Channel search results differ between FCC, REC and RFree

I conducted a channel search at my proposed location ( 39.456874, 94.237864 ). REC says 105.7 is fully spaced and available, however it does offer a note about spacing from a third adjacent channel. The FCC search and RFree searchs did not show 105.7 as an available frequency at this location.

What would cause this discrepancy? Is the 3rd adjacent channel spacing the issue?

Comments

rwarner

Is it a good freq?

Thanks for the input, I understand now what happened. I assume the FCC search failed to report that as an available channel for the same reason.

I have a followup question, if I may. Since I am entering my coordinates on the application in D/M/S form, will this effect the freq. availability as far as the FCC is concerned?

paulbame

I don't think you have a

I don't think you have a choice -- they require D-M-S format.  We don't know which version of coordinates they'll use internally, but FYI I dropped them a note about the discrepency.

paulbame

SOLVED Discrepency

I asked Michi over at REC Networks (aka myLPFM) this question since it was not obvious to me and as usual, it was obvious to Michi :-)

The FCC database records the coordinates of FM stations in their database in two different ways.  One way is in degrees-minutes-seconds and direction (NSEW) just as you would enter it on your FCC paperwork.  But that form is  pain to work with since you always have to convert to floating-point numbers anyway, and for some calculations it is also annoying that the sign can be negative, so the FCC also keeps the latitude and longitude in the database as "biased" (so as to remain positive) floating-point degrees -- much more convenient for computing.

As Michi pointed out, sometimes the FCC's floating-point degrees diverge significantly from what would be calculated from the d-m-s values -- essentially moving that station, and that's what happened here.  myLPFM uses the floating-point values and RFree uses the d-m-s values.  So RFree sees KKJO as blocking 105.7 but myLPFM does not.  This is not surprising because the floating-point vs d-m-s difference is over 2500 seconds in both latitude and longitude for KKJO,  which is probably on the order of 50 miles!

Here's a table of current FM station records where either the latitude or longitude diverge by more than 2 seconds just in case it helps track these down in the future:

+-----------------------+------------+------------+-------------+----------------+
| callsign              | d_lat(sec) | d_lon(sec) | facility_id | application_id |
+-----------------------+------------+------------+-------------+----------------+
| NULL                  |      947.4 |      233.0 |      106537 |         400862 |
| 951006MA/FA/298C1/USE |       60.0 |      178.0 |       78166 |         298653 |
| KDDX/FM/266C/LIC      |        1.0 |        6.0 |       17689 |         492187 |
| KEDG/FM/295A/LIC      |        2.0 |       16.0 |       86925 |         424579 |
| KIT-FM/FM/257A/LIC    |      552.4 |       63.6 |       88006 |         491886 |
| KKJO-FM/FM/288C1/LIC  |     2722.6 |     2586.6 |        8770 |         497995 |
| KKTZ/FM/228C3/LIC     |      129.0 |      629.0 |       84090 |         494544 |
| KLJT/FM/272C2/LIC     |     3600.0 |        0.0 |       57204 |         423001 |
| KNCK-FM/FM/235C1/LIC  |      718.0 |      423.0 |       35209 |         491872 |
| KPOI-FM/FM/290C/LIC   |        1.0 |        5.0 |       33450 |         506596 |
| KTKC-FM/FM/225C2/LIC  |        2.0 |        5.0 |       62034 |         430185 |
| KXAC/FM/263C2/LIC     |        0.6 |        2.6 |       57429 |         283542 |
| KYRX/FM/247A/LIC      |        1.0 |        8.0 |       81680 |         430517 |
| KYTC/FM/274C3/LIC     |        1.2 |        2.2 |       49798 |         430115 |
| KZZI/FM/240C/LIC      |        1.0 |        6.0 |       38630 |         431583 |
| W202AR/FX/202D/LIC    |        0.0 |    42211.0 |       60893 |         492550 |
| WBEN-FM/FM/239B/LIC   |        9.0 |       11.0 |       22308 |         423635 |
| WBZZ/FM/264B/LIC      |       82.0 |       37.0 |       20351 |         491596 |
| WCTW/FM/253A/LIC      |        3.0 |        2.0 |       63527 |         248749 |
| WDZQ/FM/236B/LIC      |        2.8 |        3.0 |       47004 |         497959 |
| WGLR-FM/FM/249C3/LIC  |       90.0 |      117.0 |       33052 |         431312 |
| WKMS-FM/FS/217C1/LIC  |        2.2 |        1.2 |       47080 |         287276 |
| WKMS-FM/FM/217C1/LIC  |        2.2 |        1.2 |       47080 |         287277 |
| WLZX/FM/257A/LIC      |        5.0 |        2.0 |       46963 |         431463 |
| WOOD-FM/FM/295B/LIC   |        0.0 |        3.0 |       25086 |         501420 |
| WRIU/FM/212A/LIC      |        0.8 |        2.2 |       69206 |         273824 |
| WRVR/FM/283C1/LIC     |        2.0 |        0.8 |       34375 |         506020 |
| WXGN/FM/213A/LIC      |      653.6 |      392.0 |       32338 |         529652 |
| WYSX/FA/244C3/USE     |        0.0 |     1378.8 |       49708 |         401559 |
+-----------------------+------------+------------+-------------+----------------+