def creator_instrument(lower, upper):
    """
    Generates the aproximated instrument string based in the frequencies, to use directly with CallistoSpectrogram
    """

    lower = int(lower)
    upper = int(upper)
    if lower>=1200 and upper<=1800 : return "BLEN5M"
    if lower>=110 and upper<=870 : return "BLEN7M"
    #The Upper value is set to 110 in order to download a bigger wide of flares
    if lower>=20 and upper<=110 : return "BLENSW"