Friday, 21 November 2014

Radio Sculpture

A sculpture is a physical representation of an idea, a concept or even a feeling. In many ways, anything we can build becomes a sculpture of our thoughts.

Scott Mitchell is a Sculpture Artist and has many works to his name. As an entrant in the Melbourne Prize for Urban Sculpture 2014, Scott set his mind on a sculpture that would divert our attention to the sky. As a propositional work (for a larger version in Melbourne's Royal Park) he decided to build a working Radio Telescope.

Scott approached the Astronomical Society of Victoria and came along to one of the Radio Astronomy section monthly meetings. We spent several hours helping him understand some of the concepts, the science and the electronics behind Radio Astronomy. We also went over the History and the Pioneers of Radio Astronomy. Eventually Scott decided a Horn Antenna would be most appropriate and sculpturally pleasing.
The Horn Antenna has an opening at the wide end to allow radio waves to enter and funnels the waves down to a receiver element at the narrow end, usually just a short wire that is tuned to the particular frequency of interest. Then it connects to an amplifier to greatly increase the signal level. In Scotts design a receiver normally plugged into a computer to pick up Radio and TV signals is used to receive signals on the Hydrogen Line at 1.420 GHz.
The Hydrogen Line is the frequency where neutral Hydrogen atoms emit radio waves and allow us to see into the Cosmos. Other atoms also emit radio waves at different frequencies but Hydrogen is by far the most abundant element and therefore is the easiest to detect. Scott has named his sculpture 'The Listener' and has thoughtfully provided a pair of headphones as part of the display so that visitors can listen in on the static from the Stars much as Ellie Arroway did in the brilliant movie 'Contact'. The display also has a chart recorder under a perspex cover that draws lines representing the level of radio noise being received. From what I saw, the chart paper is replaced every morning at 10am which will give a permanent record of the two weeks that the display is available for viewing.
I visited the sculpture at Federation Square and took a few pictures. I even chatted with quite a few people that came to find out what it was. Being the friendly and knowledgeable fellow that I am I was more than pleased to tell them. I guess I was happy that Radio Astronomy was on display.


Thursday, 5 June 2014

Steering a Dish Antenna

Motor Drives

Firstly, before I write too much more, I should apologize for taking so long to get another article on this blog. I have a new radio astronomy project thats taking a lot of time but is proving interesting. I'll try writing about that shortly.

In the meantime I've worked out a cheap and readily available method of azimuth drive on my dish antenna. Last year I was looking for a way to effectively mount and turn a TVRO type mesh dish and use it as a point-able Radio Astronomy antenna. Thanks to the amazing developments in 3D printing technology there are some very useful devices available through Ebay.

I decided that I needed a cheap and usable stepper motor to control the azimuth (from 0 to 360 degrees). With careful attention to mounting hardware in order to reduce friction and the amount of torque needed I think I have a reasonably practical method of control.

The stepper motor I'm now using is a Nema17, 2 phase, 1.8 degree step device with a 5mm shaft. This is fitted with a 12 tooth aluminium timing pulley and drives a timing belt of two meters in length. The pulley and belt are available on Ebay as part of a kit for position control on a 3D printer.

The parabolic dish mounting is a circular disk 600mm in diameter around which the timing belt is wrapped and fixed at either end. Some slack in the belt is needed to go around the timing pulley.

In the picture above, taken from a random seller on Ebay, the timing belt is a rubber belt but reinforced with fibreglass to give it a lot of strength. The belt wont stretch therefore wont lose tension once fitted to the azimuth drive table.

The best part about this is the ability (I hope) for the Arduino and associated stepper controller shield to drive the stepper motor (rated at 2 Amps) without too much effort. I have read a lot of reports where the stepper shield H-Bridge L-298 overheats very quickly so a stick-on heat sink and reduction in voltage may be needed to reduce heat.

The other important part of this will be a brake system. When power on the stepper motor is off, the motor turns easily and will result in the dish rotating in a breeze. I think the best option will be a relay controlled device that will hold the azimuth table while the stepper shield is powered off.

The next post will hopefully show the stepper motor, toothed pulley and belt with the azimuth table all mounted together.



Monday, 12 August 2013

Receiving Radio Noise

What Are We Receiving?

One of the main aims of this project is to receive noise. Actually what we will be receiving is the energy produced by neutral Hydrogen atoms when its electron changes spin direction. I don't want to get into the science in this blog but I have included a link for those that do ( Wikipedia Hydrogen line info ) but suffice to say that Hydrogen Atoms produce a radio signal on 1420 MHz that we can receive with our Radio Telescope. This is known as the Hl line and can tell us a lot about our Universe.

We don't receive a signal just at 1420 MHz. Instead, because things in our Universe are moving away or towards us, the radio frequency is shifted slightly up or down due to the Doppler Effect much as a siren changes tone as it moves toward or away from us. Some classic Galactic Charts of the Milky Way show a pronounced peak in the frequency when we look at different parts of our Galaxy.

Image courtesy of
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
This Hl chart recorded by Marcus Leech shows the offset from the center frequency of 1420.4058 MHz while centered on Cygnus. Note that the data shown in the chart is averaged over a period of 20 minutes from 40 samples. Marcus uses Gnu-Radio with an SDR receiver. We will have a look at this shortly.

Our Milky Way Galaxy is in the shape of a disk with a super massive black hole at the center. As it has evolved over time, arms have formed in the disk allowing us to see greater density in different parts of the Galaxy. Our Solar System is located in one of the arms so we see different star density in different directions.

The constellation of Cygnus lies in the area of one of the arms that moves toward us resulting in an increase in the frequency of the signal. If we looked elsewhere we might see a corresponding decrease in frequency if that part of the Galaxy was moving away from us.

One of the most exciting discoveries of the 20th Century would have to be Ewen and Purcells reception of the Hydrogen Line emission. Reported in 'Nature' in 1951, the document is worth a read Ewen and Purcell, Nature 1951

Receiving at 1420 MHz.

In a later post I will take us through building the hardware we will be mounting at the focal point of our dish antenna. While we are using a 2.4 Meter mesh dish to receive our neutral hydrogen it must be noted that a smaller dish will work although not as well. The above image from Marcus Leech was obtained through a system using a 90cm solid metal dish. The main difference with bigger dish size is a resulting larger signal peak above the noise.

Noise sources can be external and internal. If we replace our antenna feed with, say, a 50 Ohm resistor at room temperature we see noise in our receiver system plus whatever our resistor produces. This is a good way to get a 'noise figure' for our receiver. Of course each part of our receiver contributes its own little bit to our overall 'internal noise'.

When we connect our feed point antenna to the receiver our noise level should increase. If we point our antenna at the ground we will receive a higher level of noise. This is because warm objects emit radiation. If we then point our antenna at the sky we should see a drop in the level. We should now see a Noise Floor consisting of Internal Receiver Noise + Thermal Noise + Galactic Noise.

The SDR Receiver.

I am building my receiver as a complete modular unit so I can swap out a section if needed. It consists of a horn and cavity made with copper and fiberglass PCB material with a monopole antenna (4.6cm) placed 1/2 wavelength (8.8cm) from the rear of the cavity. Following this is a 28db gain Low Noise Amplifier. This is our first source of unwanted noise. This should contribute only about 0.3db of noise to our overall receiver noise. Any noise created here will get amplified later so its best to have lowest noise figures early on.

The next part of the receiver is a Bandpass Filter tuned to 1420 MHz. This limits unwanted signals on other frequencies getting into our receiver. Loss through the filter should be in the order of 1db and our 3db point is about 150MHz. I have used the microstripline 3 pole design from an article on 1296MHz Bandpass Filter and reduced the striplines slightly for 1420MHz. After this we have a second high gain low noise amplifier with approximately 20db gain and a noise figure of 0.8db.

At this point the received signal enters the SDR. The Software Defined Radio consists of two devices. A radio tuner (this can be an E4000(60MHz to 1700MHz) or R820T(24MHz to 1850MHz)) which does the actual Radio Frequency Tuning and the RTL2832U which converts the RF signal to a digital I/Q signal then serializes it for our USB connection. These are available on Ebay now for around $10.

I have read some reports but yet to run tests and confirm for myself that the SDR has a noise figure of around 3.5 to 3.7db.

The Raspberry Pi.

We need to plug our SDR into something. I'm using a Raspberry Pi computer as the host for our data as well as controlling the frequency of the SDR. In a previous post I have covered the software installed on the Raspberry Pi to interface with the SDR. Essentially the Raspberry Pi works as a server allowing us to connect to it from another computer. This can be a local computer a short distance away or if you have sufficient bandwidth > 2 Mb/s you can connect from the Internet.

Our Raspberry Pi then works like a Data Pump with an IP address we can connect to. We can receive data packets that are digital samples of our RF data that was converted in the SDR receiver. Several different software packages can take this data and process it for us, whether it be SDR# on a Windows computer and present it as a spectrum / waterfall display or more preferably using Linux and Gnu-Radio and the massive advantages of designed block processing models with Gnu Radio Companion (GRC).

GRC - Wideband FM Flow Graph

Gnu Radio - Wideband FM Receiver FFT Plot

Flow graphs can be designed in GRC to use the RTL_TCP block as a remote connected SDR receiver. Your Gnu Radio data processing can then occur on a powerful computer remote from the Dish Antenna and SDR receiver with its Raspberry Pi data pump.

Gnu Radio on Linux Mint

I thought I'd end this post with a quick run through for setting up your own data processing system. After having experimented over the last few months with different configurations I highly recommend Linux Mint as the operating system of choice. Gnu Radio installs and runs extremely smoothly and should have no problem with an SDR receiver as your signal source.

I have a preference for Linux Mint 14 (Nadia with Cinnamon). They do have different desktop interfaces so you might prefer the later Linux Mint 15 'Olivia' with the Xfce desktop. Head over to their website at and pick a version to try out. Its probably best to have a minimum of a Core2Duo processor and at least 2 GB of ram. Make sure you download the right version, either 64bit or 32bit, for your motherboard. Note that the 32bit version will run on 32 or 64bit hardware.

You should see a list of Mirror sites. Download from one closest to you and save the ISO file. Burning the ISO to a disk will depend on your current operating system. If you have Windows 7 you'll probably have a DVD burner program. If not then it might be worthwhile googling how to burn an ISO to a DVD.

Once you have your DVD ready, boot up your computer using the DVD with Linux Mint and go through the Live DVD experience. At the desktop run the Install Mint icon and fingers crossed you should now have installed Mint. Note that you can do a Dual Boot and have Windows 7 and Linux Mint on the one machine if you have the hard drive space. For our purposes though we want this to be our workhorse for analyzing our Radio Astronomy data.

You should now have a working Linux Mint operating system. Its time to set up Gnu Radio. I've seen comments from many people on hundreds of forums that make hard work out of getting Gnu Radio installed and working. By far the best way is to visit Marcus Leech's website at SBRAC and get his script for installing Gnu Radio. The file at is a shell script. You should see text starting with '#!/bin/bash'. Copy and paste the text to a file on your desktop using Gedit or similar text editor and call it ''. Right click the file, select 'Properties' and tick the box to allow the script to execute as a file.

We should now run the shell script. Right click and 'Run' or select 'Open in Terminal'. The script should now start checking for files it needs, downloading source files and compiles the software then installs it. This will take a long time! Be patient. On a slowish computer it could take over an hour.

Once installed you should have a new menu item called GRC. Marcus Leech has written a brilliant Gnu Radio Flow Graph for Radio Astronomy called 'simple_ra.grc' which is anything but 'simple'. It does however provide some really useful tools for Radio Astronomy observation.

Plug in your SDR receiver to a spare USB port and get started playing with Gnu Radio. I have set up a section on my Amateur Radio website at with useful files I've collected including Gnu Radio Flow Graphs that you can plug in to GRC and experiment with your SDR receiver.

My next post should have some interesting build information and photos of the Focal Point receiver hardware.


Robert Arrowsmith.

Wednesday, 10 July 2013

Part Six. Setting up the Dish Controller.

First Look at the Arduino

My Radio Astronomy project is slowly taking shape. The LCD shield for the Arduino Uno controller arrived today. I paid an extra $1.60 for express post from Hong Kong and it was here in three days. Amazing! It did have $28 Hong Kong dollars worth of stamps on it!

Over the last couple of days I've been putting together some preliminary software for the Arduino to communicate with the LCD shield and the L298 motor driver shield. Mostly its 'sample' code that is available for testing shields and makes it quick to run through some ideas I've got for the actual Dish Controller software.

So far it reads the six pushbuttons on the LCD shield and shows on the display which button has been pressed. I'm really pleased with the look of the display backlighting.

The stack of three boards together looks pretty cool although the L298 motor driver shield is covered by the LCD shield which makes it difficult to access the terminals for the motor power wiring. I think it may be best to bring out the wiring from the motor drive shield to a separate terminal block to give easy access for wiring back to the Azimuth and Elevation motors.

Here's a picture of the three boards stacked together. I've obtained a suitable IP66 diecast metal box for the Dish Controller and power supply to be located in. I was a bit concerned about the height of the stack of three boards but it appears there's enough room to mount it with clearance.

Some thought has gone into the power supply for the Dish Controller. I'm not happy using a switchmode power module, tempting as they are. For most people they are an off-the-shelf regulated power box but I suspect the amount of high frequency noise that would be generated by a switchmode box would be unacceptable and no amount of filtering or shielding could minimise it enough.

I've settled for a toroidal power transformer with 2 x 15 volt windings capable of about 1.6 amps each. This fits nicely at one end of the control box and should give adequate current to power the motors. As the L298 motor driver is limited to 2 amps and the Arduino is using Pulse Width Modulation to limit the power to the motors I think this should be sufficient.

The dimensions of the box are Width 146mm, Length 222mm Height 55mm (including the lid).

One of the tasks this box will also be needed for is providing power and junction wiring for the Raspberry Pi and SDR receiver module mounted at the focal point of the dish. A CAT5 network cable will run from our main computer to the Raspberry Pi through this Dish Controller box and a USB cable will run from the Raspberry Pi back to the Arduino as Dish Position commands will be coming from the Raspberry Pi.

I suck at diagrams.

In my next post I should have the power supply built up and providing power. The Arduino should also be doing some basic functions with controlling the Azimuth and Elevation motors.


Rob Arrowsmith.

Saturday, 6 July 2013

Radio Astronomy Station. Part 5.

Steering The Dish

Its been a busy few weeks in the workshop here. Researching hardware design criteria, cutting and drilling metalwork and general putting things together to see how they looked. 

So the next step in my Radio Telescope Station design has revolved around redesigning the mount for the 2.4 meter mesh dish so I can use the linear actuator I had purchased to move the dish from zero to 90 degrees elevation. The original dish mount was designed as a Polar mount with a single actuator to swing across the ecliptic where Geostationary satellites are located. This has meant changing and adding to the original mount to give the actuator full movement from zero to 90 degrees. Not an easy thing to do.

At the same time I've been looking at options to move the dish around horizontally from zero to 360 degrees. It turns out I have an old antenna rotator in my junk box that may be usable so I'm investigating how to drive it with the rest of the hardware I'm building. The big problem is whether the rotator can handle the weight and stress of the dish. I may even change the dish mount hardware to reduce the overall weight.

Using An Arduino

The other work has been centered on the dish controller electronics. In a previous post I'd mentioned about using the excellent and somewhat ubiquitous Arduino microcontroller platform in the form of the Arduino Uno. Designed as a modular platform the main board has two rows of connectors allowing other 'Shields' to be plugged in depending on the project needs.
Arduino Uno

In my case I'm using a Shield with a Motor Driver L298 to control two electric motors, one in the linear actuator for Elevation of the dish and one in a rotator for Azimuth position.

I had ordered two of the Arduino Motor Drive shields from a Hong Kong supplier through Ebay over six weeks ago and after repeated requests to find out where the goods were and why I hadn't received them I eventually had to put in a dispute with Paypal. It was only $20 for two boards but they quickly refunded the amount. If they ever arrive I'm sure I'll be quick to send them back the $20.

Motor Drive Shield
In the meantime, when it looked like the boards wouldn't arrive, I ordered two more from another supplier for $24 total. Not surprisingly they arrived in 9 days. Needless to say, got a five star rating. Buy from them through Ebay, its about 20% cheaper that way.

I've now managed to put together a pin connection chart for the Arduino.

Arduino Ports.

Arduino Ports
PB5/SCLK...13 Elevation Motor Direction
PB4/MISO...12 Azimuth Motor Direction
PB3/MOSI...11 PWMB - Elevation Motor Drive
PB2/SS........10 LCD Display Backlight Control
PB1/OC1.......9 LCD ENABLE
PB0/ICP.........8 LCD SELECT

PD7/AIN1......7 LCD 7\
PD6/AIN0..... 6 LCD 6 \ LCD 4 Bit Data Bus
PD5/T1......... 5 LCD 5 /
PD4/T0......... 4 LCD 4/
PD3/INT1..... 3 PWMA - Azimuth Motor Drive
PD2/INT0..... 2 Azimuth Pulse Counter
PD1/TXD....... 1 USB Serial Out
PD0/RXD....... 0 USB Serial In

PC5/AD5........Elevation Pulse Counter
PC4/AD4........Elevation switch 90 Degrees
PC3/AD3........Elevation switch 0 Degrees
PC2/AD2........Azimuth Limit Switch 360 Degrees
PC1/AD1........Azimuth Limit Switch 0 Degrees
PC0/AD0........LCD Keyswitch Analog Input

My Arduino hardware design includes a 16x2 LCD Display Shield that sits on top of the Motor Driver Shield. The great thing about this is the ability to get visual feedback when in field adjustments are being performed. The LCD shield also has some small pushbuttons connected through a resistive ladder to one of the A to D pins of the Arduino. Part of the software will be able to read button pushes to adjust UP/DOWN and LEFT/RIGHT control of the dish.

Ebay image of the LCD Shield
When the LCD shield arrives I can start testing the Arduino software.
So far I'm getting together a bunch of example code for the various parts of the controller.

In the next post we'll be looking at the software in some depth and how the dish position is adjusted. I might even have a preliminary enclosure design for the control hardware. There are a few nice IP66 rated waterproof boxes out there that I want to have a look at. I'm steering towards using one with a clear lid that lets me see the LCD Display while the system is in use. I also have control of the LCD backlighting so I can turn it off when not in maintenance mode.



Sunday, 2 June 2013

Using your SDR Pi. Fun stuff.

Tune In with your Pi.

Grab yourself a powered set of computer speakers. One of those amplified ones with the Bass Reflex box and two speakers.

If you're ready to have a bit of fun with your Raspberry Pi and SDR receiver connect the speakers 3.5mm stereo plug into your Raspberry Pi audio out socket. Power up your Raspberry Pi with your USB SDR plugged in and log in when the command line prompt appears. You might want to make sure your SDR stick has the cool little antenna plugged in that came with it.
RasPi + DVB + Speaker plug = FM Stereo

You could also do this remotely using PuTTY on your Windows PC or just use 'SSH' on your Linux computer.

The RTL_SDR software we installed in our Raspberry Pi has a pre-made 'FM' mode that we can call from the command line. If you are now logged in just enter the following:

rtl_fm -f XXX -W -s 200000 -r 48000 - | aplay -r 48k -f S16_LE

NOTE: Replace the XXX with the frequency you want to listen to in Hertz. For our purposes you can enter the frequency for 100MHz as 100.0e6 as per the screen grab below. Its there just after the '-f'.

 Our Raspberry Pi is now an FM Radio Tuner that we can set to pretty much any frequency from 50MHz up to 2200MHz (with a gap around 1100MHz).

While we are building the rest of our Radio Astronomy Station we now have a neat way to play with our Raspberry Pi and SDR receiver. If you want to have a look through the command line options for the FM Receiver try entering:

rtl_fm --help

This results in the following output.

pi@raspberrypi ~ $ rtl_fm --help
rtl_fm, a simple narrow band FM demodulator for RTL2832 based DVB-T receivers

Use:    rtl_fm -f freq [-options] [filename]
    -f frequency_to_tune_to [Hz]
     (use multiple -f for scanning, requires squelch)
     (ranges supported, -f 118M:137M:25k)
    [-s sample_rate (default: 24k)]
    [-d device_index (default: 0)]
    [-g tuner_gain (default: automatic)]
    [-l squelch_level (default: 0/off)]
    [-o oversampling (default: 1, 4 recommended)]
    [-p ppm_error (default: 0)]
    [-E sets lower edge tuning (default: center)]
    [-N enables NBFM mode (default: on)]
    [-W enables WBFM mode (default: off)]
     (-N -s 170k -o 4 -A fast -r 32k -l 0 -D)
    filename (a '-' dumps samples to stdout)
     (omitting the filename also uses stdout)

Experimental options:
    [-r output_rate (default: same as -s)]
    [-t squelch_delay (default: 20)]
     (+values will mute/scan, -values will exit)
    [-M enables AM mode (default: off)]
    [-L enables LSB mode (default: off)]
    [-U enables USB mode (default: off)]
    [-R enables raw mode (default: off, 2x16 bit output)]
    [-F enables high quality FIR (default: off/square)]
    [-D enables de-emphasis (default: off)]
    [-C enables DC blocking of output (default: off)]
    [-A std/fast/lut choose atan math (default: std)]

Produces signed 16 bit ints, use Sox or aplay to hear them.
    rtl_fm ... - | play -t raw -r 24k -e signed-integer -b 16 -c 1 -V1 -
                 | aplay -r 24k -f S16_LE -t raw -c 1
      -s 22.5k - | multimon -t raw /dev/stdin


Saturday, 1 June 2013

Radio Astronomy Station. Part 4.

The Software Defined Radio.

In Part 2, I discussed the various parts of the Radio Astronomy Station and the Raspberry Pi with a USB Software Defined Radio (SDR).

In Part 3 we went through getting the Raspberry Pi working. You should now have a RasPi with a USB Keyboard and Mouse plugged in, power connected with a micro USB mobile phone charger and a screen plugged in to either the composite video RCA socket or getting an awesome picture through the HDMI connector.

If you successfully reached the Linux Rasbian login prompt you should see:

raspberrypi login :

Enter your username which should have defaulted to 'pi'.
Enter your password which is 'raspberry' if you didn't alter it with raspi-config.

You should now see the login message telling you when you last logged in and the GNU/Linux message telling you about free software!

If you have an ethernet cable from your RasPi to your router you should have an active internet connection. The login message we saw earlier shows the IP address of the RasPi. Most likely something like '192.168. something dot something'. It depends on how your router is set up.

We can now do some cool stuff to test our RasPi. On the command line type 'top' (without the quotes) and hit enter. You'll see the current time, how long your RasPi has been active for, how many users are logged in and also the amount of hard work your RasPi is doing. To exit from 'top' just hit 'q' and you should end up back at the command line prompt.

Raspberry Pi running 'top'

The picture here shows two active logins, one from the keyboard and one remote login.

Remote Login

The ability to log in remotely to the Raspberry Pi or in fact any Linux computer is a pretty cool thing to do. You might want to look at installing a program on your PC for logging in with SSH (unless you already use a Linux computer and have all the tools you need). On a Windows PC I use a program called PuTTY ( to log in. Its fairly easy to use. Just dont be put off by the options for using it. Only need three things. IP address, Username, Password to do a remote login. Make sure you use the 'SSH' option.

If you have a Linux PC, just open a terminal window and type 'ssh -l pi (ip address)'. Thats a lower case L not a 'one'.
Update Your Pi.

Ok so thats the hard part over. Your Raspberry Pi is running, you've seen 'TOP' give you a rundown of whats going on. If you haven't done so yet, now might be a good time to Update your operating system. Assuming you have a working internet connection enter the following:

sudo apt-get update

*(Note - 'sudo' means 'superuser do' and 'apt-get' is the cool updating and software installing tool).

Linux being the secure operating system it is, you'll be asked for your password. You should then see your Linux Raspbian querying a bunch of different websites asking for updates on files etc. You can now go ahead and run those updates by entering the following:

sudo apt-get upgrade

Your RasPi already knows your password was entered so it should now start downloading all the relevant updated files for your Linux Raspbian operating system. You were probably also asked if it is ok to download and install xxx Megabytes of updated files.

Once the downloading and upgrading is finished you may want to restart your Linux Raspbian. If you are remotely logged in your connection will be cut so you'll need to reconnect. If you are using keyboard and screen you'll just get a restart. Go ahead and type the following:

sudo shutdown -r now

Wait about 60 seconds while your RasPi goes through its reboot. 'Shutdown' with the -r means 'Shutdown and Reboot' and the 'now' means do it NOW.

If you have a keyboard and screen you'll be seeing the normal restart stuff. If you are using a remote login you'll have to go through the PuTTY login sequence again.

Once back at the command line we're ready for setting up the Software Defined Radio.

Setting up the SDR.

You may find it just as easy to go through Peter Goodhalls web page on setting up the Raspberry Pi. You can read his page here.

Otherwise, if you want to follow it here, here's what we need to enter.

  1. sudo apt-get install git
  2. git clone git://
  3. sudo apt-get install cmake
  4. sudo apt-get install pkg-config
  5. sudo apt-get install libusb-1.0
  6. cd rtl-sdr/
  7. mkdir build
  8. cd build
  9. cmake ../ -DINSTALL_UDEV_RULES=ON
  10. make
  11. sudo make install
  12. sudo ldconfig

If you have completed the steps above you should now have a Raspberry Pi with all the software needed to use the Software Defined Radio USB stick. You should now do another restart so repeat our shutdown sequence from before.

When you get back to the command line and you are logged in, plug in the DVB SDR stick into the spare USB port where the keyboard is. If you are remotely logged in this will be a lot easier without the keyboard connected. You may also want to consider an external powered USB Hub to provide extra USB ports and extra power for USB devices.

Ok lets start up our SDR stick. Type in the following:


You should see a list of USB devices that are plugged in. One of them should be a Realtek RTL2832U which is our Digital Radio device. If you can successfully see this in the USB device list then go ahead and start the SDR.

rtl_tcp -a 192.168. (whatever your RasPi IP address is).

Our SDR is now receiving and ready
You might like to try an App on your Android phone called SDR Touch. While still buggy and prone to crashing it will interface with your SDR radio tuner and produce received audio from your phone.

On your Windows PC try using SDR Sharp ( This makes a good, easy to install application for Windows users. Go to this page and follow the instructions for installing SDR Sharp on a Windows PC.

SDR Sharp running on Windows 7 connected via the network to my Raspberry Pi and SDR receiver
Spend some time getting used to how SDR Sharp works. For now, this makes a great testing program for your SDR receiver. Later on we should look at other SDR software that can give us even more flexability.

Thats one of the advantages with a system like this. We can swap and reconfigure different parts to get better results. At a later stage we could replace the whole Raspberry Pi and SDR receiver with a different SDR package that could work on frequencies as high as 10 GHz.

I hope for now you have fun with your SDR receiver.