1 This frequency is available for assignment only to stations of communications common carriers engaged also in the business of affording public landline message telephone service.

This frequency is available for assignment only to stations of communication common carriers not also engaged in the business of providing a public landline message telephone service. (NOTE: There is pending, in Docket 13847, a proposal to delete frequencles available for central office and interoffice stations for miscellaneous common carriers and to retain the frequencies for rural subscribed stations as designated by this footnote designator 2.)

Pending promulgation of rules and regulations to govern the public air-ground radiotelephone service, and subject to further Order of the Commission, frequencies in the 454.675-455.000 Mc/s and

Mc/s bands are not available for operation of new radio facilities in the Rural Radio Service. In the interim, the authorizations of stations using such frequencies may be renewed, subject to Commission determination relative to use of such frequencies by the public air-ground radiotelephone service.

(b) New stations will not be authorized in the 890-940 Mc/s band.

However,

stations which were authorized to operate on April 16, 1958, may be granted renewed licenses subject to the following conditions:

(1) Operations shall not be protected against any interference received from the emission of industrial, scientific, and medical equipment operating on 915 Mcs or from the emission of radiolocation stations in the 890-942 Mc/s band. (2) No harmful interference shall be caused to stations operating in the radiolocation service in the 890-942 Mc/s band. (c) In the State of Hawaii, the following frequencies are available for assignment to Inter-Office stations:

77.18

79.90

82.62

459.675-460.000

76-108 Mc/s Band

and (b) of this section may be assigned, and under the same limitations of shared usage and reservations concerning interference set forth therein, such frequencies may also be assigned to radio relay stations in the Rural Radio Service upon a satisfactory showing as to why it is impracticable to achieve the requisite communication without the use of radio relay stations operating on such frequencies.

(e) In Puerto Rico and the Virgin Islands only, the bands 154.04 Mc/s to 154.46 Mc/s and 161.40 Mc/s to 161.85 Mc/s are available for assignment to stations in the Rural Radio Service on a shared basis with stations in the International Fixed Public and Aeronautical Fixed Radio Services. Spacings between assignments in these services are unspecified.

(f) Stations now authorized in the band 890-942 Mc/s may be authorized to operate in the band 942-952 Mc/s on the following conditions:

(1) That such stations can show that harmful interference is being caused by Government radiopositioning stations in the 890-942 Mc/s band or by ISM equipment operating on 915 Mc/s.

(2) That an engineering study by the Commission indicates that the proposed frequency assignment in the band 942952 Mc/s is likely to eliminate the interference.

(3) That the bandwidth of emission does not exceed 1100 kc/s.

(4) That the proposed frequency assignment will not cause interference to existing operations in the band 942-952 Mc/s.

§ 21.602 Transmitter power.

Stations in this service shall not be authorized to use transmitters having a rated power output in excess of the limits set forth in § 21.107(b). A standby transmitter having a rated power output in excess of that of the main transmitter with which it is associated will not be authorized.

§ 21.603 Types of emission.

(a) Stations in this service within the continental limits of the United States normally shall be authorized to use only types A1, A2, A3 or F1, F2 and F3 emission for radiotelephony. However, multi-channel type of amplitude or frequency modulated emission for radiotelephony may be authorized upon a satisfactory showing of need therefor and

provided that the criteria concerning bandwidth of emission set forth in $21.604 (b) are satisfied.

(b) In addition to the types of emission which may be authorized under the provisions of paragraph (a) of this section, stations in this service outside the continental limits of the United States may be authorized to employ A4 and F4.

(c) The authorization for use of A3 and F3 emission shall be construed to include the use of tone signals or signaling devices whose sole function is to establish and maintain communication between stations.

(d) Other types of emission not described in paragraph (a) of this section

50-150 Mc/s

may be authorized upon a satisfactory showing of need therefor. An application requesting such authorization shall fully describe the emission desired, shall indicate the bandwidth required for satisfactory communication, and shall state the purpose for which such emission is required.

(e) Further reference should be made to §§ 21.103 to 21.105, inclusive. § 21.604 Emission limitations.

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

A1 A2

A3

A4

FI

F2.

F3

F4

(b) Bandwidths of emission greater than shown in paragraph (a) of this section may be authorized for multi-channel operation upon an adequate showing of need therefor and provided a showing is made that the efficiency of frequency utilization per derived communication channel is equivalent to or greater than on a single channel basis. An application requesting such authorization shall fully describe the modulation, emission and bandwidth desired and shall specify the bandwidth to be occupied.

21.605 Modulation requirements.

(a) The use of modulating frequencies higher than 3000 cycles per second for single channel radiotelephony or tone signaling on frequencies below 500 Mc's is not authorized.

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

(c) When phase or frequency modulation is used for single channel operation on frequencies below 500 Mc/s, the deviation arising from modulation shall

not exceed the limits specified in § 21.604 (a).

(d) Each transmitter, which has more than 3 watts plate power input to the final radio frequency stage and was initially authorized or installed at the station in this service after July 1, 1950, employing type A3 or F3 emission shall be equipped with a device which will automatically prevent greater than normal audio level from modulating in excess of the limits specified in paragraphs (b) and (c) of this section.

(e) Each transmitter, which employs type A3 or F3 emission, shall be equipped with a modulation limiter in accordance with the provisions of paragraph (d) of this section and also shall be equipped with a low-pass audio filter installed between the modulation limiter and the modulated stage. At audio frequencies between 3 kc/s and 15 kc/s, the filter shall have an attenuation greater than the attenuation at 1 kc/s by at least:

40 log10 (1/3) decibels

where "f" is the audio frequency in kilocycles. At audio frequencies above 15 kc/s, the attenuation shall be at least 28 decibels greater than the attenuation at 1 kc/s.

§ 21.606 Permissible communications.

(a) Rural Subscriber stations normally are authorized to communicate with and through the central office station with which they are associated. However, where the establishment of central office station facilities in this service is shown to be impracticable, Rural Subscriber stations may be authorized to communicate with and through a specified base station in the Domestic Public Land Mobile Radio Service pursuant to the provisions of § 21.509 (f).

(b) Central Office stations may communicate only with Rural Subscriber stations.

(c) Inter-Office stations may communicate only with other Inter-Office stations.

(d) The foregoing paragraphs of this section shall not be construed to prohibit stations in this service from communicating through radio relay stations authorized pursuant to the provisions of § 21.601 (d).

§ 21.607 Priority of service.

Within the Rural Radio Service, the frequencies set forth in § 21.601 are intended primarily for use in rendition of public message service between Rural Subscriber and Central Office stations and to provide radio trunking facilities between central offices. However, the frequencies may also be used for the rendition of private leased line communication service provided that such usage will not reduce or impair the extent or quality of communication service which would be available, in the absence of private leased line service, to the general public receiving or subsequently requesting public message service from a central office.

§ 21.608

Supplementary

showing required with application for interoffice stations.

(a) Each application for initial installation of a radio station in this service, or for installation of additional transmitters, or for authority to communicate with new points, shall be accompanied by a statement showing how the proposed construction, etc., will serve the public interest, convenience and necessity. (When a series of related applications is filed for authority to construct a coordinated radio system or additional channels thereon, the supporting data may refer to all of the

proposed stations or transmitters in such system.) Among other things, such statement should include information concerning:

(1) The number of communication circuits (telephone, telegraph, etc.) to be derived initially from the radio facilities proposed to be established. In the case of a radio system involving one or more circuit branching points, indicate the number of such circuits to be derived in each section of the system.

(2) The availability, adequacy, and reliability of existing public communication facilities along the route or in the area proposed to be served by the proposed radio facilities, operated by the applicant or any other carrier, indicating:

(i) The type of each communication facility (open wire, cable, radio, etc.).

(ii) The number of communication circuits of each type, listed in paragraph (a) (1) of this section, currently being derived from each of these facilities in the limiting cross-section or cross-sections, as appropriate.

(iii) Current traffic load trends, as indicated by periodic traffic load studies, including an estimate as to future circuit requirements.

(iv) Where more than 24 circuits are to be derived from the proposed construction, list the principal circuit groups currently operated, the number of circuits in each group, and the estimated number of circuits required in each group to meet load demands for the ensuing one year, two year, or five year period, as may be appropriate in order to provide adequate justification for said increases.

(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, duplication of information in support of applications submitted pursuant to this part is not required provided appropriate references are made therein. After an application for the initial establishment of a radio station or for the addition of transmitters on an existing system has been granted, and where the number of communication circuits (1.e., telephone, telegraph, etc.) is to be expanded without otherwise affecting the terms of the applicable radio station authorization, authority to install necessary channelizing equipment shall be secured by an application filed pursuant to section 214(a) of the Com

munications Act of 1934, as amended, and Part 63 of the Commission's rules and regulations, in those cases where the applicant is subject to the provisions of section 214.

§ 21.609 Supplementary showing required with applications for central office stations and rural subscriber stations.

Each application in this service should be accompanied by a statement showing why it is impracticable to provide the required communication service by means of wire line facilities, including the estimated cost of such facilities as compared with radio facilities, operating or maintenance difficulties, or similar factors which indicate the desirability of providing service by means of radio facilities. Additionally, where it is proposed to provide rural subscriber service through a base station, a showing should be made that the proposed rural subscriber service will not adversely affect the availability or adequacy of service to mobile subscribers.

§ 21.610 Rural subscriber, inter-office, and central office stations at temporary fixed locations.

(a) Authorizations may be issued upon proper application for the use of frequencies listed in § 21.601(a) by rural subscriber stations, inter-office stations, and central office stations for rendition of rural radio service at temporary locations under the following conditions:

(1) When a fixed station is to remain at a single location for less than six months and the location is considered to be temporary.

(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 thirty days prior to expiration of the six-month period.

(3) The station shall be used only for rendition of communication service to remote points where the provision of wire telephone facilities is not practicable, or for restoration of communication service disrupted by storms, floods, earthquakes, or other emergencies.

(4) The antenna height employed at any location shall not exceed the criteria set forth in § 17.3 of this chapter unless,

in each instance, authorization for use of a specific maximum antenna height has been obtained from the Commission prior to erection of the antenna. Requests for such authorization shall be accompanied by FCC Form 401-A completed in triplicate.

(b) Applications for authorizations to operate rural subscriber stations, interoffice stations, and central office 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 rural subscriber, inter-office and central office transmitters.

§ 21.611 Notification of station operation at temporary locations.

(a) The licensee of stations which are authorized pursuant to the provisions of § 21.610 shall notify the Commission, and its Engineer-in-Charge of the radio district wherein operation is to be conducted, of each period of operation at least two days prior to installation of the facilities. This notification shall include:

(1) The call sign and specific location of the transmitter.

(2) The location of the transmitter control point.

(3) The identity and location of the station with which it will communicate. (4) The exact frequency or frequencies to be used.

(5) 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 Engineer-in-Charge.

(b) A copy of the foregoing notification shall be posted with the station license (see § 21.214).

Subpart 1-Point-to-Point Microwave Radio Service

AUTHORITY: §§ 21.710, 21.712 and 21.714 also issued under secs. 307, 308, 309, 310, 319, 48 Stat. 1083, 1084, 1085, 1086, 1089, as amended; 47 U.S.C. 307, 308, 309, 310, 319.

§ 21.700 Eligibility.

Authorizations for stations in this service will be issued to existing and proposed communication common carriers.