Pre-sunrise and post-sunset authorization
Encyclopedia
In USA AM broadcasting
, presunrise authorization (PSRA) and postsunset authorization (PSSA) are permission from the Federal Communications Commission
to (broadcast in AM
on mediumwave
using a power level higher than what would normally be permitted prior to sunrise
/after sunset
, or in the latter case, provide Class D stations with service into the evening where they would otherwise be required to sign off
. Sunrise
and sunset
times are provided on the licensee's basic instrument of authorization
.
The power level for both PSRA and PSSA service cannot exceed 500 watt
s. Power calculations are based on co-channel
stations.
, special provisions must be made since the PSRA time is based on local time. The exact wording of the rule states:
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.
Class D stations west of a co-channel Class A do not qualify.
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. http://www.fcc.gov/Bureaus/Mass_Media/Databases/documents_collection/81-80.pdf
AM broadcasting
AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
, presunrise authorization (PSRA) and postsunset authorization (PSSA) are permission from the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
to (broadcast in AM
AM broadcasting
AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
on mediumwave
Mediumwave
Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz...
using a power level higher than what would normally be permitted prior to sunrise
Sunrise
Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight...
/after sunset
Sunset
Sunset or sundown is the daily disappearance of the Sun below the horizon in the west as a result of Earth's rotation.The time of sunset is defined in astronomy as the moment the trailing edge of the Sun's disk disappears below the horizon in the west...
, or in the latter case, provide Class D stations with service into the evening where they would otherwise be required to sign off
Sign-off (broadcast)
Sign-off 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...
. Sunrise
Sunrise
Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight...
and sunset
Sunset
Sunset or sundown is the daily disappearance of the Sun below the horizon in the west as a result of Earth's rotation.The time of sunset is defined in astronomy as the moment the trailing edge of the Sun's disk disappears below the horizon in the west...
times are provided on the licensee's basic instrument of authorization
Instrument of authorization
The United States Federal Communications Commission uses the term instrument of authorization with its broadcast licensees. It may refer to:-External links:* *...
.
The power level for both PSRA and PSSA service cannot exceed 500 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s. Power calculations are based on co-channel
Co-channel interference
Co-channel interference or CCI is crosstalk from two different radio transmitters using the same frequency. There can be several causes of co-channel radio interference; four examples are listed here....
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 timeDaylight saving time
Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less...
, 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 hoursCritical hoursCritical Hours is that time from sunrise to two hours after sunrise, and from two hours before sunset until sunset, local time. During that time, certain American radio stations may be operating with reduced power as a result of Section 73.187 of the Federal Communications Commission's...
power)...
- 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
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 stations
- 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 skywaveSkywave
Skywave is the propagation of electromagnetic waves bent back to the Earth's surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station can sometimes be heard as clearly as local...
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. http://www.fcc.gov/Bureaus/Mass_Media/Databases/documents_collection/81-80.pdf