Re: SDR gnuradio RTL-SDR x N900
 

When I start RTL_FM I noticed that when I tune to:
sudo rtl_fm -f 120.5M -M am -g 35 -r 11000 - | aplay
I get 120.75mhz
so I tune to 120.25M and I get almost right on 120.5 AM
I am not sure how close I am on the actual freq I am trying to use, it seems this SDR tuner(assuming I am on freq) with a wire antenna cut for freq is not as sensitive as the air band transceiver with telescoping long range antenna which I am using for comparison.

Hoping that Xes has time to build Gnuradio and Gqrx in the repos so we have knobs to twiddle with, my attempt to symlink link the gnuradio libs met with failure

Re: SDR gnuradio RTL-SDR x N900
 

The internal clock of this devices is not precise at all. (That's the reason that made some guy to prepare some calibration tool to correct the shift)

About gnuradio package.. ehh.. it's an hard question, be patient.

Re: SDR gnuradio RTL-SDR x N900
 

Xes, all appreciation no pressure.
(Begins intense attempt to use Jedi mental Force to pressure Xes.)

Re: SDR gnuradio RTL-SDR x N900
 

Xes and others, I have at long last successfully built dump1090 on my Ubuntu system. Dump1090 is ADS-B air traffic controllers radar view app for the cheap SDRs we are using.
The dump1090 build instructions from here most importantly including a new build of rtl-sdr which is apparently a dep for the build http://www.hfunderground.com/wiki/RTL-SDR compile went fine and after I rmmod dvb_usb_rtl28xxu dump1090 runs and picks up updating aircraft IDs and locations but when I try to use the localhost:8080 web GUI I get the file gmap.html does exist and I can open it by pointing my browser at it though it doesn't show any aircraft despite them being listed in the --interactive list in terminal. I suspect a permissions problem, my old bane, as to even cd to /root/git/dump1090 is permission denied unless I am sudo su
If I can get this to work on Ubuntu then next step is another attempt at scratchbox.
What makes dump1090 so cool is despite the small screen of the N900 someone can take the dumbest tablet capable of using bluetooth PAN/DUN or WiFi ad-hoc to display the ADS-B plots on any web browser, compare to $900 for this http://www.sportys.com/PilotShop/product/17996 I suspect it contains a RTL-SDR and a RasberryPi, wonder if we can squeeze the GPL stuff from them?
Apparently there is also a way to rx and decode nexrad radar weather and NOTAMs near an airport.
Of interest in the future as 978mhz ADS-B transponders become common on light aircraft we will probably need to run two SDR modules to cover both th big and small aircraft freqs.

Re: SDR gnuradio RTL-SDR x N900
 

Another avenue for radio hacking geeks, back when AO-40 was alive people were using satellite LNBs to listen to the Ka or Ku band downlink on 2 meter band and uplinking on the 70cm band by transmitting FM tx as morse code.
This reminded me that we can grab a cheap LNB and use our rtl-sdr to decode some signals, with the DVB driver we bight be able to force a dvb-s decode. Who knows what the difference is between DVB-Terestrial and DVB-Satellite is?
I noticed I have a satellite dish on my rental, if I can figue how to power it up I will see what I can scan for with Kaffeine on Ubuntu as well as RTL-SDR on my N900.
this $8 LNB http://www.ebay.com/itm/New-Single-S...item2c621053ed
downconverts to freqs that the R820t can handle. No dish? DIY one with foil and cardboard or buy a wok at the department store.
http://goughlui.com/?p=5072

Re: SDR gnuradio RTL-SDR x N900
 

You can extract the attached kalibrate-rtl-sdr.tar.gz and place the executable (yes, one file) any place on the N900.

Re: SDR gnuradio RTL-SDR x N900
 

And, a teaser

Re: SDR gnuradio RTL-SDR x N900
 

Just in case, somone wants to build with some nice GUI,
It builds perfectly on scratchbox, with minor changes to the source:

1. You need to use repository https://github.com/asdil12/kalibrate-rtl., and checkout branch arm_memory

2. Also, change configure.ac line 1 "AC_PREREQ([2.64])" to "AC_PREREQ([2.61])" which will work perfectly