On October 2, 1995, the FCC adopted rules allowing the unattended operation of broadcast transmitters. The Report and Order (FCC 95-412) was released on October 23, and the new rules became effective December 1, 1995. Let's take a close look at the actual changes in the rules and how they may affect your station.
The "no licensed operator" requirement allows stations to run with an unlicensed operator, or with no operator at all, provided various other requirements are met. Stations can immediately start using unlicensed operators (who are properly trained) with no changes in station equipment or procedures. Unattended operation, however, may require special procedures to deal with various FCC requirements, including EBS.
Recall the duties of the chief operator, as listed in 73.1870(c). The chief operator (or his/her designee) must make inspections of the stations transmission system and monitors. He/she must make required field strength measurements on directional AM stations. He/she must make AM and FM equipment performance measurements (spurious emissions, occupied bandwidth) yearly for AM and on transmitter, exciter, stereo generator, or subcarrier equipment changes on FM. Finally, and this is a point that seems to be missed in many stations, the chief operator must make a weekly entry in the station log indicating that he/she has reviewed the log and found that it indicates the station has operated in compliance. If the station was not found to be operating in compliance during that week, a notation of the violation should be made, along with a notation as to what corrective action is being taken to insure it does not occur again. At a minimum, these log reviews should verify that EBS tests (for now, soon EAS) have been transmitted and received as required (weekly, on a random basis, 8:30am to local sunset), that the operating power was within tolerance at all times, that directional parameters were within tolerance, that pattern/power changes were completed at the proper time, and that the required daily tower light inspection was completed.
Attended operation is what we've been doing for years. A person watches the transmitter or a telemetry system indicating the transmitter parameters, or an automatic system (ATS) watches the transmitter and "calls for help" should it be unable to maintain parameters within licensed limits. Note that when the station is "attended", no automatic shutdown is required. A person shuts the station down upon noting an interference causing condition or being notified of such a condition by an ATS. This is a change from the previous ATS rules (73.1500), which required an automatic shutdown within three minutes. Note that no ATS is required by the Rules.
"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 first case, the equipment is "expected" to be stable enough to operate for long periods of time without going out of tolerance. In the second case, an automatic transmission system (ATS) monitors and adjusts the transmission system to keep it within tolerance. Should the system fail to keep the parameters within tolerance, it would shut the station down in three hours. However, 73.1350(d)(2) requires AM stations that change power or are directional to shut down within three minutes should they not change to a required lower power or pattern at the appopriate time. The shutdown requirement applies only to parameters that would cause interference. For example, overpower would require a shutdown while underpower would not. Overmodulation would require a shutdown while undermodulation would not. Off-frequency operation would require a shutdown. These examples are listed in section 73.1350(d). Finally, stations are allowed to continue operation with directional array parameters out of tolerance for up to 24 hours, during which time monitor points are to be checked (see 73.62(b)(5)). Under unattended operation, the ATS alarm requirement of attended operation is replaced with a three hour shutdown, since there is no operator to notify. As with attended operation, no ATS is required by the rules. It's just one of the options.
Correspondence with FCC staff on this issue indicates that the FCC wants to be able to contact a representative of a station licensee and have that person shut the station down within three minutes. The FCC may make such a request if the station is indeed causing interference, or it may request a temporary shutdown in an effort to determine the cause of interference. Further, paragraph 18 of the Report & Order states "However, because cases may arise in which the Commission identifies a broadcast station as the source of a harmonic or spurious product or other type of problem causing harmful interference, the Commission will retain the requirement that a licensee be able to shut its station down immediately (i.e., within three minutes) upon request by our enforcement personnel."
In the rulemaking, the FCC considered requiring that broadcast station licensees post contact information at the tower (as is required for translators), or establishing an on-call person database. They decided against both of these, relying instead upon existing informal means of contacting people "responsible" for the stations. It will be interesting to see what happens when nobody is home at any of these numbers, or the FCC calls the president of a group owner and asks him/her to shut down a specific transmitter. Can the prez do it within three minutes?
Although my reading of this rule section does not require stations to install a control system to shut down the station should the station choose to run unattended, the discussion in the Report and Order does indicate such a requirment. Therefore, it is suggested that, as a minimum, stations have a method of shutting down the transmitter from some remote location within three minutes of FCC request. This will typically take the form of a simple dial-up control system. To insure the FCC can find "responsible" personnel, it might be a good idea to have the station's phone answered by an answering service that can shut down the transmitter or can contact someone who can. As an alternative, the station might employ a voicemail system that drives a pager on emergency calls, though it is more difficult for a voicemail system to filter out prank calls (and we know that morning DJ's are probably responsible for most of the nation's prank calls).