The following table shows the potential availability of low-band (2-6) TV channels for use by FM radio in the Top 10 television markets after the digital TV transition of February 2009.

Squares marked in gray are not available for FM service. Either a full-power DTV station¹ exists within the zone proscribed by 73.610(b)(1)², or a LPTV (or Class A) station³ exists whose 62dBu contour comes within 113km of the market's primary TV transmitter site⁴ ⁵.

Squares marked in green are available for FM service without restriction. No full-power DTV station exists within the 73.610 proscribed zone, and no LPTV station exists whose 62dBu contour would be overlapped by the 34dBu (-28dB) contour of a maximum-power FM station⁶ at the primary transmitter site.

Squares marked in blue are available but at limited power. No full-power DTV station exists within the 73.610 proscribed zone, but one or more LPTV stations exist whose 62dBu contour would be overlapped by the 34dBu contour of a maximum-power FM station at the primary transmitter site. However, these LPTVs' 62dBu would not be overlapped by the 34dBu of a FM station of lower class, as indicated in the table. For example, a full Class C FM (100kw/600m) in Dallas' Cedar Hill antenna site would overlap with LPTV station KLUF-LP on channel 5 in Lufkin, Texas. However, a full Class C2 (50kw/150m) would not overlap with KLUF.

In each case, the station or stations that limit or prevent use of a channel are listed. Full-power stations are listed in boldface. -D indicates a digital low-power or Class A station.

The eventual end of analog LPTV/Class A service would open up more channels in this table. Specifically, channel 6 would become available without limit in Chicago; channel 2 in San Francisco; and channel 4 in Atlanta.

Adjacent-channel separations were not considered. Due to the much narrower bandwidth of a FM radio transmission, it should be possible to use most, if not all, of the channel adjacent to a local DTV station without observing the frequency separations applicable to TV service.

Also not considered was terrain obstruction. For example, the five TV translators that contribute to the restriction of the use of channel 5 in Atlanta are in the mountains of western North Carolina. It is likely that terrain would prevent an Atlanta FM station from interfering with these translators.

Directional antennas were not considered. In practice, the use of such antennas at many TV stations may make FM operation practical in markets where this table suggests it's not possible.

City	2	3	4	5	6
New York	OK	WBQM, WBQM-D	OK	W05CS-D	WEDY, WRGB, WPVI
Los Angeles	Class A (K02HY, KCWQ, KTBV)	KVTU-D, K59AO-D	Class A (KVER, KTFB, K04HX, KVHF, KBAB-D)	Class A (KEVC, K05FO)	K61AJ-D, KCIO
Chicago	OK	OK	WHBF	WGVK	WLFM
Philadelphia	OK	Class A (WBQM)	Class A (WLWP)	Class A (W05BG, W05CS-D)	WPVI
Dallas/Ft. Worth	Class A (K02QH, K02EQ	KHPK-D	OK	Class C2 (KLUF)	KZFW, KZFW-D, KBFW
San Francisco	KOTR	Class A (KMMD)	OK	Class A (K10OI)	Class A (K06DK, K06FA
Boston	Class A (WVBK)	WTMU-D, WCEA	OK	OK	WEDY, WRGB
Atlanta	Class C2 (WBXA)	Class C2 (W03AK)	WUVM	Class C2 (WBXM, 5 xltrs)	WCES, WABW
Washington	OK	OK	Class A (WLWP)	Class A (WDOB)	WPVI
Houston	OK	OK	OK	KJIB⁷	OK

1Only post-transition DTV channels were considered. Presumably the February 2009 deadline will have passed before any FM stations can be authorized in 54-88MHz, so both full-power analog and interim pre-transition DTV channels will be off the air and not subject to FM interference.

2This regulation establishes the minimum distance between full-power analog TV stations. The limit is 273km in Zone I (most top 10 markets); 305km in Zone II (Los Angeles, Dallas, San Francisco, and Atlanta), and 353km in Zone III. (Houston)

3Both analog and digital LPTV and Class A stations were considered.

4I defined the “primary transmitter site” as the average of the coordinates of the four analog TV stations affiliated with the ABC, CBS, Fox, and NBC networks, and the primary PBS-affiliated non-commercial station. In all ten markets these stations' transmitters are very close, within 5km. Presumably this would be the preferred antenna site for any new FM service as well.

5113km being the 34dBu contour of a maximum-facility Class A station. Regulation 74.707(a)(1)(I) establishes a protected contour of 62dBu for channel 2-6 analog LPTV stations, and 74.707(d)(1) establishes a 28dB protection ratio.

6“Maximum power” is Class B facilities (50kw/150m) in most markets – Class C facilities (100kw/600m) in Dallas, Atlanta, and Houston.

7KJIB-LP has filed to move to channel 29 and to establish a DTV facility on that channel. If implemented, this would free up channel 5 for FM at the Houston primary transmitter site.