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1、JOINT INTERIM STANDARD GMR-1 Series 06 (06.012) Speech Coding Specifications - Vocoder - Comfort Noise Aspects IS-J-STD-782-Series 6 NOVEMBER 2001 TELECOMMUNICATIONS INDUSTRY ASSOCIATION Rcprewnting the telennimunicationv indusiry in aysociaion with the Electronic Indusiria Alliance Elsctron ic Ind
2、wtries. Allia nee EUROPEAN TELECOMMUNICATIONS STANDARDS INSTITUTE Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without licens
3、e from IHS -,-,- NOTICE FROM THE TELECOMMUNICATIONS INDUSTRY ASSOCIATION TIA/EIA Engineering Standards and hblications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, an
4、d assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards and hblications shall not in any respect preclude any member or nonmember of TIA/EIA from manufacturing or selling products not conforming to such Standards
5、 and hblications, nor shall the existence of such Standards and hblications preclude their voluntary use by those other than TIA/EIA members, whether the standard is to be used either domestically or internationally. Standards and hblications are adopted by TIA/EIA in accordance with the American Na
6、tional Standards Institute (ANSI) patent policy. By such action, TIA/EIA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Standard or hblication. Note: The users attention is called to the possibiliS, that compliance with this docu
7、ment may require use o f one or more inventions covered by patent rights. By publication o f this standard, Interim Standard, or TSB, no position is taken with respect to the validio o f those claims or o f any patent rights in connection therewith. The patent holder) so far identified have, however
8、, filed statements o f willingness to grant licenses under those rights on reasonable and nondiscriminatory terms and conditions to applicants desiring to obtain such licenses. Details may be obtained from the standards developer. TIA/EIA AND JOINT INTERIM STANDARDS Joint Interim Standards contain i
9、nformation deemed to be of technical value to the industry, and are published at the request of the originating Committee without necessarily following the rigorous public review and resolution of comments which is a procedural part of the development of an American National Standard (ANS). Interim
10、Standards should be reviewed on a periodic basis by the formulating Committee and a decision made on whether to proceed to develop a TIA/EIA Standard on this subject. Interim Standards must be upgraded or cancelled by the Committee before the end of their third year of existence. hblication of this
11、Joint Interim Standard for trial use and comment has been approved by the Telecommunications Industry Association. Distribution of this Joint Interim Standard for comment shall not continue beyond 36 months from the date of publication. It is expected that following this 36 month period, this Joint
12、Interim Standard, revised as necessary, will be submitted to the American National Standards Institute for approval as an American National Standard. Suggestions for revision should be directed to: Standards Abbreviations and acronyms“. GMR- 1 05.008 (TIA/EIA/IS-782.05008) “GEO-Mobile Radio Interfac
13、e Specifications; Radio Subsystem Link control“. This specification is not yet published. 21 Note: 31 GMR- 1 06.03 1 (TIA/EIA/IS-782.0603 1) “GEO-Mobile Radio Interface Specifications; Discontinuous Transmission (DTX)“. Note: 41 This specification is not yet published. GMR- 1 06.00 1 (TIA/EIA/IS-782
14、.0600 1) “GEO-Mobile Radio Interface Specifications; Speech Processing Functions“. GMR- 1 O 1.20 1 (TIA/EIA/IS-782.0 120 1) “GEO-Mobile Radio Interface Specifications; Introduction to the GMR- 1 family“. 51 3 Copyright Telecommunications Industry Association Provided by IHS under license with EIALic
15、ensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,- TINEIAAS-782.06012 3 3.1 Definitions and abbreviations De fin it ions Voice Activity Detection FAD): A method of classifiing short segments
16、of speech as either “voice“ or “background noise.“ The decision is based upon comparing the current level and spectral characteristics of the input signal with that of a typical level and spectral characteristics. Comfort Noise Insertion (CNI): A method of synthesizing low-level noise on the receive
17、 side during breaks in voice transmission. To increase the perceived voice quality, the synthesized noise has characteristics that are similar to the background noise present on the transmit side. Forward Error Correction (FEC): A method of introducing redundancy to binary data that allows for the d
18、etection andor correction of errors introduced during transmission of that data. VIUVFoicedlUnvoiced): Each spectral band is declared either “voiced“ or “unvoiced“, depending upon the amount of periodic energy in that band. This voicing decision is frequently referred to as a V/UV decision. frame: T
19、he data representing a full 40 msec of continuous data input to or output from the vocoder. The frame data may consist of model parameters, quantized bits, FEC encoded channel data, or speech samples at various points in the vocoder. subframe: The data representing 10 mec of continuous data input to
20、 or output from the vocoder, or the result of processing that data through various points in the vocoder. For example, “The second subframe of model parameters is passed to the quantizer“ is a valid use of the term as is “The decoder outputs one subframe of 8 kHz speech samples.“ subframe number: Ea
21、ch frame is composed of four consecutive subframes that are each assigned a subframe number. The fiist, second, third, and fourth subframes within a frame are assigned subframe numbers O, 1,2, and 3 respectively. quantizer-frame: The data representing the 20 mec of continuous vocoder data that is fo
22、rmed by combining subframes O and 1 or subframes 2 and 3. quantizer-frame number: Each frame is composed of two consecutive quantizer-frames that are each assigned a quantizer frame number. The fiist and second quantizer-frames within a frame are assigned quantizer-frame numbers O and 1 respectively
23、. voice frame: A 40-msec frame that contains some voice data but no tone data. It may also contain comfort noise data. SID frame: (Silence Descriptor): A 20-msec frame that contains only comfort noise data. No voice or tone data may be present in a SID frame. tone frame: A 40-msec frame that contain
24、s tone data. It may also contain voice data or comfort noise data. 3.2 Abbreviations Abbreviations used in this specification are listed in GMR-1 01,004 i. 4 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie N
25、ot for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,- TIA/EIA/lS-782.06012 4 Ge ne ra I The overall operation of discontinuous transmission (DTX) is described in GMR-1 06.03 1 3. The purpose of comfort noise insertion is to eliminate the modulat
26、ion of background noise that would occur if pure silence rather than background noise was inserted during intervals where the radio transmission rate is reduced. This modulation effect would be very annoying to the listener, particularly in high background noise environments. This problem is overcom
27、e in the GMR-1 system by modeling the background noise at the transmit side and sending that information to the receive side where it is reconstructed. The characteristics of the background noise are transmitted once prior to the reduction in transmission rate and updated at a regular rate thereafte
28、r. This allows the comfort noise at the receive side to adapt to changes in the noise at the transmit side. 5 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reprodu
29、ction or networking permitted without license from IHS -,-,- TINEIAAS-782.06012 5 Functions on the transmit side When no voice activity is present at the transmit side, the voice encoder measures the characteristics of the comfort noise, then this information is quantized and FEC encoded. It is then
30、 output into a special frame called a SID (silence descriptor) frame for transmission to the receive side. The first SID frame is transmitted as part of the final 208-bit frame before the transmission rate is reduced. Subsequent SID frames will be transmitted at 100 bps using a 104-bit frame. Conseq
31、uently, during non-voice intervals, the receiver will receive a SID frame every 1 .O4 seconds. The actual transmission aspects of the SID frame on the radio link are described in GMR-1 05.008 2. 6 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Em
32、ployees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,- TIA/EIA/lS-782.06012 6 Functions on the receive side The conditions under which comfort noise will be generated on the receive side are defined in GMR-1
33、 06.03 1 3. Typically, the comfort noise generation is started whenever a valid SID frame is received and the characteristics of that comfort noise are updated upon receiving subsequent SID frames. The voice decoder can distinguish the SID frame from a voice frame or a tone frame based upon the cont
34、ents of the SID frame alone. When the decoder receives the first SID frame, it generates the first frame of comfort noise. After the first SID frame is received and decoded, the voice decoder must be executed continuously at the regular frame rate with the mute flag set until the next SID, voice, or
35、 tone frame is received. Upon receiving a subsequent 104-bit SID frame, the mute flag will be deactivated when decoding quantizer-frame O and reactivated when decoding quantizer-frame 1 (which does not exist). The mute flag will remain activated during any interval where no frame was transmitted. Wh
36、en voice activity returns, the decoder will begin receiving voice frames and the mute flag will be deactivated. The RX radio subsystem is responsible for queuing 104-bit SID frames that are received at a reduced transmission rate. Upon receiving a complete SID frame, the radio subsystem passes the S
37、ID frame to the RX DTX handler, which in turn passes it to the decoder. The RX DTX handler is responsible for activating or deactivating the mute flag appropriately. 7 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing
38、, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,- TINEINIS-782.06012 0.0.0 History January 200 1 HNS-24012 i First Drab converred from GMR- 1 060 1 ?v005 I Document history i 8 Copyright Telecommunications Industry Association Prov
39、ided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Em
40、ployees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 01:22:56 MDTNo reproduction or networking permitted without license from IHS -,-,-