Re: SDR gnuradio RTL-SDR x N900
 

News:
rtl-sdr package has been updated using latest gist snapshot and pushed to extras-devel.
multimon-ng has been packaged and pushed to extras devel too.

Re: SDR gnuradio RTL-SDR x N900
 

Thanks for RTL-SDR, multimon, and rtl_fm on the repos, I am having big fun with these.
Can we wait with hope for gqrx which depends on libs from gnuradio? Some of us are still not great at symlinking even 12 years ofter having to learn it for the old linux Zaurus PDAs which also had a too small root partition.
For those not paying attention these apps turn your N900 into a receiver with more capacity than several Kilo$ receivers and only require a $10 DVB-T receiver, a USB host cable, and Xes's magic. A wire antenna and for HF bands an upconverter do help.

Has anyone played with connecting a satellite LNB/dish to their SDR receiver for free to air? I think we could do the mpeg-2 decode with our phones.

Re: SDR gnuradio RTL-SDR x N900
 

I have been thinking what cool stuff like Van-Eck phreaking is now possible with the rtl-sdr running on our N900s?
Just imagine walking into an office or embassy and dumping or just recording the output of all nearby video cards.
If I were to remove the IrDa receiver, big USB jack, and antenna connector the smallest DVB-T dongles are really thin and might be stuffed under battery cover(Mugen?) or even the system board and connect a wire antenna with a single data pin connector from a serial cable kit.
I will have to figure out the best way to make RTL-FM a system audio device so it can interact more easily with more apps.

Xes when you are compiling stuff and sticking them on the repos can you throw WSJT weak signal processing into the mix? WSJT makes it possible to use the Earths moon as a comm sat with under 100 watts of power for very low rate data among other tricks it can be used for. The more awesome you bring the more awesome we want!

Re: SDR gnuradio RTL-SDR x N900
 

I have had trouble building dump1090 for ubuntu which turns your laptop or phone into an ADS-B aircraft radar receiver. These receivers are expensive, see here http://www.sportys.com/PilotShop/product/17165
It would be pretty cool to see the N900 finally come out with an affordable ADS-B solution for poor pilots. Makes me wish there were a Maemo5 tablet to get a larger view area since I am pretty sure we can get dump1090 working, maybe with bluetooth tethering and VNC.
http://www.hamradioscience.com/the-r...sdr-and-ads-b/

Re: SDR gnuradio RTL-SDR x N900
 

@biketool
there are a lot of things queued in my mind and dump1090 is one of those. In the same queue there is also gnuradio, rtl_433, kalibrate-rtl and gqrx but i remember very well all the problems i had last time i built some of them... and so i have to fit them well in my "nightly multitasking process scheduler"....

I hope that some of this tools (for example multimon-ng) could be used to decode the audio captured by the N900 microphone while in front of a radio receiver to "attract" more public to this kind of nice toys.
In fact multimon-ng can decode a stream piped from stdin and fldigi can record directly from portaudio. Who wants to test them? ;)

Re: SDR gnuradio RTL-SDR x N900
 

Here is a promising looking upconverter and preamp which makes the HF bands available, just tune your freq+50Mhz and everything works as it contains a normal Realtech DVB-T dongle. Everything a radio geek could want in a tiny package but transmit for $50 + $10 shipping..
http://zao.jp/radio/soft66rtl/

Re: SDR gnuradio RTL-SDR x N900
 

Can something be crammed in this ? http://talk.maemo.org/showthread.php?t=93325

Re: SDR gnuradio RTL-SDR x N900
 

Yes, you could place RTL dongle (without plastic case) into extended battery compartment (mugen cover or endsormeans' awesome elk-extender) and connect it to internal USB and Vbus under battery

/j

Re: SDR gnuradio RTL-SDR x N900
 

Just saw this post about compiling dump1090 aircraft radar and WSJT ultra weak signal radio data(moon bounce) among others for the Rasberry Pi, should be a similar process since they are both ARM. WSJT will be cool to decode signals from RTL-FM.
http://g4vxe.blogspot.co.il/2013/01/...wspr-wsjt.html

This would also be interesting, an app to minitor multiple AM airband stations, I have to schlep a big airband radio to monitor to the tower, how much better would it be to listen to my phone with intergrated audio and ability to take calls on the same bluetooth headset.
http://www.rtl-sdr.com/monitoring-mu...l-sdr-airband/

I think I will 3D print a SDR sleeve to fit the small dongle with a microUSB port on one side and an antenna port on the other. I also received my antenna port adapters, I chopped one and soldered a wire antenna cut for air band.

This is all very useful as I am currently not working and living off of student loans for retraining and licensing. Leveraging OSS software and cheap tech like this lets me use my minimal budget for more appropriate stuff like food.

Take my money! :) I want one!

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