[Hackrf-dev] Is my new (old) HackRF Deaf?

Tue Jul 11 03:43:43 EDT 2017

Oops, should say centered at 100Mhz*

On Jul 11, 2017 3:41 AM, "Anon Lister" <listeranon at gmail.com> wrote:

> Hey,
>
> So, a little DSP background.
> ------
>
> Keep in mind pretty much all the SDRs now output complex (I/Q) /
> Quadrature samples. This means two things. Nyqust BW = Sample Rate, and
> everything is centered at 0 frequency digitally. Basically, where you would
> think of a bandwidth control before, use sample rate now. Bandwidth usually
> refers to a filter applied to the sample_rate (remember, bandwidth=sample
> rate) sized chunk of spectrum.
>
> The SDR takes that original spectrum (10M of complex bandwidth centered at
> 90Mhz in your case, down converts it to baseband, and sends it to the PC.
> GR is plotting [-5M, 5M] (but helpfully overlaying the original tuned
> frequency for you, since you have told it where that is in the QT GUI sink.)
>
> Also, unlike your (probably) superhet recievers, most SDR devices,
> including the hackrf are direct conversion. This type of receive has a
> couple drawbacks over the superhet ones. (There are pros too usually
> size/weight/power/cost.) One con is DC leakage. That is the bigger spike
> you see at the center. You can avoid it by offset tuning. I think the ham
> folks would call this a VFO. Basically it, in software, will take the
> spectrum from a point not at 0, shift it down to 0, and bandpass filter it.
> Then do the FM/AM/ec demod. (You can also simply overpower the spike with
> your carrier, if possible, but the hackrf has a rather large amount of
> leakage vs others so it's not always practical, and it would need to be at
> the antenna power, not post digitization.)
>
> If you insist on using Windows I think SDRConsole might work a bit better
> for you, and is probably setup to be a little more friendly to someone
> coming into the SDR thing from a ham background or someone who is not very
> used to a Linux environment. However setting it up requires using zadig,
> but if you got it working with sdr#, it should already be setup. Also I'll
> say if you want to do hammy things, like receive AM, N/WB FM, SSB, etc.
> these software packages are what your looking for, not something like
> gnuradio. They usually have the point and click VFO/offset tuning setup, so
> you pick you modulation, click on the center, drag the box or enter the
> bandwidth you want for the demod, and you get data. Gnuradio is more akin
> to a box of wires, components, and tools you will need if you want to build
> your own radio, and many pages of manuals for each independent piece. Its
> an awesome tool if you want to experiment with building different kinds of
> radios, perhaps a bit overkill or a bit much if you just want to use one.
> (At least till you get your feet wet in the SDR world, and start thinking,
> man wouldn't it be cool if sdr#/SDRConsole/gqrx could do XYZ, and then
> realize GR provides you the tools to do just that.)
>
> I'll also mention there is a Pentoo live USB stick image you can download
> and boot into with all the drivers and such ready to go for a Linux setup.
> Just plug it in and boot off it. If you do try this the best (imho) Linux
> version of the SDR#/SDRConsole radio receiver app flavor, is gqrx, which
> should come on the Pentoo image by default.
>
> If you do keep playing with GR, you should sign up for the
> discuss-gnuradio mailing list which is very active, and can help with some
> of your gnuradio questions.
>
> ----
> So for your current setup:
>
> BW will control the digital bandpass filter on the hackrf. It will not do
> what you want. Try setting that equal to the sample rate(samp_rate by
> default), and changing the sample rate to something like 4M. From your FFT
> it looks like you have possibly two weakish FM carriers visible, but your
> bandpass is set to only a meg or two, so you might be missing some on the
> side, that are higher power.
>
> You'll need to adjust the gain sliders. The help documentation(or see [1])
> should describe what they mean for the hackrf, of which there are three.
> "RF gain" is a toggle for the rf amp. Leave this one off/0. The other two,
> the bb and if gain I believe, you can play with, setting both to about 16
> should be ok to start, however I find setting the if gain to 32 and the bb
> to about 4 seems to work better for me.
>
>
> [1]https://www.reddit.com/r/hackrf/comments/49aa2i/using_
> gain_controls_with_osmocom_sourcesink_in/
>
> -Anon
>
> On Jul 11, 2017 12:36 AM, "Jerry" <jsternmd at att.net> wrote:
>
>> Jake
>>
>>
>>
>> Thanks for the sound advice.  I have had spectrum analyzers and learned
>> early to be careful with nearby RF sources ☹
>>
>>
>>
>> Right now I am getting a wide confluence of signals between 98.5 and
>> 101.5 on the FFT.  If it were my SA I would narrow the bandwidth to improve
>> the signal resolution but on the Osmocom Source changing Ch0 Bandwidth from
>> 10 Hz to 500 Hz doesn’t appear to change the FFT display noticeably.
>>
>>
>>
>> Attached is a picture.
>>
>>
>>
>> Jerry NY2KW
>>
>>
>>
>>
>>
>> *From:* HackRF-dev [mailto:hackrf-dev-bounces at greatscottgadgets.com] *On
>> Behalf Of *Gavin Jacobs
>> *Sent:* Monday, July 10, 2017 6:22 PM
>> *To:* hackrf-dev at greatscottgadgets.com
>> *Subject:* Re: [Hackrf-dev] Is my new (old) HackRF Deaf?
>>
>>
>>
>> Jerry,
>>
>> Learning how to use Ubuntu, and Gnu, and HackRF is a challenge! I went
>> down that path about a year ago. The issue you describe hits every new
>> user. When you are running GNU radio, you have to turn up the IF gain to
>> about 40 - it defaults to 0. Also, turn up the BaseBand gain to about 30.
>> Leave the RF gain at 0 (that setting is confusing; a value of 0 just means
>> the RF LNA is left off; 14 means it is on; but you rarely need it on).
>>
>>
>>
>> Also, a word of caution. Since you are a ham, you likely have an HT or a
>> base station. You have to take care to never exceed the maximum field
>> strength anywhere near the HackRF. I don't recall the exact spec, but
>> basically if you transmit with a 5 Watt HT, right next to HackRF, you can
>> fry the RF front end.
>>
>>
>>
>> Hope that helps.
>>
>> Jake
>>
>>
>> ------------------------------
>>
>> *From:* HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com> on behalf
>> of Jerry Stern <jsternmd at att.net>
>> *Sent:* July 10, 2017 2:54:16 PM
>> *To:* hackrf-dev at greatscottgadgets.com
>> *Subject:* [Hackrf-dev] Is my new (old) HackRF Deaf?
>>
>>
>>
>> Is my HackRF deaf?  I am a ham radio hobbyist and I bought a HackRF One
>> to enhance my deeper learning of SDR but also as a broadband RF source.  To
>> my dismay, installing the software has become days of learning Ubuntu
>> basics and dealing with instructions that are at times outdated or nuanced
>> towards a person with much more than basic Linux skills.  So, I gave up on
>> Ubuntu only because it was faster for me to install and test with Windows
>> 7.   My HackRF One (GreatScott) must have been a leftover as the firmware
>> was dated 2014(August).  I installed the latest version HackRF tools and
>> updated the firmware to Feb 2017.  I followed Mike's video tutorial for
>> creating a basic GNU flow for FM and also installed SDR#.  I have very
>> strong FM broadcast stations in my area which I can easily demodulate with
>> my Rigol Spectrum analyzer using the ANT500. However both with GNU and SDR#
>> my HackRF appears deaf in FM broadcast mode.  I read that a few years back
>> there may have been some issues with cold solder joints on the HackRF
>> pcb....  I have a lot of test equipment - from RF generators up to 2 GHz,
>> etc but before I go that route is there something I am perhaps missing in
>> my setup.  Not sure where or what details to provide here without
>> overloading my question further .
>>
>>
>>
>> Thanks
>>
>>
>>
>> Jerry
>>
>>
>>
>>
>> Sent from my iPhone
>>
>> _______________________________________________
>> HackRF-dev mailing list
>> HackRF-dev at greatscottgadgets.com
>> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>>
>>
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