# template tile for Lab #7, Task #4
import numpy
import waveforms as w
import lab7
import lab7_2
reload(lab7_2)

# transmission rate
bits_per_second = 20000

if __name__ == '__main__':
    # a random binary message with zeros at both ends to
    # ensure periodicity
    message_size = 30 
    message = numpy.zeros(message_size+2,dtype=numpy.int)
    message[1:-1] = numpy.random.randint(2,size=message_size)

    # send it through transmitter, modulate to legal freq near 125 kHz
    samples_per_bit = lab7.samples_per_bit(lab7.sample_rate,
                                           bits_per_second)
    fc = lab7.quantize_frequency(500e3,lab7.sample_rate,
                                 len(message)*samples_per_bit)
    rf = lab7.am_transmit(message,samples_per_bit,lab7.sample_rate,
                     fc,lab7.channel_bw)

    ##################################################
    ## ADDED FOR TASK #4: a transmission delay
    ##################################################
    delayed_rf = rf.delay(nsamples=4)

    received = lab7_2.am_receive(delayed_rf,fc,samples_per_bit,
                          lab7.channel_bw)
    if not numpy.array_equal(message,received):
        print "Error when listening to channel"
        print 'message: ',message
        print 'received:',received
    else:
        print "Message received correctly"