prism2-usb-firmware-installer 0.2.9+dfsg-5 (armhf binary) in ubuntu trusty

 prism2-usb-firmware-installer will at the time of its own installation
 download the firmware files for the prism2_usb devices from the
 upstream code repository and convert them to the format used by the
 kernel modules since 2.6.32.
 .
 The downloaded file will be used as-is by the 2.6.31 kernel. If you
 have an earlier kernel you will have to install the
 linux-wlan-ng-firmware package instead.
 .
 Note that only some adapters really need a firmware file and that
 firmware files are not completely free (in the sense of freely
 redistributable), which is why this package exists.