From the FCC...
Identification of Translator and Booster Stations
Translator stations must be identified by the licensee by the following means:
By arranging with the primary station whose signal is being rebroadcast to identify the translator by call sign and location. The identification must occur 3 times daily: once between 7 AM and 9 AM, once between 12:55 PM and 1:05 PM, and once between 4 PM and 6 PM. Stations which do not begin operating before 9 AM must provide the identification at the beginning of the broadcast day. The licensee of the translator station must arrange for the primary station to keep in the primary FM station's file (and to make available to FCC personnel), the call sign and location of the translator station. This record must include the name, address, and telephone number of the translator licensee or his service representative to be contacted in the case of a malfunction of the translator. See 47 CFR Section 74.1283(c)(1).
OR
by transmitting the call sign in Morse Code at least once hour. See 47 CFR Section 74.1283(c)(2) for additional requirements for transmission of the call sign in this manner.