(a) Stations in this service operating on frequencies in the 72-76 MHz band shall be authorized to employ only amplitude modulated or frequency modulated emission for radiotelegraphy, radiotelephony and facsimile.

(b) Stations in this service operating on the frequency 27.255 MHz shall be authorized to employ only amplitude modulated or frequency modulated emission for radiotelephony.

(c) Except as limited by § 21.701(f) and by paragraphs (a) and (b) of this section, stations operating in the frequency bands listed in § 21.701 may be authorized to use amplitude modulated, frequency modulated or pulse type emission for radiotelephony, facsimile and television. The use of unmodulated emission may be authorized in appropriate cases upon specific request supported by a justification of the need therefor.

(d) The authorization to employ any of the various types of modulated emission below 890 MHz in this service shall be construed to include authority to employ unmodulated emission only for temporary or short periods necessary for equipment testing incident to the construction and maintenance of a radio station.

(e) The maximum authorized bandwidth of emission and, for the cases of frequency or phase modulated emission, the maximum authorized frequency deviation shall be as follows:

that, the frequency deviation is reduced to 5 kHz by June 1,

1968.

2 In the frequency bands 72.0-73.0 and 75.4-76.0 MHz, radio facilities using frequency modulated or phase modulated emission will be authorized with maximum bandwidth of 20 kHz and maximum frequency deviation of 5 kHz. Radio facilities which were authorized for operation on Dec. 1, 1961, in the frequency band 73.0-74.6 MHz may continue to be authorized without change and with bandwidth of 40 kHz and frequency deviation of 15 kHz. New or modified facilities in the frequency band 73.0-74.6 MHz will not be authorized.

(f) On frequencies in the 890-940 MHz band, the bandwidth authorized shall not exceed 400 kHz for each derived communication channel and may be restricted to lesser bandwidth when appropriate to the type of operation involved in any particular case.

(g) The maximum bandwidth authorized shall not exceed that reasonably necessary to provide the proposed service but in no event shall it exceed the limits set forth below:

(h) The bandwidths authorized on frequencies above 500 MHz shall be appropriate to the type of operation in any particular case. An application requesting such authorization shall fully describe the modulation, emission, and bandwidth desired and shall specify the bandwidth to be occupied.

[28 FR 13002, Dec. 5, 1963, as amended at 33 FR 4580, Mar. 15, 1968; 35 FR 10447, June 26, 1970; 39 FR 2766, Jan. 24, 1974; 39 FR 25494, July 11, 1974]

§ 21.704 Modulation requirements.

(a) When amplitude modulation is used, the modulation percentage shall be sufficient to provide efficient communication and shall normally be maintained above 70 percent on peaks, but shall not exceed 100 percent on negative peaks.

(b) Transmitters employing type A3 or F3 emission and operating on frequencies below 500 MHz shall conform

to the requirements set forth in §§ 21.507 and 21.508.

§ 21.705 Permissible communications.

Stations in this service are authorized to render any kind of communication service provided for in the legally applicable tariffs of the carrier, unless otherwise directed in the applicable instrument of authorization or limited by § 21.701 or § 21.703. In authorizations classed as fixed video, the services permissible are limited to the carriage of video signals and their associated audio signals unless otherwise conditioned.

[33 FR 3184, Feb. 20, 1968, as amended at 35 FR 10447, June 26, 1970]

§ 21.706 Supplementary showing required with applications.

(a) Each application for initial installation of a radio station in this service, or for installation of equipment to provide additional service, or for authority to communicate with new points, shall be accompanied by a statement showing how the proposal will serve the public interest, convenience and necessity. Such statement must include information concerning:

(1) The nature and type of services to be rendered (e.g. telephone/telegraph, private line voice/data, television transmission, etc.)

(2) The cities or communities to be served including the number of circuits to be established. Where multiple cities are to be served, specify by diagram or other appropriate means the circuit cross section between service points.

(3) Projected future circuit growth anticipated between service points and indicate the source of such projections.

(4) Where the construction of radio facilities is dependent upon the specific requirements of one or several customers of a limited class (e.g. those desiring television signals), the need for facilities should be supported by an order for service from each such customer.

(b) Where specific information required by paragraph (a) of this section has been submitted in connection with applications filed under Part 63 of this chapter, duplicate information in sup

port of applications submitted pursuant to this part is not required provided appropriate references are made therein. The information submitted in connection with paragraph (a) of this section shall not be considered to replace any requirement to acquire authority for channelizing pursuant to Section 214 of the Communications Act.

(c) In those frequency bands shared with the communication-satellite service, an applicant for a new station, for new points of communication, for the initial frequency assignment in a shared band for which coordination has not been previously effected, or for authority to modify the emission or radiation characteristics of an existing station in a manner that may increase the likelihood of harmful interference, shall ascertain in advance whether the station(s) involved lie

within the great circle coordination distance contours of an existing Earth station or one for which an application has been accepted for filing, and shall coordinate his proposal with each such Earth station operator or applicant. For each potential interference path, the applicant shall perform the computations required to determine that the expected level of interference to or from the terrestrial station does not exceed the maximum permissible interference power level in accordance with the technical standards and requirements of §§ 25.251-25.256 of this chapter. In those instances where the results of these computations indicate a safety margin of less than 5 dB, the applicant shall submit with the application to the Commission, certain additional information; the gains assumed for both the terrestrial and Earth station antennas in the direction of the other station; the calculated transmission loss; and the resulting margin above the controlling objective. The Commission may, in the course of examining any application, require the submission of additional showings, complete with pertinent data and calculations in accordance with Part 25 of this chapter, showing that harmful interference will not likely result from the proposed operation. (Technical characteristics of the Earth stations on file and coordination

contour maps for those Earth stations will be kept on file for public inspection in the offices of the Commission's Common Carrier Bureau in Washington, D.C.)

(d) Each applicant filing pursuant to paragraph (c) of this section shall also ascertain in advance whether the beam of his proposed antenna(s) intersects the beam of any Earth station antenna within the rain scatter coordination distance contour of which the terrestrial antenna is located, below the altitude given in table 1 of § 25.254(b) of this chapter for the rain climate in which the Earth station is located. In general such intersections will not be permitted. For the purposes of this paragraph, the beam of an antenna is to be taken as that portion of the antenna radiation pattern inside of which the gain is within 15 dB of the maximum antenna gain. The concepts of rain climate and rain scatter coordination distance contour are as defined in § 25.254 of this chapter. In certain cases, for good cause shown, intersections may be permitted on an individual waiver basis. In such cases, the applicant shall also submit with his application a showing setting forth (1) the nature of the proposed beam intersection, (2) the Earth station operator or applicant with whom coordination was attempted and the results of the coordination, and (3) the technical basis on which it was conIcluded that harmful interference will not likely result from this beam intersection.

[28 FR 13002, Dec. 5, 1963, as amended at 38 FR 8572, Apr. 4, 1973; 40 FR 47504, Oct. 9, 1975]

§ 21.707 Stations at temporary fixed locations.

(a) Authorizations may be issued upon proper application for the use of frequencies listed in § 21.701(a) by stations in the point-to-point microwave radio service for rendition of temporary service to subscribers under the following conditions:

(1) When a fixed station is to remain at a single location for less than 6 months, the location is considered to be temporary. Services which are initially known to be of longer than 6 months' duration shall not be pro

vided under a temporary fixed authorization but rendered pursuant to a reg. ular license.

(2) When a fixed station, authorized to operate at temporary locations, is to remain at a single location for more than six months, applications (FCC Forms 401 and 403) for a station authorization designating that single location as the permanent location shall be filed at least 30 days prior to the expiration of the six-month period.

(3) The station shall be used only for rendition of communication service at a remote point where the provision of wire facilities is not practicable.

(4) The antenna structure height employed at any location shall not exceed the criteria set forth in § 17.7 of this chapter unless, in each instance, authorization for use of a specific maximum antenna structure height for each location has been obtained from the Commission prior to erection of the antenna. See § 21.114.

(b) Applications for authorizations to operate stations at temporary locations under the provisions of this section shall be made upon FCC Form 401, and may be accompanied by completed FCC Form 403 for simultaneous consideration provided the equipment to be used is of "packaged" design. Blanket applications may be submitted for the required number of transmitters.

[28 FR 13002, Dec. 5, 1963, as amended at 35 FR 10447, June 26, 1970]

§ 21.708 Notification of station operation at temporary fixed locations.

(a) The licensee of stations which are authorized pursuant to the provisions of § 21.707 shall notify the Commission, and its engineer in charge of the radio district wherein operation is to be conducted, at least 5 days prior to installation of the facilities, stating:

(1) The call sign, manufacturer's name, type or model number, output power and specific location of the transmitter(s).

(2) The maintenance location for the transmitter.

(3) The location of the transmitting or receiving station with which it will communicate and the identity of the correspondent operating such facili

ties.

(4) The exact frequency or frequencies to be used.

(5) The public interest, convenience and necessity to be served by operation of the proposed installation.

(6) The commencement and anticipated termination dates of operation from each location. In the event the actual termination date differs from the previous notification, written notice thereof promptly shall be given to the Commission and its Engineerin-Charge.

(7) A notification of operations to be conducted within the coordination distance contours of a fixed earth station shall include compliance with the provisions of § 21.706(c).

(8) Where the notification contemplates initially a service which is to be rendered for a period longer than 90 days, the notification shall contain a showing as to why application should not be made for regular authorization.

(b) Less than 5 days advance notice may be given when circumstances require shorter notice provided such notice is promptly given and the reasons in support of such shorter notice are stated.

(c) A copy of this notification shall be posted with the station license. (See § 21.214.)

[28 FR 13002, Dec. 5, 1963, as amended at 30 FR 7176, May 28, 1965; 35 FR 10447, June 26, 1970]

$21.709 Renewal of station licenses.

(a) An application for renewal of a license of a station in the Domestic Public Point-to-Point Microwave Radio Service used to relay television signals to community antenna television systems must include a showing that at least 50 percent of the customers (on the microwave system involved), including customers of any interconnecting carrier(s), receiving applicant's service are unrelated and unaffiliated with the applicant, and that the usage by such customers, in terms of hours of use and channels delivered, constitutes at least 50 percent of the usage of applicant's microwave system. Applications which do not contain the showing required by this section will be returned as unacceptable for filing.

(b) Applicants whose licenses expired on February 1, 1961, or 1963, and who have renewal applications bending before the Commission, or presently authorized common carrier licensees whose licenses will expire on February 1, 1966, who serve affiliated or related customers may become licensees in the Community Antenna Relay Service upon application therein and be granted a waiver of the Commission's rules so that they may be authorized to continue to use common carrier frequencies under the technical standards applicable to such frequencies until February 1, 1971, if they elect to do so. Such election must be made and an application filed in the Community Antenna Relay Service within sixty (60) days after the issuance of a Report and Order on Parts II and IV of Docket No. 15586. Pending such election time, renewal applications which do not comply with the provisions of paragraph (a) of this section will be granted only for such period of time as is necessary to preserve the opportunity for election. The license issued in the Community Antenna Relay Service will not be renewable on the common carrier frequencies. Applications for renewal of such licenses shall be filed for frequencies assigned to the Community Antenna Relay Service.

(c) Any application for renewal of license, for a term commencing January 1, 1975, or after, involving facilities utilizing frequency diversity must contain a statement showing compliance with § 21.100(c) or the exceptions recognized in paragraph 141 of the "First Report and Order" in Docket No. 18920 (FCC 71-547). If not in compliance, a complete statement with the reasons therefor shall be submitted.

(d) Each applicant for renewal of license for a term commencing between January 1, 1976 and January 1, 1981 shall submit with the application all of the technical parameters of the station (as licensed) listed on page 1 of FCC Form 435. If the same information has previously been submitted for the station on a Form 435, this requirement will be waived. Applicants are urged to file this information on punched cards in accordance with the Commission publication Punched Card

(b) Exception to the limits in paragraph (a) may be made by the Commission when a showing (with supporting facts) is made that use of a frequency in conformance with the rule would entail excessive cost in construction or maintenance or would otherwise create substantial difficulties. The alternate frequency proposal must be shown to be consistent with good engineering practice under the circumstances. Stricter adherence to these limitations is expected in areas of general frequency congestion. The distance limitation does not apply to a frequency which is power split if one transmission path utilizing that frequency meets the minimum distance requirement.

(c) Except for video transmission, an application for an initial working channel over a given route will not be accepted for filing where the anticipated loading (within five years or other period subject to reasonable projection) is less than the minimum specified for the following frequency bands. Absent extraordinary circumstances, applications proposing additional frequencies over existing routes will not be granted unless it is shown that the traffic load will shortly exhaust the capacity of the existing equipment.

Where transmitters employing digital modulation techniques are designed to be used so that two may simultaneously operate on the same frequency over the same path, the minimum number of voice channels specified above is reduced from 900 to 500 per transmitter for the bands 3,700-4,200 MHz, 5,9256,425 MHz, and 10,700-11,700 MHz.

(Secs. 307, 308, 309, 310, 319, 48 Stat. 1083, 1084, 1085, 1086, 1089, as amended; 47 U.S.C. 307, 308, 309, 310, 319)

[39 FR 25495, July 11, 1974]

§ 21.711 Special requirements for operation in the band 38,600-40,000 MHz. Assigned frequency channels in the band 38,600-40,000 MHz may be subdivided and used anywhere in the authorized service area, subject to the following terms and conditions:

(a) No interference shall be caused to a previously existing station operating in another authorized service area.

(b) The Commission's Engineer in Charge of the radio district in which the intended operation is located shall be notified prior to the commencement of operation of each frequency path. Such notice shall include:

(1) The authorized call sign, transmitter station location number (assigned by the carrier in sequence of use beginning with number one) and transmitting station coordinates;

(2) Receiving station location number and coordinates;

(3) The exact frequency or frequencies to be used (which shall be considered the assigned frequency or frequencies); and

(4) Anticipated date of commencement of operation.