[Hackrf-dev] Problem with RF amplifier at UHF

[Ben Greenfield]

> On Dec 6, 2015, at 3:34 AM, MA <mehdideveloper at gmail.com> wrote:
> 
> Hi Michael.
> He (and another user) have managed to run that code successfully with HackRF.
> The number 40 is a measurement of GPS signal strength by a common software we both use on Android ("AndroiTS GPS Test").
> The common things we use: Android OS(different versions) and that GPS app, ANT500 antenna, the code itself and HackRF One.
> Does the firmware affect this? (The author uses HackRF board r2-p1 with 2014.08.1 and that user uses 2015.07.2 version)

Yes. Each difference is a variation more variation more variable answers.

Once everything is the same it sounds like everything maybe within tolerances,

Ben

> 
> Mehdi
> 
> 
> On Sat, Dec 5, 2015 at 6:09 PM, Michael Ossmann <mike at ossmann.com <mailto:mike at ossmann.com>> wrote:
> On Sat, Dec 05, 2015 at 05:15:42PM +0330, MA wrote:
> >
> > Update: I think my HackRF is not faulty; I created a simple FM
> > transmitter with GNU Radio and set the frequency to 2.0GHZ; But I
> > think it may have a drift/offset problem, because on another SDR
> > (receiver), I get that FM on about 14KHZ further !! (on 2.000.014.000
> > HZ)
> 
> 14 kHz offset at 2 GHz is 7 parts per million.  That is well within the
> expected range.  The crystal on HackRF One is specified to have clock
> stability of +/- 20 parts per million.
> 
> However, your other SDR receiver isn't perfect either, so it may be
> adding to or subtracting from the apparent clock offset of the HackRF
> One.
> 
> HackRF One has a clock input that can be used if you would like to
> synchronize it to a more stable clock source.
> 
> > > He uses a 20dB attenuator at the output (with ANT500) and the signal
> > > strength on his Android GPS diagnostics app is about 40.
> > > I don't use an attenuator and still my signal strength rarely reaches 30 !
> 
> What unit of measurement is that?  Are you and he using the same Android
> hardware and software version?  Was he using a HackRF One with the same
> software/firmware version and configuration as yours?
> 
> Mike
> 
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