Many AM stations have a PSRA or PSSA - "Presunrise Service Authorization" or "Postsunset
Service Authorization". These allow stations that otherwise would not be permitted to
operate at night to do so at reduced power.
Years ago, these authorizations were issued by the Commission's own motion; they calculated
how much power each station could use during each 15-minute period during each month without
interfering with other stations, and sent each station a letter setting forth these authorized
powers. Rumor has it the Commission since lost their copies of those letters... in any case,
we haven't known how much power each station was allowed in these periods unless the stations
This year, the dates on which we switch to/from Daylight Saving Time are changing. The FCC has
taken this opportunity to revamp and reissue these authorizations. They've posted letters to
each PSRA/PSSA-eligible station's "Correspondance Folder" indicating their allowed PSRA & PSSA
powers. These letters are also accessible to the general public, through the Commission's
website. Thus, DXers now know, for the first time in years, how much power AM stations are
actually allowed in the pre-sunrise & post-sunset periods. (but keep reading...)
These powers can get pretty confusing. Let's take station WDKN-1260, Dickson, Tennessee, as
an example. WDKN is authorized 5,000 watts daytime, 18 watts at night. For this month, they
have four authorized post-sunset powers:
- 6-6:30pm: 51 watts
- 6:30-7pm: 24 watts
- 7-8pm: 16 watts
- After 8pm: 18 watts
(these times are Standard Time. They become 7-7:30, 7:30-8, and 8-9pm Daylight Time on the 11th.)
Note however, that this third power is less than their 18 watts authorized night power... In lieu
of their 16 watts 7-8pm PSSA power, WDKN may instead elect to use their 18 watts night power.
To make things even more confusing(grin), WDKN also gets a 500-watt PSRA for use between
6am and sunrise.
But there's more. These three power levels are just for March. There are eleven more sets of
figures for the other 11 months. In November and December, there are not three, but *four*
different power levels.
And finally... these are *maximum* powers. WDKN may choose to use lower post-sunrise powers.
Or they may choose to not operate post-sunset at all.
Stations are required to notify the FCC if they intend to use these PSSA powers. We don't yet
know if the FCC will report their notifications on their website.
If you'd like to see the PSRA or PSSA authorizations for a station:
- - go to http://svartifoss2.fcc.gov/prod/cdbs/pubacc/prod/sta_sear.htm
- - Put the station's call letters in the first box.
- - Click on "Click for Details".
- - Click on "View Correspondence Folder".
- - Click on "Click to view PSRA" (or "Click to view PSSA")