Kalibrate, or kal, can scan for GSM base stations in a given frequency band and can use those GSM base stations to calculate the local oscillator frequency offset. See http://thre.at/kalibrate Copyright (c) 2010, Joshua Lackey (jl@thre.at) Copyright (c) 2012, Steve Markgraf (steve@steve-m.de) modified for use with hackrf devices, Copyright (c) 2014, Wang Kang (scateu@gmail.com) http://hackrf.net : A Chinese HackRF Community 2014-8-23 Update: Thanks to chris.kuethe@gmail.com who did a bunch of tinkering with this port of kalibrate. https://github.com/ckuethe/kalibrate-hackrf/ This now runs as fast as kalibrate-rtl 2015-3-3 Update: Add ability to specify channel when scanning to check power output for a single channel. Author: [xorrbit](https://github.com/xorrbit)