NUTS AND BOLTS OF FCC FM ALLOCATIONS

Doug Vernier – V-Soft Communications Telecommunication Consultants Prepared for the SBE Webinar

FM ALLOCATIONS SERVICE ASSUMPTIONS Operate within power and antenna

height maximum and minimums required for class

Serve the licensed Principal City Cause no interference Meet 73.207 minimum separations Short space if necessary using

73.215 rules

FM STATION CLASSES

Zone I and Zone 1A East U.S. , Southern California & P.R.• A (6 kW at 100 m HAAT)• B1 (25 kW at 100 m HAAT)• B (50 kW at 150 m HAAT

Zone II – Most of the rest of the U.S.• A (6 kW at 100 m HAAT)• C3 (25 kW at 100 m HAAT)• C2 (50 kW at 150 m HAAT)• C1 (100 kW at 299 m HAAT)• C0 (100 kW at 450 m HAAT)• C (100 kW at 600 m HAAT)

73.207 MINIMUM SEPARATIONS

FM band:Channels 200 –

30087.9 – 107.9 MHz

Channel Band Width = 200 kHz

MINIMUM SEPARATIONS STUDY

AREA TO LOCATE TRANSMITTER – 73.207 PLOT

70 DBU SERVICE TO PRINCIPAL CITY Commercial FM 70 dBu

needs 85 percent of the principal city area or population covered.

Principal City moves add Allocation Petitions to Amend the Table of Assignments require 100 percent coverage.

Non-commercial FM 60 dBu with at least 50% of the principal city covered.

Except for new allocations, in some cases, the FCC has allowed waivers where the applicant uses TechNote 101 calculations (Longley-Rice).

FCC COVERAGE CURVES F(50-50)

PROTECTED F(50-50) MAXIMUM CONTOUR DISTANCES

Class L1, 0.1 kW = 5.2 km, ~60 dBu Class A, 3 kW = 24.2 km, 60 dBu (1 mV/m), old class A Class A, 6 kw = 28.49 km, 60 dBu Class B1 = 44.7 km, 57 dBu Class B = 65.1 km, 54 dBu Class C3 = 39.1 km, 60 dBu Class C2 = 52.2 km, 60 dBu Class C1 = 72.3 km, 60 dBu Class C0 = 83.4 km, 60 dBu Class C = 91.8 km, 60 dBu

All Non-Commercial stations are protected only to the 60 dBu

INTERFERENCE CURVES F(50-10)

73.215 AND 73.509 CONTOUR PROTECTION RATIOS – U TO D

Co-channel: -20 dB - *if 60 dBu is protected F(50-10) interference contour = 40 dBu

First-Adjacent: - 6 dB 2nd and 3rd adjacent +40 dB * if the

60 dBu is the protected contour, interference contour = 100 dBu 

WHERE DID THE D/U RATIOS COME FROM?

Project #22231. In 1947, the FCC "Laboratory Division" conducted tests on FM Radios and published reports on "Characteristics of Commercial FM Broadcast Receivers".

Data was included in the results concerning the interference rejection ratios on both co-channel and adjacent channels.

These measurements are the basis for the interference ratios still used in the FM rules (first adopted in 1951.)

CONVERTING CURVES TO MACHINE READABLE TABLES

F(50-10) FORTRAN TABLE* F(50,10) FIELD STRENGTH DATA FOR THE LOW VHF PROPAGATION CURVE ** ( FM AND TV CHANNELS 2 THRU 6 ) *DATA ( ( F51LV(I,J), J = 1, IH10 ), I = 1, ID10 ) / & 52.2, 58.4, 64.3, 68., 70.5, 72.3, 74.2, 75.9, 77., 78.2, & 80.8, 81.8, 82.2,C & 41.4, 47., 53., 56.5, 59., 60.9, 63., 64.8, 66.2, 67.6, & 71.2, 73.8, 75.5,C & 36.4, 40.9, 45.9, 49., 51.7, 53.7, 56., 57.9, 59.6, 60.9, & 64.5, 67., 69.,C & 33., 36., 39.9, 43., 45.4, 47.5, 50., 52., 54., 55.2, & 58.9, 61.4, 63.3,C & 30., 31.9, 35., 37.7, 40., 41.9, 44.4, 46.7, 48.5, 50., & 53.9, 56.3, 58.4,

RADIALS FOR DETERMINING AVERAGE HAAT

HAAT FM - RADIAL 3 TO 16 KM

Minimum of 51 elevation points along a radial

DIGITAL TERRAIN ELEVATION DATABASES

POPULAR TERRAIN ELEVATION DATABASES 3 arc-second and 30 arc-second U.S.G.S. databases in use today by the FCC have the least accuracy of available databases.

The 30 arc-second database was derived from the original 3 arc-second U.S.G.S. data base which was digitized from 1:250,000 scale maps.

Since each second of latitude approximates 100 feet, the 30 arc-second terrain elevation database will have an elevation point every 3,000 feet. The 3 arc- second database will have a point every 300 feet.

Both databases are said to have a number of errors in them such as mountain

peaks being off as much as 15 seconds.

In 2004 the USGS released the National Elevation Datum (NED) data set.

This dataset was developed by merging the highest-resolution, best quality elevation data available across the United States into a seamless raster format. NED is the result of the maturation of the USGS effort to provide 1:24,000-scale Digital Elevation Model (DEM) data for the conterminous US and 1:63,360-scale DEM data for Alaska.

The newest database to be released is from the Shuttle Radar Topography Mission (SRTM). In this mission, NASA obtained elevation data on a near global scale to generate the most complete high-resolution digital topographic database of the Earth.

RETURNING TO MINIMUM SEPARATIONS STUDY

Where they came from

FCC Sec. 73.207 Spacings Table

It’s based on “flat earth” and uniform terrain.

FM SHORT-SPACING UNDER 73.215

Use when73.207 separations cannot be met you can use contour-to-contour protection between stations

Distance between short-spaced stations must be greater than that shown in the minimum short-space tables in 73.215(e)

If the protected station is not already a 73.215 short-space facility, you must change its power and HAAT to the standard class maximum

If protected station is directional and not already designated as 73.215 you must assume its an omnidirectional facility

For NCE stations and FM translators, contour-to-contour protection applies between stations without regard to Section 73.215(e), except when NCE stations are on channels 218-220 and interface with commercial band stations

THE UNDERGROUND ANTENNA

KWVE-FM WITH OMNI ANTENNA

KUZZ-FM ANTENNA GOES UNDERGROUND

Real Antenna at 6 kW HAAT: 416M

73.215 Antenna at 50 kW HAAT: 150M

KWVE-FM WITH ANTENNA AT LICENSED HEIGHT AND POWER – USING OMNI ANTENNA

GRAND FATHERED SHORTSPACE ASSIGNMENTS73.213

These assignments are numerous in Zone 1 (Eastern US and Southern California)

Created before 1964 and adoption of separations tables

2nd and 3rd adjacent minimum spacing requirements are not followed, allowing a station’s transmitter to be within the protected contour of the short-spaced station.

Post 1989 short-spaces were caused by allowing class A stations to increase from 3 kW to 6 kW

BORDER ISSUES Coordination and approval is required for

stations within 320 km of the US border with Canada and Mexico

Minimum separations are more restrictive toward Canada, less restrictive or the same toward Mexico. See 73.207(2)(table B)

Interference is allowed to be caused to Canadian stations if its located over U.S. territory

Interference in not allowed to be caused to Mexican stations, even over U.S. territory

See US Canada, US Mexico Working Treaties

FM CHANNEL 253 TO TV-6 PROTECTION Minimum Distance Separation From TV Channel 6

(82-88 MHz) FM Class TV Zone I TV Zones II & III A 17 22 B1 19 23 B 22 26 C3 19 23 C2 22 26 C1 29 33 C 36 41

UPGRADING YOUR STATION

Class upgrades require a fully spaced site with no short-space

The allocation site must cover 100 percent of the of city of license with the principal city contour

Applicants now apply for a one-step application, to advance to a higher class without going through the allocation rule petitioning

In the best situation, if the existing tower in not located in the allocation area-to-locate, 73.215 short-space rules can be used

New rules allow moving a station’s channel more than 3 channels yet maintaining a minor change proposal

ONE-STEP UPGRADE EXAMPLE

AREA-TO-LOCATE – CLASS A

AREA-TO-LOCATE – CLASS C3

FULLY SPACED C3 ALLOCATION SITE

SPACINGS SHORT FROM OLD SITE AS C3

CONTOUR PROTECTING SHORT-SPACED STATIONS

REMOVING PROHIBITED OVERLAP

USING A DIRECTION ANTENNA

COVERAGE FROM PRESENT SITE AT 15 KW

MOVING THE PRINCIPAL CITY

Coverage to new city must serve 100% of the population or area of new city

New site location must be mutually-exclusive with the old site location

The proposal must leave at least one station serving the old principal city

Moving to a larger city is harder to do. Tuck studies and other analysis will be required

Applicant must show impact on service to the public, leaving no location with less than one station coverage

MODIFIED RULES

If the new community is within an urbanized area, or the station can be modified to serve more than 50% of an urbanized area, a rebuttable assumption will be made that the applicant intends to serve the urbanized area.

The rebuttal must be a compelling showing of the following:

1. The proposed community is truly independent of the urbanized area.

2. The community’s specific need for an outlet for local expression independent of the urbanized area

3. The ability of the proposed station to provide that outlet.

PROVIDING SERVICE TO RURAL OR UNDERSERVED AREAS

A proposal to provide service to a third, fourth and/or fifth aural service to at least 25% of the population in the proposed primary service area, provided the proposed community of license has two or fewer local transmission services, will receive a dispositive Section 307(b) preference.

See: MM Docket No. 09-52 – URL: http://transition.fcc.gov/Daily_Releases/Daily_Business/2011/db0303/FCC-11-28A1.pdf

AUCTION 93

Auction 93 will offer 119 construction permits in the FM broadcast service.

The construction permits to be auctioned, are for 119 new FM allotments, including 17 construction permits that were offered but not sold or were defaulted upon in prior auctions.

These construction permits are for vacant FM allotments, reflecting FM channels assigned to the FM Table of Allotments (“Table”), pursuant to the Commission’s established rulemaking procedures, and are designated for use in the indicated communities.

47 C.F.R. § 73.202(b).

AUCTION 93

http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-11-1845A1.doc

DISCUSSION AND QUESTIONS?Doug Vernier – dvernier@v-soft.com – 319 266-8402