user: Question: What is Call Sign, when ERP W is greater than 50?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['W201DB', 88.1, 'McRae, Georgia', 3.0, 'D', 'FCC']
SQL:

assistant: SELECT "Call sign" FROM "Table" WHERE "ERP W" > 50.0;