# template tile for Lab #7, Task #1
import numpy
import waveforms as w

# parameters that control the encoding
sample_rate = 1e6
bits_per_second = 30000
samples_per_bit = int(sample_rate/bits_per_second)

# convert message bits into samples, then use samples
# to modulate the amplitude of sinusoidal carrier
def am_transmit(bits,samples_per_bit,fc):
    # use helper function to create a sampled_waveform by
    # converting each bit into samples_per_bit samples
    samples = w.symbols_to_samples(bits,samples_per_bit,
                                   sample_rate)

    # now multiply by sine wave of specified frequency
    return samples.modulate(hz=fc)

# receive amplitude-modulated transmission:
def am_receive(samples,fc,samples_per_bit):
    pass # your code here

if __name__ == '__main__':
    message_size = 32

    # a random binary message
    message = numpy.random.randint(2,size=message_size)

    # run transmitter
    fc = 125e3  # carrier frequency
    xmit_out = am_transmit(message,samples_per_bit,fc)

    # plot spectrum of transmitted message
    xmit_out.spectrum(title='spectrum of received samples',
                      npoints=256000)

    # run receiver
    received = am_receive(xmit_out,fc,samples_per_bit)

    # report results
    print 'message: ',message
    print 'received:',received
    if not numpy.array_equal(message,received):
        print 'differences'
    else:
        print 'message received okay'

    # display the plots
    w.show()