Sec. 21.938  BTA and PSA technical and interference provisions.

    (a) BTA or PSA authorization holders are expected to cooperate with 
one another by designing their stations in a manner that protects 
service in adjoining BTAs and PSAs including consideration of 
interference abatement techniques such as cross polarization, frequency 
offset, directional antennas, antenna beam tilt, EIRP decrease, 
reduction of antenna height, and terrain shielding.
    (b) Unless the affected parties have executed a written interference 
agreement in accordance with Sec. 21.937, stations licensed to a BTA or 
PSA authorization holder must not cause harmful electromagnetic 
interference to the following:
    (1) The protected service area of other authorization holders in 
adjoining BTAs or PSAs.
    (2) The 56.33 km (35 mile) protected service areas of authorized or 
previously proposed MDS stations (incumbents).
    (3) Registered receive sites and protected service areas of 
authorized or previously proposed stations in the Instructional 
Television Fixed Service pursuant to the manner in which interference is 
defined in Sec. 74.903(a).
    (c)(1) ITFS applicants may locate a new station in an unused portion 
of a BTA or PSA where interference to a previously-proposed or 
authorized MDS

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station of a BTA or PSA authorization holder would not be predicted.
    (2) With respect to ITFS applications only and for purposes of 
determining the existence of harmful electromagnetic interference as 
caused to MDS stations licensed to BTA or PSA authorization holders by 
subsequently proposed ITFS stations within that BTA, MDS stations 
licensed to BTA and PSA authorization holders and will have a protected 
service area of 56.33 km (35 miles), centered on the antenna site of the 
MDS stations.
    (3) The 56.33 km (35 mile) protected service area afforded to a 
previously-proposed or authorized MDS station of a BTA or PSA 
authorization holder with respect to a subsequently proposed ITFS 
station is entitled to the interference protection standards of 
Sec. 21.902.
    (4) An ITFS station authorized before September 15, 1995 may be 
modified, provided the power flux density of that station does not 
exceed -73 dBw/m2 at locations along the 56.33 km (35 mile) circle 
centered on the then-existing transmitting antenna site or service area 
of collocated incumbent MDS station, as applicable.
    (d) Unless the affected parties have executed a written interference 
agreement in accordance with Sec. 21.937, it shall be the responsibility 
of a BTA or PSA authorization holder to correct at its expense any 
condition of harmful electromagnetic interference caused to authorized 
MDS service at locations within other BTAs or PSAs or within the 56.33 
km (35 mile) protected service areas of authorized or previously 
proposed ITFS and MDS stations (incumbents), or at authorized or 
previously proposed ITFS receive sites.
    (e) Unless specifically expected, BTA or PSA authorization holders 
are governed by the interference protection and other technical 
provisions applicable to the Multipoint Distribution Service.
    (f) The calculated free space power flux density from an MDS 
station, other than an incumbent MDS station, may not exceed -73 dBW/m2 
at locations on BTA or PSA boundaries for which there is an unobstructed 
signal path from the transmitting antenna to the boundary, unless the 
applicant has obtained the written consent of the authorization holder 
for the adjoining BTA or PSA.
    (g)(1) Authorization holders for BTAs or PSAs must notify 
authorization holders of adjoining areas of their application filings 
for new or modified stations; provided the proposed facility would 
produce an unobstructed signal path anywhere within the adjoining BTA or 
PSA.
    (2) This service of written notification must include a copy of the 
FCC application and occur on or before the date the application is filed 
with the Commission.
    (3) With regard to incumbent MDS stations, authorization holders for 
BTAs or PSAs must comply with the requirements of Sec. 21.902.
    (h) Where a PSA adjoins a BTA and both authorizations are held by 
the same individual or entity, the PSA shall be considered an extension 
of the protected service area of the BTA regarding the interference 
protection, limiting signal strength, and notification provisions of 
this section.
[ 60 FR 36557 , July 17, 1995, as amended at  60 FR 57367 , Nov. 15, 1995]