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]] 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]> 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 list [email protected] https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
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