def calculate_band_stats(transmitters):
    """Helper function to provide data and labels for bands associated with
    transmitters provided"""
    band_label = []
    band_data = []
    bands = [{'lower_limit': 0, 'upper_limit': 30000000, 'label': 'HF'}, {
        'lower_limit': 30000000, 'upper_limit': 300000000, 'label': 'VHF'},
        {'lower_limit': 300000000, 'upper_limit': 1000000000, 'label':
        'UHF'}, {'lower_limit': 1000000000, 'upper_limit': 2000000000,
        'label': 'L'}, {'lower_limit': 2000000000, 'upper_limit': 
        4000000000, 'label': 'S'}, {'lower_limit': 4000000000,
        'upper_limit': 8000000000, 'label': 'C'}, {'lower_limit': 
        8000000000, 'upper_limit': 12000000000, 'label': 'X'}, {
        'lower_limit': 12000000000, 'upper_limit': 18000000000, 'label':
        'Ku'}, {'lower_limit': 18000000000, 'upper_limit': 27000000000,
        'label': 'K'}, {'lower_limit': 27000000000, 'upper_limit': 
        40000000000, 'label': 'Ka'}]
    for band in bands:
        filtered = transmitters.filter(downlink_low__gte=band['lower_limit'
            ], downlink_low__lt=band['upper_limit']).count()
        band_label.append(band['label'])
        band_data.append(filtered)
    band_data_sorted, band_label_sorted = list(zip(*sorted(zip(band_data,
        band_label), reverse=True)))
    return band_label_sorted, band_data_sorted
