Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_24 ( call_sign VARCHAR, erp_w VARCHAR, class VARCHAR, frequency_mhz VARCHAR )

### Question ###
Class of d, and a Frequency MHz smaller than 107.7, and a ERP W smaller than 232 has what call sign?

### Accurate SQL ###

SELECT call_sign FROM table_name_24 WHERE class = "d" AND frequency_mhz < 107.7 AND erp_w < 232