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1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.1 BCS phase | |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.1.1 BCS command/response procedures | The CCITT Recommendation T.30 procedure is segmented in sections of associated BCS commands and responses. Any command sent by a facsimile terminal must be answered by an appropriate BCS response (refer to Appendix III, CCITT Recommendation T.30). To guarantee that transmission and reception of responses take place rig... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.1.2 Compatibility checking | Some features cannot be supported in the GSM PLMN environment. The fax adaptor function is in charge of dealing with such compatibility checking which is carried out by monitoring certain BCS frames (DIS/DTC).
β GroupΒ 1 and groupΒ 2 equipments are not supported by the Teleservice as described in the present document.
β ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.1.3 Message speed checking | Although it is strongly recommended to use the maximum user rate of the MT2 (9Β 600Β bit/s), a particular user may signal a lower user rate. In this case the fax adaptors have to carry out the following additional procedures:
β max speed indicated in the call setβup message is 4Β 800Β bit/s:
β if the fax adaptor receives a... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.1.4 Control of transmission rate | The controlling entity of the fax adaptor recognizes when a change of the transmission rate β and in conjunction with this a change of the modem function β has to commence. The transmission rate is then changed only locally, i.e. between the facsimile terminal and the fax adaptor at both the MSC/IWF and the MS ends.
Th... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.1.5 Clocking | The fax adaptor or the GSM facsimile machine will acquire received data bit timing on circuit 115 (according to CCITT Recommendation V.24). The transmitter element timing circuit 114 shall be synchronized to circuit 115.
The clock rate at the CCITT Recommendation V.24 interface will reflect the user rate of the MT2 as ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.2 Message phase | During the message phase (phase C of CCITT Recommendation T.30) a single bit pattern has to be detected, the EOL character (see subclauseΒ 4.1.2/CCITT Recommendation T.4), a unique code word that can never be found within a valid line of facsimile coded data, and is used, as per CCITT Recommendation T.4:
β to identify t... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.2.1 Normal facsimile data | The message phase (see figure II.6/GSMΒ 03.46 and II.7/GSMΒ 03.46, respectively) at both the PLMN ends is triggered by the transit of a frame (either the CFR or the MCF) sent by the receiving terminal to confirm a previous frame from the transmitting terminal, and marking the end of a BCS phase.
The terminal adaptation f... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.2.2 Error correction facsimile data | As these facsimile coded data between the fax adaptor and the facsimile terminal are structured in HDLC frames, the handling of this procedure segment will exploit such formatting. The content of such an HDLC frame is further on called a block.
Each such block is included in the information field of a error correction ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.2.3 Buffering of facsimile coded data | The following subclauses only apply, when using the normal facsimile data transfer, i.e. not with the error correction mode. |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.2.3.1 Transmitter adaptation function | In the transmitter adaptation function the facsimile coded data being received from the facsimile terminal are transcoded stripping of FILL information and written into the buffer.
If there is enough information available, this data is read out from the buffer, and a FA protocol element is generated which is processed ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.2.3.2 Receiver adaptation function | In the receiver adaptation function FILL information is transmitted to the facsimile terminal at the beginning of each page, if necessary, to bridge the gap between the training sequence and the real facsimile coded data. In case of normal fax data the FILL 0's can be expanded up to 5s only and therefore after these up... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.3 Disconnect procedure | The transmitter adaptation function, upon detection of the DCN frame (see CCITT Recommendation T.30) sent by the local terminal to indicate the end of the facsimile transmission, initiates the disconnect procedure. |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 7.2.4 Timeouts | The overall fax adaptation function is in principle bound to the timing constraints associated with the endβtoβend CCITT Recommendation T.30 procedure. This means that, no matter of the reference configuration used at the mobile station, either the "standard" one (figure 2a/GSMΒ 03.46) or the "GSM facsimile machine" (fi... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8 Signalling aspects | GSMΒ 07.03 identifies the bearer capability requirements to be supported by the terminal adaptation function in the MT (see GSMΒ 07.01 for BC and HLC coding). The specific signalling requirements are those for "speech" and "facsimile groupΒ 3" or "facsimile groupΒ 3" only, respectively. The MT indicates in the call set up ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.1 Handling of tonal signals | Because the CCITT defined service uses modems, there are some signals received from the analogue link at the MSC/IWF and (where used) the fax adaptor which do not have a direct binary representation. These signals cannot therefore be passed across the radio interface in the same way as the CCITT Recommendation T.30 and... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2 Call establishment | |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.1 Mobile terminated call | The PSTN facsimile groupΒ 3 terminal may be manually or automatically calling. |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.1.1 Speech then facsimile | Refer to the diagram in figure II.1a/03.46 and II.1b/03.46. In both of the figures the initial call setup is mobile terminated. In figure I.1a/03.46 the DCD is also mobile terminated (MT), while the DCD in figureΒ I.1b/03.46 is mobile originated (MO).
In order to make the transition from the speech phase to the facsimil... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.1.2 Auto answer | Refer to diagram in figure II.2/GSMΒ 03.46. A call received from the PSTN will cause the MT to turn on circuit 125 (according to CCITT Recommendation V.24) at the R interface.
In the case where a GSM facsimile machine is used, CCITT RecommendationΒ V.25bis auto answering process is handled directly by turning on circuit ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.2 Mobile originated calls | The PSTN facsimile groupΒ 3 terminal may be manually or automatically answered. |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.2.1 Speech then facsimile | Refer to the diagram in figure II.3a/03.46 and figure II.3b/03.46. In both of the figures the initial call setup is mobile terminated. In figure II.3a/03.46 the DCD is also MO, while in figure II.3b/03.46 the DCD is MT.
In order to make the transition from the speech phase to the facsimile phase, the MODIFY command mus... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.2.2 Auto calling | Refer to diagram in figure II.4/GSMΒ 03.46. The auto calling procedure of CCITT Recommendation V.25bis is initiated at the CCITT Recommendation V.24 interface. This is done either directly from the GSM facsimile machine or, in the case where a fax adaptor is used, by loop disconnect or DTMF dialling information between ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 8.2.2.3 Manual calling | Refer to diagram in figure II.5/GSMΒ 03.46. When the call is answered, the RLP will be established across the radio interface providing circuit 108/2 in ON condition.
In the case where a fax adaptor is used, the mobile facsimile terminal must be connected to line by manual intervention at this stage, and will cause the ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 9 Interworking to fixed networks | PSTN and ISDN only are considered, both used as transit networks to complement the PLMN in the endβtoβend connection between facsimile groupΒ 3 terminal, figure 7/GSMΒ 03.46.
I W F
β β β β β β β β β β β β β β
:βββββββββββββββββββββ :
:βProtocolββ V.21 β :
βββββββ :βControl ββ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 9.1 Interworking to PSTN | As the standard access of facsimile groupΒ 3 terminals for this Teleservice is a 2βwire analogue interface, all the technical requirements for network interworking to PSTN are identical in principle to those encountered for the terminal connection to the MT. The key functional block is the fax adaptor described in claus... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 9.2 Interworking to ISDN | The use of 3.1Β kHz audio bearer capability of ISDN allows for an interworking of PLMN very similar in practice to the scheme for PSTN, figure 7/GSMΒ 03.46. The fax adaptor function is in conformance with the description given in clause 4 and subclause 7.1 of the present document.
Annex A (normative):
Structure and conte... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 1 Principle structure of an element | Each FA protocol element consists of the element discriminator (one single octet) and the optional information field (arbitrary length).
The elements are transmitted with octet 0, bit 1 first. Received information is forwarded with the same bit sequence as received.
octet: 0 1 ..... ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2 Element discriminator coding | |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.1 BCS element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β X β 0 β y β y β 0 β 0 β 0 β 0 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
β ββββ¬βββ
β 0 1 = begin of a BCS frame
β 1 0 = end of a BCS frame
β 0 0 = middle of a BCS frame
β 1 1 = entire BCS frame
0 = non-final frame
1 ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.2 BCS abort element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 1 β 0 β 1 β 0 β 0 β 0 β 0 β 1 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.3/03.46: Element discriminator of a BCS abort element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.3 BCS transmit request element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 0 β 1 β 0 β 0 β 0 β 0 β 0 β 1 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.4/03.46: Element discriminator of a BCS transmit request element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.4 Preamble element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 0 β 1 β 0 β 0 β 0 β 0 β 0 β 0 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.5/03.46: Element discriminator of a preamble element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.5 Normal fax data element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 0 β 1 β 0 β 0 β 1 β 0 β 0 β 0 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.6/03.46: Element discriminator of a normal fax data element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.6 Error correction fax data element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 0 β 1 β 0 β 0 β 1 β 0 β 0 β 1 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.7/03.46: Element discriminator of an error correction fax data element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.7 End of data element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 0 β 1 β 0 β 0 β 1 β 0 β 1 β 0 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.8/03.46: Element discriminator of an end of data element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 2.8 TCF element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 1 β 0 β 0 β 1 β 0 β 0 β 0 β 1 β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
Figure A.9/03.46: Element discriminator of a TCF element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3 Information field content | |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.1 BCS element | CCITT Recommendation ββββββββββββββββββββββββββ
T.30 frame β FCF + [FIF] β
ββββββββββββββββββββββββββ
| |
FA protocol βββββ€βββββ€βββββββββββββββββββββββββ
element β D β SN β β
βββββ§βββββ§βββββββββββββββββββββββββ
D = discriminator ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.2 BCS abort element | no information field available |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.3 BCS transmit request element | FA protocol βββββ€βββββ
element β D β SN β
βββββ§βββββ
D = discriminator octet
SN = sequence number (0 .. 255),
bit 1 = LSB = Least significant bit |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.4 Preamble element | no information field available |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.5 Normal fax data element | transcoded ββ€ββββββββββββββββββββββββββββββββββββββββ€β
facsimile β max. 936 bits of facsimile coded data β
data ββ§ββββββββββββββββββββββββββββββββββββββββ§β
β β
FA protocol βββββ€ββββββββββββββββββββββββββββββββββββββββ
element β D β ... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.6 Error correction fax data element | CCITT Recommendation
T.4 frame ββββββββββββββββββββββββββ
(FCD or RCP) β FCF + [FIF] β
ββββββββββββββββββββββββββ
| |
FA protocol βββββ€βββββββββββββββββββββββββ
element β D β β
βββββ§βββββββββββββββββββββββββ
D = discriminator octe... |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.7 End of data element | no information field available |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 3.8 TCF element | bit 8 7 6 5 4 3 2 1
βββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ¬ββββ
β 0 β 0 β 0 β 0 β 0 β 0 β 0 β X β
βββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ΄ββββ
X = 0 : TCF_OK
X = 1 : TCF_NOK
Figure A.13/03.46: Information field content of a TCF element |
1b3a41393e6b9c2d9c5a8ec454e96ca8 | 03.46 | 4 Relationship of FA protocol elements with LAPB, L2RBOP and RLP | Refer also to GSMΒ 07.03
FA protocol βββ€βββββββββββββββββββββββββ
element βDβ optional information β
βββ§βββββββββββββββββββββββββ
| |
LAPB I-frame βββ€ββ€βββββββββββββββββββββββββββ€ββββ
information βAβCβ βFCSβ
field βββ§ββ§βββββββββββββ... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 1 Scope | The present document specifies the digital test sequences for the GSM half rate speech codec. These sequences test for a bit exact implementation of the half rate speech transcoder (GSMΒ 06.20Β [2]), Voice Activity Detector (GSMΒ 06.42Β [6]), comfort noise (GSMΒ 06.22Β [4]) and the discontinuous transmission (GSMΒ 06.41Β [5]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
β’ References are either specific (identified by date of publication, edition number, version number, etc.) or nonβspecific.
β’ For a specific reference, subsequent revisions do not apply.
β’ Fo... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 3 Definitions and abbreviations | |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 3.1 Definitions | Definition of terms used in the present document can be found in GSMΒ 06.20Β [2], GSMΒ 06.21Β [3], GSMΒ 06.22 [4], GSMΒ 06.41Β [5] and GSMΒ 06.42Β [6]. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply:
ETS European Telecommunication Standard
GSM Global System for Mobile communications
For abbreviations not given in this clause, see GSMΒ 01.04Β [1]. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 4 General | Digital test sequences are necessary to test for a bit exact implementation of the half rate speech transcoder (GSMΒ 06.20Β [2]), Voice Activity Detector (GSMΒ 06.42Β [6]), comfort noise (GSMΒ 06.22Β [4]) and the discontinuous transmission (GSMΒ 06.41Β [5]).
The test sequences may also be used to verify installations of the AN... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 5 Test sequence format | This clause provides information on the format of the digital test sequences for the GSM half rate speech transcoder (GSMΒ 06.20Β [2]), Voice Activity Detector (GSMΒ 06.42Β [6]), comfort noise (GSMΒ 06.22Β [4]) and the discontinuous transmission (GSMΒ 06.41Β [5]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 5.1 File format | The test sequence files are provided in archive en_300968v080001p0.ZIP which accompanies the present document.
Following decompression, by execution of the 11 "disk*.exe" files, four types of file are provided:
β Files for input to the GSM half rate speech encoder: *.INP
β Files for comparison with the encoder output: ... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 5.2 Codec homing | Each *.INP file includes two homing frames at the start of the test sequence. The function of these frames is to reset the speech encoder state variables to their initial value. In the case of a correct installation of the ANSIβC simulation (GSMΒ 06.06Β [7]), all speech encoder output frames shall be identical to the cor... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6 Speech codec test sequences | This clause describes the test sequences designed to exercise the GSM half rate speech transcoder (GSMΒ 06.20Β [2]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.1 Codec configuration | The speech encoder shall be configured to operate in the nonβDTX mode. The VAD and SP flags shall be set to 1 at the speech encoder output. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2 Speech codec test sequences | Table 5 lists the location and size of the speech codec test sequences. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2.1 Speech encoder test sequences | Three encoder input sequences are provided:
β SEQ01.INP β Sequence for exercising the LPC vector quantization codebooks;
β SEQ02.INP β Sequence for exercising the long term predictor codebooks;
β SEQ03.INP β Sequence for exercising the remaining excitation codebooks.
The SEQ01.INP sequence causes the GSM half rate spee... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2.2 Speech decoder test sequences | Four speech decoder input sequences are provided:
β SEQ01.DEC;
β SEQ02.DEC;
β SEQ03.DEC;
β SEQ04.DEC.
The SEQ01.DEC, SEQ02.DEC, and SEQ03.DEC sequences test the operation of the GSM half rate speech decoder in the absence of channel errors. They are derived from the corresponding SEQXX.INP sequences. In a correct imple... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 6.2.3 Codec homing sequence | In addition to the test sequences described above, two homing sequences are provided to assist in codec type approval testing. SEQ05.INP contains one encoderβhomingβframe. SEQ05.DEC contains one decoderβhomingβframe. The use of these sequences is described in GSMΒ 06.02Β [8].
Table 5: Location and size of speech codec te... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7 DTX test sequences | This clause describes the test sequences designed to exercise the VAD algorithm (GSMΒ 06.42Β [6]), comfort noise (GSMΒ 06.22Β [4]) and discontinuous transmission (GSMΒ 06.41Β [5]). |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.1 Codec configuration | The VAD, comfort noise and discontinuous transmission shall be tested in conjunction with the speech encoderΒ [2]). The speech encoder shall be configured to operate in the DTX mode defined in GSMΒ 06.22Β [4]. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2 DTX test sequences | Each DTX test sequence consists of four files:
β Files for input to the GSM half rate speech encoder: *.INP
β Files for comparison with the encoder output *.COD
β Files for input to the GSM half rate speech decoder: *.DEC
β Files for comparison with the decoder output: *.OUT
The *.DEC files are generated from the corre... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.1 Predictor values computation | The computation of the predictor values described in GSMΒ 06.42Β [6] is not tested explicitly, since the results from the computation are tested many times via the spectral comparison and threshold adaptation tests. |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.2 Spectral comparison | The spectral comparison algorithm described in GSMΒ 06.42Β [6] is tested by the following test sequence:
β DTX01.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.3 Threshold adaptation | The threshold adaptation algorithm described in GSMΒ 06.42Β [6] is tested by the following test sequence:
β DTX02.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.4 Periodicity detection | The periodicity detection algorithm described in GSMΒ 06.42Β [6] is tested by the following test sequence:
β DTX03.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.5 Tone detection | The tone detection algorithm described in GSMΒ 06.42Β [6] is tested by the following test sequence:
β DTX04.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.6 Safety and initialization | This sequence checks the safety paths used to prevent zero values being passed to the norm function. It checks the functions described in the adaptive filtering and energy computation, and the prediction values computation given in GSMΒ 06.42Β [6]. This sequence also checks the initialization of thvad and the rvad array:... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.7 Comfort noise test sequence | The test sequences described in subβclauses 7.2.2 to 7.2.6 are designed to exercise the VAD described in GSMΒ 06.42Β [6] and the discontinuous transmission described in GSMΒ 06.41Β [5]. The following test sequence is defined to exercise the comfort noise algorithm described in GSMΒ 06.22Β [4]:
β DTX06.* |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 7.2.8 Real speech and tones | The test sequences cannot be guaranteed to find every possible error. There is therefore a small possibility that an incorrect implementation produces the correct output for the test sequences, but fails with real signals. Consequently, an extra sequence is included, which consists of very clean speech, barely detectab... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8 Sequences for finding the 20 ms framing of the GSM half rate speech encoder | When testing the decoder, alignment of the test sequences used to the decoder framing is achieved by the air interface (testing of MS) or can be reached easily on the Abisβinterface (testing on network side).
When testing the encoder, usually there is no information available about where the encoder starts its 20Β ms se... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8.1 Bit synchronization | The input to the speech encoder is a series of 13 bit long words (104 kbits/s, 13 bit linear PCM). When starting to test the speech encoder, no knowledge is available on bit synchronization, i.e. where the encoder expects its least significant bits, and where it expects the most significant bits.
The encoder homing fra... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8.2 Frame synchronization | Once bit synchronization is found, frame synchronization can be found by inputting one special frame that delivers 160 different output frames, depending on the 160 different positions that this frame can possibly have with respect to the encoder framing.
This special synchronization frame was found by taking one input... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 8.3 Formats and sizes of the synchronization sequences | BIT SYNC.INP:
This sequence consists of 13 frame triplets. It has the format of the speech encoder input test sequences (13 bit left justified with the three least significant bits set to zero).
The size of it is therefore:
SIZE (BITSYNC.INP) = 13 * 3 * 160 * 2 bytes = 12480 bytes.
SEQSYNC.INP:
This sequence consists o... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 9 Trau Testing with 8 Bit A- and Β΅-law PCM Test Sequences | In the previous clauses tests for the transcoder in the TRAU are described using 13 bit linear test sequences. However, these 13 bit test sequences require a special interface in the Trau and do not allow testing in the field. In most cases the TRAU has to be set in special mode before testing.
As an option, the speech... |
8b410df87e6e8f32e6bbafe6636ff843 | 06.07 | 10 Test sequences for the GSM half rate speech codec | NOTE: This clause is contained in archive en_300968v080001p0.ZIP which accompanies the present document.
Annex A (informative):
Change Request History
Change history
SMG No.
TDoc. No.
CR. No.
Section affected
New version
Subject/Comments
SMG#16
4.0.3
ETSI Publication
SMG#20
5.0.1
Release 1996 version
SMG#23
97-737
A003... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 0.1 Scope | The present document specifies the Voice Activity Detector (VAD) to be used in the Discontinuous Transmission (DTX) as described in GSMΒ 06.31. It also specifies the test methods to be used to verify that a VAD complies with the technical specification.
The requirements are mandatory on any VAD to be used either in the ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 0.2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
β’ References are either specific (identified by date of publication, edition number, version number, etc.) or nonβspecific.
β’ For a specific reference, subsequent revisions do not apply.
β’ Fo... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 0.3 Abbreviations | Abbreviations used in the present document are listed in GSMΒ 01.04Β [1]. |
ad3845652ec99fdffd75badceec5143f | 06.32 | 1 General | The function of the VAD is to indicate whether each 20Β ms frame produced by the speech encoder contains speech or not. The output is a binary flag which is used by the TX DTX handler defined in GSMΒ 06.31Β [4].
The ETS is organized as follows.
Clause 2 describes the principles of operation of the VAD.
In clauseΒ 3, the co... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2 Functional description | The purpose of this clause is to give the reader an understanding of the principles of operation of the VAD, whereas the detailed description is given in clauseΒ 3. In case of discrepancy between the two descriptions, the detailed description of clauseΒ 3 shall prevail.
In the following clauses of clauseΒ 2, a Pascal prog... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.1 Overview and principles of operation | The function of the VAD is to distinguish between noise with speech present and noise without speech present. The biggest difficulty for detecting speech in a mobile environment is the very low speech/noise ratios which are often encountered. The accuracy of the VAD is improved by using filtering to increase the speech... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2 Algorithm description | The block diagram of the VAD algorithm is shown in figure 2.1. The individual blocks are described in the following clauses. ACF, N and sof are calculated in the speech encoder.
Figure 2.1: Functional block diagram of the VAD
The global variables shown in the block diagram are described as follows:
β ACF are autoβcorre... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.1 Adaptive filtering and energy computation | Pvad is computed as follows:
This corresponds to performing an 8th order block filtering on the input samples to the speech encoder, after zero offset compensation and preβemphasis. This is explained in clauseΒ A.1. |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.2 ACF averaging | Spectral characteristics of the input signal have to be obtained using blocks that are larger than one 20Β ms frame. This is done by averaging the autoβcorrelation values for several consecutive frames. This averaging is given by the following equations:
Where n represents the current frame, nβ1 represents the previous ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.3 Predictor values computation | The filter predictor values aav1 are obtained from the autoβcorrelation values av1 according to the equation:
where:
β β
R = | av1[0], av1[1], av1[2], av1[3], av1[4], av1[5], av1[6], av1[7] |
| av1[1], av1[0], av1[1], av1[2], ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.4 Spectral comparison | The spectra represented by the autocorrelated predictor values rav1 and the averaged autoβcorrelation values av0 are compared using the distortion measure dm defined below. This measure is used to produce a Boolean value stat every 20Β ms, as given by these equations:
difference = |dm β lastdm|
lastdm = dm
stat = differ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.5 Periodicity detection | The frequency spectrum of mobile noise is relatively stationary over quite long periods. The Inverse Filter Autocorrelated Predictor coefficients of the adaptive filter rvad are only updated when this stationarity is detected. Vowel sounds however, also have this stationarity, but can be excluded by detecting the perio... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.6 Information tone detection | The tone flag is only evaluated in the downlink VAD. In the uplink VAD, tone detection is not performed and tone = false.
Computation of the tone flag is complex. It is therefore evaluated after the processing of the current speech encoder frame. In this way transmission of the speech or SID frame is not delayed.
Infor... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.7 Threshold adaptation | A check is made every 20Β ms to determine whether the VAD decision threshold (thvad) should be changed. This adaptation is carried out according to the flowchart shown in figure 2.2. The constants used are given in table 2.5.
Adaptation takes place in two different situations: firstly whenever ACF[0] is very low and sec... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.8 VAD decision | Prior to hangover the VAD decision condition is:
vvad = pvad > thvad |
ad3845652ec99fdffd75badceec5143f | 06.32 | 2.2.9 VAD hangover addition | VAD hangover is only added to bursts of speech greater than or equal to burstconst blocks. The Boolean variable vad indicates the decision of the VAD with hangover included. The values of the constants are given in table 2.6. The hangover algorithm is as follows:
if vvad then increment(burstcount) else burstcount = 0
i... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3 Computational details | In the next paragraphs, the detailed description of the VAD algorithm follows the preceding high level description. This detailed description is divided in ten clauses related to the blocks of figure 2.1 (except periodicity updating) in the high level description of the VAD algorithm.
Those clauses are:
1) adaptive fil... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.1 Adaptive filtering and energy computation | This clause computes the e_pvad and m_pvad variables which represent the pvad value. It needs the L_ACF[0..8] and scalauto variables of the RPEβLTP algorithm and the rvad[0..8] and normrvad variables produced by clauseΒ 3.6 of the VAD algorithm. It also computes a floating point representation of L_ACF[0] (e_acf0 and m_... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.2 ACF averaging | This clause uses the L_ACF[0..8] and the scalvad variables to compute the array L_av0[0..8] and L_av1[0..8] used in clauseΒ 3.3 and 3.4.
Computation of the scaling factor:
scal = sub( 10, (scalvad << 1) );
Computation of the arrays L_av0[0..8] and L_av1[0..8]:
| FOR i = 0 to 8:
| L_temp = L_ACF[i] >> scal;
| L_av0[i] ... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.3 Predictor values computation | This clause computes the array rav1[0..8] needed for the spectral comparison and the threshold adaptation. It uses the L_av1[0..8] computed in clauseΒ 3.2, and is divided in the three following clauses:
β Schur recursion to compute reflection coefficients.
β Step up procedure to obtain the aav1[0..8].
β Computation of t... |
ad3845652ec99fdffd75badceec5143f | 06.32 | 3.3.1 Schur recursion to compute reflection coefficients | This clause is identical to the one used in the RPEβLTP algorithm. The array vpar[1..8] is computed with the array L_av1[0..8] as an input.
Schur recursion with 16 bits arithmetic:
IF( L_av1[0] == 0 ) THEN
|== FOR i = 1 to 8:
| vpar[i] = 0;
|== NEXT i:
| EXIT; /continue with clause 3.3.2/
temp = norm( L_av1[0] );... |
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