calc_freq_offset.m

The GSMSP uses the USRP hardware device to receive data from the GSM band. This data is raw and pre

function frequency_offset_rads = calc_freq_offset(s, bcch_start, OSR)

SR = 270833;
GUARD = 6 * OSR;
LENGTH = 148 * OSR - 2 * GUARD;


t = s(bcch_start+GUARD:bcch_start+GUARD+LENGTH);
L = length(t);
da = angle(t(1:L-1) .* conj(t(2:L)));
v = mean(da);


frequency_offset_rads = -(pi/2/OSR) - v;