[Hackrf-dev] Sensitivity

[Michael Ossmann]

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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