Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic channel; Part 4: Codec conformance testing

The objective of the present document is to define the conformance bounds for the TETRA speech and channel codec as deployed in the TETRA Speech Traffic Channel (TCH/S) channel type used in the TETRA Voice plus Data (V+D) equipment. For the speech part of the TCH/S codec, the conformance testing (clause 7 of the present document) consists of a bit-exact test where the reference is pre-computed and fixed. For the TCH/S channel encoding a bit exact conformance test is also defined (see clause 6.4). For the TCH/S channel decoding, a non-bit exact test is employed with the specifications designed such that a sufficient quality of performance is met by the TETRA equipment (see clause 6.3).

Prizemni snopovni radio (TETRA) – Govorni kodek za kanal s polno hitrostjo – 4. del: Preskušanje skladnosti kodeka

General Information

Status
Published
Publication Date
31-Mar-2006
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Apr-2006
Due Date
01-Apr-2006
Completion Date
01-Apr-2006

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SLOVENSKI STANDARD
SIST EN 300 395-4 V1.3.1:2006
01-april-2006
Prizemni snopovni radio (TETRA) – Govorni kodek za kanal s polno hitrostjo – 4.
del: Preskušanje skladnosti kodeka

Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic channel; Part 4:

Codec conformance testing
Ta slovenski standard je istoveten z: EN 300 395-4 Version 1.3.1
ICS:
33.070.10 Prizemni snopovni radio Terrestrial Trunked Radio
(TETRA) (TETRA)
SIST EN 300 395-4 V1.3.1:2006 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 300 395-4 V1.3.1:2006
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SIST EN 300 395-4 V1.3.1:2006
ETSI EN 300 395-4 V1.3.1 (2005-06)
European Standard (Telecommunications series)
Terrestrial Trunked Radio (TETRA);
Speech codec for full-rate traffic channel;
Part 4: Codec conformance testing
---------------------- Page: 3 ----------------------
SIST EN 300 395-4 V1.3.1:2006
2 ETSI EN 300 395-4 V1.3.1 (2005-06)
Reference
REN/TETRA-05115-4
Keywords
TETRA, codec
ETSI
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Important notice
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Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2005.
All rights reserved.
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DECT , PLUGTESTS and UMTS are Trade Marks of ETSI registered for the benefit of its Members.

TIPHON and the TIPHON logo are Trade Marks currently being registered by ETSI for the benefit of its Members.

3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.

ETSI
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SIST EN 300 395-4 V1.3.1:2006
3 ETSI EN 300 395-4 V1.3.1 (2005-06)
Contents

Intellectual Property Rights................................................................................................................................4

Foreword.............................................................................................................................................................4

1 Scope........................................................................................................................................................5

2 References................................................................................................................................................5

3 Definitions and abbreviations...................................................................................................................5

3.1 Definitions..........................................................................................................................................................5

3.2 Abbreviations.....................................................................................................................................................5

4 General.....................................................................................................................................................6

5 Radio test configuration, test signals and test modes ...............................................................................6

6 TCH/S channel codec...............................................................................................................................7

6.1 Objectives...........................................................................................................................................................7

6.2 Conformance test methodology..........................................................................................................................7

6.3 Test decoding mode............................................................................................................................................7

6.3.1 General..........................................................................................................................................................7

6.3.2 TCH/S reference sensitivity performance.....................................................................................................8

6.3.3 Methods of measurement for TCH/S testing ................................................................................................8

7 TCH/S speech codec................................................................................................................................9

7.1 Objectives...........................................................................................................................................................9

7.2 Conformance test methodology..........................................................................................................................9

7.3 Option 1: Internal link method .........................................................................................................................10

7.3.1 Definition and applicability ........................................................................................................................10

7.3.2 Conformance requirement and purpose ......................................................................................................11

7.3.3 Method of test .............................................................................................................................................11

7.3.3.1 Initial conditions...................................................................................................................................11

7.3.3.2 Procedure..............................................................................................................................................11

7.3.3.3 Internal link method requirements ........................................................................................................12

7.3.3.4 Test requirements..................................................................................................................................13

7.4 Option 2: Baseband method .............................................................................................................................13

7.4.1 Definition and applicability ........................................................................................................................13

7.4.2 Conformance requirement and purpose ......................................................................................................13

7.4.3 Method of test .............................................................................................................................................14

7.4.3.1 Initial conditions...................................................................................................................................14

7.4.3.2 Procedure..............................................................................................................................................14

7.4.3.3 Test requirements..................................................................................................................................14

Annex A (normative): TCH/S test cases and conditions for BS and MS receivers ........................15

Annex B (normative): Codec conformance test vector sequences ...................................................17

Annex C (informative): Codec reference test vector sequences .........................................................18

Annex D (informative): Bibliography...................................................................................................19

History ..............................................................................................................................................................20

ETSI
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SIST EN 300 395-4 V1.3.1:2006
4 ETSI EN 300 395-4 V1.3.1 (2005-06)
Intellectual Property Rights

IPRs essential or potentially essential to the present document may have been declared to ETSI. The information

pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in

respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web

server (http://webapp.etsi.org/IPR/home.asp).

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee

can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web

server) which are, or may be, or may become, essential to the present document.
Foreword

This European Standard (Telecommunications series) has been produced by ETSI Project Terrestrial Trunked Radio

(TETRA).

The present document is part 4 of a multi-part deliverable covering speech codec for full-rate traffic channel, as

identified below:
Part 1: "General description of speech functions";
Part 2: "TETRA codec";
Part 3: "Specific operating features";
Part 4: "Codec conformance testing".
National transposition dates
Date of adoption of this EN: 24 June 2005
Date of latest announcement of this EN (doa): 30 September 2005
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 March 2006
Date of withdrawal of any conflicting National Standard (dow): 31 March 2006
ETSI
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SIST EN 300 395-4 V1.3.1:2006
5 ETSI EN 300 395-4 V1.3.1 (2005-06)
1 Scope

The objective of the present document is to define the conformance bounds for the TETRA speech and channel codec as

deployed in the TETRA Speech Traffic Channel (TCH/S) channel type used in the TETRA Voice plus Data (V+D)

equipment.

For the speech part of the TCH/S codec, the conformance testing (clause 7 of the present document) consists of a

bit-exact test where the reference is pre-computed and fixed.

For the TCH/S channel encoding a bit exact conformance test is also defined (see clause 6.4).

For the TCH/S channel decoding, a non-bit exact test is employed with the specifications designed such that a sufficient

quality of performance is met by the TETRA equipment (see clause 6.3).
2 References

The following documents contain provisions which, through reference in this text, constitute provisions of the present

document.

• References are either specific (identified by date of publication and/or edition number or version number) or

non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.

Referenced documents which are not found to be publicly available in the expected location might be found at

http://docbox.etsi.org/Reference.

[1] ETSI EN 300 394-1: "Terrestrial Trunked Radio (TETRA); Conformance testing specification;

Part 1: Radio".

[2] ETSI EN 300 395-2: "Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic

channel; Part 2: TETRA codec".

[3] ETSI EN 300 395-3: "Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic

channel; Part 3: Specific operating features".
3 Definitions and abbreviations
3.1 Definitions

For the purposes of the present document, the terms and definitions given in EN 300 392-2 (see bibliography) and

EN 300 394-1 [1] apply.
3.2 Abbreviations

For the purposes of the present document, the abbreviations given in EN 300 394-1 [1] and the following apply:

AACH Access Assignment CHannel
ACELP Algebraic Code Excited Linear Predictive
AMR Adaptive Multi-Rate
BER Bit Error Rate
BS Base Station
DAI Digital Audio Interface
dBm deciBels relative to one milliWatt
ETSI
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SIST EN 300 395-4 V1.3.1:2006
6 ETSI EN 300 395-4 V1.3.1 (2005-06)
MER Message Erasure Rate
MS Mobile Station
PCM Pulse Coded Modulation
PDO Packet Data Optimized
PRBS Pseudo Random Bit Sequence
PUEM Probability of Undetected Erroneous Message
RF Radio Frequency
RX Receive
STCH STealing CHannel
TCH/S full rate Speech Traffic CHannel
TDM Time Division Multiplexing
TE Terminal Equipment
TSS TETRA System Simulator
TTCI TETRA Test Connector Interface
TX Transmit
VAD Voice Activity Detector
4 General

The conformance testing of the TCH/S channel shall be conducted in identical or similar methodology as specified in

EN 300 394-1 [1]. However, as EN 300 394-1 [1] is specified for both the TETRA V+D and TETRA Packet Data

Optimized (PDO), only the TETRA V+D part of EN 300 394-1 [1] shall be applicable to the present document.

Therefore, all references to EN 300 394-1 [1] clauses shall refer to the TETRA V+D sections only. For the purpose of

the present document, the following where applicable shall apply:

- presentation of equipment for testing purposes shall be as specified in EN 300 394-1 [1], clause 4.1;

- facilities and information required for testing shall be as specified in EN 300 394-1 [1], clause 4.1.1;

- choice of radio frequency channels to be tested shall be as specified in EN 300 394-1 [1], clause 4.1.2;

- interpretation of the measurement results shall be as specified in EN 300 394-1 [1], clause 4.1.3;

- mechanical and electrical design shall be as specified in EN 300 394-1 [1], clause 4.2.

5 Radio test configuration, test signals and test modes

In order to perform the conformance testing specified in the present document, the Terminal Equipment (TE) shall have

been tested to, and passed, the relevant specifications as given in EN 300 394-1 [1]. Thus, all appropriate logical

channel types apart from the TCH/S shall have been tested.

In the present document, the TETRA speech and channel codec as specified in EN 300 395-2 [2], shall be conformance

tested under standard TETRA specified configurations. All unspecified or informative parts of the TETRA speech and

channel codec shall be disabled and not tested. For example, sub-systems such as the Voice Activity Detector (VAD) as

given in EN 300 395-3 [3] shall be excluded from the tests in the present document. If these and other speech related

sub-systems are standardized in future phases of TETRA then a separate conformance test may be generated to test

these new additions. The present document also covers testing of the AMR 4,75 kb/s speech and channel codec.

In the present document, only the standard un-encrypted TCH/S shall be tested. Thus the TE's encryption capability, if

implemented by the TE, shall be disabled for the duration of the tests specified in the present document. Similarly, all

parts related to the STealing CHannel (STCH) and the eventually associated half slot containing encoded speech shall

not be tested and shall not be activated in the test.
The test signal T1 shall be as specified in EN 300 394-1 [1], clause 5.3.2.
ETSI
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SIST EN 300 395-4 V1.3.1:2006
7 ETSI EN 300 395-4 V1.3.1 (2005-06)

In accordance to EN 300 394-1 [1], the channel type tested under the present document shall be designated as channel

type 15 and 16 for TCH/S channel codec testing and 19 and 20 for TCH/S speech codec testing. For Mobile Station

(MS) testing, on frame 1 to 17, table 1 shall apply. For Base Station (BS) testing, on frame 1 to 17, table 2 shall apply.

Table 1: Channel type for MS testing
Channel type Burst type Block 1 Block 2 Broadcast block
15 normal TCH/S Access Assignment
PRBS Channel (AACH)
19 normal TCH/S Access Assignment
speech codec test Channel (AACH)
Table 2: Channel type for BS testing
Channel type Burst type Sub slot 1 Sub slot 2
16 normal TCH/S
PRBS
20 normal TCH/S
speech codec test
6 TCH/S channel codec
6.1 Objectives

The objective of this clause is to specify and present performance limits for the TCH/S channel encoding and decoding

sub-system. The TCH/S channel encoder is specified in bit exact terms and is given in EN 300 395-2 [2], clause 5, and

all TE shall operate according to it. The TCH/S channel decoder is specified in non-bit exact terms and is given in

EN 300 395-2 [2], clause 6, while an informative example implementation is given in EN 300 395-2 [2], annex A. The

performance of the TCH/S channel decoder is specified in this clause.
6.2 Conformance test methodology

The presentation of the conformance testing procedures for the TCH/S shall be the same as for the other logical channel

types as specified in EN 300 394-1 [1]. Therefore, as described in EN 300 394-1 [1], all conformance test data between

the TETRA System Simulator (TSS) and the TE shall be via two ports, namely the antenna port and the test connector.

The type tests described in the present document shall be performed under normal test conditions as specified in

EN 300 394-1 [1], clauses 6.2 and 6.2.1.
6.3 Test decoding mode

For the TCH/S channel decoding test mode, the TE under test shall perform the test in a similar manner as other channel

coded channels as specified in EN 300 394-1 [1], clause 5.2.1.
6.3.1 General

The test set up, procedures and measurement methods detailed in EN 300 394-1 [1] shall be used in testing TETRA

V+D equipment TCH/S performance.

The required minimum number of samples and test limit error rates used in the following TCH/S receiver test are

defined such that:
a) the probability of passing a bad unit is lower than 0,3 %;

b) the probability of passing a good unit, operating on the limit of performance, is at least 99,5 %.

ETSI
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SIST EN 300 395-4 V1.3.1:2006
8 ETSI EN 300 395-4 V1.3.1 (2005-06)

The Bit Error Ratio/Message Erasure Rate (BER/MER) test limits adopted have been selected in order not to pass a unit

with a sensitivity performance 1 dB worse than that of a unit which just meets the specification.

NOTE: The above definition does not apply to Probability of Undetected Erroneous Message (PUEM)

measurements.
6.3.2 TCH/S reference sensitivity performance

The minimum required reference sensitivity performance for V+D equipment is specified in annex A according to test

condition, propagation condition and receiver class.

The maximum dynamic and static reference sensitivity levels for a BS receiver under normal test conditions shall not

exceed the signal levels shown in table 3.
Table 3: BS receiver minimum reference sensitivity
Test condition Dynamic reference sensitivity Static reference sensitivity
Normal -106 dBm -115 dBm

The maximum dynamic and static reference sensitivity levels for a MS receiver under normal test conditions shall not

exceed the signal levels shown in table 4.
Table 4: MS receiver minimum reference sensitivity
Test condition Dynamic reference sensitivity Static reference sensitivity
Normal -103 dBm -112 dBm

The TCH/S cases to be tested and the corresponding limit values for BER and MER are given in tables A.1 to A.5.

All MS equipment shall achieve a PUEM on TCH/S class 2 bits of < 0,01 % measured in static channel conditions. The

test cases, number of required samples and test limit values are given in table A.6.

All TCH/S receiver tests shall be carried out under normal conditions only.
6.3.3 Methods of measurement for TCH/S testing

The test system, test conditions and test configuration used in TCH/S testing are detailed in EN 300 394-1 [1], clauses 4

and 5 with the following exceptions:

- unlike other protected logical channels, the TCH/S channel splits the data bits from the TETRA speech codec

into three classes of bits, the lowest priority designated class 0, medium priority designated class 1, and highest

priority designated class 2. The assignment of the bits of the TETRA speech parameters to its sensitivity

classification shall be as given in EN 300 395-2 [2], clause 5.4.1, table 4;

- in the case of BS V+D receiver testing the test system shall transmit in T1 time-slot 1 on frames 1 to 17 an

uplink channel type 16 burst (see table 5).
Table 5: TCH/S uplink channel type
Channel type Burst type Subslot 1 + Subslot 2
16 Normal TCH/S

- in the case of MS V+D receiver testing the test system shall transmit in T1 timeslot 1 on frames 1 to 17 a

downlink channel type 15 burst (see table 6).
Table 6: TCH/S downlink channel type
Channel type Burst type Block 1 + Block 2
15 Normal TCH/S
ETSI
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SIST EN 300 395-4 V1.3.1:2006
9 ETSI EN 300 395-4 V1.3.1 (2005-06)
The equipment shall be connected to the test system via its antenna connector.

The test procedures detailed in EN 300 394-1 [1], clauses 9.3.1 to 9.3.3 for sensitivity performance and PUEM

performance shall be adopted for TCH/S testing.

The TSS shall incorporate some mechanism for preserving frame synchronization between the transmitted and decoded

data so that the error rates for each class of bits can be correctly determined.
In summary, the following procedure is adopted for channel decoding testing:
- establish test receive mode for the TE under test;

- transmit test sequence (7,2 kbit/s) from TSS to TE via the antenna port using the TCH/S type;

- the TE receives the test sequence and performs channel decoding;

- the TE transmits the decoded information bits in the correct type classification to the TSS via the test port;

- the TSS receives and processes the TE data bits.

The above procedure shall be repeated for all the different conditions as set out in annex A.

7 TCH/S speech codec
7.1 Objectives

The objective of this clause is to specify the test methodology and the conformance requirements for the TETRA speech

coding and decoding sub-systems as given by EN 300 395-2 [2], clause 4 of the TETRA TCH/S channel type. The

objective of the test is to present to both the TETRA speech encoder and decoder a pre-defined sequence which when

processed shall match exactly with a stored conformance output sequence. The matching shall be performed on a

bit-by-bit basis, thus the testing is a bit exact conformance test. Similar conformance sequences are provided for testing

the AMR 4,75 kb/s speech coding and decoding sub-systems.
7.2 Conformance test methodology
TETRA System Simulator
Signals 8 kHz with
TETRA ACELP 16 bits PCM per TETRA ACELP
packets sample packets
Point A Point B Point C Point E Point D
Air Interface
Air Interface TETRA Test
with bit, slot
with bit, slot Connector
PCM test
and
and Interface
port interface
frame sync
frame sync (TTCI)
Option 2 path
External PCM port
ACELP
Channel ACELP Channel
of TETRA
decoder
decoder encoder encoder
equipment
Internal
link
TETRA equipment Option 1 path

Figure 1: Diagram illustrating the test points for conformance testing the TE's speech codec

ETSI
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SIST EN 300 395-4 V1.3.1:2006
10 ETSI EN 300 395-4 V1.3.1 (2005-06)

In figure 1, the various stages and blocks involved in testing a speech codec are illustrated. As can be seen, the injection

of the test sequence can be made at various points in the chain. In order to minimize the cost overhead for testing TE

and provide as much flexibility as possible for the different types of TE, two options are available to perform the

conformance testing of the TETRA speech coding and decoding. It shall be the responsibility of the TE manufacturer

together with the test laboratory to select the most appropriate option. The two options are:

Option 1) Internal link method: The injection of the test data shall be from Point A (see figure 1) and the reception

of the resultant processed data shall be at Point E or D going via the internal link path. Therefore this

option shall test both the decoder and the encoder together.

NOTE 1: This option is most suitable for TE capable of operating the codec in full-duplex mode or in fast

half-duplex mode (i.e. able to switch between decode and encode within one TETRA frame).

An alternative arrangement for the Internal link method is that the internal link (figure 1) is replaced with an external

link between two pieces of TETRA equipment. In this way, the output of the decoder of one piece of equipment is fed

via an external Pulse Coded Modulation (PCM) port and link to the encoder of the second piece of equipment. The

interface to the TSS is still the air interface at the input, and TCCI or air-interface at the output of the TE.

Option 2) Baseband method: The test data shall be injected from Point A (see figure 1) and the resultant processed

data shall be received at Point B thus testing the decoder. The received data, having been effectively

buffered, shall then be re-injected into the TE from Point C and the resultant processed data shall be

received at Point E or D, thus testing the encoder. Therefore, an extra PCM data port shall be required for

this option.

NOTE 2: This option is a baseband data injection method, and is most suitable for TE only capable of operating the

codec in simplex mode.

For both options the recovered data from the speech codec can be recovered either by the test connector interface at

point E or by the air-interface method at point D, it shall be the responsibility of the TE manufacturer together with the

test laboratory to select the most appropriate point.

The TETRA TEST Connector Interface and the RF-loopback as referred to in figure 1, is not specified in the present

document. However, an informative implementation of this port is given by EN 300 394-1 [1], annex C, a normative

implementation of the air-interface method is given by EN 300 394-1 [1], annex D.

The test sequences for the TETRA speech codec as specified in EN 300 395-2 [2], clause 4 are defined and

pre-computed. The test sequences are available on floppy disks in IBM/AT MS-DOS format (attached to the back page

of the present document). The details for the format and size of the sequences are given in annex B.

The PCM test port as referred to in figure 1, is not specified in the present document. However, an informative

implementation of this port is given by EN 300 607-1 (see bibliography), clause 36.4 (Digital Audio Interface (DAI)).

As the exact construction and capability of the TSS is unspecified for the TETRA system, this clause cannot be too

specific on the exact interactions between the TSS and the TE. However, whatever is the exact set-up the conformance

specified shall be met.

In accordance to EN 300 394-1 [1], for the purpose of speech codec testing the channel type 19 for MS and 20 for BS

shall be used.
7.3 Option 1: Internal link method
7.3.1 Definition and applicability

Speech transcoding transforms the TCH/S 7,2 kbit/s bit stream by channel decoding the incoming bit stream from the

air interface and performing speech decoding to produce the resultant 16-bit linear PCM. This is followed by speech

encoding the 16-bit linear PCM bit stream and channel encoding it to produce the TCH/S 7,2 kbit/s. Therefore, this

clause provides the conformance test of the TETRA speech encoder and speech decoder as specified in

EN 300 395-2 [2].

The requirements and test shall apply to all TE supporting TCH/S and supporting the Option 1 configuration as given in

clause 7.2. The encoder and decoder may reside in different TEs, and be linked via external PCM ports and a link.

ETSI
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SIST EN 300 395-4 V1.3.1:2006
11 ETSI EN 300 395-4 V1.3.1 (2005-06)
7.3.2 Conformance requirement and purpose

Using figure 1 as reference, the pre-defined input bit sequence designated SEQ1_72.IN injected from Point A shall

produce the output bit stream at Point E or D after passing through the TE's processing blocks. The resultant output

sequence shall be bit-by-bit exactly the same as the pre-defined output sequence SEQ4_72.OUT.

As an alternative test set-up, the internal link shown in figure 1 may be replaced by an external link between two TEs.

In this way, the decoder from one TE feeds the encoder of the second.
7.3.3 Method of test
7.3.3.1 Initial conditions
Encryption and frame stealing mechanisms shall be de-activated.

The TCH/S speech codec shall be tested at -85 dBm at point A or at a signal level specified by the TE manufacturer, so

the bit-by-bit matching of the output sequences are not influenced. If such a level does not exist, it shall be the

responsibility of the TE manufacturer together with the test laboratory to find an alternative injection point for the test

sequence
...

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