Re: FM Carrier Recovery for AOA Calculation

[Marcus Müller]

Always wondered what the state-of-the-art is in oscillator drift compensation; I bet 
there's more to it than estimating a second derivative of one LO's phase against the other 
and throwing Kalman at it until it doesn't move anymore, or whether there's better models...


but you're right. If this is more than "a one-shot measurement immediately after 
calibration", you'll need to share a reference clock; even an extremely nice frequency 
error of $2\cdot 10^{-8}$ between the two receivers would, at 1 GHz carrier, mean that the 
phase of one rotates away from the other by $40 \pi$ every second, so you have like 10 ms 
until you lose any sensible idea of direction. I don't know how well the calibration 
routine is able to compensate such small frequency errors, it might actually be OK for 
longer, or it might not.


Best regards,
Marcus

On 01.09.23 22:48, Marcus D. Leech wrote:


On 01/09/2023 16:39, Marcus Müller wrote:
Ah, nice! yeah, then this would work – but! any oscillator has drift, so two local 
oscillators will not stay on the same phase for long; if your first couple measurements 
are correct, but suddenly your directions become very wrong, that's what I'd investigate.


Cheers,
Marcus
Looks like the BB60C supports an external 10MHz reference clock, which would be utterly 
mandatory for anything requiring
  mutual phase-coherence, whether that's *sufficient* depends very very much on the 
internal architecture of the BB60C.





On 01.09.23 19:16, Michael Berman wrote:
The gr-aoa module has a calibration phase where you connect a source with a splitter 
and roughly equally lengthened cables to the two sources and it cross-correlates the 
two inputs to determine an initial phase difference.  Then, while the script is still 
running, you disconnect the calibration source and connect the antenna's, again with 
roughly equally lengthened cables to run the MUSIC algorithm.



Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 11:00 AM Marcus Müller > wrote:


    If you don't know the relative phase of your two receiver chains, how are you 
going to

    know the direction of a signal?

    On 01.09.23 17:37, Michael Berman wrote:

    Marcus,

    Thanks for the reply!  I apologize, the GR package is gr-aoa, not gr-music, 
and can
    be found here (https://github.com/MarcinWachowiak/gr-aoa
    ). The NOAA broadcast is a NBFM 
signal.     I am using 2 Signal Hound receivers (https://signalhound.com/products/bb60c/

    ) with 2 antennas spaced on a 
beam.  Do I
    need to synchronize the 2 receivers with an external clock, or should they 
be fine
    free running independently?


    Thank you very much,

    Michael Berman

    On Fri, Sep 1, 2023 at 9:25 AM Marcus Müller mailto:mmuel...@gnuradio.org>> wrote:

    Not familiar with the details of NOAA signalling, but isn't the carrier 
of an FM
    signal
    *the FM signal*?

    For a DoA estimate, you'd correlate the different receive chains with 
each other
    to get a
    phase; so, as long as the signals do have some bandwidth that makes the 
problem
    less
    ambiguous, it'd work with any signal. I'm sadly not familiar with 
gr-music (and
    can't find
    it on cgran.org ), but MUSIC works as long as the 
signals at
    the different receive antennas
    are correlated and noise is not. You do not have to preprocess your FM 
signal!

    Best,
    Marcus

    On 01.09.23 17:09, Michael Berman wrote:
    > Does anybody know if there is a way to recover a carrier of an FM 
signal to
    use for an
    > Angle of Arrival calculation?  I am using GNURadio and gr-music and I 
am
    trying to use the
    > NOAA Weather Radio signals.
    >
    > Thank you very much,
    >
    > Michael Berman

Re: FM Carrier Recovery for AOA Calculation

[Marcus D. Leech]

On 01/09/2023 16:39, Marcus Müller wrote:
Ah, nice! yeah, then this would work – but! any oscillator has drift, 
so two local oscillators will not stay on the same phase for long; if 
your first couple measurements are correct, but suddenly your 
directions become very wrong, that's what I'd investigate.


Cheers,
Marcus
Looks like the BB60C supports an external 10MHz reference clock, which 
would be utterly mandatory for anything requiring
  mutual phase-coherence, whether that's *sufficient* depends very very 
much on the internal architecture of the BB60C.





On 01.09.23 19:16, Michael Berman wrote:
The gr-aoa module has a calibration phase where you connect a source 
with a splitter and roughly equally lengthened cables to the two 
sources and it cross-correlates the two inputs to determine an 
initial phase difference.  Then, while the script is still running, 
you disconnect the calibration source and connect the antenna's, 
again with roughly equally lengthened cables to run the MUSIC algorithm.



Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 11:00 AM Marcus Müller 
mailto:marcus.muel...@ettus.com>> wrote:


    If you don't know the relative phase of your two receiver chains, 
how are you going to

    know the direction of a signal?

    On 01.09.23 17:37, Michael Berman wrote:

    Marcus,

    Thanks for the reply!  I apologize, the GR package is gr-aoa, 
not gr-music, and can

    be found here (https://github.com/MarcinWachowiak/gr-aoa
    ). The NOAA broadcast 
is a NBFM signal.     I am using 2 Signal Hound receivers 
(https://signalhound.com/products/bb60c/
    ) with 2 antennas 
spaced on a beam.  Do I
    need to synchronize the 2 receivers with an external clock, or 
should they be fine

    free running independently?


    Thank you very much,

    Michael Berman

    On Fri, Sep 1, 2023 at 9:25 AM Marcus Müller mailto:mmuel...@gnuradio.org>> wrote:

    Not familiar with the details of NOAA signalling, but isn't 
the carrier of an FM

    signal
    *the FM signal*?

    For a DoA estimate, you'd correlate the different receive 
chains with each other

    to get a
    phase; so, as long as the signals do have some bandwidth 
that makes the problem

    less
    ambiguous, it'd work with any signal. I'm sadly not familiar 
with gr-music (and

    can't find
    it on cgran.org ), but MUSIC works as long 
as the signals at

    the different receive antennas
    are correlated and noise is not. You do not have to 
preprocess your FM signal!


    Best,
    Marcus

    On 01.09.23 17:09, Michael Berman wrote:
    > Does anybody know if there is a way to recover a carrier 
of an FM signal to

    use for an
    > Angle of Arrival calculation?  I am using GNURadio and 
gr-music and I am

    trying to use the
    > NOAA Weather Radio signals.
    >
    > Thank you very much,
    >
    > Michael Berman

Re: FM Carrier Recovery for AOA Calculation

[Marcus Müller]

Ah, nice! yeah, then this would work – but! any oscillator has drift, so two local 
oscillators will not stay on the same phase for long; if your first couple measurements 
are correct, but suddenly your directions become very wrong, that's what I'd investigate.


Cheers,
Marcus

On 01.09.23 19:16, Michael Berman wrote:
The gr-aoa module has a calibration phase where you connect a source with a splitter and 
roughly equally lengthened cables to the two sources and it cross-correlates the two 
inputs to determine an initial phase difference.  Then, while the script is still running, 
you disconnect the calibration source and connect the antenna's, again with roughly 
equally lengthened cables to run the MUSIC algorithm.



Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 11:00 AM Marcus Müller > wrote:


If you don't know the relative phase of your two receiver chains, how are 
you going to
know the direction of a signal?

On 01.09.23 17:37, Michael Berman wrote:

Marcus,

Thanks for the reply!  I apologize, the GR package is gr-aoa, not gr-music, 
and can
be found here (https://github.com/MarcinWachowiak/gr-aoa
). The NOAA broadcast is a NBFM signal. 
I am using 2 Signal Hound receivers (https://signalhound.com/products/bb60c/

) with 2 antennas spaced on a 
beam.  Do I
need to synchronize the 2 receivers with an external clock, or should they 
be fine
free running independently?


Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 9:25 AM Marcus Müller mailto:mmuel...@gnuradio.org>> wrote:

Not familiar with the details of NOAA signalling, but isn't the carrier 
of an FM
signal
*the FM signal*?

For a DoA estimate, you'd correlate the different receive chains with 
each other
to get a
phase; so, as long as the signals do have some bandwidth that makes the 
problem
less
ambiguous, it'd work with any signal. I'm sadly not familiar with 
gr-music (and
can't find
it on cgran.org ), but MUSIC works as long as the 
signals at
the different receive antennas
are correlated and noise is not. You do not have to preprocess your FM 
signal!

Best,
Marcus

On 01.09.23 17:09, Michael Berman wrote:
> Does anybody know if there is a way to recover a carrier of an FM 
signal to
use for an
> Angle of Arrival calculation?  I am using GNURadio and gr-music and I 
am
trying to use the
> NOAA Weather Radio signals.
>
> Thank you very much,
>
> Michael Berman

Re: FM Carrier Recovery for AOA Calculation

[Michael Berman]

The gr-aoa module has a calibration phase where you connect a source with a
splitter and roughly equally lengthened cables to the two sources and it
cross-correlates the two inputs to determine an initial phase difference.
Then, while the script is still running, you disconnect the calibration
source and connect the antenna's, again with roughly equally lengthened
cables to run the MUSIC algorithm.


Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 11:00 AM Marcus Müller 
wrote:

> If you don't know the relative phase of your two receiver chains, how are
> you going to know the direction of a signal?
> On 01.09.23 17:37, Michael Berman wrote:
>
> Marcus,
>
> Thanks for the reply!  I apologize, the GR package is gr-aoa, not
> gr-music, and can be found here (https://github.com/MarcinWachowiak/gr-aoa).
> The NOAA broadcast is a NBFM signal.  I am using 2 Signal Hound receivers (
> https://signalhound.com/products/bb60c/) with 2 antennas spaced on a
> beam.  Do I need to synchronize the 2 receivers with an external clock, or
> should they be fine free running independently?
>
>
> Thank you very much,
>
> Michael Berman
>
> On Fri, Sep 1, 2023 at 9:25 AM Marcus Müller 
> wrote:
>
>> Not familiar with the details of NOAA signalling, but isn't the carrier
>> of an FM signal
>> *the FM signal*?
>>
>> For a DoA estimate, you'd correlate the different receive chains with
>> each other to get a
>> phase; so, as long as the signals do have some bandwidth that makes the
>> problem less
>> ambiguous, it'd work with any signal. I'm sadly not familiar with
>> gr-music (and can't find
>> it on cgran.org), but MUSIC works as long as the signals at the
>> different receive antennas
>> are correlated and noise is not. You do not have to preprocess your FM
>> signal!
>>
>> Best,
>> Marcus
>>
>> On 01.09.23 17:09, Michael Berman wrote:
>> > Does anybody know if there is a way to recover a carrier of an FM
>> signal to use for an
>> > Angle of Arrival calculation?  I am using GNURadio and gr-music and I
>> am trying to use the
>> > NOAA Weather Radio signals.
>> >
>> > Thank you very much,
>> >
>> > Michael Berman
>>
>

Re: FM Carrier Recovery for AOA Calculation

[Marcus Müller]

If you don't know the relative phase of your two receiver chains, how are you going to 
know the direction of a signal?


On 01.09.23 17:37, Michael Berman wrote:

Marcus,

Thanks for the reply!  I apologize, the GR package is gr-aoa, not gr-music, and can be 
found here (https://github.com/MarcinWachowiak/gr-aoa). The NOAA broadcast is a NBFM 
signal.  I am using 2 Signal Hound receivers (https://signalhound.com/products/bb60c/) 
with 2 antennas spaced on a beam.  Do I need to synchronize the 2 receivers with an 
external clock, or should they be fine free running independently?



Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 9:25 AM Marcus Müller  wrote:

Not familiar with the details of NOAA signalling, but isn't the carrier of 
an FM signal
*the FM signal*?

For a DoA estimate, you'd correlate the different receive chains with each 
other to
get a
phase; so, as long as the signals do have some bandwidth that makes the 
problem less
ambiguous, it'd work with any signal. I'm sadly not familiar with gr-music 
(and
can't find
it on cgran.org ), but MUSIC works as long as the signals 
at the
different receive antennas
are correlated and noise is not. You do not have to preprocess your FM 
signal!

Best,
Marcus

On 01.09.23 17:09, Michael Berman wrote:
> Does anybody know if there is a way to recover a carrier of an FM signal 
to use
for an
> Angle of Arrival calculation?  I am using GNURadio and gr-music and I am 
trying to
use the
> NOAA Weather Radio signals.
>
> Thank you very much,
>
> Michael Berman

Re: FM Carrier Recovery for AOA Calculation

[Michael Berman]

Marcus,

Thanks for the reply!  I apologize, the GR package is gr-aoa, not gr-music,
and can be found here (https://github.com/MarcinWachowiak/gr-aoa).  The
NOAA broadcast is a NBFM signal.  I am using 2 Signal Hound receivers (
https://signalhound.com/products/bb60c/) with 2 antennas spaced on a beam.
Do I need to synchronize the 2 receivers with an external clock, or should
they be fine free running independently?


Thank you very much,

Michael Berman

On Fri, Sep 1, 2023 at 9:25 AM Marcus Müller  wrote:

> Not familiar with the details of NOAA signalling, but isn't the carrier of
> an FM signal
> *the FM signal*?
>
> For a DoA estimate, you'd correlate the different receive chains with each
> other to get a
> phase; so, as long as the signals do have some bandwidth that makes the
> problem less
> ambiguous, it'd work with any signal. I'm sadly not familiar with gr-music
> (and can't find
> it on cgran.org), but MUSIC works as long as the signals at the different
> receive antennas
> are correlated and noise is not. You do not have to preprocess your FM
> signal!
>
> Best,
> Marcus
>
> On 01.09.23 17:09, Michael Berman wrote:
> > Does anybody know if there is a way to recover a carrier of an FM signal
> to use for an
> > Angle of Arrival calculation?  I am using GNURadio and gr-music and I am
> trying to use the
> > NOAA Weather Radio signals.
> >
> > Thank you very much,
> >
> > Michael Berman
>

Re: FM Carrier Recovery for AOA Calculation

[Marcus Müller]

Not familiar with the details of NOAA signalling, but isn't the carrier of an FM signal 
*the FM signal*?


For a DoA estimate, you'd correlate the different receive chains with each other to get a 
phase; so, as long as the signals do have some bandwidth that makes the problem less 
ambiguous, it'd work with any signal. I'm sadly not familiar with gr-music (and can't find 
it on cgran.org), but MUSIC works as long as the signals at the different receive antennas 
are correlated and noise is not. You do not have to preprocess your FM signal!


Best,
Marcus

On 01.09.23 17:09, Michael Berman wrote:
Does anybody know if there is a way to recover a carrier of an FM signal to use for an 
Angle of Arrival calculation?  I am using GNURadio and gr-music and I am trying to use the 
NOAA Weather Radio signals.


Thank you very much,

Michael Berman

FM Carrier Recovery for AOA Calculation

[Michael Berman]

Does anybody know if there is a way to recover a carrier of an FM signal to
use for an Angle of Arrival calculation?  I am using GNURadio and gr-music
and I am trying to use the NOAA Weather Radio signals.

Thank you very much,

Michael Berman