I tried to install librtlsdr-dev package and for some reasons I got a nasty
error:
> sudo apt-get install librtlsdr-dev
...
The following packages have unmet dependencies:
librtlsdr-dev : Depends: libusb-1.0-0-dev but it is not installable
I noticed that there was no lib-usb-1.0-0-dev package, so the repository is inconsistent. So what I did was to install the package from Debian Stretch that can be downloaded from here.
You can install it as follows:
wget http://ftp.es.debian.org/debian/pool/main/libu/libusb-1.0/libusb-1.0-0-dev_1.0.21-1_armhf.deb
sudo dpkg -i libusb-1.0-0-dev_1.0.21-1_armhf.deb
Then you should be able to install librtlsdr-dev package correctly.