Sec. 101.105  Interference protection criteria.

    (a) The interference protection criteria for fixed stations subject 
to this part are as follows:
    (1) To long-haul analog systems, employing frequency modulated radio 
and frequency division multiplexing to provide multiple voice channels, 
the allowable interference level per exposure:
    (i) Due to co-channel sideband-to-sideband interference must not 
exceed 5 pwpO (Picowatts of absolute noise power psophometrically 
weighted (pwpO), appearing in an equivalent voice band channel of 300-
3400 Hz); or
    (ii) Due to co-channel carrier-beat interference must not exceed 50 
pwpO.
    (2) To short-haul analog systems employing frequency modulated radio 
and frequency division multiplexing to provide multiple voice channels, 
the allowable interference level per exposure:
    (i) Due to co-channel sideband-to-sideband interference must not 
exceed 25 pwpO except in the 952-960 MHz band interference into single 
link fixed relay and control stations must not exceed 250 pwpO per 
exposure; or
    (ii) Due to co-channel carrier-beat interference must not exceed 50 
pwpO except in the 952-960 MHz band interference into single link fixed 
relay and control stations must not exceed 1000 pwpO per exposure.
    (3) FM-TV. In analog systems employing frequency modulated radio 
that is modulated by a standard, television (visual) signal, the 
allowable interference level per exposure may not exceed the levels 
which would apply to long-haul or short-haul FM-FDM systems, as outlined 
in paragraphs (b) (1) and (2) of this section, having a 600-1200 voice 
channel capacity.
    (b) In addition to the requirements of paragraph (a) of this section 
the adjacent channel interference protection criteria to be afforded, 
regardless of system length, or type of modulation, multiplexing, or 
frequency band, must be such that the interfering signal does not 
produce more than 1.0 dB degradation of the practical threshold of the 
protected receiver. The ``practical threshold'' of the protected 
receiver can be based upon the definition in TSB 10, referenced in 
paragraph (c) of this section, or upon alternative generally acceptable 
good engineering standards.
    (c) Applying the criteria. (1) Guidelines for applying the 
interference protection criteria for fixed stations subject to this part 
are specified in the Telecommunications Industry Association's 
Telecommunications Systems Bulletin TSB 10, ``Interference Criteria for 
Microwave Systems'' (TSB 10). Other procedures that follow generally 
acceptable good engineering practices are also acceptable to the 
Commission.
    (2) If TSB 10 guidelines cannot be used, the following interference 
protection criteria may be used by calculating the ratio in dB between 
the desired (carrier signal) and the undesired (interfering) signal (C/I 
ratio) appearing at the input to the receiver under investigation 
(victim receiver): Except as provided in Sec. 101.147 where the 
applicants proposed facilities are of a type not included in paragraphs 
(a) and (b) of this section or where the development of the carrier-to-
interference (C/I) ratio is not covered by generally acceptable 
procedures, or where the applicant does not wish to develop the carrier-
to-interference ratio, the applicant must, in the absence of criteria or 
a developed C/I ratio, employ the following C/I protection ratios:
    (i) Co-channel interference. Both sideband and carrier-beat, 
applicable to all bands; the existing or previously authorized system 
must be afforded a carrier to interfering signal protection ratio of at 
least 90 dB except in the 952-960 MHz band where it must be 75 dB; or
    (ii) Adjacent channel interference. Applicable to all bands; the 
existing or previously authorized system must be afforded a carrier to 
interfering signal protection ratio of at least 56 dB.
    (3) Applicants for frequencies listed in Sec. 101.147(b)(1) must 
make the following showings that protection criteria have been met over 
the entire service area of existing systems. Such showings may be made 
by the applicant or may be satisfied by a statement from a frequency 
coordinator.

[[Page 758]]

    (i) For multiple address stations in the 928-929/952-960 MHz bands, 
a statement that the proposed system complies with the following co-
channel separations from all existing stations and pending applications:

Fixed-to-fixed--145 km;
Fixed-to-mobile--113 km:
Mobile-to-mobile 81 km

    Note to (3)(i): Multiple address systems employing only remote 
stations will be treated as mobile for the purposes of determining the 
appropriate separation. For mobile operation, the mileage is measured 
from the reference point specified on the license application. For fixed 
operation on subfrequencies in accordance with Sec. 101.147 the mileage 
also is measured from the reference point specified on the license 
application;

    (ii) For multiple address stations in the 932-932.5/941-941.5 MHz 
bands, a statement that the proposed system complies with the following 
co-channel separation from all existing stations and pending 
applications:

Fixed-to-fixed--113 Km

    (iii) In cases where the geographic separation standard in 
paragraphs (c)(3)(i) and (c)(3)(ii) of this section are not followed, an 
engineering analysis must be submitted to show the coordination of the 
proposed assignment with existing systems located closer than those 
standards. The engineering analyses will include:
    (A) Specification of the interference criteria and system parameters 
used in the interference study;
    (B) Nominal service areas of each system included in the 
interference analysis.;
    (C) Modified service areas resulting from the proposed system. The 
propagation models used to establish the service boundary limits must be 
specified and any special terrain features considered in computing the 
interference impact should be described; and
    (D) A statement that all parties affected have agreed to the 
engineering analysis and will accept the calculated levels of 
interference.
    (4) Multiple address systems operating on subfrequencies in 
accordance with Sec. 101.147 that propose to operate master stations at 
unspecified locations must define the operating area by a radius about a 
geographical coordinate and describe how interference to co-channel 
users will be controlled.
    (5) Multiple address frequencies in the 956 MHz band may be assigned 
for use by mobile master stations on a primary basis. Multiple address 
frequencies in the 952 MHz band may be assigned for use by mobile master 
stations on a case-by-case basis. Mobile operation in the 952 MHz band 
will be on a secondary basis to fixed operations.
    (6) Each application for new or modified nodal station on channels 
numbered 4A, 4B, 7, 9, and 19/20 in the 10.6 GHz band and all point-to-
multipoint channels in the 18 GHz band must demonstrate that all 
existing co-channel stations are at least 56 kilometers from the 
proposed nodal station site. Applicants for these channels must certify 
that all licensees and applicants for stations on the adjacent channels 
within 56 kilometers of the proposed nodal station have been notified of 
the proposed station and do not object. Alternatively, or if one of the 
affected adjacent channel interests does object, the applicant may show 
that all affected adjacent channel parties are provided a C/I protection 
ratio of 0 dB. An applicant proposing to operate at an AAT greater than 
91 meters must reduce its EIRP in accordance with the following table; 
however, in no case may EIRP exceed 70 dBm on the 10.6 GHz channels.

------------------------------------------------------------------------
                         AAT (meters)                           EIRP dBm
------------------------------------------------------------------------
Above 300....................................................        +38
251 to 300...................................................         41
201 to 250...................................................         43
151 to 200...................................................         49
101 to 150...................................................         55
100 and below................................................         85
------------------------------------------------------------------------

    (7) Each application for new or modified nodal station on channels 
numbered 21, 22, 23, and 24 in the 10.6 GHz band must include an 
analysis of the potential for harmful interference to all other licensed 
and previously applied for co-channel and adjacent channel station 
located within 80 kilometers of the location of the proposed station. 
The criteria contained in Sec. 101.103(d)(2) must be used in this 
analysis. Applicants must certify that copies of this analysis have been 
served on all parties which might reasonably be

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expected to receive interference above the levels set out in 
Sec. 101.103(d)(2) within 5 days of the date the subject application is 
filed with the Commission.
    (8) If the potential interference will exceed the prescribed limits, 
a statement shall be submitted with the application for new or modified 
stations to the effect that all parties have agreed to accept the higher 
level of interference.
    (d) Effective August 1, 1985, when a fixed station that conforms to 
the technical standards of this subpart (or, in the case of the 12,200-
12,700 MHz band, a direct broadcast satellite station) receives or will 
receive interference in excess of the levels specified in this section 
as a result of an existing licensee's use of non-conforming equipment 
authorized between July 20, 1961 and July 1, 1976, and the interference 
would not result if the interfering station's equipment complied with 
the current technical standards, the licensee of the non-conforming 
station must take whatever steps are necessary to correct the situation 
up to the point of installing equipment which fully conforms to the 
technical standards of this subpart. In such cases, if the engineering 
analysis demonstrates that:
    (1) The conforming station would receive interference from a non-
conforming station in excess of the levels specified in this section; 
and
    (2) The interference would be eliminated if the non-conforming 
equipment were replaced with equipment which complies with the standards 
of this subpart, the licensee (or prospective licensee) of the station 
which would receive interference must provide written notice of the 
potential interference to both the non-conforming licensee and the 
Commission's office in Gettysburg, PA. The non-conforming licensee must 
make all required equipment changes within 180 days from the date of 
official Commission notice informing the licensee that it must upgrade 
its equipment, unless an alternative solution has been agreed to by all 
parties involved in the interference situation. If a non-conforming 
licensee fails to make all required changes within the specified period 
of time, the Commission may require the licensee to suspend operation 
until the changes are completed.
    (e) Interference dispute resolution procedures. Should a licensee 
licensed under this part receive harmful interference from another 
licensee licensed under this chapter, the parties involved shall comply 
with the dispute resolution procedures set forth herein:
    (1) The licensee experiencing the harmful interference shall notify 
the licensee believed to be causing the harmful interference and shall 
supply information describing its problem and supporting its claim;
    (2) Upon receipt of the harmful interference notice, the licensee 
alleged to be causing the harmful interference shall respond immediately 
and make every reasonable effort to identify and resolve the conflict; 
and
    (3) Licensees are encouraged to resolve the harmful interference 
prior to contacting the Commission.