[Hackrf-dev] HackRF-dev - Response to Cinead & Douglas McDonald from O.T. Powell

[O.T. Powell]

>
>
> ​Thank you both for the great responses.  I have a 1090 ADS-B bandpass
> filter as well as an LNA.  I am looking into buying an adjustable bandpass
> filter, or I'm sure I can make an RLC circuit that serves the same
> purpose.  As for an external amplifier, is the LNA the same thing?  Does it
> amplify transmitted signals as well?    I am using SDR# right now, but I'm
> also going to try Skywave Linux and the SDR package in Kali Linux.  I
> already have them setup I just have to plug in my HackRF and start testing.
>
​
In regard to the full metal shield, I just bought the HackRF shield from
NooElec.  Is this what you are talking about?  I am going to install that
this week.  I also have an aluminum box coming, but was not planning on
putting my hackRF in the aluminum box because I read that if you have the
shield, adding the aluminum box does not add any extra shielding.  Do you
guys think that information is accurate?  Should I add the sheild and then
enclose the whole thing in an aluminum box?

Can you reccommend any bandpass filters or external amplifiers that aren't
too expensive?

I'm not sure what my sample rate or bandwidth is.  I guess I'd want the
largest bandwidth which is 20MHz.  Sample rate, I usually go up as high as
I can while having everything run smoothly.

Thanks guys for being patient, I'm still learning.  Most of you sound like
RF guru's.  lol.





​
>
>
> Today's Topics:
>
>    1. Re: HackRF-dev Digest, Vol 42, Issue 10 (Cinaed Simson)
>
>
>
> From: Cinaed Simson <cinaed.simson at gmail.com>
> To: hackrf-dev at greatscottgadgets.com
>
>
> On 04/15/2016 06:15 AM, McDonald, J Douglas wrote:
> >
> > In my opinion the HackRF receive is fairly poor because of the conflation
> > of two things:
> >
> > only 8 bits
> >
> > inadequately steep frequency skirt filters
> >
>
> The HackRF doesn't have a front-end. Either buy a band pass filter or
> construct one using gnuradio.
>
> It's highly recommend to use an external band pass filter with an
> external amplifier.
>
> Also, you didn't indicate which software package you were using - the
> bandwidth or sampling rate.
>
> > This means there are spurious responses all over the place.
> > These are really really a nuisance.
> >
> > Also, the connections to the box are not well done: any serious RF
> device needs
> > a full metal shield with all connections bonded to the box, not sticking
> > through holes.
>
> See Michael Ossmann's tutorial on the HackRF
>
>   https://greatscottgadgets.com/sdr/
>
> >
> > On the short wave bands I can get a usable signal from my amplified
> > outside antenna by touching the shield of the RG6 coax to the input
> connector,
> > and the actual differential mode signal (center conductor versus shield)
> does not
> > fully swamp that.
>
> Isn't RG6 75 ohm cable? The HackRF unlike the RTL-SDR dongle is a 50 ohm
> device. It's not a big deal provided you already have a good impedance
> match with the antenna. If you reflect roughly 10 mW of power back at
> the HackRF, you'll smoke the RF amplifier on the HackRF - see the link
> above.
>
> Regarding the antenna problem, did you try a different antenna -
> preferably one which sees the same ground as your computer?
>
> In any case, nothing you described above has anything to do with the 8
> bit ADC.
>


-- 
*O.T. Timothy PowellEE Engineering TechM: 386.299.6991
<386.299.6991>otpowell at gmail.com*
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