Hi all, on some systems building librtlsdr can fail when libusb-1.0 is not installed in the standard library locations (e.g. macOS with libusb installed via homebrew can have the shared library in /usr/local/Cellar/libusb/1.0.24/lib).
The below patch includes LIBUSB_LIBRARY_DIRS in the search path for the linker to correct this issue.
For your kind consideration. Thanks, Jasper
Author: jvde.github <jvde.github(a)gmail.com>
Date: Mon Jan 24 19:21:44 2022 +0100
fix build for macOS
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7b47309..3b8060b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -21,6 +21,7 @@
add_library(rtlsdr SHARED librtlsdr.c
tuner_e4k.c tuner_fc0012.c tuner_fc0013.c tuner_fc2580.c tuner_r82xx.c)
target_link_libraries(rtlsdr ${LIBUSB_LIBRARIES} ${THREADS_PTHREADS_LIBRARY})
+target_link_directories(rtlsdr PUBLIC ${LIBUSB_LIBRARY_DIRS})
target_include_directories(rtlsdr PUBLIC
$<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/include>
$<INSTALL_INTERFACE:include> # <prefix>/include
From: Clayton Smith <argilo(a)gmail.com>
Librtlsdr has a workaround for libusb versions that lack
libusb_handle_events_timeout_completed, which was added in version 1.0.9
(released 2012-04-02). The workaround is always applied unless the
HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED macro is set, but the cmake
code that sets this macro was removed in
849f8efca42b659bf7e8fe17156ee0aa67b47233. As a result, the workaround is
now always applied. This results in an extra 1-second delay whenever a
GNU Radio flowgraph containing an RTL-SDR block is stopped, which makes
operations like switching between demodulators in Gqrx annoyingly slow.
To solve this problem, I've simply removed the workaround, as it should
no longer be needed.
I wonder if perhaps the workaround recently applied in
2659e2df31e592d74d6dd264a4f5ce242c6369c8 might stem from the same bug.
---
src/librtlsdr.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/src/librtlsdr.c b/src/librtlsdr.c
index 2682d77ec2..096abaeffc 100644
--- a/src/librtlsdr.c
+++ b/src/librtlsdr.c
@@ -39,12 +39,6 @@
#define LIBUSB_CALL
#endif
-/* libusb < 1.0.9 doesn't have libusb_handle_events_timeout_completed */
-#ifndef HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED
-#define libusb_handle_events_timeout_completed(ctx, tv, c) \
- libusb_handle_events_timeout(ctx, tv)
-#endif
-
/* two raised to the power of n */
#define TWO_POW(n) ((double)(1ULL<<(n)))
--
2.25.1
Error codes from libhackrf are not very legible, and in the case of
HACKRF_ERROR_LIBUSB, don't uniquely describe the cause of the error.
Calling hackrf_error_name() provides a human-readable message, and
in the case of libusb errors, identifies the actual cause rather than
just indicating that the error came from libusb.
This came up whilst trying to diagnose a libhackrf bug which showed
up when using libhackrf, via gr-osmosdr, via gqrx:
https://github.com/greatscottgadgets/hackrf/issues/883
---
lib/hackrf/hackrf_source_c.cc | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/lib/hackrf/hackrf_source_c.cc b/lib/hackrf/hackrf_source_c.cc
index 03ea3bd..2826924 100644
--- a/lib/hackrf/hackrf_source_c.cc
+++ b/lib/hackrf/hackrf_source_c.cc
@@ -170,7 +170,8 @@ bool hackrf_source_c::start()
hackrf_common::start();
int ret = hackrf_start_rx( _dev.get(), _hackrf_rx_callback, (void *)this );
if ( ret != HACKRF_SUCCESS ) {
- std::cerr << "Failed to start RX streaming (" << ret << ")" << std::endl;
+ const char *msg = hackrf_error_name( (enum hackrf_error) ret );
+ std::cerr << "Failed to start RX streaming (" << ret << ": " << msg << ")" << std::endl;
return false;
}
return true;
@@ -184,7 +185,8 @@ bool hackrf_source_c::stop()
hackrf_common::stop();
int ret = hackrf_stop_rx( _dev.get() );
if ( ret != HACKRF_SUCCESS ) {
- std::cerr << "Failed to stop RX streaming (" << ret << ")" << std::endl;
+ const char *msg = hackrf_error_name( (enum hackrf_error) ret );
+ std::cerr << "Failed to stop RX streaming (" << ret << ": " << msg << ")" << std::endl;
return false;
}
return true;
--
2.30.2
Dear Osmocom community,
today our mailing list server lists.osmocom.org has finally been migrated
from mailman2-on-freebsd to mailman3-on-linux. This also included a variety
of changes to DNS. I'll spare you the details, but everything _should_ be up
and running now.
* The List-Id headers should not have changed.
* all list subscriptions + user accounts have been converted.
* old 'static html' archives are still available (read only) at URLs like
https://lists.osmocom.org/pipermail/baseband-devel/
* old List URLs like https://lists.osmocom.org/mailman/listinfo/baseband-devel
are redirected to their respective modern counterparts
In case you notice any mailing list related problem, please don't hesitate to
contact me.
Happy hacking,
Harald
--
- Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
(ETSI EN 300 175-7 Ch. A6)
o decode the VOR's morse code station ID. From that, I will have a shor=
t list of VORs that I can currently receive. From those, if the geometry is=
appropriate (I know the VORs positions from a database) I can calculate a =
position.<u></u><u></u></p>
</div><div><p class=3D"MsoNormal"><u></u> <u></u></p></div><div><p cla=
ss=3D"MsoNormal">The software then just round-robin tunes the VORs in range=
and continually tries to calculate positions. If too many drop out, it ret=
urns to the initial scan mode.<u></u><u></u></p>
</div><div><p class=3D"MsoNormal"><u></u> <u></u></p></div><div><p cla=
ss=3D"MsoNormal">Not being able to receive this VOR or that VOR is not gene=
rally a problem, but obviously, the more the better. With extra VORs I have=
better options for choosing the closest ones or the ones with the best geo=
metry.<u></u><u></u></p>
</div><div><p class=3D"MsoNormal"><u></u> <u></u></p></div><div><p cla=
ss=3D"MsoNormal"><u></u> <u></u></p></div><div><p class=3D"MsoNormal">=
This is actually quite difficult to test, because VORs can generally only b=
e received line-of-sight -- which means in the air. I'm a private pilot=
but I found that flying and noodling with a laptop is too much trouble. Fr=
om my office window, on a high floor in Oakland, CA, I can receive one VOR =
from the Oakland airport. And I have now discovered a ridge near my home wi=
th a scenic overlook from which I can receive two.<u></u><u></u></p>
</div><div><p class=3D"MsoNormal"><u></u> <u></u></p></div><div><p cla=
ss=3D"MsoNormal">I've tested the software enough to know that the initi=
al scan function seems to work, and the morse decoding kind of works, but I=
am not confident I'll get it to work very well. (One transmitter's=
dit looks a lot like another's dah.) The nav signal decoding is simple=
. (A 30 Hz AM modulated tone is phase compared with a 30 Hz tone FM modulat=
ed at 9960 Hz. The phase obtained is the azimuth to the station.)<u></u><u>=
</u></p>
</div><div><p class=3D"MsoNormal"><u></u> <u></u></p></div><div><p cla=
ss=3D"MsoNormal"><u></u> <u></u></p></div><div><p class=3D"MsoNormal">=
If I ever get this working, I looking forward to sharing it with the commun=
ity. In the process of building this, I created a simple SDR toolkit of DSP=
functions. It's like Gnuradio in concept, but 16b fixed-point, and has=
no external dependencies, and C89, so is easier to build on weird and limi=
ted platforms. It also has perl bindings. Compared to GR, it looks like the=
work of a rank amateur just learning DSP, but I do like the concept of the=
re being a GR-like library out there, lightweight and embedded-friendly.<u>=
</u><u></u></p>
</div><div><p class=3D"MsoNormal"><u></u> <u></u></p></div><div><p cla=
ss=3D"MsoNormal"><u></u> <u></u></p></div><div><p class=3D"MsoNormal">=
Regards,<u></u><u></u></p></div><div><p class=3D"MsoNormal">Dave J<u></u><u=
></u></p></div>
<div><div><div><p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><u></u=
> <u></u></p><div><p class=3D"MsoNormal">On Tue, Oct 22, 2013 at 3:06 =
AM, jdow <<a href=3D"mailto:jdow@earthlink.net" target=3D"_blank">jdow@e=
arthlink.net</a>> wrote:<u></u><u></u></p>
<p class=3D"MsoNormal">He sent me two frequencies in private email. These w=
ere in the FM<br>broadcast band (in the US). He probably needs to notch the=
m out<br>in order to get adequate response.<br><br>As for wanting narrow ba=
ndwidth - I am not quite sure why he thinks<br>
that is a benefit. I use a large FFT (about 10 Hz per bin) and use<br>the z=
oom control to see fine detail. (Different FFT settings suite<br>different =
uses. This one seems to be a good compromise with my two<br>needs. I'm =
too lazy to change it.)<br>
<br>{^_^}<u></u><u></u></p><div><div><p class=3D"MsoNormal"><br><br><br>On =
2013/10/22 02:08, Sylvain Munaut wrote:<u></u><u></u></p><blockquote style=
=3D"border:none;border-left:solid #cccccc 1.0pt;padding:0cm 0cm 0cm 6.0pt;m=
argin-left:4.8pt;margin-right:0cm">
<p class=3D"MsoNormal">Effective filtering must occur between antenna and r=
eceiver. All the<br>problems that a saturated preamp and ADC cause can&rsqu=
o;t be repaired by<br>software. Never.<u></u><u></u></p></blockquote><p cla=
ss=3D"MsoNormal" style=3D"margin-bottom:12.0pt">
<br>But his original problem is not with saturated preamps or ADC ... it=
9;s<br>aliasing ... and that can be solved in the digital domain provided<b=
r>fast enough ADC.<br><br>Cheers,<br><br> Sylvain<br><br><u></=
u><u></u></p>
</div></div></div><p class=3D"MsoNormal"><u></u> <u></u></p></div></di=
v></div></div></div><p class=3D"MsoNormal"><u></u> <u></u></p></div></=
div></div></div></div></div></blockquote></div><br></div>
--001a11346d7c0fd5fd04f20c4ef9--
receive. From those, if the geometry is appropriate (I know the VORs =
positions from a database) I can calculate a =
position.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>The software then just round-robin tunes the VORs in =
range and continually tries to calculate positions. If too many drop =
out, it returns to the initial scan mode.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>Not being able to receive this VOR or that VOR is not =
generally a problem, but obviously, the more the better. With extra VORs =
I have better options for choosing the closest ones or the ones with the =
best geometry.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>This is actually quite difficult to test, because VORs =
can generally only be received line-of-sight -- which means in the air. =
I'm a private pilot but I found that flying and noodling with a laptop =
is too much trouble. From my office window, on a high floor in Oakland, =
CA, I can receive one VOR from the Oakland airport. And I have now =
discovered a ridge near my home with a scenic overlook from which I can =
receive two.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>I've tested the software enough to know that the =
initial scan function seems to work, and the morse decoding kind of =
works, but I am not confident I'll get it to work very well. (One =
transmitter's dit looks a lot like another's dah.) The nav signal =
decoding is simple. (A 30 Hz AM modulated tone is phase compared with a =
30 Hz tone FM modulated at 9960 Hz. The phase obtained is the azimuth to =
the station.)<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>If I ever get this working, I looking forward to =
sharing it with the community. In the process of building this, I =
created a simple SDR toolkit of DSP functions. It's like Gnuradio in =
concept, but 16b fixed-point, and has no external dependencies, and C89, =
so is easier to build on weird and limited platforms. It also has perl =
bindings. Compared to GR, it looks like the work of a rank amateur just =
learning DSP, but I do like the concept of there being a GR-like library =
out there, lightweight and =
embedded-friendly.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>Regards,<o:p></o:p></p></div><div><p =
class=3DMsoNormal>Dave J<o:p></o:p></p></div><div><div><div><p =
class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'><o:p> </o:p></p><div><p =
class=3DMsoNormal>On Tue, Oct 22, 2013 at 3:06 AM, jdow <<a =
href=3D"mailto:jdow@earthlink.net" =
target=3D"_blank">jdow(a)earthlink.net</a>> wrote:<o:p></o:p></p><p =
class=3DMsoNormal>He sent me two frequencies in private email. These =
were in the FM<br>broadcast band (in the US). He probably needs to notch =
them out<br>in order to get adequate response.<br><br>As for wanting =
narrow bandwidth - I am not quite sure why he thinks<br>that is a =
benefit. I use a large FFT (about 10 Hz per bin) and use<br>the zoom =
control to see fine detail. (Different FFT settings suite<br>different =
uses. This one seems to be a good compromise with my two<br>needs. I'm =
too lazy to change it.)<br><br>{^_^}<o:p></o:p></p><div><div><p =
class=3DMsoNormal><br><br><br>On 2013/10/22 02:08, Sylvain Munaut =
wrote:<o:p></o:p></p><blockquote style=3D'border:none;border-left:solid =
#CCCCCC 1.0pt;padding:0cm 0cm 0cm =
6.0pt;margin-left:4.8pt;margin-right:0cm'><p class=3DMsoNormal>Effective =
filtering must occur between antenna and receiver. All the<br>problems =
that a saturated preamp and ADC cause can’t be repaired =
by<br>software. Never.<o:p></o:p></p></blockquote><p class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'><br>But his original problem is not with =
saturated preamps or ADC ... it's<br>aliasing ... and that can be solved =
in the digital domain provided<br>fast enough =
ADC.<br><br>Cheers,<br><br> =
Sylvain<br><br><o:p></o:p></p></div></div></div><p =
class=3DMsoNormal><o:p> </o:p></p></div></div></div></div></div><p =
class=3DMsoNormal><o:p> </o:p></p></div></div></div></body></html>
------=_NextPart_000_0073_01CF2656.CE93A820--
direct sampling mode, only from signal processing view):
If you already have analog signal as separated I&Q in baseband (so called
zero-IF), and do I&Q two channel A/D converter, you can processing signal,
highest frequency of which is less than sampling rate, without aliasing.
That means, for example, you can processing signal, frequency of which is
up to 28.8MHz, when sampling rate is 28.8MHz. (There is an implicit
assumption that your zero-IF analog channel is ideal)
If you have to do sampling on a single channel analog signal( not zero-IF,
I&Q not separated by analog circuit, I&Q are still mixed together by an IF
carrier/frequency), you have to ensure the highest frequency of signal less
than half of sampling rate to ensure no aliasing.
On Wed, Jan 29, 2014 at 7:50 AM, Richard Koch <n1gp(a)hotmail.com> wrote:
> Can someone clarify what the frequency range is in Direct sampling mode.
>
> The rtl2832u dongle has a 28.8Mhz osc.
>
> So can the dongle in "direct sampling mode" (with appropriate antenna
> connection)
> receive > 14.4 Mhz (Nyquist) ?
>
> Googling I find conflicting advice.
>
> I've been able to receive > 14.4 Mhz in direct mode, but I'm not sure if
> that's due to some non-optimal method...?
>
> I'm guessing it can because the tuner chip provides both I & Q data
> therefore
> allowing the double rate...?
>
>
>
>
--047d7bf15fc8eed8c404f1137e92
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div><div>From the point of view of signal processing (not=
very clear about your direct sampling mode, only from signal processing vi=
ew):<br></div>If you already have analog signal as separated I&Q in bas=
eband (so called zero-IF), and do I&Q two channel A/D converter, you ca=
n processing signal, highest frequency of which is less than sampling rate,=
without aliasing.<br>
</div><div>That means, for example, you can processing signal, frequency of=
which is up to 28.8MHz, when sampling rate is 28.8MHz. (There is an implic=
it assumption that your zero-IF analog channel is ideal)<br><br></div>If yo=
u have to do sampling on a single channel analog signal( not zero-IF, I&=
;Q not separated by analog circuit, I&Q are still mixed together by an =
IF carrier/frequency), you have to ensure the highest frequency of signal l=
ess than half of sampling rate to ensure no aliasing.<br>
<br></div><div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On =
Wed, Jan 29, 2014 at 7:50 AM, Richard Koch <span dir=3D"ltr"><<a href=3D=
"mailto:n1gp@hotmail.com" target=3D"_blank">n1gp(a)hotmail.com</a>></span>=
wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
<div><div dir=3D"ltr">Can someone clarify what the frequency range is in Di=
rect sampling mode.<br><br>The rtl2832u dongle has a 28.8Mhz osc. <br><br>S=
o can the dongle in "direct sampling mode" (with appropriate ante=
nna connection)<br>
receive > 14.4 Mhz (Nyquist) ?<br><br>Googling I find conflicting advice=
.<br><br>I've been able to receive > 14.4 Mhz in direct mode, but I&=
#39;m not sure if<br>that's due to some non-optimal method...?<br><br>
I'm guessing it can because the tuner chip provides both I & Q data=
therefore<br>allowing the double rate...?<br><br><br><br> </div=
></div>
</blockquote></div><br></div>
--047d7bf15fc8eed8c404f1137e92--
VOR from the Oakland airport. And I have now discovered a ridge near my
home with a scenic overlook from which I can receive two.
I've tested the software enough to know that the initial scan function
seems to work, and the morse decoding kind of works, but I am not confident
I'll get it to work very well. (One transmitter's dit looks a lot like
another's dah.) The nav signal decoding is simple. (A 30 Hz AM modulated
tone is phase compared with a 30 Hz tone FM modulated at 9960 Hz. The phase
obtained is the azimuth to the station.)
If I ever get this working, I looking forward to sharing it with the
community. In the process of building this, I created a simple SDR toolkit
of DSP functions. It's like Gnuradio in concept, but 16b fixed-point, and
has no external dependencies, and C89, so is easier to build on weird and
limited platforms. It also has perl bindings. Compared to GR, it looks like
the work of a rank amateur just learning DSP, but I do like the concept of
there being a GR-like library out there, lightweight and embedded-friendly.
Regards,
Dave J
On Tue, Oct 22, 2013 at 3:06 AM, jdow <jdow(a)earthlink.net> wrote:
> He sent me two frequencies in private email. These were in the FM
> broadcast band (in the US). He probably needs to notch them out
> in order to get adequate response.
>
> As for wanting narrow bandwidth - I am not quite sure why he thinks
> that is a benefit. I use a large FFT (about 10 Hz per bin) and use
> the zoom control to see fine detail. (Different FFT settings suite
> different uses. This one seems to be a good compromise with my two
> needs. I'm too lazy to change it.)
>
> {^_^}
>
>
>
> On 2013/10/22 02:08, Sylvain Munaut wrote:
>
>> Effective filtering must occur between antenna and receiver. All the
>>> problems that a saturated preamp and ADC cause can=92t be repaired by
>>> software. Never.
>>>
>>
>> But his original problem is not with saturated preamps or ADC ... it's
>> aliasing ... and that can be solved in the digital domain provided
>> fast enough ADC.
>>
>> Cheers,
>>
>> Sylvain
>>
>>
>>
--089e01184768dfc65f04e955c0d5
Content-Type: text/html; charset=windows-1252
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr">I originally posted about 115.8 and 116.8 MHz, both square=
in the VOR band of 108 to 117.95. I might have sent something else in a PM=
, but if so it was a typo. :-) I am definitely only interested in the VOR b=
and right now -- though, as you say, it is adjacent to commercial FM with i=
ts high power.<div>
<br></div><div>My application is simple in concept: A fully auomatic VOR-ba=
sed positioning system, a fallback from GPS. I want to scan the entire VOR =
band, looking for signals in the standard VOR format that can be demodulate=
d. I do the initial scan with a fast sample rate and FFT, just looking for =
peaks. From those, I examine the signals to see if it looks like a VOR sign=
al. From that list, I will "park" on each signal long enough (~30=
s) to decode the VOR's morse code station ID. From that, I will have a =
short list of VORs that I can currently receive. From those, if the geometr=
y is appropriate (I know the VORs positions from a database) I can calculat=
e a position.</div>
<div><br></div><div>The software then just round-robin tunes the VORs in ra=
nge and continually tries to calculate positions. If too many drop out, it =
returns to the initial scan mode.</div><div><br></div><div>Not being able t=
o receive this VOR or that VOR is not generally a problem, but obviously, t=
he more the better. With extra VORs I have better options for choosing the =
closest ones or the ones with the best geometry.</div>
<div><br></div><div><br></div><div>This is actually quite difficult to test=
, because VORs can generally only be received line-of-sight -- which means =
in the air. I'm a private pilot but I found that flying and noodling wi=
th a laptop is too much trouble. From my office window, on a high floor in =
Oakland, CA, I can receive one VOR from the Oakland airport. And I have now=
discovered a ridge near my home with a scenic overlook from which I can re=
ceive two.</div>
<div><br></div><div>I've tested the software enough to know that the in=
itial scan function seems to work, and the morse decoding kind of works, bu=
t I am not confident I'll get it to work very well. (One transmitter=
9;s dit looks a lot like another's dah.) The nav signal decoding is sim=
ple. (A 30 Hz AM modulated tone is phase compared with a 30 Hz tone FM modu=
lated at 9960 Hz. The phase obtained is the azimuth to the station.)</div>
<div><br></div><div><br></div><div class=3D"gmail_extra">If I ever get this=
working, I looking forward to sharing it with the community. In the proces=
s of building this, I created a simple SDR toolkit of DSP functions. It'=
;s like Gnuradio in concept, but 16b fixed-point, and has no external depen=
dencies, and C89, so is easier to build on weird and limited platforms. It =
also has perl bindings. Compared to GR, it looks like the work of a rank am=
ateur just learning DSP, but I do like the concept of there being a GR-like=
library out there, lightweight and embedded-friendly.</div>
<div class=3D"gmail_extra"><br></div><div class=3D"gmail_extra"><br></div><=
div class=3D"gmail_extra">Regards,</div><div class=3D"gmail_extra">Dave J</=
div><div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Tue, O=
ct 22, 2013 at 3:06 AM, jdow <span dir=3D"ltr"><<a href=3D"mailto:jdow@e=
arthlink.net" target=3D"_blank">jdow(a)earthlink.net</a>></span> wrote:<br=
>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">He sent me two frequencies in private email.=
These were in the FM<br>
broadcast band (in the US). He probably needs to notch them out<br>
in order to get adequate response.<br>
<br>
As for wanting narrow bandwidth - I am not quite sure why he thinks<br>
that is a benefit. I use a large FFT (about 10 Hz per bin) and use<br>
the zoom control to see fine detail. (Different FFT settings suite<br>
different uses. This one seems to be a good compromise with my two<br>
needs. I'm too lazy to change it.)<br>
<br>
{^_^}<div class=3D"HOEnZb"><div class=3D"h5"><br>
<br>
<br>
On 2013/10/22 02:08, Sylvain Munaut wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><blockquote class=3D"gmail_quote" style=3D"m=
argin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Effective filtering must occur between antenna and receiver. All the<br>
problems that a saturated preamp and ADC cause can=92t be repaired by<br>
software. Never.<br>
</blockquote>
<br>
But his original problem is not with saturated preamps or ADC ... it's<=
br>
aliasing ... and that can be solved in the digital domain provided<br>
fast enough ADC.<br>
<br>
Cheers,<br>
<br>
=A0 =A0 Sylvain<br>
<br>
<br>
</blockquote>
</div></div></blockquote></div><br></div></div>
--089e01184768dfc65f04e955c0d5--
it was a saturation issue in RF, it would show up no matter what the
sample rate is.
Also :
- RF filter are often only band specific and not channel specific
(because tunable RF filters to do channel selection would be
prohibitively expensive)
- IF filter (or BB filters for zero-if) are then used for channel selection.
So in his case being two channel in the same band (and given the
architecture of the dongles), the only saturation that IF filters
would provide would be against ADC saturation and it's easy to check
if this happens or not just looking at the time domain signal.
Cheers,
Sylvain
