Going full duplex with amateur satellites, part 2 : Installing Gqrx SDR software and the first tests / 2017-03-26

With the hardware available it's now time to test the first part of the software setup: whether I can have running software defined radio.

To (re)install Gqrx I followed the instructions at Install Gqrx SDR on Ubuntu Linux. The first 'sudo apt-get purge --auto-remove' steps removed a lot of software and the latter 'sudo apt-get install' steps added newer (or maybe the same) versions. But I was glad to do a full reinstall, I have had weird problems with gqrx versions before. The laptop on which I am doing this has had an install of gqrx before, but was upgraded from Ubuntu 14.04 LTS to Ubuntu 16.04 LTS in the mean time, so a clean reinstall seemed a good idea.

I plugged in the RTL-SDR stick and checked whether no drivers were installed, which was indeed still correct. The kernel messages:

[156490.915435] usb 2-2: new high-speed USB device number 7 using xhci_hcd
[156491.111136] usb 2-2: New USB device found, idVendor=0bda, idProduct=2838
[156491.111141] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[156491.111143] usb 2-2: Product: RTL2838UHIDIR
[156491.111145] usb 2-2: Manufacturer: Realtek
[156491.111147] usb 2-2: SerialNumber: 00000001

To make sure the drivers aren't loaded, I have a /etc/modprobe.d/local-blacklist.conf with:

blacklist dvb_usb_rtl28xxu
blacklist rtl2830
blacklist rtl2832
blacklist lirc_dev

To test it with the 'minimal' setup I started with just the RTL-SDR and a simple antenna, and Gqrx. Enabled remote control in Gqrx and added a radio 'gqrx-sdr' in Gpredict with host 'localhost' and port '7356' (default for gqrx remote control) and Radio type 'RX only', PTT status 'none'.

Gqrx controlled by Gpredict, tracking a satellite

Now I can select this radio as '1. Device' in the 'Gpredict Radio Control' window, and select 'Engage' when the right satellite, transponder and 'Track' are selected, after which Gqrx nicely follows the frequency Gpredict has calculated.

No signal yet as I am testing this indoors with the small default antenna that came with the RTL-SDR stick. That will not pick up weak signals!