#!/usr/bin/env python

import sys
import math
from gnuradio import gr, gru, audio, eng_notation, blks2, optfir
from gnuradio import uhd
from gnuradio.eng_option import eng_option
from optparse import OptionParser

# Load it locally or from the module
try:
    import cqpsk
except:
    from tetra_demod import cqpsk

# accepts an input file in complex format 
# applies frequency translation, resampling (interpolation/decimation)

class my_top_block(gr.top_block):
    def __init__(self, options):
        gr.top_block.__init__(self)

        # Create a UHD source
        self._u = uhd.usrp_source(
               device_addr=options.device_addr,
               io_type=uhd.io_type.COMPLEX_FLOAT32,
               num_channels=1)
        
        sample_rate = 100e6/512
        symbol_rate = 18000
        sps = 2
        
        # set sampling rate and antenna port
        self._u.set_samp_rate(sample_rate)
        self._u.set_antenna(options.antenna, 0)
        
        # output rate will be 36,000
        ntaps = 11 * sps
        new_sample_rate = symbol_rate * sps
        
        # Set receive daughterboard gain
        if options.gain is None:
            g = self._u.get_gain_range()
            options.gain = float(g.stop()+g.start())/2
            print "Using mid-point gain of", options.gain, "(", g.start(), "-", g.stop(), ")"
        self._u.set_gain(options.gain)
 
        # Set receive frequency
        if options.lo_offset is not None:
            self._u.set_lo_offset(options.lo_offset)

        tr = self._u.set_center_freq(options.freq)
        if tr == None:
            sys.stderr.write('Failed to set center frequency\n')
            raise SystemExit, 1

        channel_taps = gr.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.1, gr.firdes.WIN_HANN)

        FILTER = gr.freq_xlating_fir_filter_ccf(1, channel_taps, options.calibration, sample_rate)

        sys.stderr.write("sample rate: %d\n" %(sample_rate))

        DEMOD = cqpsk.cqpsk_demod( samples_per_symbol = sps,
                                 excess_bw=0.35,
                                 costas_alpha=0.03,
                                 gain_mu=0.05,
                                 mu=0.05,
                                 omega_relative_limit=0.05,
                                 log=options.log,
                                 verbose=options.verbose)

        OUT = gr.file_sink(gr.sizeof_float, options.output_file)

        r = float(sample_rate) / float(new_sample_rate)

        INTERPOLATOR = gr.fractional_interpolator_cc(0, r)

        self.connect(self._u, FILTER, INTERPOLATOR, DEMOD, OUT)

def get_options():
    parser = OptionParser(option_class=eng_option)
    # usrp related settings
    parser.add_option("-d", "--device_addr", type="string", default="",
                      help="UHD device address [default=%default]")
    parser.add_option("-a", "--antenna", type="string", default="TX/RX",
                      help="daughterboard antenna [default=%default]")
    parser.add_option("-f", "--freq", type="eng_float", default=None,
                      help="set frequency to FREQ", metavar="FREQ")
    parser.add_option("-g", "--gain", type="eng_float", default=None,
                      help="set gain in dB (default is midpoint)")
    parser.add_option("", "--lo-offset", type="eng_float", default=None,
                      help="set daughterboard LO offset to OFFSET [default=hw default]")

    # demodulator related settings
    parser.add_option("-c", "--calibration", type="int", default=0, help="freq offset")
    parser.add_option("-l", "--log", action="store_true", default=False, help="dump debug .dat files")
    parser.add_option("-L", "--low-pass", type="eng_float", default=25e3, help="low pass cut-off", metavar="Hz")
    parser.add_option("-o", "--output-file", type="string", default="out.float", help="specify the bit output file")
    parser.add_option("-v", "--verbose", action="store_true", default=False, help="dump demodulation data")

    (options, args) = parser.parse_args()
    if len(args) != 0:
        parser.print_help()
        raise SystemExit, 1
    
    if options.freq is None:
        parser.print_help()
        sys.stderr.write('You must specify the frequency with -f FREQ\n');
        raise SystemExit, 1
    
    return (options)

if __name__ == "__main__":
    (options) = get_options()
    tb = my_top_block(options)
    try:
        tb.run()
    except KeyboardInterrupt:
        tb.stop()