[Hackrf-dev] HackRF-dev Digest, Vol 49, Issue 8

Dana Shtun ve3dss at hotmail.com
Thu Nov 10 16:28:10 EST 2016 

David - install GQRX receiver its very sensitive - I've worked 2 x contacts over 20 km at 3456 Mhz SSB with my Hack RF, and copied signals on 2304 Mhz (CW) from over 100 km,  but I've found the flow graph stuff to be much more finicky . Also you have to pay attention to the gain settings as if not set right then the Hack is deaf.

It is actually as sensitive as any handheld using the right software and decent antennas.


73 Dana VE3DS


________________________________
From: HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com> on behalf of hackrf-dev-request at greatscottgadgets.com <hackrf-dev-request at greatscottgadgets.com>
Sent: November 10, 2016 1:29 AM
To: hackrf-dev at greatscottgadgets.com
Subject: HackRF-dev Digest, Vol 49, Issue 8

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Today's Topics:

   1. FM 96.5MHz rx works but 70cm 441.1MHz rx does not? (David Hubbard)
   2. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (David Hubbard)
   3. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (Gavin Jacobs)
   4. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (Chuck McManis)
   5. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (David Hubbard)
   6. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (David Hubbard)
   7. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (David Hubbard)
   8. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (Simon Kennedy)
   9. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (Cinaed Simson)
  10. Re: FM 96.5MHz rx works but 70cm 441.1MHz rx does not?
      (David Hubbard)


----------------------------------------------------------------------

Message: 1
Date: Wed, 9 Nov 2016 05:56:39 -0800
From: David Hubbard <david.c.hubbard+hackrf at gmail.com>
To: hackrf-dev at greatscottgadgets.com
Subject: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does
        not?
Message-ID:
        <CAC-0EqhkEFvSKozmsZzJzs1SeXY0Qyv+gEM8f+v48HqAzYWRBw at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

I just purchased a HackRF, so there's a good chance I overlooked something.
I followed http://greatscottgadgets.com/sdr/1/ and am able to receive FM
Great Scott Gadgets - SDR with HackRF, Lesson 1, Welcome<http://greatscottgadgets.com/sdr/1/>
greatscottgadgets.com
25 August 2014: The original video encoding had some problems. I produced a new encoding so that iPad and Safari users can hear the sound. I also improved the audio ...



but not 70cm Ham Radio transmissions.

Here is how I tested it:

1. Received 96.5MHz fine on the HackRF. center_freq = 97.9e6,
channel_freq=96.5e6, channel_width=200e3, samp_rate=10e6

2. Tuned to 441.1MHz on a handheld ham radio close by, received ham
transmissions on it

3. Changed the flow graph center_freq to 440.0MHz and channel_freq to
441.1MHz, did not see any visible bumps in the FFT plot, and just a quiet
hiss on the audio.

4. Swapped antennas from the handheld ham radio and the HackRF. The ham
radio received transmissions at S9 with its antenna and S5 with the HackRF
antenna. But the HackRF did not receive anything with either antenna.

5. Swapped antennas back, double checked the ham radio was still receiving
transmissions.

6. Changed the flow graph center_freq back to 97.9e6, channel_freq back to
96.5e6, and double checked the HackRF could still receive 96.5MHz ok.

I can send the flow graph and a screen shot of the FFT but it's just the
flow graph from Lesson 1.

Cheers,
David
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Message: 2
Date: Wed, 9 Nov 2016 06:23:31 -0800
From: David Hubbard <david.c.hubbard+hackrf at gmail.com>
To: John Ostrander <john at crackroot.org>,
        hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CAC-0EqiQg92C8qetK9tCpFF=Q5TVG9Hhh8A6eP-Hm9AtkagURQ at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

On Wed, Nov 9, 2016 at 6:10 AM, John Ostrander <john at crackroot.org> 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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Message: 3
Date: Wed, 9 Nov 2016 14:51:47 +0000
From: Gavin Jacobs <apriljunkbox at hotmail.com>
To: "hackrf-dev at greatscottgadgets.com"
        <hackrf-dev at greatscottgadgets.com>
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <YQBPR01MB0099979A7E2A5A87E52662DEC6B90 at YQBPR01MB0099.CANPRD01.PROD.OUTLOOK.COM>

Content-Type: text/plain; charset="us-ascii"

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.


Jake





________________________________
From: HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com> on behalf of David Hubbard <david.c.hubbard+hackrf at gmail.com>
Sent: November 9, 2016 7:23:31 AM
To: John Ostrander; hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx does not?

On Wed, Nov 9, 2016 at 6:10 AM, John Ostrander <john at crackroot.org<mailto:john at crackroot.org>> 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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Message: 4
Date: Wed, 9 Nov 2016 07:41:43 -0800
From: Chuck McManis <chuck.mcmanis at gmail.com>
To: David Hubbard <david.c.hubbard+hackrf at gmail.com>
Cc: John Ostrander <john at crackroot.org>, Hackrf-dev
        <hackrf-dev at greatscottgadgets.com>
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CAHTjPiqKBAfpC2Zc5doqEb=uDkBnW9aegmAChVVefW4u_NXUAA at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

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" <david.c.hubbard+hackrf at gmail.com>
wrote:

> On Wed, Nov 9, 2016 at 6:10 AM, John Ostrander <john at crackroot.org> 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?
>
>
>
> _______________________________________________
> HackRF-dev mailing list
> HackRF-dev at greatscottgadgets.com
> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
HackRF-dev Info Page - pairlist9.pair.net<https://pairlist9.pair.net/mailman/listinfo/hackrf-dev>
pairlist9.pair.net
This is a discussion list for users and developers of HackRF from Great Scott Gadgets. This is the preferred place to ask questions about HackRF, get help with ...



>
>
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Message: 5
Date: Wed, 9 Nov 2016 09:52:57 -0800
From: David Hubbard <david.c.hubbard+hackrf at gmail.com>
To: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CAC-0EqgBnbjcBn-2=cy8OnUz+9mnvkZfLd2HrNNg56ANA9Kshw at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

On Wed, Nov 9, 2016 at 9:00 AM, Silverfox <alan.r.hill at gmail.com> 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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Message: 6
Date: Wed, 9 Nov 2016 11:19:33 -0800
From: David Hubbard <david.c.hubbard+hackrf at gmail.com>
To: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CAC-0Eqgw_o4S+GuOrUcJ_G=DXtjTvWF_yNH9oBr-N_GjXf17aw at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

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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Message: 7
Date: Wed, 9 Nov 2016 12:06:13 -0800
From: David Hubbard <david.c.hubbard+hackrf at gmail.com>
To: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CAC-0EqjuaQ=znkm-5Jn2wbEpdyCOQfWYF2X2C1d56FoSV24CWQ at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

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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Message: 8
Date: Wed, 9 Nov 2016 23:15:11 +0000
From: Simon Kennedy <simon at thekennedys.info>
To: hackrf-dev <hackrf-dev at greatscottgadgets.com>
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CACopv_ieCEWGJjsgzD02=hvdb5J2OV5p+YqARwhK_br=9Aod8g at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

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" <david.c.hubbard+hackrf at gmail.com>
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!
>
> _______________________________________________
> HackRF-dev mailing list
> HackRF-dev at greatscottgadgets.com
> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>
>
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Message: 9
Date: Wed, 9 Nov 2016 15:16:04 -0800
From: Cinaed Simson <cinaed.simson at gmail.com>
To: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID: <7945bd12-4db2-bff3-1316-aafe1ea80429 at GMail.COM>
Content-Type: text/plain; charset=windows-1252

On 11/09/2016 12:06 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!
>
>
> _______________________________________________
> HackRF-dev mailing list
> HackRF-dev at greatscottgadgets.com
> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>

In the NBFM receive block, try reducing Tau to 50u, and Max deviation to
4k.

-- Cinaed


------------------------------

Message: 10
Date: Wed, 9 Nov 2016 20:31:19 -0800
From: David Hubbard <david.c.hubbard+hackrf at gmail.com>
To: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] FM 96.5MHz rx works but 70cm 441.1MHz rx
        does not?
Message-ID:
        <CAC-0EqiDR4C+2cXa3O-G=kNeWx6V1rMW1G5sCT+uiHf7-hqphg at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

On Wed, Nov 9, 2016 at 3:16 PM, Cinaed Simson <cinaed.simson at gmail.com>
wrote:

>
> In the NBFM receive block, try reducing Tau to 50u, and Max deviation to
> 4k.
>
>
(to the hackrf-dev list this time)

Thanks, Cinaed! Playing around with max deviation in particular helps with
reception quality, for the one good recording (see below).

I wasn't hearing anything but noise out the audio sink even eyeballing it
on the FFT plot, the signal is 20dB over the noise floor. So I added a file
sink, saved a few seconds of the 2.4Msps complex data output of the DC
blocker (so almost directly out of the osmocom source). I then used a file
source instead of the osmocom source -> DC blocker, and the result is loud
and clear audio.

Even more puzzling is it only did it once. I collected several more
recordings at 2.4Msps but they do not play back audio. Only the first
recording produces audio. They all show a strong 20dB signal in the FFT
plot and waterfall.

My grc file is attached. Possibly a lack of precision on frequency? I tried
setting the tune_offset to values from 598e3 to 654e3, which has the normal
effect on the first recording, but only static on the subsequent recordings.

I would like to add a "sync block," (is that the right term?) so that the
graph only plays back at real time, to make it easier to change tuning
parameters while playing back a recording. Any tips on how to do that? The
attached grc plays back at real time but buffers a lot of audio at the
audio sink so that changing things like tune_offset cannot be heard for
about 2 sec.
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