[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 <apriljunkbox at hotmail.com>
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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