Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does not?

[Simon Kennedy]

Just a thought but why don't you install gqrx? Then you can see the HackRF
in action and experiment with the settings before diving into gnuradio.

Simon.

On 9 Nov 2016 8:06 pm, "David Hubbard" 
wrote:

> Just to follow up with a final note, this is now the waterfall plot I am
> receiving: lots of interesting digital signals, I added a DC blocker, and I
> can still "sort of" hear the ham radio transmissions.
>
> Thanks for the help!
>
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Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does not?

[David Hubbard]

On Wed, Nov 9, 2016 at 6:51 AM, Gavin Jacobs 
wrote:

> The hackrf is MUCH less sensitive than a typical handheld. If you are
> using the vertical antenna that came with the hackrf, then you will have
> trouble receiving any ham transmissions. I had the same experience as you,
> so here are some tips that got me going:
>
> - calculate the 1/4 wavelength and set the telescoping antenna to that
> length
>
> - put the antenna (and the hackrf unless you have some appropriate rf
> cable) high in the room
>
> - increase the if_gain to 40; use a QT GUI slider to decrease it once you
> acquire a signal
>
> - set the center frequency to an even multiple of MHz; then set your
> offset to hit the desired channel
>
> It takes some patience, but eventually you will get the frequency visible
> on the chart.
>
> Also, be careful not to hit PTT on your handheld, at any time, at any
> frequency, in the vicinity of the hackrf; any moderately strong rf can
> damage the front end of the hackrf. So, I suggest starting with the APRS
> frequency (in North America 144.39 MHz); you get steady traffic, you can
> hear it on your handheld, but you don't have to transmit anything.
>
>
> Unfortunately, my flowgraphs are 2000 km away right now, but we can
> probably help you get going.
>
>
Thanks, Jake! Setting the IF gain higher did the trick. I do see that my
handheld ham radio is more sensitive, but I can receive the audio signal on
the HackRF, with a signal quality that is only clear enough to know there
are voices. (I cannot hear well enough to tell what is being said.)
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Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does not?

[David Hubbard]

On Wed, Nov 9, 2016 at 9:00 AM, Silverfox  wrote:

> Some antennas do not make a solid connection with the hackrf.  Try a short
> piece of wire in the center connector.
>
> Good luck,
>
> Alan – W5ARH
>
>
>

Hi Chuck, Alan, I'm using the included vertical antenna. Thanks for the
tip, I double checked I had it attached right and that the center connector
was making good contact.

It's easy to double-check by doing FM radio reception too.

David
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Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does not?

[Chuck McManis]

Just to check off the obvious question, you are sure the antennae is the
right sex right?

On Nov 9, 2016 6:23 AM, "David Hubbard" 
wrote:

> On Wed, Nov 9, 2016 at 6:10 AM, John Ostrander  wrote:
>
>> David,
>>
>> You're likely receiving it, but 70cm is nbfm not wbfm so you're probably
>> getting loads of noise around the signal you're trying to get at. Try a
>> flowgraph like the one attached, but with the osmocom source of course.
>>
>> regards,
>>
>>
> Thanks, John! I ran your flowgraph tuned to 443.000 and looked for a
> 443.700 signal that was coming in at S9 on my handheld ham radio.
>
> I have attached the flowgraph with my modifications and the screenshot. I
> believe there's no signal. What do you think?
>
>
>
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