When 1180 am is the frequency how many call signs are there?
CREATE TABLE "table1_1949746_1" (
  "call_sign" text,
  "frequency" text,
  "city_of_license" text,
  "licensee" text,
  "format" text
);
SELECT COUNT("call_sign") FROM "table1_1949746_1" WHERE "frequency"='1180 AM';