[Hackrf-dev] Sensitivity

[indy747 at gmail.com]

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.
>> _______________________________________________
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