Reserved-band channel study per 47 C.F.R. §74.1204 / §74.1205 — November 2026 NCE translator window
engine…
Proposed Site
Fills the coordinates below from the FCC tower database
1–250 W (§74.1235 ceiling)
Used for FCC terrain HAAT lookup
Ground elevation is fetched automatically; RCAMSL = ground + AGL
Scalar HAAT applied on all radials
Fills the tabulation below with a stored relative-field pattern. You can edit it afterward. The server always re-validates.
Filed values are pattern-relative; rotation is added to get true azimuth (§73.316(c)(1), rotation contract).
For the blank template button below.
One point per line: azimuth field (space, comma, or tab). Field 0–1, max must be 1.0. Gaps ≤10° (§73.316(c)(1)). Example: 0 1.0
Primary Station Check (optional — §73.860 / fill-in)
LPFM primary: verifies the 60 dBu contour touch and 10/20-mile spacing. Full-service primary: reports fill-in / non-fill-in (no touch requirement applies).
Channel Ranking — 88.1–91.9 MHz
Ch
Freq
Status
Margin
Blocking stations
Max ERP
Requirements
HF
(d)
TV6
IF
Click a channel row for the full protection study. In the Blocking stations column, ☐ ignores that station (each ignored facility is disclosed on the exhibit).
Channel Detail
User Guide
What this does. For a proposed FM translator site, each reserved-band channel (201–220, 88.1–91.9 MHz) is tested against every authorized FM facility — full-service, translators, boosters, Class D, and LPFM (including pending LPFM applications at maximum facilities) — using the contour-overlap protection standard of 47 C.F.R. §74.1204.
Methodology. The protected contour distance uses the FCC F(50,50) curves and the interfering contour distance uses the F(50,10) curves, per §74.1204(b), computed along the actual inter-site radial by a server-side implementation of the FCC CURVES program verified against the Commission's reference code. A channel fails when the protected + interfering contour distances exceed the site separation for any protected station.
Statuses.
PASS — no prohibited overlap with any protected station.
PWR_LIMITED — co- or first-adjacent overlap exists at the requested ERP, but the site is outside every protected contour, so reducing power cures it; the Max ERP column is the highest power that clears all co/1st-adjacent overlap on that channel (2nd/3rd-adjacent (d) candidates may remain — see the channel detail).
D_CANDIDATE — the only prohibited overlap is 2nd/3rd-adjacent and confined to the proposal's own 94–100 dBu interfering contour (roughly a 1–1.5 km circle around the site). §74.1204(d) accepts otherwise-precluded applications on a showing of no actual interference (lack of population, terrain, overlap over water) — the standard reserved-band translator cure. Engineering judgment required; not automated.
TV6_FAIL — the computed §74.1205(c) Grade B study shows prohibited overlap that power reduction cannot cure (the site is inside the TV station's 47 dBu contour); licensee concurrence, collocation within 0.4 km, or a §74.1205 waiver is required. Power-curable TV6 overlap folds into PWR_LIMITED instead.
TV6_REVIEW — a TV Channel 6 facility inside the §74.1205(a) trigger distance could not be evaluated automatically (record missing ERP or height data); verify and complete the Grade B study manually.
IF_REVIEW — proposal is 100 W+ with ±10.6/10.8 MHz stations present; §73.207 IF spacing must be verified.
FOREIGN_FAIL — the translator's 34 dBu (F(50,10)) interfering contour overlaps a Mexican or Canadian allotment's class-based protected radius (§74.1204(h) → §74.1235(d); 1992 US–Mexico / 1991 US–Canada FM Agreements). The allotment is protected at its maximum class facilities. Overlap is prohibited outright — no power-reduction cure and no 2nd/3rd-adjacent waiver toward a foreign allotment.
FOREIGN_REVIEW — a foreign allotment whose class-based protection could not be computed precisely (class undetermined, or a Canadian allotment pending the Canadian class table); verify the 34 dBu overlap against the allotment radius manually. Never a silent pass.
FAIL — prohibited contour overlap. Note §74.1204(d): an otherwise-precluded application may still be accepted on a showing of no actual interference (terrain, population, overlap over water).
Proposal HAAT. Enter radiation center AMSL for automatic 360-radial terrain HAAT (FCC terrain API), or supply a scalar HAAT override. Incumbent HAAT defaults to the authorized value from the FCC database; the precision mode fetches per-radial terrain HAAT toward the site for every incumbent.
Primary station check. For an LPFM-owned translator, 47 CFR §73.860 requires the translator\u2019s 60 dBu service contour to overlap the LPFM\u2019s 60 dBu contour (even slightly) and the translator antenna to be within 10 miles of the LPFM antenna in top-50 markets (20 miles elsewhere). For a full-service primary, no touch requirement applies; the check reports the fill-in / non-fill-in designation instead. In all cases the translator must receive the primary off-air \u2014 the reported field strength at the site informs that judgment. Contours are evaluated along the inter-site radial.
Tower lookup. Enter an FCC Antenna Structure Registration number to fill the site coordinates from the ASR database (NAD83). The lookup also reports the tower's ground elevation \u2014 add your radiation center height above ground to get the RCAMSL figure. Coordinates remain fully editable; manual entry works exactly as before.
Data. Nightly standalone build from the FCC LMS public files. The header badge shows database freshness.