In USA

AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transm ...

, presunrise authorization (PSRA) and postsunset authorization (PSSA) are permission from the

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains j ...

to broadcast in AM on

mediumwave Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM broadcasting, AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. Duri ...

using a power level higher than what would normally be permitted prior to

sunrise Sunrise (or sunup) is the moment when the upper rim of the Sun appears on the horizon in the morning, at the start of the Sun path. The term can also refer to the entire process of the solar disk crossing the horizon. Terminology Although the S ...

/after

sunset Sunset (or sundown) is the disappearance of the Sun at the end of the Sun path, below the horizon of the Earth (or any other astronomical object in the Solar System) due to its Earth's rotation, rotation. As viewed from everywhere on Earth, it ...

, or in the latter case, provide Class D stations with service into the evening where they would otherwise be required to

sign off A sign-on (or start-up in Commonwealth countries except Canada) 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 in Commonwealth countries exce ...

Sunrise Sunrise (or sunup) is the moment when the upper rim of the Sun appears on the horizon in the morning, at the start of the Sun path. The term can also refer to the entire process of the solar disk crossing the horizon. Terminology Although the S ...

and

times are provided on the licensee's basic instrument of authorization. The power level for both PSRA and PSSA service cannot exceed 500

watt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), quantify the rate of Work ...

s. Power calculations are based on

co-channel Co-channel interference or CCI is crosstalk from two different radio transmitters using the same channel. Co-channel interference can be caused by many factors from weather conditions to administrative and design issues. Co-channel interferenc ...

stations.

PSRA

At 6:00am local time, stations may power up using the station's daytime antenna (if applicable).

Daylight saving

Provided the locale participates in

daylight saving time Daylight saving time (DST), also referred to as daylight savings time, daylight time (Daylight saving time in the United States, United States and Daylight saving time in Canada, Canada), or summer time (British Summer Time, United Kingdom, ...

, special provisions must be made since the PSRA time is based on ''local time''. The exact wording of the rule states: ::''Between the first Sunday in April and the end of the month of April, Class D stations will be permitted to conduct pre-sunrise operation beginning at 6 a.m. local time with a maximum power of 500 watts (not to exceed the station's regular daytime or

critical hours Critical hours for radio stations is the time from sunrise to two hours after sunrise, and from two hours before sunset until sunset, local time. During this time, certain American radio stations may be operating with reduced power as a result of Se ...

power)...'' For example, if the instrument of authorization states sunrise as being at 5:30am local standard time in April, the station does not require PSRA operation since sunrise time is prior to the 6:00am rule. When the clocks advance, this becomes 6:30am ''local time''. PSRA will permit the station to power up at 5:00am ''standard'' time, since that would be 6:00am ''advanced time'' and ''local time'' would reflect the advanced time. As of 2007 (when the new US daylight saving times went into effect), the FCC instructed licensees to use the April advanced times when DST goes into effect in March.

PSSA

At sunset, Class D stations must sign off if they do not possess a nighttime license. PSSA operation allows the station to remain on the air an additional two hours at reduced power level determined by several factors: * International boundaries * Class A

Clear-channel station A clear-channel station is a North American AM radio station that has the highest level of protection from interference from other stations, particularly from nighttime skywave signals. This classification exists to ensure the viability of cross ...

s * Whether the station is on a Regional channel

Daylight saving

There are no specific provisions related to daylight saving time within PSSA operation.

Exceptions

PSSA operation must cease at local sunset time for the closest co-channel Class A located west of the Class D station. Class D stations west of a co-channel Class A do not qualify.

History

The first presunrise authorizations came from a proposed rulemaking in 1967 (''Operation by Standard Broadcast Stations'', 8 FCC 2d 698 (1967)). There were major concerns of

skywave In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvatur ...

interference to clear channel stations, so only a handful of stations were permitted to apply. On February 25, 1981, the FCC determined that there were no detrimental effects to clear-channel stations in remote areas, therefore, they permitted even more stations to apply for authorization

Current authorization

Applications for PSRA and PSSA operation are no longer required. The licensee must merely notify the FCC.

External links

47 CFR 73.99 (Official)

FCC Radio and Television Rules 47 CFR Part 73 (Official)

FCC Rules and Regulations (unofficial)
Broadcast engineering