47 CFR § 73.1400 - Transmission system monitoring and control.
The licensee of an AM, FM, TV or Class A TV station is responsible for assuring that at all times the station operates within tolerances specified by applicable technical rules contained in this part and in accordance with the terms of the station authorization. Any method of complying with applicable tolerances is permissible. The following are typical methods of transmission system operation:
(a) Attended operation.
(i) Direct supervision and control of transmission system parameters by a person at the transmitter site; or
(ii) Remote control of the transmission system by a person at a studio or other location. The remote control system must provide sufficient transmission system monitoring and control capability so as to ensure compliance with § 73.1350.
(2) A station may also be monitored and controlled by an automatic transmission system (ATS) that is configured to contact a person designated by the licensee in the event of a technical malfunction. An automatic transmission system consists of monitoring devices, control and alarm circuitry, arranged so that they interact automatically to operate the station's transmitter and maintain technical parameters within licensed values.
(3) A hybrid system containing some remote control and some ATS features is also permissible.
(4) In the case of remote control or ATS operation, not every station parameter need be monitored or controlled if the licensee has good reason to believe that its stability is so great that its monitoring and control are unnecessary.
(b) Unattended operation. Unattended operation is either the absence of human supervision or the substitution of automated supervision of a station's transmission system for human supervision. In the former case, equipment is employed which is expected to operate within assigned tolerances for extended periods of time. The latter consists of the use of a self-monitoring or ATS-monitored and controlled transmission system that, in lieu of contacting a person designated by the licensee, automatically takes the station off the air within three hours of any technical malfunction which is capable of causing interference.