On 04/18/2016 07:12 AM, O.T. Powell wrote: > > Thank you both for the great responses. I have a 1090 ADS-B > bandpass filter as well as an LNA.
I'd recommend buying a variable attenuator and a couple of 1,3 and 6 dB fixed attenuators and experimenting with the external LNA on a rtl dongle. And you should figure out how much power it takes to smoke the LNA inside the rtl dongle. > 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 <[email protected] > <mailto:[email protected]>> > To: [email protected] > <mailto:[email protected]> > > > 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 Powell > EE Engineering Tech > M: 386.299.6991 <tel:386.299.6991> > [email protected] > * > * > * > > > _______________________________________________ > HackRF-dev mailing list > [email protected] > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > _______________________________________________ HackRF-dev mailing list [email protected] https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
