PhoneSats and SDR Fun – Build your own Sat Station Cheap!

UPDATE: On 27 Apr 2013 the phonesats are officially silent. Use can still use this guide for many other current and future satellites.

Sidebar update 23 Nov 2013: Please visit my post on how to use RTL-SDR and (V2) to listen to and decode the recently launched Funcube


The recent launch of the PhoneSats got my SDR and satellite juices flowing again. This time I decided to automate things because work seems to get in the way of my satellite listening fun. I found a combination that works great and incorporates FREE software and inexpensive hardware.

What you will need:

Software List

Hardware List

  • Computer – A fairly decent powered computer or laptop is needed to run HDSDR, DDE and Orbitron
  • Cheap Realtek RTL2832U USB DVB Dongle with the E4000 or R820T tuner chipsets
    • Sources:
    • NooElec – Best Price Fast shipping guaranteed compatible chipset R820T
    • – It’s Amazon!
    • Aliexpress – Slow from China shipping but great prices
  • Antenna

Putting it all together:

Please visit the page for the latest information on the cubesats. NOTE: They are not solar powered and are expected to fail about a week after deployment which occurred on April 21st 2013.

Antares Launch Video – As you can see all systems were nominal and deployed nominally. 🙂


  1. Install the Driver with Zadig  – DO NOT install the OEM driver that comes shipped with the device. Use Zadig only. Instructions HERE
  2. Install HDSDR using the defaults
  3. Download the ExtIO_RTL.dll file and place the file in the HDSDR program location (C:Program FilesHDSDR or C:Program Files (x86)HDSDR)
  4. Download and Install Orbitron
  5. Download the MyDDE driver for Orbitron
  6. Unzip the MyDDE driver and place the mydde folder in the Orbitron program directory (C:Program FilesOrbitron or C:Program Files (x86)Orbitron)
  7. Download the PhoneSAT TLE’s and place them in a directory of your choice
  8. Download and unzip UZ7HO’s Sound Modem


  1. Setup Orbitron first by setting your Home location. It will use your Grid square to translate to the lat/long coordinates.
    • Click the Load TLE button and browse to the PhoneSat.txt file. Select the PHONESAT satellite in the Satellites list.
    • Select the Rotor/Radio tab. Input the Downlink frequency, for Phonesats it is 437.425 Mhz.
    • Click the Driver drop down box and select MyDDE
    • Click the Activate button. This will prompt you to browse for the driver. Go to the folder you copied it to under the program directory (C:Program FilesOrbitronmydde or C:Program Files (x86)Orbitronmydde)
    • The MyDDE status window should now be displayed with Satellite data
  2. Launch HDSDR and confirm the  USB Dongle is functioning.
    • Left-click the EXTIO button and turn on the Tuner AGC and RTL AGC.
    •  NOTE: I ran into an issue that required me to launch HDSDR with “Run as Administrator” or I would end up with a ExtIO DLL not active error. Right-click on the HDSDR icon and select “Run as Administrator”. If you want the settings to be persistent you check the run as administrator box located under the compatibility tab while in the shortcut properties.
    • Click on the Options button then Select DDE Client. Set the format to Orbitron and the Sync Type to Tune. If you would like to record the Satellite passes automatically check the “Record all satellite passes” box.
    • Click the Manual connect button and it should give you a green connection successful message.
    • The TUNE indicator on HDSDR should be synced with the Doppler readout in Orbitron. If the Record all satellites option was checked when a satellite comes into view at AOS it will automatically record based on the options set in HDSDR.
  3. Launch UZ7HO’s Sound Modem program
    • In the Modem settings change the modem type to VHF AX.25 1200 baud.
    • Select your input sound device to either Stereo Mix if you have one or you can download VAC (Virtual Audio Cable)
    • Another option would be to use a separate computer or use a Stereo cable loopback. (Actual audio cable looped back to input)

Recording options:

To access the record options, right-click on the red record button. There are a three ways to record on HDSDR: Full RF, IF RF and AF. Full RF will give you the largest file size but capture the entire RF session to go back and replay and analyze. If you are only interested in the audio portion pick the AF recording option for the smallest file size. I like to record the Full RF to see what I missed or see how far the Doppler settings were off. In the case of the Phonesats you can see all three satellites clearly at different frequencies although they are all transmitting on 437.425 Mhz due to Doppler shift. Very cool to see it visually!


  • If you are running Windows 7/8 Pro you may need to add User modify rights to the Program directories (C:Program FilesHDSDR and C:Program FilesOrbitron). You can install the software in a Non-Program Files location (e.g. User Documents) to avoid this step.
  • Use “Run as administrator” when launching HDSDR
  • Be sure no other programs are running in the background causing your system to slow down. The SDR decoding can be CPU intensive.
  • Make sure EXTIO_RTL.dll is located in the program directory C:Program FilesHDSDR or C:Program Files (x86)HDSDR

I hope you enjoy some satellite listening!

Posted on April 24, 2013, in Digital, Satellites, SDR, Software. Bookmark the permalink. Leave a comment.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: