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Fri Jan 29 12:04:30 UTC 2016

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 =

</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=

</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>=

</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>=

</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=

<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 at" target=3D"_blank">jdow at e=</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=

<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&#3=
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></=

</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></=


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