[BC] FCC query re AM

[Alan Gearing]

Tom,

Even the FCC apparently has trouble understanding PSRA/PSSA issues, 
since they don't seem to be able to fix their program to calculate new 
authorizations.

Without knowing the particular station, can't give specifics as to why 
their PSSA powers are less than their authorized secondary nighttime powers.

One possible explanation is the nighttime power doesn't fully protect 
all other stations like its supposed to.  This is not an uncommon 
occurrence.  When running nighttime RSS calculations, if the secondary 
night facilities of Class D stations are included in the calculation 
(which shouldn't normally be done) I almost always find some such 
facilities entering into the 25% RSS value (and sometimes even the 50% 
RSS) for Class B stations.  The history of secondary nighttime 
authorizations (as well as PSRA's and PSSA's) is more than a little 
convoluted.  When these secondary nighttime authorizations were first 
being issued, in calculating the existing RSS night limits of protected 
stations the Commission included contributions from stations that are no 
longer included under today's rules and policies.  As a result, the 
protected RSS's on which the secondary powers were based were too high 
and hence so are the secondary power authorizations if one uses the 
criteria in place today.  Also, (I'd have to go back and check the time 
line to be sure) but I think the original secondary nighttime 
authorizations were issued before the Commission adopted the current 25% 
RSS protection criteria and were based on the former less restrictive 
50% criteria.

Another possible explanation is that, as you suggest, the PSSA powers 
are wrong.  Is the station using the PSRA/PSSA's that were issued by the 
FCC in Feb/Mar 2007?  The vast majority of these were wrong (the 
specified powers were well below what they should have been) and these 
authorizations were rescinded by the Commission a few days after they 
were issued.  As a general matter PSSA's specify different power levels 
covering 3 time periods.  The 1st time period is for the 1st 1/2 hour 
after sunset, the 2nd for the 2nd 1/2 hour and the 3rd for the last hour 
of the whole 2 hour post sunset period.  Sometimes one of these basic 
time periods is split further giving a total of 4 different power 
levels.  This is caused by the way the sunset line travels across the 
country and the relative locations of the station with the PSSA and the 
protected stations.  The change in the sunset line characteristic is 
also why power levels differ month to month.  If calculated correctly 
the power level for the last hour normally should be close to that for 
regular nighttime operation.  (They don't always match exactly as 
slightly different protection criteria are employed.)  If the Class D 
station is on a clear channel and the limiting factor is protection to a 
Class A station, I can think of a scenario where the permitted power 
during the middle time period would be greater than either before or 
after, and might also be less than the correctly computed regular 
nighttime power.  (Has to do with east coast Class A stations that are 
authorized to operate with daytime facilities for a period after local 
sunset.)

As for the PSRA, these authorizations are based on significantly 
different protection criteria than used for normal nighttime operation. 
  As such, these power levels provide no guidance for what might be 
permitted for regular nighttime operation.  PSRA powers levels can be 
for powers up to the authorized daytime power or 500 watts, whichever is 
less.  Hence, if the PSRA power is 500 watts (or daytime power, if less 
than 500 watts) there is no limiting station for PSRA purposes, but 
there very likely is for regular nighttime operation.

Final comments:  PSSA's don't normally specify the limiting station only 
PSRA's do and neither a PSRA or a PSSA would supersede the authorized 
nighttime operation.  A station is not required to implement these 
authorities, although they are supposed to inform the Commission if they 
aren't.

I think I've addressed all your questions, if not ask again.

Regards,

Al Gearing

Tom Spencer wrote:
> In perusing various stations' licenses, I've run across a puzzler...
>
> Class D AM; listed as licensed to use some power (typically 100 - 150
> watts) sunset to sunrise; unlimited-time operation, with a higher day
> power (of course);
>
> Here's the kicker - most of the Class D AMs I've looked at ALSO have
> PSSAs and PSRAs with some other power specified.
>
>   One in particular, as an example, is a 500-watt station with authorized
> night power of 114 watts;
>
> The PSRA allows full day power (500 watts) at 6 AM, which would be cool;
> but the PSSA calls for 4 watts, not the previously-authorized 114
> watts... 3.29 A into the 50-ohm CP day, and 1.57 N
>
> The really goofy part is, the PSSA allows a 30-minute period at 50 watts
> in December and 15 minutes in January - a full HOUR past average sunset!
>    Both before and after, the power - according to the PSSA letter - is
> supposed to be 4 watts...  There are no limiting stations listed, either...
>
> If that were MY station, I'd be consulting with my Washington Lawyer to
> get that clarified...
>
> And while I realize no-one here is (or will admit it, anyway) a lawyer...
>
> Thoughts and opinions?  Would the PSRA/PSSA supersede the actual license?
>
> Second question - given the PSRA allows the full day facilities and
> shows no limiting station, what are the odds that the station could be
> converted to Class B with 500 watts full-time (DA-1)?
>

-- 

####################
Alan E. Gearing, PE
Mullaney Engineering, Inc.
PH: 301-921-0115