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# DAB Frame constants
# Sources:
# - etsi_EN_300_401_v010401p p145
# - Measured with USRP B200
import numpy as np
class const:
def __init__(self, sample_rate):
self.sample_rate = sample_rate
# Time domain
self.T_F = sample_rate / 2048000 * 196608 # Transmission frame duration
self.T_NULL = sample_rate / 2048000 * 2656 # Null symbol duration
self.T_S = sample_rate / 2048000 * 2552 # Duration of OFDM symbols of indices l = 1, 2, 3,... L;
self.T_U = sample_rate / 2048000 * 2048 # Inverse of carrier spacing
self.T_C = sample_rate / 2048000 * 504 # Duration of cyclic prefix
# Frequency Domain
# example: np.delete(fft[3328:4865], 768)
self.FFT_delete = 768
self.FFT_delta = 1536 # Number of carrier frequencies
if sample_rate == 2048000:
self.FFT_start = 256
self.FFT_end = 1793
elif sample_rate == 8192000:
self.FFT_start = 3328
self.FFT_end = 4865
else:
raise RuntimeError("Sample Rate '{}' not supported".format(
sample_rate
))
# Calculate sample offset from phase rotation
# time per sample = 1 / sample_rate
# frequency per bin = 1kHz
# phase difference per sample offset = delta_t * 2 * pi * delta_freq
self.phase_offset_per_sample = 1. / sample_rate * 2 * np.pi * 1000
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