Sign-on and sign-off

A sign-on (or startup) is the beginning of operations for a radio or television station, generally at the start of each day. It is the opposite of a sign-off (or closedown), which is the sequence of operations involved when a radio or television station shuts down its transmitters and goes off the air for a predetermined period; generally this occurs during the overnight hours.

Sign-ons, like sign-offs, vary from country to country, from station to station, and from time to time; however, most follow a similar general pattern. Many stations follow the reverse process to their sign-off sequence at the close of the day. It is common for sign-ons to be followed by a network's early morning newscast, or their morning or breakfast show.

While both sign-ons and sign-offs have become less common with the increasing prevalence of twenty-four-hour-a-day, seven-day-a-week broadcasting, they are still conducted by a number of stations around the world. For broadcasters that do still close for a period each day, this station close is most often during the early hours of the morning, with the daily sign-on typically occurring between 5:00 a.m. and 7:00 a.m. However, in some countries with more limited broadcast coverage, such as North Korea, sign-on may be as late as 5:00 p.m. A particular type of AM radio station known as a daytimer usually only operates during daytime hours, and will therefore run a sign-on sequence each day.

The sign-on sequence may include some or all of the following stages, but not necessarily in this order:

While most of these sign-on steps are done as a service to the public, or for advertising reasons, some of them may be required by the government of the country.

Sign-offs, like sign-ons, vary from country to country, from station to station, and from time to time; however, most follow a similar general pattern. Many stations follow the reverse process to their sign-on sequence at the start of the day. Sign-off messages can be initiated by a broadcast automation system just as for other television programming, and automatic transmission systems can cut off the carrier signal and trigger the actual shutdown of the transmitter by remote control. Generally, after the carrier signal is cut, the viewer only sees or hears static after an analog television station signs off. Digital stations will likely display a message after the sign off; however, they may simply cut to a black screen with no sound. Occasionally, the signal is cut off entirely, causing digital broadcast receivers (cable/satellite boxes, digital TVs/converter boxes) to display error messages.

...
Wikipedia