Discussion:
[Hackrf-dev] HackRF as a function generator
MA
2015-11-14 09:56:04 UTC
Permalink
Hi
Can I use HackRF as a function generator?
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)

Thanks
Mehdi
Dominic Spill
2015-11-15 17:50:53 UTC
Permalink
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).

Dominic

[1] https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
[2] Loading Image...
MA
2015-11-21 19:57:06 UTC
Permalink
Hi Dominic
Thank you. Can I connect HackRF's output directly to an oscilloscope? (in
TX mode, running osmocom_siggen)
I was worried whether connecting it (without using an antenna or dummy
load) would hurt HackRF's output.

Thanks
Mehdi
Post by Dominic Spill
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).
Dominic
[1]
https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
[2] https://i.imgur.com/og7TGVz.jpg
Dominic Spill
2015-11-22 11:20:10 UTC
Permalink
Can I connect HackRF's output directly to an oscilloscope? (in TX mode, running osmocom_siggen)
I was worried whether connecting it (without using an antenna or dummy load)
would hurt HackRF's output.
I would suggest using a dummy load to be cautious, but I really have
no experience of connecting HackRF One directly to other equipment.

Mike Ossmann, Jared Boone or anyone else who has tried this can
probably give a better response as to why you would/wouldn't need to.

Thanks,
Dominic
Post by Dominic Spill
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).
Dominic
[1]
https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
[2] https://i.imgur.com/og7TGVz.jpg
MA
2015-11-22 12:48:36 UTC
Permalink
Thanks Dominic.
Here's the answers I got from IRC, for the record:

1- if the scope has a 50ohm termination mode and you use it, that's fine.
otherwise it's almost the same as leaving the output open circuit which is
bad. you should use a dummy load, an easy way to set it up is with a BNC T
piece & dummy load on one side
2- If your scope does not have a way to switch the input into 50 ohm mode,
you can get a 50 ohm adapter.)

Anyway, I bought a 50-ohm terminator and a T-shape BNC connector (I will
post some pictures later)

Best regards
Mehdi
Post by MA
Can I connect HackRF's output directly to an oscilloscope? (in TX mode,
running osmocom_siggen)
I was worried whether connecting it (without using an antenna or dummy
load)
would hurt HackRF's output.
I would suggest using a dummy load to be cautious, but I really have
no experience of connecting HackRF One directly to other equipment.
Mike Ossmann, Jared Boone or anyone else who has tried this can
probably give a better response as to why you would/wouldn't need to.
Thanks,
Dominic
Post by Dominic Spill
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).
Dominic
[1]
https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
Post by Dominic Spill
[2] https://i.imgur.com/og7TGVz.jpg
MA
2015-11-22 21:28:02 UTC
Permalink
Ok, I managed to see the output of HackRF with my oscilloscope, but I have
two problems:
1- When I use osmocom_siggen, I see nothing on oscilloscope (are there any
tweaks/tips I should know?)
2- I used a very simple FM transmitter (on 14MHZ) and connected its output
to oscilloscope, but what I see is a pure sinusoidal wave, not an FM
modulated one. A picture and the GRC file are attached.
I have tested this file with 80MHZ and could easily listen it on a FM
radio, so it works and produces something, but I don't know why the output
on oscilloscope is like this.

Best regards
Mehdi
Post by MA
Can I connect HackRF's output directly to an oscilloscope? (in TX mode,
running osmocom_siggen)
I was worried whether connecting it (without using an antenna or dummy
load)
would hurt HackRF's output.
I would suggest using a dummy load to be cautious, but I really have
no experience of connecting HackRF One directly to other equipment.
Mike Ossmann, Jared Boone or anyone else who has tried this can
probably give a better response as to why you would/wouldn't need to.
Thanks,
Dominic
Post by Dominic Spill
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).
Dominic
[1]
https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
Post by Dominic Spill
[2] https://i.imgur.com/og7TGVz.jpg
Dominic Spill
2015-11-23 16:48:37 UTC
Permalink
Post by MA
1- When I use osmocom_siggen, I see nothing on oscilloscope (are there any
tweaks/tips I should know?)
I've never used it, but could you share the command line arguments
that you used?
Do you see any change at all when you change the parameters?
Post by MA
2- I used a very simple FM transmitter (on 14MHZ) and connected its output
to oscilloscope, but what I see is a pure sinusoidal wave, not an FM
modulated one. A picture and the GRC file are attached.
I see that this works for you, but have you tried something simpler?
Perhaps based on the one here:
http://wiki.opendigitalradio.org/Simple_FM_transmitter_using_gnuradio
Post by MA
I have tested this file with 80MHZ and could easily listen it on a FM radio,
so it works and produces something
Is the only thing that you change between the 80MHz/14MHz runs the
frequency in the osmocom sink?
Post by MA
Post by Dominic Spill
Can I connect HackRF's output directly to an oscilloscope? (in TX mode,
running osmocom_siggen)
I was worried whether connecting it (without using an antenna or dummy load)
would hurt HackRF's output.
I would suggest using a dummy load to be cautious, but I really have
no experience of connecting HackRF One directly to other equipment.
Mike Ossmann, Jared Boone or anyone else who has tried this can
probably give a better response as to why you would/wouldn't need to.
Thanks,
Dominic
Post by Dominic Spill
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page in
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).
Dominic
[1]
https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
[2] https://i.imgur.com/og7TGVz.jpg
MA
2015-11-23 17:21:06 UTC
Permalink
1- Here's the arguments:
osmocom_siggen -a hackrf -f 100e6 --sine

2- I haven't, but I will

3- Yes. (Default freq, Max freq and Min freq)

Maybe that's because the deviations in FM frequency is very small (50KHZ
each side), so I can't see them on oscilloscope and I should use a spectrum
analyzer

Thanks
Mehdi
Post by Dominic Spill
Post by MA
1- When I use osmocom_siggen, I see nothing on oscilloscope (are there
any
Post by MA
tweaks/tips I should know?)
I've never used it, but could you share the command line arguments
that you used?
Do you see any change at all when you change the parameters?
Post by MA
2- I used a very simple FM transmitter (on 14MHZ) and connected its
output
Post by MA
to oscilloscope, but what I see is a pure sinusoidal wave, not an FM
modulated one. A picture and the GRC file are attached.
I see that this works for you, but have you tried something simpler?
http://wiki.opendigitalradio.org/Simple_FM_transmitter_using_gnuradio
Post by MA
I have tested this file with 80MHZ and could easily listen it on a FM
radio,
Post by MA
so it works and produces something
Is the only thing that you change between the 80MHz/14MHz runs the
frequency in the osmocom sink?
Post by MA
Post by Dominic Spill
Can I connect HackRF's output directly to an oscilloscope? (in TX
mode,
Post by MA
Post by Dominic Spill
running osmocom_siggen)
I was worried whether connecting it (without using an antenna or dummy load)
would hurt HackRF's output.
I would suggest using a dummy load to be cautious, but I really have
no experience of connecting HackRF One directly to other equipment.
Mike Ossmann, Jared Boone or anyone else who has tried this can
probably give a better response as to why you would/wouldn't need to.
Thanks,
Dominic
Post by Dominic Spill
Post by MA
Can I use HackRF as a function generator?
From a software point of view, it's very easy to accomplish. If you
want to use GNU Radio you can use the waveform generator block [1]
Post by MA
(The only thing I've found is "osmocomm_siggen" and a single page
in
Post by MA
Post by Dominic Spill
Post by Dominic Spill
Post by MA
Michael's Recon2014 presentation, under "Baseband Expansion Board" title)
From the hardware side, there is a header on HackRF (P9 on the right
hand side of this image) which allows access to the baseband, giving
you direct access to the output of the DACs (and input to the ADCs).
The "Baseband Expansion Board" would be plugged in to that header to
allow signals to be used without passing through the analogue
front-end. The expansion board would be used to mix the I and Q
signals (and possibly offer some other features).
Dominic
[1]
https://gnuradio.org/doc/doxygen/group__waveform__generators__blk.html#gac97c0f42ffb63f1265decceaaeab9177
Post by MA
Post by Dominic Spill
Post by Dominic Spill
[2] https://i.imgur.com/og7TGVz.jpg
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