There are also multiple gain settings for the HackRF. I'm not sure what the gain settings are for an RTL device, but I believe both the rtl and the tuner have their own gain settings as well.
Keep in mind that there are engineering tradeoffs when designing any device. The HackRF is designed to be a low-cost TX/RX SDR peripheral with a large frequency range and high bandwidth. RTL devices are RX-only, have a smaller frequency range, and significantly less bandwidth. On Mon, Jan 19, 2015 at 12:51 PM, Paul Connolly <[email protected]> wrote: > As the sample rate increases, so does the the noise floor. Or with more > bandwidth comes more noise. So giving the numbers without the sample rates > used is not useful. In SDR# for the HackRF you can type in a sample rate in > the sample rate pull down box, try using 2 MSPS. And for the RTL2832 try > dropping the sample rate to 0.25MHz. And repeat your experiment again. > > > On 19/01/2015 20:25, Stephen wrote: > > Hi Tom, > > > > Thanks for the reply. > > > > The RX sensitivity figure I quoted is dBm – ‘Decibels above a MilliWatt’. > -95dBm is 95 db below a MilliWatt, wheras -127dBm is 127 db below a MilliWatt. > > This test was conducted with an RF signal generator. > > > > Regarding the test, to register minimum scale on the SDR# spectrum, the > HackRF required -95dBm , the RTL2832 required only -127dBm. > > > > Expressing this as microvolts instead of dBm, the equivalent level in > microvolts (to register the same scale on SDR#) are: > > > > 0.1uV for the RTL2832 > > 3.5uV for the hack RF > > > > Accordingly, The HackRF requires considerably more signal to register the > same scale on SDR#. > > > > I discovered this performance limitation when I attempted to try to receive > NOAA weather satellites, I found HackRF barely registered, wheras the RTL2832 > registered a strong signal for the same satellite pass on the same antenna. > > > > I appreciate you are trying to help & I don’t mean to be rude by > contradicting you, but the HackRF I have is definitely ‘deaf’. > > > > Regards, > > Stephen > > > > > > From: Tom Buelens [mailto:[email protected] <[email protected]>] > Sent: Monday, 19 January 2015 8:23 PM > To: Stephen > Subject: Re: [Hackrf-dev] deaf HackRF > > > > Hi Stephen, > > > > > > I might be mistaken but I actually think the numbers you mention show that > the HackRF is better at receiving the signal. > > You see, an attenuation of -105 dBm is resulting in a smaller signal then > -69dBm. Please also see here: > http://en.wikipedia.org/wiki/DBm > > > > > > Cheers, > > Tom > > > > On Mon, Jan 19, 2015 at 2:36 AM, Stephen <[email protected]> > <[email protected]> wrote: > > Hi, > > Ive just bought a HackRF, but I have found RF performance is poor. Compared > to a $12 USB RTL2832 SDR, it is deaf by about 32-36dB. > > > > The tests were done with an HP 8922 test set & an unmodulated carrier at > 137.5MHz. The test was the generated RF signal required for both devices to > achieve the same scale level in SDR#. > > > > RTL SDR HackRF Difference > > Scale1 -127dBm -95dBm 32dB > > Scale2 -115dBm -79dBm 36dB > > Scale3 -105dBm -69dBm 36dB > > > > > > The tests were done with max gain on both devices, but with the HackRF AMP > off. > > > > I have seen from posts that others have had this problem – related soldering > of RF switches in the manufacturing process. > > Can anyone provide further details on the fix or suggest a resolution please? > > > > > > Thanks, > > > > Stephen > > > > > > > > > _______________________________________________ > HackRF-dev mailing > [email protected]https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > > > > > > _______________________________________________ > HackRF-dev mailing > [email protected]https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > > > > _______________________________________________ > HackRF-dev mailing list > [email protected] > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > >
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