def __init__(self, fft_length, cp_length, occupied_tones, snr, ks, logging=False):
"""
Hierarchical block for receiving OFDM symbols.
The input is the complex modulated signal at baseband.
Synchronized packets are sent back to the demodulator.
Args:
fft_length: total number of subcarriers (int)
cp_length: length of cyclic prefix as specified in subcarriers (<= fft_length) (int)
occupied_tones: number of subcarriers used for data (int)
snr: estimated signal to noise ratio used to guide cyclic prefix synchronizer (float)
ks: known symbols used as preambles to each packet (list of lists)
logging: turn file logging on or off (bool)
"""
gr.hier_block2.__init__(self, "ofdm_receiver",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature2(2, 2, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_char)) # Output signature
bw = (float(occupied_tones) / float(fft_length)) / 2.0
tb = bw*0.08
chan_coeffs = filter.firdes.low_pass (1.0, # gain
1.0, # sampling rate
bw+tb, # midpoint of trans. band
tb, # width of trans. band
filter.firdes.WIN_HAMMING) # filter type
self.chan_filt = filter.fft_filter_ccc(1, chan_coeffs)
win = [1 for i in range(fft_length)]
zeros_on_left = int(math.ceil((fft_length - occupied_tones)/2.0))
ks0 = fft_length*[0,]
ks0[zeros_on_left : zeros_on_left + occupied_tones] = ks[0]
ks0 = fft.ifftshift(ks0)
ks0time = fft.ifft(ks0)
# ADD SCALING FACTOR
ks0time = ks0time.tolist()
SYNC = "pn"
if SYNC == "ml":
nco_sensitivity = -1.0/fft_length # correct for fine frequency
self.ofdm_sync = ofdm_sync_ml(fft_length,
cp_length,
snr,
ks0time,
logging)
elif SYNC == "pn":
nco_sensitivity = -2.0/fft_length # correct for fine frequency
self.ofdm_sync = ofdm_sync_pn(fft_length,
cp_length,
logging)
elif SYNC == "pnac":
nco_sensitivity = -2.0/fft_length # correct for fine frequency
self.ofdm_sync = ofdm_sync_pnac(fft_length,
cp_length,
ks0time,
logging)
# for testing only; do not user over the air
# remove filter and filter delay for this
elif SYNC == "fixed":
self.chan_filt = blocks.multiply_const_cc(1.0)
nsymbols = 18 # enter the number of symbols per packet
freq_offset = 0.0 # if you use a frequency offset, enter it here
nco_sensitivity = -2.0/fft_length # correct for fine frequency
self.ofdm_sync = ofdm_sync_fixed(fft_length,
cp_length,
nsymbols,
freq_offset,
logging)
# Set up blocks
self.nco = analog.frequency_modulator_fc(nco_sensitivity) # generate a signal proportional to frequency error of sync block
self.sigmix = blocks.multiply_cc()
self.sampler = digital.ofdm_sampler(fft_length, fft_length+cp_length)
self.fft_demod = gr_fft.fft_vcc(fft_length, True, win, True)
self.ofdm_frame_acq = digital.ofdm_frame_acquisition(occupied_tones,
fft_length,
cp_length, ks[0])
self.connect(self, self.chan_filt) # filter the input channel
self.connect(self.chan_filt, self.ofdm_sync) # into the synchronization alg.
self.connect((self.ofdm_sync,0), self.nco, (self.sigmix,1)) # use sync freq. offset output to derotate input signal
self.connect(self.chan_filt, (self.sigmix,0)) # signal to be derotated
self.connect(self.sigmix, (self.sampler,0)) # sample off timing signal detected in sync alg
self.connect((self.ofdm_sync,1), (self.sampler,1)) # timing signal to sample at
self.connect((self.sampler,0), self.fft_demod) # send derotated sampled signal to FFT
self.connect(self.fft_demod, (self.ofdm_frame_acq,0)) # find frame start and equalize signal
self.connect((self.sampler,1), (self.ofdm_frame_acq,1)) # send timing signal to signal frame start
self.connect((self.ofdm_frame_acq,0), (self,0)) # finished with fine/coarse freq correction,
self.connect((self.ofdm_frame_acq,1), (self,1)) # frame and symbol timing, and equalization
if logging:
self.connect(self.chan_filt, blocks.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-chan_filt_c.dat"))
self.connect(self.fft_demod, blocks.file_sink(gr.sizeof_gr_complex*fft_length, "ofdm_receiver-fft_out_c.dat"))
self.connect(self.ofdm_frame_acq,
blocks.file_sink(gr.sizeof_gr_complex*occupied_tones, "ofdm_receiver-frame_acq_c.dat"))
self.connect((self.ofdm_frame_acq,1), blocks.file_sink(1, "ofdm_receiver-found_corr_b.dat"))
self.connect(self.sampler, blocks.file_sink(gr.sizeof_gr_complex*fft_length, "ofdm_receiver-sampler_c.dat"))
self.connect(self.sigmix, blocks.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-sigmix_c.dat"))
self.connect(self.nco, blocks.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-nco_c.dat"))
def __init__(
self, fft_length, cp_length, occupied_tones, snr, ks, threshold, options, logging=False
): # apurv++: added num_symbols, use_chan_filt
"""
Hierarchical block for receiving OFDM symbols.
The input is the complex modulated signal at baseband.
Synchronized packets are sent back to the demodulator.
@param params: Raw OFDM parameters
@type params: ofdm_params
@param logging: turn file logging on or off
@type logging: bool
"""
gr.hier_block2.__init__(
self,
"ofdm_receiver",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature3(
3, 3, gr.sizeof_gr_complex * occupied_tones, gr.sizeof_char, gr.sizeof_gr_complex * occupied_tones
),
) # Output signature
# low-pass filter the input channel
bw = (float(occupied_tones) / float(fft_length)) / 2.0
tb = bw * 0.08
lpf_coeffs = gr.firdes.low_pass(
1.0, # gain
1.0, # sampling rate
bw + tb, # midpoint of trans. band
tb, # width of trans. band
gr.firdes.WIN_HAMMING,
) # filter type
self.chan_filt = gr.fft_filter_ccc(1, lpf_coeffs)
self.connect(self, self.chan_filt)
self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "rx-filt.dat"))
zeros_on_left = int(math.ceil((fft_length - occupied_tones) / 2.0))
ks0 = fft_length * [0]
ks0[zeros_on_left : zeros_on_left + occupied_tones] = ks[0]
ks0 = fft.ifftshift(ks0)
ks0time = fft.ifft(ks0)
ks0time = ks0time.tolist()
ks1 = fft_length * [0]
ks1[zeros_on_left : zeros_on_left + occupied_tones] = ks[1]
ks1 = fft.ifftshift(ks1)
ks1time = fft.ifft(ks1)
ks1time = ks1time.tolist()
# sync = ofdm_sync_pn(fft_length, cp_length, True, logging) # raw
sync = ofdm_sync_pn(fft_length, cp_length, True, ks0time, ks1time, threshold, logging) # crosscorr version
use_chan_filt = 1
if use_chan_filt == 0:
self.connect(gr.file_source(gr.sizeof_gr_complex, "chan-filt.dat"), sync)
else:
self.connect(self.chan_filt, sync)
# correct for fine frequency offset computed in sync (up to +-pi/fft_length)
nco_sensitivity = 2.0 / fft_length
nco = gr.frequency_modulator_fc(nco_sensitivity)
sigmix = gr.multiply_cc()
# sample at symbol boundaries
# NOTE: (sync,2) indicates the first sample of the symbol!
sampler = digital_swig.ofdm_sampler(fft_length, fft_length + cp_length, len(ks) + 1, timeout=100) # apurv--
# frequency offset correction #
self.connect((sync, 0), (sigmix, 0))
self.connect((sync, 1), nco, (sigmix, 1))
self.connect(sigmix, (sampler, 0))
self.connect((sync, 2), (sampler, 1))
"""
self.connect((sync,0), (sampler,0))
self.connect((sync,2), (sampler,1)) # timing signal to sample at
self.connect((sync,1), gr.file_sink(gr.sizeof_float, "offset.dat"))
"""
self.connect((sampler, 1), gr.file_sink(gr.sizeof_char, "sampler_timing.dat"))
# self.connect((sampler, 2), gr.file_sink(gr.sizeof_char*fft_length, "sampler_timing_fft.dat"))
# fft on the symbols
win = [1 for i in range(fft_length)]
# see gr_fft_vcc_fftw that it works differently if win = []
fft1 = gr.fft_vcc(fft_length, True, win, True)
self.connect((sampler, 0), fft1)
# use the preamble to correct the coarse frequency offset and initial equalizer
###frame_acq = raw.ofdm_frame_acquisition(fft_length, cp_length, preambles_raw, carriers)
frame_acq = digital_swig.ofdm_frame_acquisition(occupied_tones, fft_length, cp_length, ks)
self.frame_acq = frame_acq
# normal operation #
self.connect((fft1, 0), gr.file_sink(gr.sizeof_gr_complex * options.fft_length, "fft-out.dat"))
self.connect((sampler, 1), gr.file_sink(gr.sizeof_char, "sampler_timing.dat"))
self.connect(fft1, (frame_acq, 0))
self.connect((sampler, 1), (frame_acq, 1))
"""
# enable to have manual input to frame_acq #
self.connect(fft1, gr.null_sink(gr.sizeof_gr_complex*options.fft_length))
self.connect(gr.file_source(gr.sizeof_gr_complex*options.fft_length, "combined.dat"), (frame_acq,0))
self.connect(gr.file_source(gr.sizeof_char, "combined_t.dat"), (frame_acq,1))
"""
# self.connect(fft, gr.null_sink(gr.sizeof_gr_complex*options.fft_length))
# self.connect((sampler, 1), gr.null_sink(gr.sizeof_char))
# self.connect(gr.file_source(gr.sizeof_gr_complex*options.fft_length, "symbols_src.dat"), (frame_acq, 0))
# self.connect(gr.file_source(gr.sizeof_char, "timing.dat"), (frame_acq, 1))
self.connect((frame_acq, 0), (self, 0)) # finished with fine/coarse freq correction
self.connect((frame_acq, 1), (self, 1)) # frame and symbol timing
self.connect((frame_acq, 2), (self, 2)) # hestimates
self.connect((frame_acq, 0), gr.file_sink(gr.sizeof_gr_complex * occupied_tones, "rx-acq.dat"))
self.connect((frame_acq, 1), gr.file_sink(gr.sizeof_char, "timing-acq.dat"))
if logging:
self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "rx-filt.dat"))
self.connect(fft1, gr.file_sink(gr.sizeof_gr_complex * fft_length, "rx-fft.dat"))
self.connect((frame_acq, 0), gr.file_sink(gr.sizeof_gr_complex * occupied_tones, "rx-acq.dat"))
self.connect((frame_acq, 1), gr.file_sink(1, "rx-detect.datb"))
self.connect(sampler, gr.file_sink(gr.sizeof_gr_complex * fft_length, "rx-sampler.dat"))
self.connect(sigmix, gr.file_sink(gr.sizeof_gr_complex, "rx-sigmix.dat"))
self.connect(nco, gr.file_sink(gr.sizeof_gr_complex, "rx-nco.dat"))
def __init__(self,
fft_length,
cp_length,
occupied_tones,
snr,
ks,
threshold,
options,
logging=False):
"""
Hierarchical block for receiving OFDM symbols.
The input is the complex modulated signal at baseband.
Synchronized packets are sent back to the demodulator.
@param fft_length: total number of subcarriers
@type fft_length: int
@param cp_length: length of cyclic prefix as specified in subcarriers (<= fft_length)
@type cp_length: int
@param occupied_tones: number of subcarriers used for data
@type occupied_tones: int
@param snr: estimated signal to noise ratio used to guide cyclic prefix synchronizer
@type snr: float
@param ks: known symbols used as preambles to each packet
@type ks: list of lists
@param logging: turn file logging on or off
@type logging: bool
"""
gr.hier_block2.__init__(
self,
"ofdm_receiver",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
#gr.io_signature2(2, 2, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_char)) # Output signature apurv--
gr.io_signature3(3, 3, gr.sizeof_gr_complex * occupied_tones,
gr.sizeof_char,
gr.sizeof_gr_complex * occupied_tones
)) # apurv++, goes into frame sink for hestimates
#gr.io_signature4(4, 4, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_char, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_gr_complex*fft_length)) # apurv++, goes into frame sink for hestimates
bw = (float(occupied_tones) / float(fft_length)) / 2.0
tb = bw * 0.08
chan_coeffs = gr.firdes.low_pass(
1.0, # gain
1.0, # sampling rate
bw + tb, # midpoint of trans. band
tb, # width of trans. band
gr.firdes.WIN_HAMMING) # filter type
self.chan_filt = gr.fft_filter_ccc(1, chan_coeffs)
win = [1 for i in range(fft_length)]
zeros_on_left = int(math.ceil((fft_length - occupied_tones) / 2.0))
ks0 = fft_length * [
0,
]
ks0[zeros_on_left:zeros_on_left + occupied_tones] = ks[0]
ks0 = fft.ifftshift(ks0)
ks0time = fft.ifft(ks0)
# ADD SCALING FACTOR
ks0time = ks0time.tolist()
nco_sensitivity = -2.0 / fft_length # correct for fine frequency
self.ofdm_sync = ofdm_sync_pn(fft_length, cp_length, ks0time,
threshold, options.threshold_type,
options.threshold_gap,
logging) # apurv++
# Set up blocks
self.nco = gr.frequency_modulator_fc(
nco_sensitivity
) # generate a signal proportional to frequency error of sync block
self.sigmix = gr.multiply_cc()
self.sampler = digital_swig.ofdm_sampler(
fft_length, fft_length + cp_length,
len(ks) + 1, 100
) # 1 for the extra preamble which ofdm_rx doesn't know about (check frame_sink)
self.fft_demod = gr.fft_vcc(fft_length, True, win, True)
self.ofdm_frame_acq = digital_swig.ofdm_frame_acquisition(
occupied_tones, fft_length, cp_length, ks)
if options.verbose:
self._print_verbage(options)
# apurv++ modified to allow collected time domain data to artifically pass through the rx chain #
# to replay the input manually, use this #
#self.connect(self, gr.null_sink(gr.sizeof_gr_complex))
#self.connect(gr.file_source(gr.sizeof_gr_complex, "input.dat"), self.chan_filt)
############# input -> chan_filt ##############
self.connect(self, self.chan_filt)
use_chan_filt = options.use_chan_filt
correct_freq_offset = 0
if use_chan_filt == 1:
##### chan_filt -> SYNC, chan_filt -> SIGMIX ####
self.connect(self.chan_filt, self.ofdm_sync)
if correct_freq_offset == 1:
# enable if frequency offset correction is required #
self.connect(self.chan_filt,
gr.delay(gr.sizeof_gr_complex, (fft_length)),
(self.sigmix, 0)) # apurv++ follow freq offset
else:
self.connect(self.chan_filt, (self.sampler, 0))
###self.connect(self.chan_filt, gr.delay(gr.sizeof_gr_complex, (fft_length)), (self.sampler, 0)) ## extra delay
#self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-chan_filt_c.dat"))
elif use_chan_filt == 2:
#### alternative: chan_filt-> NULL, file_source -> SYNC, file_source -> SIGMIX ####
self.connect(self.chan_filt, gr.null_sink(gr.sizeof_gr_complex))
if correct_freq_offset == 1:
self.connect(
gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"),
self.ofdm_sync)
self.connect(
gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"),
gr.delay(gr.sizeof_gr_complex, (fft_length)),
(self.sigmix, 0))
else:
self.connect(
gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"),
self.ofdm_sync)
self.connect(
gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"),
(self.sampler, 0))
else:
# chan_filt->NULL #
self.connect(self.chan_filt, gr.null_sink(gr.sizeof_gr_complex))
method = options.method
if method == -1:
################## for offline analysis, dump sampler input till the frame_sink, using io_signature4 #################
if correct_freq_offset == 1:
# enable if frequency offset correction is required #
self.connect((self.ofdm_sync, 0), self.nco,
(self.sigmix, 1)) # freq offset (0'ed :/)
self.connect(self.sigmix,
(self.sampler, 0)) # corrected output (0'ed FF)
self.connect((self.ofdm_sync, 1),
gr.delay(gr.sizeof_char, fft_length),
(self.sampler, 1)) # timing signal
else:
# disable frequency offset correction completely #
self.connect((self.ofdm_sync, 0),
gr.null_sink(gr.sizeof_float))
self.connect((self.ofdm_sync, 1),
(self.sampler, 1)) # timing signal,
#self.connect((self.ofdm_sync,0), (self.sampler, 2)) ##added
##self.connect((self.ofdm_sync,1), gr.delay(gr.sizeof_char, fft_length+cp_length), (self.sampler, 1)) # timing signal, ##extra delay
# route received time domain to sink (all-the-way) for offline analysis #
self.connect((self.sampler, 0), (self.ofdm_frame_acq, 2))
#self.connect((self.sampler, 1), gr.file_sink(gr.sizeof_char*fft_length, "sampler_timing.dat"))
elif method == 0:
# NORMAL functioning #
if correct_freq_offset == 1:
self.connect(
(self.ofdm_sync, 0), self.nco, (self.sigmix, 1)
) # use sync freq. offset output to derotate input signal
self.connect(
self.sigmix,
(self.sampler,
0)) # sample off timing signal detected in sync alg
self.connect((self.ofdm_sync, 1),
gr.delay(gr.sizeof_char, fft_length),
(self.sampler, 1)) # delay?
else:
self.connect((self.ofdm_sync, 1), (self.sampler, 1))
#self.connect((self.sampler, 2), (self.ofdm_frame_acq, 2))
#######################################################################
use_default = options.use_default
if use_default == 0: #(set method == 0)
# sampler-> NULL, replay trace->fft_demod, ofdm_frame_acq (time domain) #
#self.connect((self.sampler, 0), gr.null_sink(gr.sizeof_gr_complex*fft_length))
#self.connect((self.sampler, 1), gr.null_sink(gr.sizeof_char*fft_length))
self.connect(
gr.file_source(gr.sizeof_gr_complex * fft_length,
"symbols_src.dat"), self.fft_demod)
self.connect(
gr.file_source(gr.sizeof_char * fft_length, "timing_src.dat"),
(self.ofdm_frame_acq, 1))
self.connect(self.fft_demod, (self.ofdm_frame_acq, 0))
elif use_default == 1: #(set method == -1)
# normal functioning #
self.connect(
(self.sampler, 0),
self.fft_demod) # send derotated sampled signal to FFT
self.connect((self.sampler, 1),
(self.ofdm_frame_acq,
1)) # send timing signal to signal frame start
self.connect(self.fft_demod, (self.ofdm_frame_acq, 0))
elif use_default == 2:
# replay directly to ofdm_frame_acq (frequency domain) #
self.connect(
gr.file_source(gr.sizeof_gr_complex * fft_length,
"symbols_src.dat"), (self.ofdm_frame_acq, 0))
self.connect(
gr.file_source(gr.sizeof_char * fft_length, "timing_src.dat"),
(self.ofdm_frame_acq, 1))
########################### some logging start ##############################
#self.connect((self.ofdm_sync,1), gr.delay(gr.sizeof_char, fft_length), gr.file_sink(gr.sizeof_char, "ofdm_sync_pn-peaks_b.dat"))
#self.connect((self.sampler, 0), gr.file_sink(gr.sizeof_gr_complex*fft_length, "ofdm_receiver-sampler_c.dat"))
#self.connect((self.sampler, 1), gr.file_sink(gr.sizeof_char*fft_length, "ofdm_timing_sampler_c.dat"))
############################ some logging end ###############################
self.connect((self.ofdm_frame_acq, 0),
(self, 0)) # finished with fine/coarse freq correction,
self.connect((self.ofdm_frame_acq, 1),
(self, 1)) # frame and symbol timing, and equalization
self.connect((self.ofdm_frame_acq, 2),
(self, 2)) # equalizer: hestimates
#self.connect((self.ofdm_frame_acq,3), (self,3)) # ref sampler above
# apurv++ ends #
#self.connect(self.ofdm_frame_acq, gr.file_sink(gr.sizeof_gr_complex*occupied_tones, "ofdm_receiver-frame_acq_c.dat"))
#self.connect((self.ofdm_frame_acq,1), gr.file_sink(1, "ofdm_receiver-found_corr_b.dat"))
# apurv++ log the fine frequency offset corrected symbols #
#self.connect((self.ofdm_frame_acq, 1), gr.file_sink(gr.sizeof_char, "ofdm_timing_frame_acq_c.dat"))
#self.connect((self.ofdm_frame_acq, 2), gr.file_sink(gr.sizeof_gr_complex*occupied_tones, "ofdm_hestimates_c.dat"))
#self.connect(self.fft_demod, gr.file_sink(gr.sizeof_gr_complex*fft_length, "ofdm_receiver-fft_out_c.dat"))
#self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-chan_filt_c.dat"))
#self.connect(self, gr.file_sink(gr.sizeof_gr_complex, "ofdm_input_c.dat"))
# apurv++ end #
if logging:
self.connect(
self.chan_filt,
gr.file_sink(gr.sizeof_gr_complex,
"ofdm_receiver-chan_filt_c.dat"))
self.connect(
self.fft_demod,
gr.file_sink(gr.sizeof_gr_complex * fft_length,
"ofdm_receiver-fft_out_c.dat"))
self.connect(
self.ofdm_frame_acq,
gr.file_sink(gr.sizeof_gr_complex * occupied_tones,
"ofdm_receiver-frame_acq_c.dat"))
self.connect((self.ofdm_frame_acq, 1),
gr.file_sink(1, "ofdm_receiver-found_corr_b.dat"))
self.connect(
self.sampler,
gr.file_sink(gr.sizeof_gr_complex * fft_length,
"ofdm_receiver-sampler_c.dat"))
#self.connect(self.sigmix, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-sigmix_c.dat"))
self.connect(
self.nco,
gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-nco_c.dat"))
def __init__(self, fft_length, cp_length, occupied_tones, snr, ks, threshold, options, logging=False):
"""
Hierarchical block for receiving OFDM symbols.
The input is the complex modulated signal at baseband.
Synchronized packets are sent back to the demodulator.
@param fft_length: total number of subcarriers
@type fft_length: int
@param cp_length: length of cyclic prefix as specified in subcarriers (<= fft_length)
@type cp_length: int
@param occupied_tones: number of subcarriers used for data
@type occupied_tones: int
@param snr: estimated signal to noise ratio used to guide cyclic prefix synchronizer
@type snr: float
@param ks: known symbols used as preambles to each packet
@type ks: list of lists
@param logging: turn file logging on or off
@type logging: bool
"""
gr.hier_block2.__init__(
self,
"ofdm_receiver",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
# gr.io_signature2(2, 2, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_char)) # Output signature apurv--
gr.io_signature3(
3, 3, gr.sizeof_gr_complex * occupied_tones, gr.sizeof_char, gr.sizeof_gr_complex * occupied_tones
),
) # apurv++, goes into frame sink for hestimates
# gr.io_signature4(4, 4, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_char, gr.sizeof_gr_complex*occupied_tones, gr.sizeof_gr_complex*fft_length)) # apurv++, goes into frame sink for hestimates
bw = (float(occupied_tones) / float(fft_length)) / 2.0
tb = bw * 0.08
chan_coeffs = gr.firdes.low_pass(
1.0, # gain
1.0, # sampling rate
bw + tb, # midpoint of trans. band
tb, # width of trans. band
gr.firdes.WIN_HAMMING,
) # filter type
self.chan_filt = gr.fft_filter_ccc(1, chan_coeffs)
win = [1 for i in range(fft_length)]
zeros_on_left = int(math.ceil((fft_length - occupied_tones) / 2.0))
ks0 = fft_length * [0]
ks0[zeros_on_left : zeros_on_left + occupied_tones] = ks[0]
ks0 = fft.ifftshift(ks0)
ks0time = fft.ifft(ks0)
# ADD SCALING FACTOR
ks0time = ks0time.tolist()
nco_sensitivity = -2.0 / fft_length # correct for fine frequency
self.ofdm_sync = ofdm_sync_pn(
fft_length, cp_length, ks0time, threshold, options.threshold_type, options.threshold_gap, logging
) # apurv++
# Set up blocks
self.nco = gr.frequency_modulator_fc(
nco_sensitivity
) # generate a signal proportional to frequency error of sync block
self.sigmix = gr.multiply_cc()
self.sampler = digital_swig.ofdm_sampler(
fft_length, fft_length + cp_length, len(ks) + 1, 100
) # 1 for the extra preamble which ofdm_rx doesn't know about (check frame_sink)
self.fft_demod = gr.fft_vcc(fft_length, True, win, True)
self.ofdm_frame_acq = digital_swig.ofdm_frame_acquisition(occupied_tones, fft_length, cp_length, ks)
if options.verbose:
self._print_verbage(options)
# apurv++ modified to allow collected time domain data to artifically pass through the rx chain #
# to replay the input manually, use this #
# self.connect(self, gr.null_sink(gr.sizeof_gr_complex))
# self.connect(gr.file_source(gr.sizeof_gr_complex, "input.dat"), self.chan_filt)
############# input -> chan_filt ##############
self.connect(self, self.chan_filt)
use_chan_filt = options.use_chan_filt
correct_freq_offset = 0
if use_chan_filt == 1:
##### chan_filt -> SYNC, chan_filt -> SIGMIX ####
self.connect(self.chan_filt, self.ofdm_sync)
if correct_freq_offset == 1:
# enable if frequency offset correction is required #
self.connect(
self.chan_filt, gr.delay(gr.sizeof_gr_complex, (fft_length)), (self.sigmix, 0)
) # apurv++ follow freq offset
else:
self.connect(self.chan_filt, (self.sampler, 0))
###self.connect(self.chan_filt, gr.delay(gr.sizeof_gr_complex, (fft_length)), (self.sampler, 0)) ## extra delay
# self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-chan_filt_c.dat"))
elif use_chan_filt == 2:
#### alternative: chan_filt-> NULL, file_source -> SYNC, file_source -> SIGMIX ####
self.connect(self.chan_filt, gr.null_sink(gr.sizeof_gr_complex))
if correct_freq_offset == 1:
self.connect(gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"), self.ofdm_sync)
self.connect(
gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"),
gr.delay(gr.sizeof_gr_complex, (fft_length)),
(self.sigmix, 0),
)
else:
self.connect(gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"), self.ofdm_sync)
self.connect(gr.file_source(gr.sizeof_gr_complex, "chan_filt.dat"), (self.sampler, 0))
else:
# chan_filt->NULL #
self.connect(self.chan_filt, gr.null_sink(gr.sizeof_gr_complex))
method = options.method
if method == -1:
################## for offline analysis, dump sampler input till the frame_sink, using io_signature4 #################
if correct_freq_offset == 1:
# enable if frequency offset correction is required #
self.connect((self.ofdm_sync, 0), self.nco, (self.sigmix, 1)) # freq offset (0'ed :/)
self.connect(self.sigmix, (self.sampler, 0)) # corrected output (0'ed FF)
self.connect(
(self.ofdm_sync, 1), gr.delay(gr.sizeof_char, fft_length), (self.sampler, 1)
) # timing signal
else:
# disable frequency offset correction completely #
self.connect((self.ofdm_sync, 0), gr.null_sink(gr.sizeof_float))
self.connect((self.ofdm_sync, 1), (self.sampler, 1)) # timing signal,
# self.connect((self.ofdm_sync,0), (self.sampler, 2)) ##added
##self.connect((self.ofdm_sync,1), gr.delay(gr.sizeof_char, fft_length+cp_length), (self.sampler, 1)) # timing signal, ##extra delay
# route received time domain to sink (all-the-way) for offline analysis #
self.connect((self.sampler, 0), (self.ofdm_frame_acq, 2))
# self.connect((self.sampler, 1), gr.file_sink(gr.sizeof_char*fft_length, "sampler_timing.dat"))
elif method == 0:
# NORMAL functioning #
if correct_freq_offset == 1:
self.connect(
(self.ofdm_sync, 0), self.nco, (self.sigmix, 1)
) # use sync freq. offset output to derotate input signal
self.connect(self.sigmix, (self.sampler, 0)) # sample off timing signal detected in sync alg
self.connect((self.ofdm_sync, 1), gr.delay(gr.sizeof_char, fft_length), (self.sampler, 1)) # delay?
else:
self.connect((self.ofdm_sync, 1), (self.sampler, 1))
# self.connect((self.sampler, 2), (self.ofdm_frame_acq, 2))
#######################################################################
use_default = options.use_default
if use_default == 0: # (set method == 0)
# sampler-> NULL, replay trace->fft_demod, ofdm_frame_acq (time domain) #
# self.connect((self.sampler, 0), gr.null_sink(gr.sizeof_gr_complex*fft_length))
# self.connect((self.sampler, 1), gr.null_sink(gr.sizeof_char*fft_length))
self.connect(gr.file_source(gr.sizeof_gr_complex * fft_length, "symbols_src.dat"), self.fft_demod)
self.connect(gr.file_source(gr.sizeof_char * fft_length, "timing_src.dat"), (self.ofdm_frame_acq, 1))
self.connect(self.fft_demod, (self.ofdm_frame_acq, 0))
elif use_default == 1: # (set method == -1)
# normal functioning #
self.connect((self.sampler, 0), self.fft_demod) # send derotated sampled signal to FFT
self.connect((self.sampler, 1), (self.ofdm_frame_acq, 1)) # send timing signal to signal frame start
self.connect(self.fft_demod, (self.ofdm_frame_acq, 0))
elif use_default == 2:
# replay directly to ofdm_frame_acq (frequency domain) #
self.connect(gr.file_source(gr.sizeof_gr_complex * fft_length, "symbols_src.dat"), (self.ofdm_frame_acq, 0))
self.connect(gr.file_source(gr.sizeof_char * fft_length, "timing_src.dat"), (self.ofdm_frame_acq, 1))
########################### some logging start ##############################
# self.connect((self.ofdm_sync,1), gr.delay(gr.sizeof_char, fft_length), gr.file_sink(gr.sizeof_char, "ofdm_sync_pn-peaks_b.dat"))
# self.connect((self.sampler, 0), gr.file_sink(gr.sizeof_gr_complex*fft_length, "ofdm_receiver-sampler_c.dat"))
# self.connect((self.sampler, 1), gr.file_sink(gr.sizeof_char*fft_length, "ofdm_timing_sampler_c.dat"))
############################ some logging end ###############################
self.connect((self.ofdm_frame_acq, 0), (self, 0)) # finished with fine/coarse freq correction,
self.connect((self.ofdm_frame_acq, 1), (self, 1)) # frame and symbol timing, and equalization
self.connect((self.ofdm_frame_acq, 2), (self, 2)) # equalizer: hestimates
# self.connect((self.ofdm_frame_acq,3), (self,3)) # ref sampler above
# apurv++ ends #
# self.connect(self.ofdm_frame_acq, gr.file_sink(gr.sizeof_gr_complex*occupied_tones, "ofdm_receiver-frame_acq_c.dat"))
# self.connect((self.ofdm_frame_acq,1), gr.file_sink(1, "ofdm_receiver-found_corr_b.dat"))
# apurv++ log the fine frequency offset corrected symbols #
# self.connect((self.ofdm_frame_acq, 1), gr.file_sink(gr.sizeof_char, "ofdm_timing_frame_acq_c.dat"))
# self.connect((self.ofdm_frame_acq, 2), gr.file_sink(gr.sizeof_gr_complex*occupied_tones, "ofdm_hestimates_c.dat"))
# self.connect(self.fft_demod, gr.file_sink(gr.sizeof_gr_complex*fft_length, "ofdm_receiver-fft_out_c.dat"))
# self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-chan_filt_c.dat"))
# self.connect(self, gr.file_sink(gr.sizeof_gr_complex, "ofdm_input_c.dat"))
# apurv++ end #
if logging:
self.connect(self.chan_filt, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-chan_filt_c.dat"))
self.connect(self.fft_demod, gr.file_sink(gr.sizeof_gr_complex * fft_length, "ofdm_receiver-fft_out_c.dat"))
self.connect(
self.ofdm_frame_acq,
gr.file_sink(gr.sizeof_gr_complex * occupied_tones, "ofdm_receiver-frame_acq_c.dat"),
)
self.connect((self.ofdm_frame_acq, 1), gr.file_sink(1, "ofdm_receiver-found_corr_b.dat"))
self.connect(self.sampler, gr.file_sink(gr.sizeof_gr_complex * fft_length, "ofdm_receiver-sampler_c.dat"))
# self.connect(self.sigmix, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-sigmix_c.dat"))
self.connect(self.nco, gr.file_sink(gr.sizeof_gr_complex, "ofdm_receiver-nco_c.dat"))