundamental parameter to specify the
> > >> sensitivity of a receiver. All the other, more common, sensitivity
> > >> specifications can be derived from it. For example NF=3dB will give
> > >> an input sensitivity of S=-174dBm+NF+48dB=-123dBm for typical NBFM
> > >> signal. The factor "48dB"
> > >> somewhat depends on the test parameters.
> > >> _______________________________________________
> > >> HackRF-dev mailing list
> > >> HackRF-dev at greatscottgadgets.com
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> > > _______________________________________________
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> >
> >
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