[Code of Federal Regulations]

[Title 47, Volume 4]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 47CFR73.758]



[Page 268-269]

 

                       TITLE 47--TELECOMMUNICATION

 

                    CHAPTER I--FEDERAL COMMUNICATIONS

                         COMMISSION (CONTINUED)

 

PART 73_RADIO BROADCAST SERVICES--Table of Contents

 

               Subpart F_International Broadcast Stations

 

Sec. 73.758  System specifications for digitally modulated emissions 

in the HF broadcasting service.



    (a) For digitally modulated emissions, the Digital Radio Mondiale 

(DRM) standard shall be employed. Both digital audio broadcasting and 

datacasting are authorized. The RF requirements for the DRM system are 

specified in paragraphs (b) and (c), of this section.



[[Page 269]]



    (b) System parameters--(1) Channel spacing. The initial spacing for 

digitally modulated emissions shall be 10 kHz. However, interleaved 

channels with a separation of 5 kHz may be used in accordance with the 

appropriate protection criteria appearing in Resolution 543 (WRC-03), 

provided that the interleaved emission is not to the same geographical 

area as either of the emissions between which it is interleaved.

    (2) Channel utilization. Channels using digitally modulated 

emissions may share the same spectrum or be interleaved with analog 

emissions in the same high frequency broadcasting (HFBC) band, provided 

the protection afforded to the analog emissions is at least as great as 

that which is currently in force for analog-to-analog protection. 

Accomplishing this may require that the digital spectral power density 

(and total power) be lower by several dB than is currently used for 

either DSB or SSB emissions.

    (c) Emission characteristics--(1) Bandwidth and center frequency. A 

full digitally modulated emission will have a 10 kHz bandwidth with its 

center frequency at any of the 5 kHz center frequency locations in the 

channel raster currently in use within the HFBC bands. Among several 

possible ``simulcast'' modes are those having a combination of analog 

and digital emissions of the same program in the same channel, that may 

use a digital emission of 5 kHz or 10 kHz bandwidth, next to either a 5 

kHz or 10 kHz analog emission. In all cases of this type, the 5 kHz 

interleaved raster used in HFBC shall be adhered to in placing the 

emission within these bands.

    (2) Frequency tolerance. The frequency tolerance shall be 10 Hz. See 

Section 73.757(b)(2), notes 1 and 2.

    (3) Audio-frequency band. The quality of service, using digital 

source coding within a 10 kHz bandwidth, taking into account the need to 

adapt the emission coding for various levels of error avoidance, 

detection and correction, can range from the equivalent of monophonic FM 

(approximately 15 kHz) to the low-level performance of a speech codec 

(of the order of 3 kHz). The choice of audio quality is connected to the 

needs of the broadcaster and listener, and includes the consideration of 

such characteristics as the propagation conditions expected. There is no 

single specification, only the upper and lower bounds noted in this 

paragraph.

    (4) Modulation. Quadrature amplitude modulation (QAM) with 

orthogonal frequency division multiplexing (OFDM) shall be used. 64-QAM 

is feasible under many propagation conditions; others such as 32-, 16- 

and 8-QAM are specified for use when needed.

    (5) RF protection ratio values. The protection ratio values for 

analogue and digital emissions for co-channel and adjacent channel 

conditions shall be in accordance with Resolution 543 (WRC-03) as 

provisional RF protection ratio values subject to revision or 

confirmation by a future competent conference.



[70 FR 46677, Aug. 10, 2005]