Month: October 2012

Amateur Radio Projects and Software Defined Radio

RTL2832U / R820T HF Reception

One of the bonuses you get with the RTL2832U / R820T DVB-T stick is some HF reception. The RTL2832U / R820T will cover HF between 24-30 MHz. Using SDR Sharp you can easily listen to the CB, 10 Meter, and 12 Meter bands. The working frequency range for the RTL2832U / R820T is roughly around 24MHz to 1850MHz when used as a SDR receiver. I did a quick test of the RTL2832U / 820T by connecting a random wire antenna to the screw on the stock antenna base. While by no means was this the best antenna for the HF reception, I still managed to pickup a few 10 Meter SSB broadcasts and some 12 Meter CW broadcasts. …

$10 ADS-B Receiver – RTL2832U / R820T

I finally got my RTL2832U / R820T DVB-T stick from China for about $9.50 shipped. While I was working up a comparison between the well known RTL2832U / E4000 and the “new kid on the block” the RTL2832U / R820T, I did a little testing of ADS-B reception with the RTL2832U / R820T. While not expecting much, I was very surprised to see that the RTL2832U / R820T handily outperformed the RTL2832U / E4000 by a wide margin.
Using the stock antenna, the RTL2832U / R820T pulled in easily double the ADS-B messages than the RTL2832U / E4000 with it’s stock antenna. The frequency range of the RTL2832U is roughly from 24MHz to 1860MHz. It also appears that it is a bit more sensitive than the RTL2832U / E4000. This was especially true on 1090MHz, by a lot. The RTL2832U also has no DC offset spike in the middle of the spectrum. The down side is that the RTL2832U / R820T seems more susceptible to RFI. I did not get to try an external ADS-B antenna on this unit because the DVB-T stick has an MCX antenna jack on it and I did not have an adapter handy. I suspect …

RTL2832U ADS-B Performance Testing Part II

Stock vs Commercial ADS-B Antenna

This is a follow up to RTL2832U ADS-B Performance Testing

We have already determined that an RTL2832U DVB-T stick running gr-air-modes makes a fairly good ADS-B data receiver for ~$25. Even with the little stock antenna that comes with it sitting indoors can give you a 60 – 70 nm range. So how would it do with a commercial 1090MHz antenna connected? I was able to borrow a commercial 1090MHz antenna to see how much difference it would make in regards to receiving ADS-B signals using the RTL2832U stick. I was expecting a little better performance, but not much. Boy was I wrong, the commercial 1090MHz antenna made a huge difference in ADS-B reception with the RTL2832U stick. The ADS-B message rate increased dramatically as well as the range. Also, the directional sensitivity improved allowing reception of ADS-B signals from wider area. To be fair to the stock antenna, I did not mount the commercial antenna out side, but left in on my workbench in the same location that I originally tested the stock antenna.…

Raspberry Pi as Remote Server for RTL2832u SDR

Since this project was posted it has been brought to our attention that RTL2832U / R820T sticks may not be fully supported in the RTL drivers used here. The RTL2832U / E4000 sticks work fine.

One of the often overlooked features of the RTL drivers for the RTL2832U SDR sticks is the TCP server. The TCP server allows you to send data from the RTL2832U stick across your home network to a remote PC running a program to process the data back into SDR information such as SDR Sharp. While the Raspberry Pi is not quite powerful enough to run current programs to decode and process the SDR data from the RTL2832U stick, it can do a very good job of running the rtl_tcp server. This means that you can plug the RTL2832U stick directly into the Raspberry Pi and wind up with a very small and portable SDR radio server. You can either plug the Raspberry Pi directly to your router or use Wifi for more flexibility in placement. If you decide to go the wifi route, I would suggest you use wireless N since bandwidth can be an issue. You can use either a WiFi dongle …

ADS-B Sharing Server on a Stick (or a Pi)

Many ADS-B hobbyist like to share data with the public. Their are several sharing services out there that one can use to do this. However, one of the draw backs of sharing data to some hobbyist is having to tie up a large, ¬†power hungry, noisy, and expensive computer to do this. Why not use a small, low power, quiet, cheap computer to do this? Well you can, with either the $35 Raspberry Pi or the $70 MK802. Both units include fanless low power ARM chips to provide the computing power you need in a tiny package. The ARM processors in the MK802 or Raspberry Pi are not very powerful, but they are plenty powerful for ADS-B data sharing. Both systems run modified versions of common Linux distributions that you will need to install. This project is more of a proof of concept and there are probably more details to be worked out depending on the type of ADS-B receiver, how it’s connected to the server (USB or IP), and the data format it sends. The testing was done with a RTL3832u as a receiver with gr-air-modes sending ADS-B data over TCP port 30003 in Kinetics SBS-1 format.…