Playing around with RTLSDR

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1 Introduction & Motivation

Long time has passed by with lots of things and new developments. I have seen now that modern digital radar cards sample the radar signal with ~~ 100 MSPS and can produce a good radar resolution of 7m per pixel. Since I'm working in the radar technology field now (expecially configuring and tweaking Terma Scanter 2001 radars, I have been wondering what I can do with SDR and radar. First of all I thought maybe I can get some precision out of an RTL SDR stick. For my first attempts, sampling a signal at those 3 MSPS should bee good enough before shifting over to my USRP2.

Let me note that my USRP2 was a fantastic device in 2010 and it still is. But it is noteworthy that the RedPitaya costs 230 Euro today and samples at 125 MSPS.

2 First attempts on the RTLSDR stick

I have purchased this device: (lsusb output)

Realtek Semiconductor Corp. RTL2832U DVB-T

I have blacklisted the native driver in /etc/modprobe.d/blacklist.conf

blacklist dvb_usb_rtl28xxu

and I have played around with Alex Csete's GQRX tool. Really great, I can receive BC FM stations, notably the classical music station at 103.2 MHz.

After this attempt, I started to go a little urther and play around with GNURadio again. I noticed that so many things have changed since I last tried out gnuradio-companion. Many more blocks, much more functionality, everything has changed. Anyway, here is my first sketch. I copied from here:

2015-09-18-gnuradio rtlsdr1.png


3 Multichannel Reception

A lot of responses have come on a thread I triggered on the gnuradio discussion list on how to receive multiple channels in parallel.

Discuss-gnuradio] isolate channels from wideband

Here is another thread:

[Discuss-gnuradio] GRC Polyphase Channelizer examples?

Here is a program that can do it: ham2mon

Another tool that can do it:

4 Multichannel Transmission

Here are some notes. This solution does not work with the RTLSDR stick, but it works with the USRP2...: