gqrx-sdr software package provides Software defined radio receiver, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gqrx-sdr
gqrx-sdr is installed in your system.
Make ensure the gqrx-sdr package were installed using the commands given below,
$ sudo dpkg-query -l | grep gqrx-sdr *
You will get with gqrx-sdr package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Ham Radio |
| Package | gqrx-sdr |
| Version | 2.6-1 |
| Description | Software defined radio receiver |
| Sub Section | hamradio |