help="set Tx frequency to FREQ [required]", metavar="FREQ")
parser.add_option("-n", "--nchannels", type="int", default=4,
help="number of Tx channels [1,4]")
help="set Tx frequency to FREQ [required]", metavar="FREQ")
parser.add_option("-n", "--nchannels", type="int", default=4,
help="number of Tx channels [1,4]")