That's my function to shift a signal (1024 IQ samples) by some freq. f0. But that doesn't work as intended... def shift_by(x, shift): f0 = shift t = np.arange(0, 1024, 1) exp = np.exp(2j*np.pi*-f0*t) # this is essentially a complex sine wave return x * exp For example, x = shift_by(x, 2000000.0) gives me (weird): this And for x = shift_by(x, 2000000.1): this What am I doing wrong? upd: So, as Paul suggested, the problem was in scaling. def shift_by(x, shift): Ts = 1/sample_rate f0 = shift t = np.arange(0.0, Ts*len(x), Ts) exp = np.exp(2j*np.pi*-f0*t) # this is essentially a complex sine wave return x * exp It gives nice picture: Continue reading...
