In USAAM broadcasting,presunrise authorization (PSRA) andpostsunset authorization (PSSA) are permission from theFederal Communications Commission tobroadcast in AM onmediumwave using a power level higher than what would normally be permitted prior tosunrise/aftersunset, or in the latter case, provideClass D stations with service into the evening where they would otherwise be required tosign off.Sunrise andsunset times are provided on the licensee's basicinstrument of authorization.
The power level for both PSRA and PSSA service cannot exceed 500watts. Power calculations are based onco-channel stations.
At 6:00am local time, stations may power up using the station's daytime antenna (if applicable).
Provided the locale participates indaylight saving time, special provisions must be made since the PSRA time is based onlocal 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 6:30amlocal time. PSRA will permit the station to power up at 5:00amstandard time, since that would be 6:00amadvanced time andlocal 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.
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:
There are no specific provisions related to daylight saving time within PSSA operation.
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.
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 ofskywave 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.[1]
Applications for PSRA and PSSA operation are no longer required. The licensee must merely notify the FCC.